An Outbreak of Rift Valley Fever in Northeastern Kenya, 1997-98

Abstract

In December 1997, 170 hemorrhagic fever-associated deaths were reported in Carissa District, Kenya. Laboratory testing identified evidence of acute Rift Valley fever virus (RVFV). Of the 171 persons enrolled in a cross-sectional study, 31(18%) were anti-RVFV immunoglobulin (Ig) M positive. An age-adjusted IgM antibody prevalence of 14% was estimated for the district. We estimate approximately 27,500 infections occurred in Garissa District, making this the largest recorded outbreak of RVFV in East Africa. In multivariate analysis, contact with sheep body fluids and sheltering livestock in one’s home were significantly associated with infection. Direct contact with animals, particularly contact with sheep body fluids, was the most important modifiable risk factor for RVFV infection. Public education during epizootics may reduce human illness and deaths associated with future outbreaks.

Epidemiologic and Clinical Aspects of a Rift Valley Fever Outbreak in Humans in Tanzania, 2007

“…4 Outbreaks of RFV have been reported most frequently in East Africa, especially Kenya, Somalia, and Tanzania, with the last major outbreak in the region recorded in 1997-1998. 5 However, outbreaks have also been reported in other African countries including Egypt, South Africa, Madagascar, and Senegal. [6][7][8][9][10] In 2000, the first RVF outbreak outside of Africa was reported in Saudi Arabia and Yemen.…”

Prediction of a Rift Valley fever outbreak

“…Outbreaks of the disease are episodic and closely linked to climate variability, especially widespread elevated rainfall that facilitates Rift Valley fever (RVF) virus transmission by vector mosquitoes (1)(2)(3). A RVF outbreak in 1997-1998 was the largest documented outbreak in the Horn of Africa and involved 5 countries with a loss of Ϸ100,000 domestic animals, Ϸ90,000 human infections (4), and had a significant economic impact due to a ban on livestock exports from the region (5).…”

Bats as Potential Reservoir Hosts for Vector-Borne Diseases

“…However, RVF occurs not only in humans. Outbreaks can also result in devastating economic losses when livestock is infected (Woods et al 2002). In 1991, the virus was also isolated from bats in West Africa (Fontenille et al 1998).…”

“…RVFV can be transmitted into mosquito offspring transovarially (Ikegami and Makino 2011). Outbreaks of RVF are associated with heavy rainfalls during the El Niño/Southern Oscillation (ENSO) phenomenon WHO 2013a) because the floods create optimal breeding conditions (Bowen et al 2001;Fontenille et al 1998;Woods et al 2002). (Ikegami 2012;WHO 2013b).…”