Spectrum of Rift Valley Fever Virus Transmission in Kenya: Insights From Three Distinct Regions

LaBeaud, A. Desirée; Ochiai, Yusuke; Peters, C. J.; Muchiri, Eric M.; King, Charles H.

doi:10.4269/ajtmh.2007.76.795

Cited by 75 publications

(91 citation statements)

References 25 publications

(38 reference statements)

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“…This level of community seropositivity was high and comparable with rates found in previous serosurveys of communities in more arid regions of Garissa County and Turkana Province (Table 1). 12,13 In this Bodhei sample, there were significant differences in seropositivity rates between males (25%) and females (11%) and between adults (28%) and children (3%) ( Table 2). The youngest seropositive subject was 3 years old, and the oldest seropositive subject was 76 years old.…”

Section: Resultsmentioning

confidence: 99%

“…Specimens were screened for the presence of anti-RVF IgG by ELISA using lysates of Vero cells infected with the MP-12 strain (vaccine strain) of RVFV as the test antigen and lysates of mock-infected cells as the internal control antigen. This ELISA was established and validated in previous studies by LaBeaud and others 13 and Niklasson and others. 14 Serum samples diluted 1:100 were read at 405 nm, and those scoring an optical density (OD) value greater than the mean + 2 SDs of the values for negative control sera were deemed positive.…”

Section: Methodsmentioning

confidence: 99%

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

Muiruri¹,

Kabiru²,

Muchiri³

et al. 2015

The American Society of Tropical Medicine and Hygiene

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Abstract. Few studies have focused on Rift Valley fever virus (RVFV) transmission in less arid, transitional landscapes surrounding known high-risk regions. The objective of this study was to identify evidence of RVFV exposure in Bodhei Village in a forested area at the edge of the RVFV-epidemic Garissa region. In a household cluster-based survey conducted between epidemics in early 2006, 211 participants were enrolled. Overall seroprevalence for anti-RVFV was high (18%) and comparable with rates in the more arid, dense brush regions farther north. Seroprevalence of adults was 28%, whereas that of children was significantly lower (3%; P 0.001); the youngest positive child was age 3 years. Males were more likely to be seropositive than females (25% versus 11%; P 0.01), and animal husbandry activities (birthing, sheltering, and butchering) were strongly associated with seropositivity. The results confirm that significant RVFV transmission occurs outside of recognized high-risk areas and independent of known epidemic periods.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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

Muiruri¹,

Kabiru²,

Muchiri³

et al. 2015

The American Society of Tropical Medicine and Hygiene

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“…3,4 In East Africa, RVF is mainly noted in arid and semi-arid areas as sudden, dramatic epidemics of the disease at intervals of approximately 10 years, associated with widespread flooding and the resultant swarms of mosquitoes. [5][6][7][8][9] In late 2006 through early 2007, following a period of heavier than usual rainfall and widespread flooding, an outbreak of RVF occurred in East Africa.…”

Section: Introductionmentioning

confidence: 99%

Epidemiological Assessment of the Rift Valley Fever Outbreak in Kenya and Tanzania in 2006 and 2007

Jost

Nzietchueng²,

Kihu³

et al. 2010

The American Journal of Tropical Medicine and Hygiene

105

125

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Abstract. To capture lessons from the 2007 Rift Valley fever (RVF) outbreak, epidemiological studies were carried out in Kenya and Tanzania. Somali pastoralists proved to be adept at recognizing symptoms of RVF and risk factors such as heavy rainfall and mosquito swarms. Sandik, which means "bloody nose," was used by Somalis to denote disease consistent with RVF. Somalis reported that sandik was previously seen in 1997/98, the period of the last RVF epidemic. Pastoralists communicated valuable epidemiological information for surveillance and early warning systems that was observed before international warnings. The results indicate that an all or none approach to decision making contributed to the delay in response. In the future, a phased approach balancing actions against increasing risk of an outbreak would be more effective. Given the time required to mobilize large vaccine stocks, emergency vaccination did not contribute to the mitigation of explosive outbreaks of RVF.* Address correspondence to Christine C. Jost, International Livestock Research Institute, P.O. Box 30709, Nairobi, 00100 Kenya. E-mail: c.jost@cgiar.org 66 JOST AND OTHERS approach, participants were asked to focus on the period when the RVF outbreak was observed and to divide the individual piles of counters previously used to rank the livestock species by numbers into two sub-groups: those that developed RVF and those that did not. For those that had RVF, the counters were further subdivided into the proportion that died and the proportion that recovered. This method provided an estimate of the incidence of RVF in each species during the outbreak, as well as the outbreak case fatality rates and the overall mortality rate during the outbreak.Abortions attributable to RVF. Using the results of the proportional piling exercise for the relative numbers of each livestock species as the starting point, participants were asked to allocate the counters into two groups in proportion to those livestock that were pregnant before the RVF outbreak and those that were not. For the pregnant group, participants next divided the counters in proportion to those animals that aborted because of RVF and those that carried their pregnancies to full term. The pregnant pile was then restored, and participants asked to divide the counters to represent the proportions that would have been expected to abort in a normal year (with no RVF outbreak) and those that would have carried to full term. Supplementary questioning probed the causes of abortion other than RVF.Disease impact matrix score. For each livestock species a matrix was constructed on the ground, with benefits derived from that species along the y axis and diseases on the x axis. Participants were given 100 counters and asked to allocate them among the livestock-associated benefits according to the relative importance of each benefit, with the most important benefit receiving the highest number of counters. The counters for each benefit were then sub-allocated to each disease to show the relative negative ...

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“…7 Limited surveillance efforts in the years between outbreaks suggest low-level endemic transmission even outside initial geographic outbreak boundaries. 2,[7][8][9] Many more diseases of arboviral origin have likely occurred but have gone unrecognized, especially in more remote locations.…”

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confidence: 99%

Serologic Evidence of Arboviral Infections among Humans in Kenya

Sutherland

Cash

Huang

et al. 2011

The American Society of Tropical Medicine and Hygiene

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Abstract. Outbreaks of arthropod-borne viral infections occur periodically across Kenya. However, limited surveillance takes place during interepidemic periods. Using serum samples obtained from asymptomatic persons across Kenya in 2000-2004, we assessed (by indirect immunofluorescent assay) prevalence of IgG against yellow fever virus (YFV), West Nile virus (WNV), tick-borne encephalitis virus (TBEV), dengue virus serotypes 1-4 (DENV1-4), and chikungunya virus (CHIKV). Older persons on the Indian Ocean coast were more likely to be seropositive than children inland: YFV = 42% versus 6%, WNV = 29% versus 6%, TBEV = 16% versus 6%, DENV-1 = 63% versus 9%, DENV-2 = 67% versus 7%, DENV-3 = 55% versus 6%, DENV-4 = 44% versus 8%, and CHIKV = 37% versus 20%. Among inland samples, children in lowlands were more likely to be seropositive for CHIKV (42% versus 0%) than children in highlands. In Kenya, transmission of arboviral infection continues between known epidemics and remains common across the country.

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Spectrum of Rift Valley Fever Virus Transmission in Kenya: Insights From Three Distinct Regions

Cited by 75 publications

References 25 publications

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

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

Epidemiological Assessment of the Rift Valley Fever Outbreak in Kenya and Tanzania in 2006 and 2007

Serologic Evidence of Arboviral Infections among Humans in Kenya

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