Pathological findings in 61 free-ranging leopards (Panthera pardus) from the Greater Kruger National Park, South Africa. Part One : parasites

Abstract

The Kruger National Park and surrounding protected areas in South Africa are home to a core unmanaged population of approximately 1,200 free-ranging leopards (Panthera pardus). Leopard populations outside of protected areas are in decline due to trophy hunting, habitat fragmentation and human-wildlife conflict. Apart from single descriptions of parasites detected by faecal or necropsy examinations and serology, very little information is available on parasitic conditions in free-ranging leopards. This paper provides baseline information on parasites in free-ranging leopards that may be relevant to the management of threatened populations of leopards outside of the Greater Kruger National Park (GKNP). Opportunistic field necropsies with routine histological examination of formalin-fixed tissues and, where possible, identification of helminths preserved in ethanol or by histology were performed on 61 free-ranging leopards in the GKNP between 1998 and 2023 for long-term disease monitoring. Most (52/61, 85%) of these leopards were euthanized because they attacked or killed a person or had severe traumatic injuries or disease. Five leopards died during anaesthesia performed to evaluate traumatic injuries or tuberculosis status. Three animals died naturally due to traumatic injuries and one due to electrocution on an electric fence. Parasitic disease was seen in similar numbers of males (n = 29) and females (n = 23) and in animals ranging from 1 to 16 years old. Common conditions included myocardial hepatozoonosis (34/61, 56%), gastroduodenitis due to Cylicospirura pardalis (31/61, 51%), verminous pneumonia attributed to metastrongyles (14/61, 23%) and skeletal muscle sarcocystosis (17/61, 28%). Single cases of infestation with Dirofilaria sudanensis, Armillifer armillatus and Linguatula serrata were recorded. In the majority of these free-ranging leopards, even heavy parasitic infestations were associated with minimal inflammation and were likely subclinical. However, two leopards had gastric outflow obstruction due to C. pardalis lesions, two had severe mange and one had severe myocarditis due to hepatozoonosis, which may have significantly affected the health of the affected animals. The factors that trigger the transformation of common subclinical parasitic conditions to potentially life-threatening disease require further elucidation.