AboutZoos, Since 2008


Zoos not respon­si­ble for spread of deadly her­pesvirus that kills ele­phant calves

pub­lished 15 Octo­ber 2014 | mod­i­fied 15 Octo­ber 2014

Elephant Kumari and motherEle­phants are among the most intel­li­gent non-​humans, arguably on par with chim­panzees, but both African and Asian ele­phants – which are sep­a­rate species – are endan­gered. In 1995, 16-​month old Kumari, the first Asian ele­phant born at the National Zoo in Wash­ing­ton, DC, died of a then-​mysterious ill­ness. In 1999, Gary Hay­ward of Johns Hop­kins Uni­ver­sity and col­lab­o­ra­tors pub­lished their results iden­ti­fy­ing a novel her­pesvirus, EEHV1 (Elep­hant Endothe­liotropic Herpes virus1) as the cause of Kumari’s sud­den death. They now show that severe cases like this one are caused by viruses that nor­mally infect the species, rather than by viruses that have jumped from African ele­phants, which was their orig­i­nal hypoth­e­sis. Hayward’s lat­est research appears ahead of print in the Jour­nal of Virology.

There­fore, the viruses have not spread between zoos, and the sources of the viruses were most likely wild-​born ele­phant herdmates …..
«Gary Hay­ward, Johns Hop­kins University

At the time of Kumari’s death, anti-​zoo activists seized on the sit­u­a­tion to call for aban­don­ing all efforts to breed Asian ele­phants in zoos, as they claimed that zoos were spread­ing the deadly her­pesvirus, says Hay­ward. Con­trary to that, in the cur­rent research, “We showed that whereas some iden­ti­cal her­pesvirus strains infected both healthy and dis­eased ani­mals con­cur­rently at par­tic­u­lar facil­i­ties, the major­ity were dif­fer­ent strains, and there has not been a sin­gle proven case of the same strain occur­ring at any two dif­fer­ent facil­i­ties,” says Hay­ward. “There­fore, the viruses have not spread between zoos, and the sources of the viruses were most likely wild-​born ele­phant herd­mates. In fact, we also found the same dis­ease in sev­eral Asian range coun­tries, includ­ing in orphans and wild calves, and showed that the EEHV1 strains in India dis­played the same genetic diver­sity as those in West­ern zoos.”

In the study, the researchers per­formed exten­sive DNA fin­ger­print­ing of the genetic sig­na­tures of all the known EEHV cases, includ­ing those in zoos, as well as sam­ples of EEHV virus that were obtained from wild Asian and African ele­phants, says Hay­ward. For this DNA fin­ger­print­ing the research team devel­oped a spe­cific ana­lyt­i­cal tech­nique, because these viruses can­not be grown in cell cul­ture. In the process, they iden­ti­fied seven dif­fer­ent species of EEHVs and mul­ti­ple dif­fer­ent sub­types of each. All these dif­fer­ent her­pesvirus species and sub­types had their own host, either the African ele­phant or the Asian ele­phant, and were nat­ural, endoge­nous and found every­where. For instance, sev­eral of these viruses are occa­sion­ally shed in trunk washes and saliva of most healthy asymp­to­matic adult Asian elephants.

Close mon­i­tor­ing of Asian ele­phant calves in zoos has so far enabled life-​saving treat­ment for at least nine infected Asian calves, says Hay­ward, sug­gest­ing that such mon­i­tor­ing may ulti­mately enable deter­min­ing why some ani­mals become sus­cep­ti­ble to severe dis­ease after their pri­mary EEHV1 infec­tions, while most do not. “About 20% of all Asian ele­phant calves are sus­cep­ti­ble to haem­or­rhagic dis­ease [caused by her­pesvirus], whereas symp­to­matic dis­ease is extremely rare in African ele­phant calves under the same zoo con­di­tions,” says Hayward.

Accord­ing to Philip Pel­lett, of Wayne State Uni­ver­sity School of Med­i­cine, Detroit: “The infor­ma­tion gained in the new EEHV paper will be impor­tant for devel­op­ing diag­nos­tic tools for these viruses, and for devel­op­ing ther­a­peu­tic approaches to dis­eases caused by EEHV.”

Ele­phants in the wild
Ele­phant pop­u­la­tions have been plum­met­ing. African ele­phants declined roughly from 10 mil­lion to half a mil­lion dur­ing the 20th cen­tury, due largely to habi­tat destruc­tion, and intense poach­ing has since fur­ther dec­i­mated their num­bers. The African ele­phant (Lox­odonta africana) is cur­rently listed as Vul­ner­a­ble by the IUCN Red List of Threat­ened Species. While the Asian ele­phant (Ele­phas max­imus) is listed as Endan­gered. The Asian species, once in the mil­lions, now num­ber less than 50,000. They are threat­ened mostly by habi­tat frag­men­ta­tion. Poach­ing is not an issue since they lack tusks.

The full paper will appear in the Decem­ber issue of the Jour­nal of Virology.

(Source: Amer­i­can Soci­ety for Micro­bi­ol­ogy press release, 08.10.2014)

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Tiger map” (CC BY 2.5) by Sander­son et al., 2006.

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