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{{Short description|Species of virus}}
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[[File:Baby Elephant.jpg|thumb|300px|right|"Donaldson", a male Asian elephant calf at [[Whipsnade Zoo]], died of EEHV in May 2009.<ref>[http://www.elephant.se/database2.php?elephant_id=3412 Database entry at elephant.se]</ref>]]
{{Virusbox
{{Taxobox
| color = violet
| image =
| image_alt =
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| name = Elephantid herpesvirus 1
| virus_group = i
| image_caption =
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| parent = Proboscivirus
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| ordo = ''[[Herpesvirales]]''
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| species = Elephantid betaherpesvirus 1
| familia = ''[[Herpesviridae]]''
| subfamilia = ''[[Betaherpesvirinae]]''
| synonyms = ''Elephantid herpesvirus 1''
| synonyms_ref = <ref name="2015.010aD">{{cite web |last1=Davison |first1=Andrew |title=Rename species in the family ''Herpesviridae'' to incorporate a subfamily designation |url=https://ictv.global/ictv/proposals/2015.010aD.A.v2.Herpesvirales_spren.pdf |website=International Committee on Taxonomy of Viruses (ICTV) |access-date=10 July 2019 |page=3 |language=en |date=27 January 2016 |quote=''Betaherpesvirinae'' ''Proboscivirus'' ''Elephantid herpesvirus 1'' ''Elephantid betaherpesvirus 1''}}</ref>
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| genus = ''[[Proboscivirus]]''
| subdivision_ranks = Species
| subdivision_ranks =
| subdivision = '''Elephantid herpesvirus 1'''
| subdivision =
}}
}}
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'''Elephant endotheliotropic herpesviruses''' ('''EEHV''') or '''Elephantid herpesvirus 1'''' is a type of [[herpesviridae|herpesvirus]], which can cause a highly fatal hemorrhagic disease when transmitted to young [[Asian elephant]]s. In African elephants, related forms of these viruses, which have been identified in wild populations, are generally benign, occasionally surfacing to cause small growths or lesions. However, some types of EEHV can cause a highly fatal disease in Asian elephants, which kills up to 80% of severely affected individuals. The disease can be treated with the rapid application of [[antiviral drugs]], but this has only been effective in around a third of cases.


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'''Elephant endotheliotropic herpesviruses''' (EEHV) or '''''Elephantid betaherpesvirus 1''''' (ElHV-1) is a type of [[Herpesviridae|herpesvirus]], which can cause a highly fatal hemorrhagic disease when transmitted to young [[Asian elephant]]s. In African elephants, related forms of these viruses, which have been identified in wild populations, are generally benign, occasionally surfacing to cause small growths or lesions. However, some types of EEHV can cause a highly fatal disease in Asian elephants, which kills up to 80% of severely affected individuals. The disease can be treated with the rapid application of [[antiviral drugs]], but this has only been effective in around a third of cases.
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The first case of a fatal form of the disease was documented in 1995, though tissue samples from as early as the 1980s have since tested positive for the virus, and localized skin lesions in wild African elephants were recorded in the 1970s. Since 1995, there have been over fifty documented disease cases in North America and Europe, of which only nine have been successfully cured. Those affected are mostly young animals born in captivity, though a small number of older wild-born adults held in zoos have died, and a number of cases caused by the same pathogenic type of EEHV have been identified in both orphan and wild calves in Asian elephant populations.

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The first case of a fatal form of the disease was documented in 1990,<ref>{{Cite journal|last1=Ossent|first1=P.|last2=Guscetti|first2=F.|last3=Metzler|first3=A. E.|last4=Lang|first4=E. M.|last5=Rübel|first5=A.|last6=Hauser|first6=B.|date=March 1990|title=Acute and Fatal Herpesvirus Infection in a Young Asian Elephant (Elephas maximus)|url=https://journals.sagepub.com/doi/pdf/10.1177/030098589002700212|journal=Veterinary Pathology|volume=27|issue=2|pages=131–133|doi=10.1177/030098589002700212|pmid=2161138 |s2cid=37224170 |issn=0300-9858}}</ref> though tissue samples from as early as the 1980s have since tested positive for the virus, and localized skin lesions in wild African elephants were recorded in the 1970s. Since 1995, there have been over fifty documented disease cases in North America and Europe, of which only nine have been successfully cured. Those affected are mostly young animals born in captivity, though a small number of older wild-born adults held in zoos have died, and a number of cases caused by the same pathogenic type of EEHV have been identified in both orphan and wild calves in Asian elephant populations.


== Virus and transmission ==
== Virus and transmission ==
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[[File:Baby Elephant.jpg|thumb|300px|right|"Donaldson", a male Asian elephant calf at [[Whipsnade Zoo]], died of EEHV in May 2009.<ref>[http://www.elephant.se/database2.php?elephant_id=3412 Database entry at elephant.se]</ref>]]
The EEHVs are members of the [[Proboscivirus]] genus, a novel clade most closely related to the mammalian [[betaherpesvirinae|betaherpesviruses]] that have been responsible for as many as 70 deaths of both zoo and wild Asian elephants worldwide, especially in young calves.<ref name=Koehl2009/><ref name=Latimer2011/> There are currently six known species/types of the probosciviruses, and the most commonly encountered and most pathogenic form EEHV1 also has two chimeric subtypes, 1A and 1B.,<ref name=Koehl2009/><ref name=Zong2007/><ref name=Fickel2001/><ref name=Mikota2007/><ref name=Cracknell2008/> as well as numerous distinct strains.<ref name=Zong2008/>
The EEHVs are members of the ''[[Proboscivirus]]'' genus, a novel clade most closely related to the mammalian [[Betaherpesvirinae|betaherpesviruses]] that have been responsible for as many as 70 deaths of both zoo and wild Asian elephants worldwide, especially in young calves.<ref name=Koehl2009/><ref name=Latimer2011/> There are currently six known species/types of the probosciviruses, and the most commonly encountered and most pathogenic form EEHV1 also has two chimeric subtypes, 1A and 1B,<ref name=Koehl2009/><ref name=Zong2007/><ref name=Fickel2001/><ref name=Mikota2007/><ref name=Cracknell2008/> as well as numerous distinct strains.<ref name=Zong2008/>


EEHV1A (originally just known as EEHV1) was the first species/type identified, which causes an acute hemorrhagic disease with a very high mortality rate in Asian elephants.<ref name=Fickel2001/><ref name=Richman1999/><ref name=Richman2000/> This form of the virus was originally believed to occur naturally in African elephants (occasionally producing skin nodules), and to be transmitted to Asian elephants within captivity, but more extensive studies have since largely disproved this concept because several other species/types of EEHV (e.g. EEHV2, EEHV3 and EEHV6) instead have been identified in African elephants.<ref name=Latimer2011/><ref name=Ehlers2006/> A second lethal subtype, EEHV1B, was identified in Asian elephants in 2001.<ref name=Fickel2001/> EEHV3, EEHV4 and EEHV5 have also each been responsible for the deaths of at least one Asian elephant calf.<ref name=Garner2009/><ref name=Denk2012/>
EEHV1A (originally just known as EEHV1) was the first species/type identified, which causes an acute hemorrhagic disease with a very high mortality rate in Asian elephants.<ref name=Fickel2001/><ref name=Richman1999/><ref name=Richman2000/> This form of the virus was originally believed to occur naturally in African elephants (occasionally producing skin nodules), and to be transmitted to Asian elephants within captivity, but more extensive studies have since largely disproved this concept because several other species/types of EEHV (e.g. EEHV2, EEHV3 and EEHV6) instead have been identified in African elephants.<ref name=Latimer2011/><ref name=Ehlers2006/> A second lethal subtype, EEHV1B, was identified in Asian elephants in 2001.<ref name=Fickel2001/> EEHV3, EEHV4 and EEHV5 have also each been responsible for the deaths of at least one Asian elephant calf.<ref name=Garner2009/><ref name=Denk2012/>
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EEHV2 has caused hemorrhagic disease in several African elephants as reported by.<ref name=Cracknell2008/><ref name=Richman1999/> Along with EEHV3 and EEHV6 it has also been found in [[Pulmonary system|pulmonary]] [[lymph node]]s of several autopsied wild and zoo African elephants.<ref name=Koehl2009/><ref>Zong ''et al'', 2010</ref>
EEHV2 has caused hemorrhagic disease in several African elephants as reported by.<ref name=Cracknell2008/><ref name=Richman1999/> Along with EEHV3 and EEHV6 it has also been found in [[Pulmonary system|pulmonary]] [[lymph node]]s of several autopsied wild and zoo African elephants.<ref name=Koehl2009/><ref>Zong ''et al'', 2010</ref>


There are a further five or six species/types and varieties of elephant gammaherpesvirus (EGHVs) found in eye and genital secretions of many healthy Asian and African zoo elephants - e.g. EGHV1, EGHV2, EGHV3A, EGHV3B, EGHV4 and EGHV5 (also called Elephantid herpesviruses EIHV3, EIHV4, EIHV5, EIHV6, ElHV9 and ElHV10 - which are [[gamma herpesviruses]]. But these are neither closely related to the EEHVs, nor the known cause of any disease symptoms.<ref name=Latimer2011/><ref name=Wellehan2008/>
There are a further five or six species/types and varieties of elephant gammaherpesvirus (EGHVs) found in eye and genital secretions of many healthy Asian and African zoo elephants - e.g. EGHV1, EGHV2, EGHV3A, EGHV3B, EGHV4 and EGHV5 (also called Elephantid gammaherpesviruses EIHV3, EIHV4, EIHV5, EIHV6, ElHV9 and ElHV10) - all of which are classified in the subfamily ''[[Gammaherpesvirinae]]'' rather than ''Betaherpesvirinae''. These viruses are neither closely related to the EEHVs, nor the known cause of any disease symptoms.<ref name=Latimer2011/><ref name=Wellehan2008/>


Studies have also detected both EEHV1A and EEHV1B as being shed in trunk wash secretions by healthy asymptomatic Asian zoo elephant herdmates of calves that previously had disease.<ref name=Stanton2010/><ref name=Stanton2013/> and similarly for EEHV5.<ref name=Atkins2013/> Thus, similar to saliva for most human and animal herpesviruses, the trunk secretions may be a source of transmission for EEHVs. Because of concerns about the origins of EEHV1 and evidence of cross-species transmission for EEHV3, long-term contact between Asian and African elephants has been discouraged,<ref name=Mikota2007/> along with avoiding new contacts between young captive-born Asian elephants and wild-born Asian elephants, as the latter may be carriers of the disease.<ref name=Koehl2009/> An analysis of a number of North American cases, which ruled out the direct transmission of the virus between any of the affected facilities studied, strongly supported the idea of a significant Asian carrier population.<ref name=Koehl2009/> This is supported by the fact that some of the deceased calves had no possible contact with any African elephants.<ref name=Mikota2007/> [[Artificial insemination]] is not believed to be a transmission factor,<ref name=Koehl2009/> notes that when multiple calves of a single bull or cow elephant died at different times (even at the same facility) they nearly all had distinct strains of the virus, yet when two calves died or became infected at the same time at the same facility the pairs have always had identical virus strains.<ref name=Tracking/> A program of [[enzyme-linked immunosorbent assay]] testing began in 2005, aiming to test blood samples from around a thousand elephants for [[antibodies]] to the virus in order to help identify carriers and possible transmission patterns.<ref name=Tracking/>
Studies have also detected both EEHV1A and EEHV1B as being shed in trunk wash secretions by healthy asymptomatic Asian zoo elephant herdmates of calves that previously had disease.<ref name=Stanton2010/><ref name=Stanton2013/> and similarly for EEHV5.<ref name=Atkins2013/> Thus, similar to saliva for most human and animal herpesviruses, the trunk secretions may be a source of transmission for EEHVs. Because of concerns about the origins of EEHV1 and evidence of cross-species transmission for EEHV3, long-term contact between Asian and African elephants has been discouraged,<ref name=Mikota2007/> along with avoiding new contacts between young captive-born Asian elephants and wild-born Asian elephants, as the latter may be carriers of the disease.<ref name=Koehl2009/> An analysis of a number of North American cases, which ruled out the direct transmission of the virus between any of the affected facilities studied, strongly supported the idea of a significant Asian carrier population.<ref name=Koehl2009/> This is supported by the fact that some of the deceased calves had no possible contact with any African elephants.<ref name=Mikota2007/> [[Artificial insemination]] is not believed to be a transmission factor,<ref name=Koehl2009/> notes that when multiple calves of a single bull or cow elephant died at different times (even at the same facility) they nearly all had distinct strains of the virus, yet when two calves died or became infected at the same time at the same facility the pairs have always had identical virus strains.<ref name=Tracking/> A program of [[enzyme-linked immunosorbent assay]] testing began in 2005, aiming to test blood samples from around a thousand elephants for [[antibodies]] to the virus in order to help identify carriers and possible transmission patterns.<ref name=Tracking/>


==Effects and treatment==
== Effects and treatment ==
In benign infections found in some wild and captive African elephants, these viruses can affect either the skin or the pulmonary system.<ref name=Mikota2007/> In the former case, it produces small pinkish [[Nodule (medicine)|nodules]] on the head and trunk in juveniles, which appear for a few weeks and then regress, suggesting an intermittently reactivated localized infection that mostly remains dormant.<ref name=Koehl2009/> In the second case, it has been found in small white pulmonary [[Nodule (medicine)|nodules]] on necropsy of many asymptomatic adults. These are both characteristic of EEHV2, EEHV3 and EEHV6.<ref name=Koehl2009/>
In benign infections found in some wild and captive African elephants, these viruses can affect either the skin or the pulmonary system.<ref name=Mikota2007/> In the former case, it produces small pinkish [[Nodule (medicine)|nodules]] on the head and trunk in juveniles, which appear for a few weeks and then regress, suggesting an intermittently reactivated localized infection that mostly remains dormant.<ref name=Koehl2009/> In the second case, it has been found in small white pulmonary [[Nodule (medicine)|nodules]] on necropsy of many asymptomatic adults. These are both characteristic of EEHV2, EEHV3 and EEHV6.<ref name=Koehl2009/>


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A [[polymerase chain reaction]] test on a blood sample from affected animals will confirm a suspected case by identifying the viral DNA, though it is now common to start famciclovir treatment at the earliest possible moment rather than waiting for confirmation of the case.<ref name=Koehl2009/><ref name=Tracking/> Prior to the development of the test, or in circumstances where it is not available, the disease may be misdiagnosed as any of a number of other conditions which have a quick onset leading to rapid death, including [[encephalomyocarditis]] and [[salmonellosis]].<ref name=Mikota2007/>
A [[polymerase chain reaction]] test on a blood sample from affected animals will confirm a suspected case by identifying the viral DNA, though it is now common to start famciclovir treatment at the earliest possible moment rather than waiting for confirmation of the case.<ref name=Koehl2009/><ref name=Tracking/> Prior to the development of the test, or in circumstances where it is not available, the disease may be misdiagnosed as any of a number of other conditions which have a quick onset leading to rapid death, including [[encephalomyocarditis]] and [[salmonellosis]].<ref name=Mikota2007/>


==History==
== History ==
The virus has been identified in the pulmonary nodules of African elephants as far back as the 1970s.<ref name=Mikota2007/> The first recognised fatal case of EEHV in an Asian elephant was identified at the [[National Zoological Park (United States)|National Zoo in Washington, D.C.]], in 1995;<ref name=Akst150601/> testing on stored tissue samples was able to identify a number of earlier deaths as being due to the same virus. These cases have so far been identified as early as 1983.<ref name=Koehl2009/> Since this date, there have been a total of 54 more cases in North America and Europe, nine of which were successfully treated.<ref name=Koehl2009/> The May 2009 deaths of two calves at Whipsnade Zoo were not included in this calculation. This gives a fatality rate of over 80% among known symptomatic disease cases. In cases where antiviral medication was applied, treatment was effective in about one in three cases. As of 2005, there were twelve cases where famciclovir had been used, eight of which were fatal. As a fraction of the overall population, it has been calculated that of the 78 Asian elephants born in captivity in North America between 1978 and 2007, 19 are known to have died of EEHV, and five more were successfully treated with antiviral medication.<ref name=Koehl2009/><ref name=Zong2007/>
The virus has been identified in the [[pulmonary nodule]]s of African elephants as far back as the 1970s.<ref name=Mikota2007/> The first recognised fatal case of EEHV in an Asian elephant was identified at the [[National Zoological Park (United States)|National Zoo in Washington, D.C.]], in 1995;<ref name=Akst150601/> testing on stored tissue samples was able to identify a number of earlier deaths as being due to the same virus. These cases have so far been identified as early as 1983.<ref name=Koehl2009/> Since this date, there have been a total of 54 more cases in North America and Europe, nine of which were successfully treated.<ref name=Koehl2009/> The May 2009 deaths of two calves at Whipsnade Zoo were not included in this calculation. This gives a fatality rate of over 80% among known symptomatic disease cases. In cases where antiviral medication was applied, treatment was effective in about one in three cases. As of 2005, there were twelve cases where [[famciclovir]] had been used, eight of which were fatal. As a fraction of the overall population, it has been calculated that of the 78 Asian elephants born in captivity in North America between 1978 and 2007, 19 are known to have died of EEHV, and five more were successfully treated with antiviral medication.<ref name=Koehl2009/><ref name=Zong2007/>


The affected animals are mostly young Asian elephants that had been born in captivity, with half the cases in North America being between the ages of one and four years (and three-quarters between one and eight years old). Some cases have affected newborns or adult elephants born in the wild (oldest aged 40 years), and three recorded cases have affected African elephants.<ref name=Koehl2009/><ref name=Zong2007/> The first documented fatal case for African elephants was Kijana, an eleven-month-old male in 1996.<ref name=Koehl2009/><ref name=Richman1999/> Since 2008, a number of cases have been attributed to EEHV1 among wild Asian elephants.<ref name=Koehl2009/><ref name=Zachariah2008/>
The affected animals are mostly young Asian elephants that had been born in captivity, with half the cases in North America being between the ages of one and four years (and three-quarters between one and eight years old). Some cases have affected newborns or adult elephants born in the wild (oldest aged 40 years), and three recorded cases have affected African elephants.<ref name=Koehl2009/><ref name=Zong2007/> The first documented fatal case for African elephants was Kijana, an eleven-month-old male in 1996.<ref name=Koehl2009/><ref name=Richman1999/> Since 2008, a number of cases have been attributed to EEHV1 among wild Asian elephants.<ref name=Koehl2009/><ref name=Zachariah2008/>
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The first suspected case in Asia was in 1997, though it was not until the fifth suspected case that the presence of the virus could be confirmed. This case was reported in 2006, with the death of a young wild-born female calf at an elephant sanctuary in Cambodia. The virus was identified as part of the EEHV1 group, the same as previously identified in the North American and European captive populations.<ref name=Reid2006/> In 2013, nine lethal cases from India were extensively characterized and found to consist of a wide variety of genetically diverged strains of EEHV1A and EEHV1B matching the subtypes and genetic range of nearly all those found previously in Europe and North America.<ref name=Zachariah2013/> Cases attributed to EEHV1A and EEHV4 have also been reported in Thailand<ref name=Sripiboon2013/> and there is both confirmed and anecdotal evidence for similar hemorrhagic disease deaths of between 16 and 30 more calves in Asian countries including Thailand, India, Nepal, Myanmar and Indonesia within the past five years. Thus, this is not just a disease of captive elephants, but is endogenous to and possibly rampant in Asian elephants in the wild also.<ref name=Hayward2012/> Further research has been noted as "urgently required" to study the situation in regions with wild Asian elephant populations.<ref name=Koehl2009/>
The first suspected case in Asia was in 1997, though it was not until the fifth suspected case that the presence of the virus could be confirmed. This case was reported in 2006, with the death of a young wild-born female calf at an elephant sanctuary in Cambodia. The virus was identified as part of the EEHV1 group, the same as previously identified in the North American and European captive populations.<ref name=Reid2006/> In 2013, nine lethal cases from India were extensively characterized and found to consist of a wide variety of genetically diverged strains of EEHV1A and EEHV1B matching the subtypes and genetic range of nearly all those found previously in Europe and North America.<ref name=Zachariah2013/> Cases attributed to EEHV1A and EEHV4 have also been reported in Thailand<ref name=Sripiboon2013/> and there is both confirmed and anecdotal evidence for similar hemorrhagic disease deaths of between 16 and 30 more calves in Asian countries including Thailand, India, Nepal, Myanmar and Indonesia within the past five years. Thus, this is not just a disease of captive elephants, but is endogenous to and possibly rampant in Asian elephants in the wild also.<ref name=Hayward2012/> Further research has been noted as "urgently required" to study the situation in regions with wild Asian elephant populations.<ref name=Koehl2009/>


On 12 June 2019 it was reported<ref>{{Cite news | url=https://www.bbc.co.uk/news/uk-england-merseyside-48599106 | title=Elephant's virus survival 'momentous'| work=BBC News| date=2019-06-12}}</ref> that in [[Chester Zoo]] the 2-year-old Indian elephant calf Indali Hi Way had fully recovered from EEHV, after numerous treatments over 2 weeks, and that there is now hope of a [[vaccine]] for EEHV.
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==References==

In 2020, a 1-year-old Asian elephant named Ajay, from the [[Rosamond Gifford Zoo]] in [[Syracuse, New York|Syracuse]], [[New York (state)|New York]], which was popular in the area, died from the virus.<ref>{{Cite web |title=Rosamond Gifford Zoo Mourns Loss of Elephant Calf to Herpes Virus |url=https://rosamondgiffordzoo.org/ |access-date=2024-02-28 |website=Rosamond Gifford Zoo |language=en-US}}</ref><ref>{{Cite web |last=CNYCentral |date=2020-12-09 |title=Baby elephant Ajay dies at Rosamond Gifford Zoo in Syracuse |url=https://cnycentral.com/news/local/baby-elephant-ajay-dies-at-rosamond-gifford-zoo-in-syracuse |access-date=2024-02-28 |website=WSTM |language=en}}</ref>

In July 2024, Dublin Zoo reported two deaths from the virus.Avani, who was 8 years old, and Zinda, who was 7, both died from the virus.<ref name=RTEdublin>{{cite news |date=7 July 2024 |title=Dublin Zoo announces death of seven-year-old elephant
|url=https://www.rte.ie/news/regional/2024/0707/1458709-dublin-zoo-elephant/ |work=RTÉ News |location= |access-date=8 July 2024 }}</ref>
In November 2024, a young African Elephant "Bumi" died at [[Ouwehands Dierenpark]] in [[Rhenen]] in the Netherlands. Later that month two calves named "Nagarr" and "Ka Yan" died in the Dutch zoo [[Wildlands (zoo)|Wildlands]] in [[Emmen, Netherlands|Emmen]].<ref>{{Cite web |date=2024-11-21 |title=Opnieuw olifant overleden in dierenpark Emmen, tweede in vijf dagen |url=https://www.rtl.nl/nieuws/artikel/5481504/olifant-emmen-gestorven-virus |access-date=2024-12-15 |website=RTL Nieuws & Entertainment |language=nl}}</ref> On 11th of December, the first test took place of a new vaccine developed by the University of Utrecht against the virus variant that only affects Asian elephants.<ref>{{Cite web |title=Nederland test als eerste vaccin tegen olifantenherpes |url=https://www.nu.nl/binnenland/6338981/nederland-test-als-eerste-vaccin-tegen-olifantenherpes.html |access-date=2024-12-15 |website=nu.nl |language=nl}}</ref>

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== References ==
{{Reflist|2|refs=
{{Reflist|2|refs=


<ref name=Richman1999>{{cite journal|year=1999|title=Novel endotheliotropic herpesviruses fatal for Asian and African elephants|journal=Science|volume=283|pages=1171–1176|author1=Richman LK |author2=Montali RJ |author3=Garber RL |author4=Kennedy MA |author5=Lehnhardt J |author6=Hildebrandt T |author7=Schmitt D |author8=Hardy D |author9=Alcendor DJ |author10=Hayward GS |doi=10.1126/science.283.5405.1171|issue=5405}}</ref>
<ref name=Richman1999>{{cite journal|year=1999|title=Novel endotheliotropic herpesviruses fatal for Asian and African elephants|journal=Science|volume=283|pages=1171–1176|author1=Richman LK |author2=Montali RJ |author3=Garber RL |author4=Kennedy MA |author5=Lehnhardt J |author6=Hildebrandt T |author7=Schmitt D |author8=Hardy D |author9=Alcendor DJ |author10=Hayward GS |doi=10.1126/science.283.5405.1171|issue=5405|pmid=10024244|bibcode=1999Sci...283.1171R}}</ref>


<ref name=Richman2000>{{cite journal|year=2000|title=Clinical and pathological findings of a newly recognized disease of elephants caused by endotheliotropic herpesviruses|journal=J Wildlife Disease|volume=36|pages=1–12|author1=Richman LK |author2=Montali RJ |author3=Cambre RC |author4=Schmitt D |author5=Hardy D |author6=Hildbrandt T |author7=Bengis RG |author8=Hamzeh FM |author9=Shahkolahi A |author10=Hayward GS |doi=10.7589/0090-3558-36.1.1}}</ref>
<ref name=Richman2000>{{cite journal|year=2000|title=Clinical and pathological findings of a newly recognized disease of elephants caused by endotheliotropic herpesviruses|journal=Journal of Wildlife Diseases|volume=36|pages=1–12|author1=Richman LK |author2=Montali RJ |author3=Cambre RC |author4=Schmitt D |author5=Hardy D |author6=Hildbrandt T |author7=Bengis RG |author8=Hamzeh FM |author9=Shahkolahi A |author10=Hayward GS |issue=1|doi=10.7589/0090-3558-36.1.1|pmid=10682740|doi-access=free }}</ref>


<ref name=Fickel2001>{{cite journal|doi=10.1016/S0378-1135(01)00363-7|year=2001|title=A variant of the endotheliotropic herpesvirus in Asian elephants (Elephas maximus) in European zoos.|journal=Veterinary Microbiology|volume=82|issue=2|pages=103–109|vauthors=Fickel J, Richman LK, Montali R, Schaftenaar W, Göritz F, Hildebrandt TB, Pitra C |pmid=11423201}}</ref>
<ref name=Fickel2001>{{cite journal|doi=10.1016/S0378-1135(01)00363-7|year=2001|title=A variant of the endotheliotropic herpesvirus in Asian elephants (Elephas maximus) in European zoos.|journal=Veterinary Microbiology|volume=82|issue=2|pages=103–109|vauthors=Fickel J, Richman LK, Montali R, Schaftenaar W, Göritz F, Hildebrandt TB, Pitra C |pmid=11423201}}</ref>


<ref name=Tracking>{{cite web|url=http://nationalzoo.si.edu/ConservationAndScience/SpotlightOnScience/elephantvirus.cfm |title=Tracking an Elephant Killer |date=2005-04-01 |work=Spotlight on Zoo Science |publisher=National Zoological Park |accessdate=2009-05-10 |archiveurl=https://web.archive.org/web/20090502010057/http://nationalzoo.si.edu/ConservationAndScience/SpotlightOnScience/elephantvirus.cfm |archivedate=2009-05-02 |deadurl=yes |df= }}</ref>
<ref name=Tracking>{{cite web|url=http://nationalzoo.si.edu/ConservationAndScience/SpotlightOnScience/elephantvirus.cfm |title=Tracking an Elephant Killer |date=2005-04-01 |work=Spotlight on Zoo Science |publisher=National Zoological Park |access-date=2009-05-10 |archive-url=https://web.archive.org/web/20090502010057/http://nationalzoo.si.edu/ConservationAndScience/SpotlightOnScience/elephantvirus.cfm |archive-date=2009-05-02 |url-status=dead }}</ref>


<ref name=Reid2006>{{cite journal|year=2006|title=Endotheliotropic elephant herpes virus (EEHV) infection. The first PCR-confirmed fatal case in Asia.|journal=Veterinary Quarterly|volume=28|issue=2|pages=61–64|vauthors=Reid CE, Hildebrandt TB, Marx N, Hunt M, Thy N, Reynes JM, Schaftenaar W, Fickel J |pmid=16841568|doi=10.1080/01652176.2006.9695209}}</ref>
<ref name=Reid2006>{{cite journal|year=2006|title=Endotheliotropic elephant herpes virus (EEHV) infection. The first PCR-confirmed fatal case in Asia.|journal=Veterinary Quarterly|volume=28|issue=2|pages=61–64|vauthors=Reid CE, Hildebrandt TB, Marx N, Hunt M, Thy N, Reynes JM, Schaftenaar W, Fickel J |pmid=16841568|doi=10.1080/01652176.2006.9695209|s2cid=25537428}}</ref>


<ref name=Ehlers2006>{{cite journal|year=2006|title=Endotheliotropic elephant herpesvirus, the first betaherpesvirus with a thymidine kinase gene|journal=Journal of General Virology|volume=87|pages=2781–2789|doi=10.1099/vir.0.81977-0|author1=Ehlers B. |author2=Dural G. |author3=Marschall M. |pmid=16963736|issue=Pt 10}}</ref>
<ref name=Ehlers2006>{{cite journal|year=2006|title=Endotheliotropic elephant herpesvirus, the first betaherpesvirus with a thymidine kinase gene|journal=Journal of General Virology|volume=87|pages=2781–2789|doi=10.1099/vir.0.81977-0|author1=Ehlers B. |author2=Dural G. |author3=Marschall M. |pmid=16963736|issue=Pt 10|doi-access=free}}</ref>


<ref name=Mikota2007>{{cite web |url=http://www.elephantcare.org/herpes.htm |archive-url=https://web.archive.org/web/20060223062153/http://www.elephantcare.org/herpes.htm |dead-url=yes |archive-date=2006-02-23 |title=Endotheliotropic Herpesvirus (EEHV) |last=Mikota |first=Susan |year=2007 |work=Elephant Care International Fact Sheets |publisher=Elephant Care International |accessdate=2009-05-07 |df= }}</ref>
<ref name=Mikota2007>{{cite web |url=http://www.elephantcare.org/herpes.htm |archive-url=https://web.archive.org/web/20060223062153/http://www.elephantcare.org/herpes.htm |url-status=dead |archive-date=2006-02-23 |title=Endotheliotropic Herpesvirus (EEHV) |last=Mikota |first=Susan |year=2007 |work=Elephant Care International Fact Sheets |publisher=Elephant Care International |access-date=2009-05-07 }}</ref>


<ref name=Zong2007>{{cite conference|year=2007|title=Pathogenesis and Molecular Epidemiology of Fatal Elephant Endotheliotrophic Disease Associated with the Expanding Proboscivirus Genus of the Betaherpesvirinae. Proc. Internat. Elephant Conservation and Res. Symp, Orlando, Florida|pages=23–35|author1=Zong J-C |author2=Latimer E |author3=Heaggans SY |author4=Richman LK |author5=Hayward GS }}</ref>
<ref name=Zong2007>{{cite conference|year=2007|title=Pathogenesis and Molecular Epidemiology of Fatal Elephant Endotheliotrophic Disease Associated with the Expanding Proboscivirus Genus of the Betaherpesvirinae. Proc. Internat. Elephant Conservation and Res. Symp, Orlando, Florida|pages=23–35|author1=Zong J-C |author2=Latimer E |author3=Heaggans SY |author4=Richman LK |author5=Hayward GS }}</ref>


<ref name=Zong2008>{{cite conference|year=2008|title=Viral Gene Subtyping of Eighteen North American Cases of EEHV Hemorrhagic Disease|conference=International Elephant Conservation and Research Symposium, Bangkok, Thailand|author=Zong, J-C|author2=Latimer E|author3=Heaggans SY|author4=Richman LK|author5=Hayward GS|last-author-amp=yes}}</ref>
<ref name=Zong2008>{{cite conference|year=2008|title=Viral Gene Subtyping of Eighteen North American Cases of EEHV Hemorrhagic Disease|conference=International Elephant Conservation and Research Symposium, Bangkok, Thailand|author=Zong, J-C|author2=Latimer E|author3=Heaggans SY|author4=Richman LK|author5=Hayward GS|name-list-style=amp}}</ref>


<ref name=Cracknell2008>{{cite web|url=http://static.zsl.org/files/zsl-abstract-10-6-2008-528.pdf|title=Herpes-viruses in Asian elephants (abstract)|year=2008|last=Cracknell|first=Jonathan|accessdate=2009-05-11}}</ref>
<ref name=Cracknell2008>{{cite web|url=http://static.zsl.org/files/zsl-abstract-10-6-2008-528.pdf|title=Herpes-viruses in Asian elephants (abstract)|year=2008|last=Cracknell|first=Jonathan|access-date=2009-05-11|archive-url=https://web.archive.org/web/20160303180644/http://static.zsl.org/files/zsl-abstract-10-6-2008-528.pdf|archive-date=2016-03-03|url-status=dead}}</ref>


<ref name=Wellehan2008>{{cite journal|year=2008|title=Six novel gammaherpesviruses of Afrotheria provide insight into the early divergence of the Gammaherpesvirinae|journal=Veterinary Microbiology|volume=127|issue=3-4|pages=249–257|doi=10.1016/j.vetmic.2007.08.024|author1=Wellehan JFX |author2=Johnson AJ |author3=Childressa AL |author4=Harr KE |author5=Isaza R |pmid=17884307}}</ref>
<ref name=Wellehan2008>{{cite journal|year=2008|title=Six novel gammaherpesviruses of Afrotheria provide insight into the early divergence of the Gammaherpesvirinae|journal=Veterinary Microbiology|volume=127|issue=3–4|pages=249–257|doi=10.1016/j.vetmic.2007.08.024|author1=Wellehan JFX |author2=Johnson AJ |author3=Childressa AL |author4=Harr KE |author5=Isaza R |pmid=17884307}}</ref>


<ref name=Zachariah2008>{{cite conference|year=2008|title=Fatal Endotheliotropic Elephant Herpes Virus Infection in Captive and Free-ranging Asian Elephants in South India|conference=International Elephant Conservation and Research Symposium, Bangkok, Thailand|author1=Zachariah A |author2=Richman LK |author3=Latimer E |author4=Hayward GS |author5=Kalaivannan N |author6=Zachariah A |author7=Balan S }}</ref>
<ref name=Zachariah2008>{{cite conference|year=2008|title=Fatal Endotheliotropic Elephant Herpes Virus Infection in Captive and Free-ranging Asian Elephants in South India|conference=International Elephant Conservation and Research Symposium, Bangkok, Thailand|author1=Zachariah A |author2=Richman LK |author3=Latimer E |author4=Hayward GS |author5=Kalaivannan N |author6=Zachariah A |author7=Balan S }}</ref>


<ref name=Garner2009>{{cite journal|year=2009|title=Clinico-pathologic Features of Fatal Disease Attributed to New Variants of Endotheliotropic Herpesviruses in Two Asian Elephants (Elephas maximus)|journal=Veterinary Pathology|volume=46|pages=97–104|vauthors=Garner MM, Helmick K, Ochsenrieter J, Richman LK, Latimer E, Wise AG, Maes K, Kuipel M, Nordhausen RW, ((Zong J-C)), Hayward GS|last-author-amp=yes|pmid=19112123|issue=1|doi=10.1354/vp.46-1-97|pmc=3572918}}</ref>
<ref name=Garner2009>{{cite journal|year=2009|title=Clinico-pathologic Features of Fatal Disease Attributed to New Variants of Endotheliotropic Herpesviruses in Two Asian Elephants (Elephas maximus)|journal=Veterinary Pathology|volume=46|pages=97–104|vauthors=Garner MM, Helmick K, Ochsenrieter J, Richman LK, Latimer E, Wise AG, Maes K, Kuipel M, Nordhausen RW, ((Zong J-C)), Hayward GS|pmid=19112123|issue=1|doi=10.1354/vp.46-1-97|pmc=3572918}}</ref>


<ref name=Koehl2009>{{cite web|url=http://www.elephant.se/elephant_herpes_virus.php|title=EEHV - Elephant endotheliotropic herpes virus|last=Koehl|first=Dan|year=2009|work=elephant.se|accessdate=2009-05-07}}</ref>
<ref name=Koehl2009>{{cite web|url=http://www.elephant.se/elephant_herpes_virus.php|title=EEHV - Elephant endotheliotropic herpes virus|last=Koehl|first=Dan|year=2009|work=elephant.se|access-date=2009-05-07}}</ref>


<ref name=Stanton2010>{{cite journal|year=2010|title=Detection of pathogenic elephant endotheliotropic herpesvirus in routine trunk washes from healthy adult Asian elephants (Elephas maximus) by use of a real-time quantitative polymerase chain reaction assay|journal=American Journal of Veterinary Research|volume=71|pages=925–933|vauthors=Stanton JJ, Zong JC, Latimer E, Tan J, Herron A, Hayward GS, Ling PD |doi=10.2460/ajvr.71.8.925|pmc=3725808}}</ref>
<ref name=Stanton2010>{{cite journal|year=2010|title=Detection of pathogenic elephant endotheliotropic herpesvirus in routine trunk washes from healthy adult Asian elephants (Elephas maximus) by use of a real-time quantitative polymerase chain reaction assay|journal=American Journal of Veterinary Research|volume=71|issue=8|pages=925–933|vauthors=Stanton JJ, Zong JC, Latimer E, Tan J, Herron A, Hayward GS, Ling PD |doi=10.2460/ajvr.71.8.925|pmc=3725808|pmid=20673092}}</ref>


<ref name=Latimer2011>{{cite journal|year=2011|title=Detection and evaluation of novel herpesviruses in routine and pathological samples from Asian and African elephants: Identification of two new probosciviruses (EEHV5 and EEHV6) and two new gammaherpesviruses (EGHV3B and EGHV5)|journal=Veterinary Microbiology|volume=147|pages=28–41|author1=Latimer E |author2=Zong JC |author3=Heaggans SY |author4=Richman LK |author5=Hayward GS |pmc=2976818|pmid=20579821|doi=10.1016/j.vetmic.2010.05.042}}</ref>
<ref name=Latimer2011>{{cite journal|year=2011|title=Detection and evaluation of novel herpesviruses in routine and pathological samples from Asian and African elephants: Identification of two new probosciviruses (EEHV5 and EEHV6) and two new gammaherpesviruses (EGHV3B and EGHV5)|journal=Veterinary Microbiology|volume=147|issue=1–2|pages=28–41|author1=Latimer E |author2=Zong JC |author3=Heaggans SY |author4=Richman LK |author5=Hayward GS |pmc=2976818|pmid=20579821|doi=10.1016/j.vetmic.2010.05.042}}</ref>


<ref name=Denk2012>{{cite journal|year=2012|title=Fatal elephant endotheliotropic herpesvirus type 5 infection in a captive Asian elephant|journal=The Veterinary Record|volume=148|pages=380–381|author1=Denk D |author2=Stidworthy MF |author3=Redrobe E |author4=Latimer E |author5=Hayward GS |author6=Cracknell J |author7=Classens A |author8=Steinbach F |author9=McGowan S |author10=Dasterjerdi A }}</ref>
<ref name=Denk2012>{{cite journal|year=2012|title=Fatal elephant endotheliotropic herpesvirus type 5 infection in a captive Asian elephant|journal=The Veterinary Record|volume=148|issue=15|pages=380–381|author1=Denk D |author2=Stidworthy MF |author3=Redrobe E |author4=Latimer E |author5=Hayward GS |author6=Cracknell J |author7=Classens A |author8=Steinbach F |author9=McGowan S |author10=Dasterjerdi A |doi=10.1136/vr.e6833|pmid=23065589|s2cid=30781584}}</ref>


<ref name=Hayward2012>{{cite journal|year=2012|title=Conservation:clarifying the risk from herpesvirus to captive Asian elephants|journal=The Veterinary Record|volume=212|pages=202–203|author=Hayward GS}}</ref>
<ref name=Hayward2012>{{cite journal|year=2012|title=Conservation:clarifying the risk from herpesvirus to captive Asian elephants|journal=The Veterinary Record|volume=212|issue=8|pages=202–203|author=Hayward GS|doi=10.1136/vr.e1212|pmc=3587150|pmid=22368209}}</ref>


<ref name=Atkins2013>{{cite journal|year=2013|title=EEHV-5, A newly recognized elephant herpesvirus associated with clinical and sub-clinical infections in captive Asian elephants (Elephas maximus) |journal=Journal of Zoo and Wildlife Medicine|volume=44|pages=136–143|author1=Atkins L |author2=Zong J-C |author3=Tan J |author4=Meija A |author5=Heaggans SY |author6=Nofs S |author7=Stanton JJ |author8=Flanagan JP |author9=Howard L |author10=Latimer E |author11=Stevens MR |author12=Hoffman DS |author13=Hayward GS |author14=Ling PD |doi=10.1638/1042-7260-44.1.136|pmc=3746547}}</ref>
<ref name=Atkins2013>{{cite journal|year=2013|title=EEHV-5, A newly recognized elephant herpesvirus associated with clinical and sub-clinical infections in captive Asian elephants (Elephas maximus) |journal=Journal of Zoo and Wildlife Medicine|volume=44|pages=136–143|author1=Atkins L |author2=Zong J-C |author3=Tan J |author4=Meija A |author5=Heaggans SY |author6=Nofs S |author7=Stanton JJ |author8=Flanagan JP |author9=Howard L |author10=Latimer E |author11=Stevens MR |author12=Hoffman DS |author13=Hayward GS |author14=Ling PD |issue=1 |doi=10.1638/1042-7260-44.1.136|pmc=3746547 |pmid=23505714}}</ref>


<ref name=Stanton2013>{{cite journal|year=2013|title=Kinetics of viral loads and genotypic analysis of elephant endotheliotropic herpesvirus-1 infection in captiveAsian elephants (Elephas maximus)|journal=Journal of Zoo and Wildlife Medicine|volume=44|pages=42–54|author1=Stanton JJ |author2=Zong J-C |author3=Eng C |author4=Howard L |author5=Flanagan J |author6=Stevens S |author7=Schmitt D |author8=Weidner E |author9=Graham D |author10=Junge R |author11=Weber ME |author12=Fischer M |author13=Meija A |author14=Tan J |author15=Latimer E |author16=Herron A |author17=Hayward GS |author18=Ling PD |doi=10.1638/1042-7260-44.1.42|pmc=3746492 }}</ref>
<ref name=Stanton2013>{{cite journal|year=2013|title=Kinetics of viral loads and genotypic analysis of elephant endotheliotropic herpesvirus-1 infection in captiveAsian elephants (Elephas maximus)|journal=Journal of Zoo and Wildlife Medicine|volume=44|pages=42–54|author1=Stanton JJ |author2=Zong J-C |author3=Eng C |author4=Howard L |author5=Flanagan J |author6=Stevens S |author7=Schmitt D |author8=Weidner E |author9=Graham D |author10=Junge R |author11=Weber ME |author12=Fischer M |author13=Meija A |author14=Tan J |author15=Latimer E |author16=Herron A |author17=Hayward GS |author18=Ling PD |issue=1|doi=10.1638/1042-7260-44.1.42|pmc=3746492 |pmid=23505702}}</ref>


<ref name=Zachariah2013>{{cite journal|year=2013|title=Fatal herpesvirus (EEHV) hemorrhagic disease in wild and orphan Asian elephants in southern India|journal=Journal of Wildlife Disease|volume=49|pages=381–393|author1=Zachariah A |author2=Zong J-C |author3=Long SY |author4=Latimer EM |author5=Heaggans SY |author6=Richman LK |author7=Hayward GS |doi=10.7589/2012-07-193}}</ref>
<ref name=Zachariah2013>{{cite journal|year=2013|title=Fatal herpesvirus (EEHV) hemorrhagic disease in wild and orphan Asian elephants in southern India|journal=Journal of Wildlife Diseases|volume=49|pages=381–393|author1=Zachariah A |author2=Zong J-C |author3=Long SY |author4=Latimer EM |author5=Heaggans SY |author6=Richman LK |author7=Hayward GS |issue=2|doi=10.7589/2012-07-193|pmc=3707512 |pmid=23568914}}</ref>


<ref name=Sripiboon2013>{{cite journal|year=2013|title=(Case Report) The occurrence of elephant herpesviruses in captive Asian elephants: the first case of EEHV4 in Asia|journal=Journal of Zoo and Wildlife Medicine|volume=44|pages=100–104|author1=Sripiboon S |author2=Tanjaew P |author3=Lungka G |author4=Thitaram C |doi=10.1638/1042-7260-44.1.100}}</ref>
<ref name=Sripiboon2013>{{cite journal|year=2013|title=(Case Report) The occurrence of elephant herpesviruses in captive Asian elephants: the first case of EEHV4 in Asia|journal=Journal of Zoo and Wildlife Medicine|volume=44|pages=100–104|author1=Sripiboon S |author2=Tanjaew P |author3=Lungka G |author4=Thitaram C |issue=1|doi=10.1638/1042-7260-44.1.100|pmid=23505709|s2cid=44649231}}</ref>


<ref name=Akst150601>{{cite news |url= http://www.the-scientist.com/?articles.view/articleNo/43010/title/A-Plague-on-Pachyderms/ |title=A Plague on Pachyderms |first= Jef |last= Akst |work= the-scientist.com |date= 2015-06-01 }}</ref>
<ref name=Akst150601>{{cite news |url= http://www.the-scientist.com/?articles.view/articleNo/43010/title/A-Plague-on-Pachyderms/ |title=A Plague on Pachyderms |first= Jef |last= Akst |work= the-scientist.com |date= 2015-06-01 }}</ref>
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*{{cite conference|year=2011|title=Detection and Significance of Multiple EEHV Species in African Elephants|conference=International Elephant Conservation and Research Symposium, Pretoria, South Africa|author1=Hayward GS |author2=Heaggans SY |author3=Zong J-C |author4=Latimer E |author5=Richman LK }}
* {{cite conference|year=2011|title=Detection and Significance of Multiple EEHV Species in African Elephants|conference=International Elephant Conservation and Research Symposium, Pretoria, South Africa|author1=Hayward GS |author2=Heaggans SY |author3=Zong J-C |author4=Latimer E |author5=Richman LK }}

== External links ==
* {{Wikispecies-inline|Elephantid betaherpesvirus 1|''Elephantid betaherpesvirus 1''}}


{{Good article}}
{{Good article}}
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{{Herpesvirales}}
{{Taxonbar|from=Q5359390}}
{{Taxonbar|from=Q24808737|from2=Q5359390}}


{{DEFAULTSORT:Elephant Endotheliotropic Herpesvirus}}
{{DEFAULTSORT:Elephant Endotheliotropic Herpesvirus}}

Latest revision as of 13:28, 18 December 2024

Elephantid betaherpesvirus 1
Virus classification Edit this classification
(unranked): Virus
Realm: Duplodnaviria
Kingdom: Heunggongvirae
Phylum: Peploviricota
Class: Herviviricetes
Order: Herpesvirales
Family: Orthoherpesviridae
Genus: Proboscivirus
Species:
Elephantid betaherpesvirus 1
Synonyms[1]

Elephantid herpesvirus 1

Elephant endotheliotropic herpesviruses (EEHV) or Elephantid betaherpesvirus 1 (ElHV-1) is a type of herpesvirus, which can cause a highly fatal hemorrhagic disease when transmitted to young Asian elephants. In African elephants, related forms of these viruses, which have been identified in wild populations, are generally benign, occasionally surfacing to cause small growths or lesions. However, some types of EEHV can cause a highly fatal disease in Asian elephants, which kills up to 80% of severely affected individuals. The disease can be treated with the rapid application of antiviral drugs, but this has only been effective in around a third of cases.

The first case of a fatal form of the disease was documented in 1990,[2] though tissue samples from as early as the 1980s have since tested positive for the virus, and localized skin lesions in wild African elephants were recorded in the 1970s. Since 1995, there have been over fifty documented disease cases in North America and Europe, of which only nine have been successfully cured. Those affected are mostly young animals born in captivity, though a small number of older wild-born adults held in zoos have died, and a number of cases caused by the same pathogenic type of EEHV have been identified in both orphan and wild calves in Asian elephant populations.

Virus and transmission

[edit]
"Donaldson", a male Asian elephant calf at Whipsnade Zoo, died of EEHV in May 2009.[3]

The EEHVs are members of the Proboscivirus genus, a novel clade most closely related to the mammalian betaherpesviruses that have been responsible for as many as 70 deaths of both zoo and wild Asian elephants worldwide, especially in young calves.[4][5] There are currently six known species/types of the probosciviruses, and the most commonly encountered and most pathogenic form EEHV1 also has two chimeric subtypes, 1A and 1B,[4][6][7][8][9] as well as numerous distinct strains.[10]

EEHV1A (originally just known as EEHV1) was the first species/type identified, which causes an acute hemorrhagic disease with a very high mortality rate in Asian elephants.[7][11][12] This form of the virus was originally believed to occur naturally in African elephants (occasionally producing skin nodules), and to be transmitted to Asian elephants within captivity, but more extensive studies have since largely disproved this concept because several other species/types of EEHV (e.g. EEHV2, EEHV3 and EEHV6) instead have been identified in African elephants.[5][13] A second lethal subtype, EEHV1B, was identified in Asian elephants in 2001.[7] EEHV3, EEHV4 and EEHV5 have also each been responsible for the deaths of at least one Asian elephant calf.[14][15]

EEHV2 has caused hemorrhagic disease in several African elephants as reported by.[9][11] Along with EEHV3 and EEHV6 it has also been found in pulmonary lymph nodes of several autopsied wild and zoo African elephants.[4][16]

There are a further five or six species/types and varieties of elephant gammaherpesvirus (EGHVs) found in eye and genital secretions of many healthy Asian and African zoo elephants - e.g. EGHV1, EGHV2, EGHV3A, EGHV3B, EGHV4 and EGHV5 (also called Elephantid gammaherpesviruses EIHV3, EIHV4, EIHV5, EIHV6, ElHV9 and ElHV10) - all of which are classified in the subfamily Gammaherpesvirinae rather than Betaherpesvirinae. These viruses are neither closely related to the EEHVs, nor the known cause of any disease symptoms.[5][17]

Studies have also detected both EEHV1A and EEHV1B as being shed in trunk wash secretions by healthy asymptomatic Asian zoo elephant herdmates of calves that previously had disease.[18][19] and similarly for EEHV5.[20] Thus, similar to saliva for most human and animal herpesviruses, the trunk secretions may be a source of transmission for EEHVs. Because of concerns about the origins of EEHV1 and evidence of cross-species transmission for EEHV3, long-term contact between Asian and African elephants has been discouraged,[8] along with avoiding new contacts between young captive-born Asian elephants and wild-born Asian elephants, as the latter may be carriers of the disease.[4] An analysis of a number of North American cases, which ruled out the direct transmission of the virus between any of the affected facilities studied, strongly supported the idea of a significant Asian carrier population.[4] This is supported by the fact that some of the deceased calves had no possible contact with any African elephants.[8] Artificial insemination is not believed to be a transmission factor,[4] notes that when multiple calves of a single bull or cow elephant died at different times (even at the same facility) they nearly all had distinct strains of the virus, yet when two calves died or became infected at the same time at the same facility the pairs have always had identical virus strains.[21] A program of enzyme-linked immunosorbent assay testing began in 2005, aiming to test blood samples from around a thousand elephants for antibodies to the virus in order to help identify carriers and possible transmission patterns.[21]

Effects and treatment

[edit]

In benign infections found in some wild and captive African elephants, these viruses can affect either the skin or the pulmonary system.[8] In the former case, it produces small pinkish nodules on the head and trunk in juveniles, which appear for a few weeks and then regress, suggesting an intermittently reactivated localized infection that mostly remains dormant.[4] In the second case, it has been found in small white pulmonary nodules on necropsy of many asymptomatic adults. These are both characteristic of EEHV2, EEHV3 and EEHV6.[4]

In a fatal attack, however, it manifests very quickly. In a number of cases, death has occurred within 24 hours of the onset of the infection,[4] while other cases do not last longer than around five days.[8] The virus attacks endothelial cells, rupturing capillaries and causing blood loss and haemorrhaging; once this reaches the heart, the haemorrhage kills quickly through shock. Symptoms include lethargy and an unwillingness to eat, a rapid heartbeat, and decreased blood-cell count, as well as cyanosis of the tongue, mouth ulcers, and oedema of the head and trunk.[8]

Rapid treatment with famciclovir, sustained for around a month, has appeared to cure eight calves infected with EEHV1; however, this treatment is very expensive, only partially effective, and relies on early identification of the infection.[4]

A polymerase chain reaction test on a blood sample from affected animals will confirm a suspected case by identifying the viral DNA, though it is now common to start famciclovir treatment at the earliest possible moment rather than waiting for confirmation of the case.[4][21] Prior to the development of the test, or in circumstances where it is not available, the disease may be misdiagnosed as any of a number of other conditions which have a quick onset leading to rapid death, including encephalomyocarditis and salmonellosis.[8]

History

[edit]

The virus has been identified in the pulmonary nodules of African elephants as far back as the 1970s.[8] The first recognised fatal case of EEHV in an Asian elephant was identified at the National Zoo in Washington, D.C., in 1995;[22] testing on stored tissue samples was able to identify a number of earlier deaths as being due to the same virus. These cases have so far been identified as early as 1983.[4] Since this date, there have been a total of 54 more cases in North America and Europe, nine of which were successfully treated.[4] The May 2009 deaths of two calves at Whipsnade Zoo were not included in this calculation. This gives a fatality rate of over 80% among known symptomatic disease cases. In cases where antiviral medication was applied, treatment was effective in about one in three cases. As of 2005, there were twelve cases where famciclovir had been used, eight of which were fatal. As a fraction of the overall population, it has been calculated that of the 78 Asian elephants born in captivity in North America between 1978 and 2007, 19 are known to have died of EEHV, and five more were successfully treated with antiviral medication.[4][6]

The affected animals are mostly young Asian elephants that had been born in captivity, with half the cases in North America being between the ages of one and four years (and three-quarters between one and eight years old). Some cases have affected newborns or adult elephants born in the wild (oldest aged 40 years), and three recorded cases have affected African elephants.[4][6] The first documented fatal case for African elephants was Kijana, an eleven-month-old male in 1996.[4][11] Since 2008, a number of cases have been attributed to EEHV1 among wild Asian elephants.[4][23]

The first suspected case in Asia was in 1997, though it was not until the fifth suspected case that the presence of the virus could be confirmed. This case was reported in 2006, with the death of a young wild-born female calf at an elephant sanctuary in Cambodia. The virus was identified as part of the EEHV1 group, the same as previously identified in the North American and European captive populations.[24] In 2013, nine lethal cases from India were extensively characterized and found to consist of a wide variety of genetically diverged strains of EEHV1A and EEHV1B matching the subtypes and genetic range of nearly all those found previously in Europe and North America.[25] Cases attributed to EEHV1A and EEHV4 have also been reported in Thailand[26] and there is both confirmed and anecdotal evidence for similar hemorrhagic disease deaths of between 16 and 30 more calves in Asian countries including Thailand, India, Nepal, Myanmar and Indonesia within the past five years. Thus, this is not just a disease of captive elephants, but is endogenous to and possibly rampant in Asian elephants in the wild also.[27] Further research has been noted as "urgently required" to study the situation in regions with wild Asian elephant populations.[4]

On 12 June 2019 it was reported[28] that in Chester Zoo the 2-year-old Indian elephant calf Indali Hi Way had fully recovered from EEHV, after numerous treatments over 2 weeks, and that there is now hope of a vaccine for EEHV.

In 2020, a 1-year-old Asian elephant named Ajay, from the Rosamond Gifford Zoo in Syracuse, New York, which was popular in the area, died from the virus.[29][30]

In July 2024, Dublin Zoo reported two deaths from the virus.Avani, who was 8 years old, and Zinda, who was 7, both died from the virus.[31]

In November 2024, a young African Elephant "Bumi" died at Ouwehands Dierenpark in Rhenen in the Netherlands. Later that month two calves named "Nagarr" and "Ka Yan" died in the Dutch zoo Wildlands in Emmen.[32] On 11th of December, the first test took place of a new vaccine developed by the University of Utrecht against the virus variant that only affects Asian elephants.[33]

References

[edit]
  1. ^ Davison, Andrew (27 January 2016). "Rename species in the family Herpesviridae to incorporate a subfamily designation" (PDF). International Committee on Taxonomy of Viruses (ICTV). p. 3. Retrieved 10 July 2019. Betaherpesvirinae Proboscivirus Elephantid herpesvirus 1 Elephantid betaherpesvirus 1
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  • Hayward GS; Heaggans SY; Zong J-C; Latimer E; Richman LK (2011). Detection and Significance of Multiple EEHV Species in African Elephants. International Elephant Conservation and Research Symposium, Pretoria, South Africa.
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