Reemerging/Notifiable Diseases to Watch.

Reemerging and notifiable diseases of cattle and bison continue to pose potential risks to their health and lives and affecting production and the livelihoods of producers. It is essential to understand the clinical presentation of these diseases to watch for possible incursions and infections and to immediately report your suspicions to your State and Federal Animal Health Officials. Three of these reemerging and notifiable diseases of cattle and bison, malignant catarrhal fever, bluetongue virus, and New World screwworm, are presented in this article for increased awareness to consider as a differential if examinations present suggestive clinical signs.

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.

Foot-and-mouth disease in North American bison (Bison bison) and elk (Cervus elaphus nelsoni): susceptibility, intra- and interspecies transmission, clinical signs, and lesions.

There is limited information about the pathogenesis and epidemiology of foot-and-mouth 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.

Evaluation of risk factors for the spread of low pathogenicity H7N2 avian influenza virus among commercial poultry farms.

OBJECTIVE: To identify risk factors associated with the spread of low pathogenicity H7N2 avian influenza (AI) virus among commercial poultry farms in western Virginia during an outbreak in 2002. DESIGN: Case-control study. PROCEDURE: Questionnaires were used to collect information about farm characteristics, biosecurity measures, and husbandry practices on 151 infected premises (128 turkey and 23 chicken farms) and 199 noninfected premises (167 turkey and 32 chicken farms). RESULTS: The most significant risk factor for AI infection was disposal of dead birds by rendering (odds ratio [OR], 73). In addition, age > or = 10 weeks (OR for birds aged 10 to 19 weeks, 4.9; OR for birds aged > or = 20 weeks, 4.3) was a significant risk factor regardless of poultry species involved. Other significant risk factors included use of nonfamily caretakers and the presence of mammalian wildlife on the farm. Factors that were not significantly associated with infection included use of various routine biosecurity measures, food and litter sources, types of domestic animals on the premises, and presence of wild birds on the premises. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that an important factor contributing to rapid early spread of AI virus infection among commercial poultry farms during this outbreak was disposal of dead birds via rendering off-farm. Because of the highly infectious nature of AI virus and the devastating economic impact of outbreaks, poultry farmers should consider carcass disposal techniques that do not require off-farm movement, such as burial, composting, or incineration.