AboutZoos, Since 2008


Dog dis­ease in African lions spread by mul­ti­ple species

pub­lished 01 Feb­ru­ary 2015 | mod­i­fied 01 Feb­ru­ary 2015

Lions in SerengetiIn nat­ural ecosys­tems, the deadly canine dis­tem­per virus can jump between species and thrive, thereby threat­en­ing vul­ner­a­ble ani­mal pop­u­la­tions, accord­ing to find­ings of a recently pub­lished study.

Canine dis­tem­per, a viral dis­ease that’s been infect­ing the famed lions of Tanzania’s Serengeti National Park, appears to be spread not only by dogs but by mul­ti­ple ani­mal species, an inter­na­tional team of sci­en­tists has con­cluded. In their study, pub­lished online before print on 20 Jan­u­ary in the jour­nal Pro­ceed­ings of the National Acad­emy of Sci­ences, they say domes­tic dogs are no longer the pri­mary source of the trans­mis­sion of the dis­ease to lions and that wild car­ni­vores may con­tribute as well.

Our study shows that the dynam­ics of canine dis­tem­per virus are extremely com­plex, and a broad­ened approach — focus­ing not only on domes­tic dogs — is required if we are to con­trol the dis­ease among lions and other wild ani­mal species
Felix Lankester, co-​author, Paul G. Allen School for Global Ani­mal Health, Wash­ing­ton State University »

Dogs and beyond
In 1994, a mys­te­ri­ous neu­ro­log­i­cal ail­ment wiped out 30 per­cent of the lion pop­u­la­tion in the Serengeti, one of the largest wildlife regions in the world. Sci­en­tists deter­mined it was canine dis­tem­per, a dis­ease pre­vi­ously thought to infect only dogs, coy­otes and a small num­ber of other mammals.

Evi­dence revealed the lions had con­tracted dis­tem­per from dogs liv­ing in vil­lages and set­tle­ments nearby. A domes­tic dog vac­ci­na­tion cam­paign was launched to curb the infection’s spread. It worked — among dogs, at least.

After analysing three decades of blood serum data col­lected from lions and domes­tic dogs, the study’s researchers dis­cov­ered that the virus con­tin­ues to cir­cu­late in the lion pop­u­la­tion while sig­nif­i­cantly declin­ing among dogs.

The dog’s role in spread­ing the dis­ease appears to be shrink­ing, con­clude the paper’s authors, a col­lab­o­ra­tion of vet­eri­nar­i­ans, dis­ease ecol­o­gists, epi­demi­ol­o­gists and math­e­mat­i­cal biologists.

Why, then, do the lions con­tinue to get infected?
“Domes­tic dog pop­u­la­tions imme­di­ately sur­round­ing the Serengeti National Park are not the sole dri­ver of canine dis­tem­per infec­tions in lions, and its per­sis­tence is likely to involve a larger multi-​host com­mu­nity,” the sci­en­tists write in their study.

Other big cats are threat­ened by the canine dis­tem­per virus as well. Espe­cially the vul­ner­a­ble wild Amur tiger pop­u­la­tion turns out to be exposed to the virus and become dis­eased with one of the wor­ry­ing symp­toms that the cats seem to lose their fear of man, which increases the chance of human-​tiger con­flict and leaves them easy prey for poachers.

Risk of out­breaks
Other species, includ­ing hye­nas and jack­als, are prob­a­bly trans­mit­ting the dis­ease and keep­ing it loom­ing in the wild, the authors say. Con­se­quently, out­breaks among lions and other already-​threatened ani­mals could occur at any time.

Researchers say more work is nec­es­sary to iden­tify which species spread dis­tem­per and what trig­gers the spillovers. For exam­ple, pre­vi­ous analy­ses sug­gest that an infected hyena or other car­ni­vore feed­ing on a car­cass can dis­perse the virus through mucus secre­tions to other preda­tors at the same site.

A bet­ter under­stand­ing of canine dis­tem­per virus and its dynam­ics in the wild is nec­es­sary to bet­ter mon­i­tor and con­trol the dis­ease among lions and other threat­ened ani­mals,” said Felix Lankester, the Tanzania-​based vet­eri­nary researcher.

(Source: Wash­ing­ton State Uni­ver­sity press release, 28.01.2015)

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