Canine Distemper Virus in Tigers (Panthera tigris) and Leopards (P. pardus) in Nepal

Abstract

From wild dogs (Lycaon pictus) in the Serengeti to tigers (Panthera tigris altaica) in the Russian Far East, canine distemper virus (CDV) has been repeatedly identified as a threat to wild carnivores. Between 2020 and 2022, six Indian leopards (P. pardus fusca) presented to Nepali authorities with fatal neurological disease, consistent with CDV. Here, we report the findings of a serosurvey of wild felids from Nepal. A total of 48 serum samples were tested, comprising 28 Bengal tigers (P. t. tigris) and 20 Indian leopards. Neutralizing antibodies were identified in three tigers and six leopards, equating to seroprevalences of 11% (CI: 2.8–29.3%, n = 28) and 30% (CI: 12.8–54.3%, n = 20), respectively. More than one-third of seropositive animals were symptomatic, and three died within a week of being sampled. The predation of domestic dogs (Canis lupus familiaris) has been posited as a potential route of infection. A comparison of existing diet studies revealed that while leopards in Nepal frequently predate on dogs, tigers do not, potentially supporting this hypothesis. However, further work, including molecular analyses, would be needed to confirm this.

Phylogenetic characterization of canine distemper virus from stray dogs in Kathmandu Valley

“…These studies suggest that CDV strains that are similar or closely related circulate regionally among sympatric carnivore hosts. This leads us to believe that CDV in wild carnivores, such as leopards and tigers, affected by the virus in Nepal [ 13 ] may also belong to the Asia-5 lineage. According to Bodgener et al (2023), higher levels of dog predation behavior among leopards than tigers may have increased the level of associated exposure to CDV in leopards [ 13 ].…”

“…Understanding and managing CDV outbreaks is particularly important in Nepal, which is home to many species of threatened wild carnivores including tigers, leopards, snow leopards ( Panthera uncia ), dholes ( Cuon alpinus ) and wolves ( Canis lupus chanco ), and also has a large population of stray dogs [ 12 ]. Moreover, a recent serosurveillance study on wild felids in Nepal confirmed CDV exposure on tigers and leopards, where more than one third of the tested big cats were symptomatic and three died soon after being sampled [ 13 ]. Similarly, previous studies have shown that CDV is prevalent in stray dog populations across Nepal.…”

Canine distemper outbreak and laryngeal paralysis in captive tigers (Panthera tigris)

“…Although there was unclear evidence of the outbreak's origin in this animal population, contact with bodily excretions among tigers and fomite contamination was suspected as the cause of the spread of the pathogen among their population. A vaccination program was recommended for disease prevention in some countries 5,9,29,30 . Moreover, the restriction of biosecurity became a high concern in captive wildlife in Thailand.…”

Disease threats to tigers and their prey

“…Death from CDV is additive to other causes of tiger mortality (Robinson et al, 2015) and a population viability model has shown that infection increased the 50-year extinction probability of small Russian populations by up to 65% (Gilbert et al, 2014). Recent tiger cases have been confirmed in Malaysia (Ten et al, 2021) and India (Kadam et al, 2022), while antibodies indicating prior infection have been detected in tigers in Indonesia (Mulia et al, 2021) and in Nepal (Bodgener et al, 2023). Although only a small number of cases have been diagnosed, the presence of infection in at least five of the 10 tiger range states suggests that all populations are probably at risk of infection.…”

“…Commercial diagnostic kits for measuring CDV antibodies are designed for use in domestic dogs and should be considered unreliable for use in tigers without validation. Serum neutralization tests are available or have been introduced to several tiger range countries to measure titers of CDV neutralizing antibodies (Techakriengkrai et al, 2019;Mulia et al, 2021;Bodgener et al, 2023). Resulting seroprevelance estimates provide a useful means of validating population viability models based on the demography and structure of local tiger populations, which test the impact of realistic CDV exposure parameters (Gilbert et al, 2014(Gilbert et al, , 2020.…”