Foot-And-Mouth Disease In North American Bison (\u3ci\u3eBison Bison\u3c/i\u3e) And Elk (\u3ci\u3eCervus Elaphus Nelsoni\u3c/i\u3e): Susceptibility, Intra- And Interspecies Transmission, Clinical Signs, And Lesions

There is limited information about the pathogenesis and epidemiology of foot-andmouth disease (FMD) in North American bison (Bison bison) or elk (Cervus elaphus nelsoni). In these two experimental infection studies, we compared the susceptibilities of bison and elk to FMD virus (FMDV), respectively, with that of cattle; determined whether intra- and interspecies transmission could occur in bison and cattle, and elk and cattle; determined suitability of conventional available laboratory tests to detect FMDV infection in bison and elk; and investigated whether bison or elk are efficient long-term carriers of FMDV. In both studies, after a period of acclimation to the containment at Plum Island Animal Disease Center, animals were infected by intraepithelial tongue inoculation with 10,000 bovine tongue infective doses of FMDV, strain O1 Manisa. Inoculated animals were kept with contact animals; subsequently, inoculated and/or exposed contact animals were placed in rooms with unexposed animals. All bison developed oral mucosal and foot lesions similar to those of cattle. Bison developed fever, lameness, inappetence, and ptyalism. Physical examinations on bison revealed numerous small vesicles and erosions affecting tongue, gingiva, muzzle, hard and soft palates, coronary bands, and interdigital skin. Inoculated elk developed transient fever and mild focal tongue and foot lesions. Contact elk developed neither clinical signs nor gross pathologic lesions of FMD. At necropsy, lesions in bison included numerous extensive vesicles, erosions, and/or ulcers in the oral cavities, feet, and rumen pillars depending on the stage of disease. Less extensive oral, foot, and rumen lesions were present in the inoculated elk. All bison and inoculated elk developed antibodies to FMDV and were positive for FMDV by reverse transcription-polymerase chain reaction (RT-PCR). Transmission occurred between cattle and bison, and bison and bison. It did not occur between elk and cattle. Elk-to-elk transmission studies resulted in only one contact elk developing serologic evidence of a subclinical infection. Other exposed elk developed neither clinical, pathologic, virologic, nor serologic evidence of disease. FMDV was not isolated from animals past 28 days postinfection

Rift Valley Fever Outbreak in Livestock in Kenya, 2006–2007

We analyzed the extent of livestock involvement in the latest Rift Valley fever (RVF) outbreak in Kenya that started in December 2006 and continued until June 2007. When compared with previous RVF outbreaks in the country, the 2006–07 outbreak was the most extensive in cattle, sheep, goats, and camels affecting thousands of animals in 29 of 69 administrative districts across six of the eight provinces. This contrasted with the distribution of approximately 700 human RVF cases in the country, where over 85% of these cases were located in four districts; Garissa and Ijara districts in Northeastern Province, Baringo district in Rift Valley Province, and Kilifi district in Coast Province. Analysis of livestock and human data suggests that livestock infections occur before virus detection in humans, as supported by clustering of human RVF cases around livestock cases in Baringo district. The highest livestock morbidity and mortality rates were recorded in Garissa and Baringo districts, the same districts that recorded a high number of human cases. The districts that reported RVF in livestock for the first time in 2006/07 included Kitui, Tharaka, Meru South, Meru central, Mwingi, Embu, and Mbeere in Eastern Province, Malindi and Taita taveta in Coast Province, Kirinyaga and Murang'a in Central Province, and Baringo and Samburu in Rift Valley Province, indicating that the disease was occurring in new regions in the country