NEWLY DESCRIBEDTOXOPLASMA GONDIISTRAIN CAUSES HIGH MORTALITY IN RED NECKED WALLABIES (MACROPUS RUFOGRISEUS) IN A ZOO

Abstract

This manuscript describes an outbreak of fatal toxoplasmosis in wallabies. Ten adult red necked wallabies (Macropus rufogriseus) were imported from New Zealand to the Virginia Zoo. Agglutination testing upon admission into quarantine showed all animals to be negative for antibodies to Toxoplasma gondii. Nine of these wallabies died from acute toxoplasmosis within 59-565 (average 224) days after being moved onto exhibit. Clinical signs included lethargy, diarrhea, tachypnea, and ataxia that progressed rapidly; death without premonitory signs occurred in one case. Histopathologic examination revealed interstitial pneumonia, encephalomyelitis, myositis, enteritis, and myocarditis. The diagnosis was confirmed through serologic, histopathologic, and polymerase chain reaction (PCR) testing. Multilocus PCR-RFLP (restriction fragment length polymorphism) genotyping revealed that the first six animals were infected by a previously undiscovered Toxoplasma gondii genotype, designated as ToxoDB PCR-RFLP genotype No. 263. These six cases survived for an average of 118 days on exhibit before succumbing to toxoplasmosis. The other three wallabies were infected with a Toxoplasma gondii strain of ToxoDB PCR-RFLP genotype No. 4, which is a common strain type circulating in wild animals in North America. These three cases survived for an average of 435 days on exhibit before succumbing to toxoplasmosis. The outbreaks of toxoplasmosis in these wallabies are likely from two different sources. Furthermore, the results highlight Toxoplasma gondii PCR-RFLP genotyping in parasite diagnosis and understanding parasite transmission and potential mitigation procedures.

Toxoplasma gondii in four captive kangaroos (Macropus spp.) in China: Isolation of a strain of a new genotype from an eastern grey kangaroo (Macropus giganteus)

“…This is in agreement with the findings of More et al (2010). Furthermore, T. gondii- specific DNA was detected in the brain or tongue of all seropositive kangaroos, indicating a high level of infection by T. gondii in this species (Parameswaran et al, 2009; Guthrie et al, 2017). The infection level of T. gondii cysts may also be related to the genotype or strain of T. gondii, the infective dose, the host species, and the immunity of hosts.…”

“…in zoos around the world were imported from Australia and New Zealand; some zoos then started to breed these animals locally. Mortality of captive marsupials infected with T. gondii has been reported, and some animals have also been reported to develop chronic infection (More et al, 2010; Guthrie et al, 2017; Dubey, 2010; Diaz-Ayala et al, 2016). There are few reports concerning genotyping of T. gondii from kangaroos and wallabies.…”

“…Non-archetypal type II-like strains of T. gondii were found in marsupials from Australia (Parameswaran et al, 2010). ToxoDB#263 and ToxoDB#4 T. gondii strains were identified in wallaby tissues from the Virginia Zoo (Guthrie et al, 2017).…”

Recent aspects on epidemiology, clinical disease, and genetic diversity of Toxoplasma gondii infections in Australasian marsupials

“…Genotyping of the isolates suggested 2 sources of infection acquired in the USA. From 6 wallaby tissues, the DNA was typed as PCR-RFLP-ToxoDB genotype #263, and from the 3 others the genotype was ToxoDB #4, commonly found in wildlife [ 8 ] Bennett’s wallaby ( Macropus rufogriseus ) USA See text. Case 3, DNA extracted from heart and lung tissues, genotype #2 [ 5 ] Eastern grey kangaroo ( Macropus giganteus ) Argentina Non-suppurative encephalitis was found at necropsy of 1 captive kangaroo that died.…”

“…None of the currently available medicines are very effective in treating clinical toxoplasmosis in marsupials. Atovaquone, pyrimethamine, trimethoprim-sulfadiazine, ponazuril, and clindamycin are some of the medicines that have been used to treat affected marsupials [ 6 , 8 , 17 ]. In Germany, a wallaby with neurological signs improved after treatment with trimethoprim/sulfadoxin for 7 days; the diagnosis was based on serological results and clinical signs [ 6 ].…”