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

Abstract

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.

Cross-Sectional Survey of Rift Valley Fever Virus Exposure in Bodhei Village Located in a Transitional Coastal Forest Habitat in Lamu County, Kenya

“…7 Although in semiarid areas, blooms in mosquito numbers (caused by excess rainfall) play an important role in epidemic/enzootic transmission of RVFV to both humans and animals, much is still not known about the drivers of disease occurrence in other areas of Kenya. [8][9][10][11] For this study, we hypothesized that patterns of RVFV exposure and transmission in a more settled forested region (Bodhei) would prove different from those among seminomadic populations of more arid areas farther north who had been included in our previous surveys. 12 …”

Epidemiology and Emergence of Schmallenberg Virus Part 1: Origin, Transmission and Differential Diagnosis

“…Humans infect themselves through direct or indirect (aerosols) contact with blood, secretions or tissues of infected animals, which occurs in veterinary procedures (obstetrical manoeuvres, medical treatments), animal husbandry [75], slaughtering, consumption of raw milk and in food preparation. Another source of infection for humans and livestock is the infected blood sucking mosquitoes' vector [76].…”

“…In sheep, the most common symptoms are (highly susceptible) fever (40-41°C), inappetence, nasal discharge, incoordination, weakness, depression, bloody or fetid diarrhoea [76]. Newborn lambs are considered extremely susceptible, and the main symptoms are: sudden death, fever prior to death (40-42°C), weakness, depression, listless, abdominal pain, tachypnea, increased respiratory rate abdominal respiration prior to death [72].…”

Response to Rift Valley Fever in Tanzania: Challenges and Opportunities

“…Therefore, since independence Tanzania has recorded three epidemics, however the most notable one was in 2006/2007. The 1997 epidemic in East Africa occurred after exceptionally high precipitation (El Nino), which resulted in the death of at least 300 people and large numbers of animals in remote parts of Northern and southern Kenya and southern Somalia (Munyua et al, 2010;Shieh et al, 2010). However, in Tanzania it was mild and had little pathologic effect to livestock and was confined in the northern zone with no confirmed human cases.…”

“…In humans it is a febrile (38 to 39.5 O C) or influenza like illness that can be associated with, severe headaches, muscle and joint pains, anorexia, high respiration rate, vomiting, diarrhoea, hepatitis, jaundice, marked leucopoenia and extreme eye pain with sensitivity to light (photophobia). Few severe fatal haemorrhagic syndrome cases have occurred in humans as a consequence of hepatic necrosis, myocarditis, retinitis and/or encephalitis (Daubney et al, 1931;Harper, 2004;Mohammed et al, 2010;Munyua et al, 2010). In livestock the clinical signs include anorexia, high temperature (up to 40 O C), blood-stained nasal and lachrymal discharges, a high respiration rate, prostration, lateral recumbence with opisthotonous, respiratory distress and death (Davies & Martin, 2003).…”