Prevalence of brucellosis in livestock and incidences in humans in east Africa

Abstract

Brucellosis is an emerging zoonotic disease that poses a threat to both livestock and public health in east Africa. There are several reports of occurrence of the disease in livestock populations especially in Tanzania and Kenya, suggesting chances of increased spread to humans, and the disease being misdiagnosed for malaria. The objective of this study was to determine brucellosis prevalence in livestock and incidence in humans among pastoralists and agro-pastoralists communities in some areas of Kenya and Tanzania. A total of 2349 ruminants were screened using different serological techniques, in the selected areas. Serum samples from the Southern Highlands Zone (SHZ), Northern zone (NZ) and Eastern Zone (EZ) were screened using Rose Bengal Plate Test (RBPT) antigen, and later positive samples were confirmed using competitive enzyme linked immune-sorbent assay (c-ELISA). Results showed prevalence of 11.4% in the SHZ (n=799), 2.4% in the EZ (n=169) and 1% in the NZ (n= 408). Milk ring test was used to test milk samples from Migori, West Pokot and Mwingi, and the prevalences recorded in cattle were 17.9% (n=56) in 2012 and 11.7 (n=77) in 2014. Within the same period, West Pokot recorded prevalence of up to 21.9% (n=96) in cattle and 16.7% (n=6) in goats. Generally, Migori had lower prevalence in Kenya, but being the third lower in Tanzania and Kenya with the prevalence being 4.3% (n=70) in goats and 2.2% (n=45) in goats. Serum from cattle and goats were tested using compliment fixation test (CFT); showing 0.9% (n=212) prevalence in Migori. In West Pokot, the prevalence was 4.0% (n=101) in cattle, 20% (n=100) in goats and 13.8% (=29) in sheep; whereas in Mwingi prevalence was 4.75% (n=43) and 9.5% (n=21) in cattle and goats respectively. A total of 1,140 human cases were followed up in selected study areas where livestock samples were collected, and an overall incidence of 22.7% (n=1140) was confirmed. Selected areas in Tanzania had an incidence of 28.2% (n=578) and in Kenya 17.1% (n=562). Brucellosis is endemic in many areas of Tanzania and Kenya and pose a high risk to human health.

Key Words: Agro-pastoral, pastoral, public health