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.

Keywords: CDV; Panthera pardus; Panthera tigris; canine distemper virus; leopard; serology; serum neutralization test; tiger.

Figure 1

Geographic distribution of samples and results. The locations of tiger and leopard samples are marked by squares (seropositive = red, seronegative = blue) and circles (seropositive = black, seronegative = white), respectively. Unsampled sick leopards are indicated using pink circles. Protected areas are shaded in green (Nepal) and tan (India). In Nepal, these include: Shuklaphanta National Park (ShNP), Bardia–Banke Complex (BBC), Annapurna Conservation Area (ACA), Chitwan–Parsa Complex (CPC) and Koshi Thappu Wildlife Reserve (KTWR). Indian protected areas include: Dudwha Tiger Reserve (DTR), Katarniaghat Tiger Reserve (KTR) and Valmiki Tiger Reserve (VTR). The cities of Kathmandu (KTM) and Pokhara (PKR) are indicated by yellow diamonds.

Figure 2

Images illustrating clinical findings for leopard Pp17. (a) Prior to anesthetic, in lateral recumbency (prior to drug administration). The left eye (which appears to the right of this image) is markedly enlarged, and the pupil is dilated. The right eye is normal size but appears cloudy. (b) In lateral recumbency under general anesthetic. There is poor body condition, which is more pronounced over the hindlimbs where there is accompanying muscle wastage. (c) The footpads of Pp17, the skin appears darker and thicker. (d) Normal footpads from another leopard, included for comparison.