Seroprevalence of Yellow Fever Virus in Selected Health Facilities in Western Kenya from 2010 to 2012

Abstract

SUMMARY: Yellow fever (YF), which is caused by a mosquito-borne virus, is an important viral hemorrhagic fever endemic in equatorial Africa and South America. Yellow fever virus (YFV) is the prototype of the family Flaviviridae and genus Flavivirus. The aim of this study was to determine the seroprevalence of YFV in selected health facilities in Western Kenya during the period 2010-2012. A total of 469 serum samples from febrile patients were tested for YFV antibodies using in-house IgM-capture ELISA, in-house indirect IgG ELISA, and 50z focus reduction neutralization test (FRNT 50 ). The present study did not identify any IgM ELISA-positive cases, indicating absence of recent YFV infection in the area. Twenty-eight samples (6z) tested positive for YFV IgG, because of either YFV vaccination or past exposure to various flaviviruses including YFV. Five cases were confirmed by FRNT 50 ; of these, 4 were either vaccination or natural infection during the YF outbreak in 1992-1993 or another period and 1 case was confirmed as a West Nile virus infection. Domestication and routine performance of arboviral differential diagnosis will help to address the phenomenon of pyrexia of unknown origin, contribute to arboviral research in developing countries, and enhance regular surveillance.Yellow fever (YF), a disease caused by mosquitoborne virus, is an important viral hemorrhagic fever endemic in equatorial Africa and South America (1,2). Yellow fever virus (YFV) is the prototype of the family Flaviviridae and genus Flavivirus (3). The genus Flavivirus contains approximately 70 viruses including YFV, dengue viruses (DENVs), Japanese encephalitis virus (JEV), and West Nile virus (WNV) that are of major human public health concern (4). An estimated annual incidence of 200,000 cases of YF causing 30,000 deaths is reported each affected individuals without treatment (4,5). In the eastern African region, YF outbreaks have been reported in Kenya (1992-1993) (6,7), South Sudan (2003, Uganda (2010-2011) (10), Sudan (2012) (11), and Ethiopia (2013) (12).YF cases are difficult to diagnose from the clinical symptoms in the early stages of the illness because of`n on-specific influenza-like symptoms'' that are similar to those of other febrile illnesses. Differential diagnoses may include malaria, viral hepatitis, dengue, leptospirosis, or other hemorrhagic fevers (13). WHO recommends case definition for suspected YF as``any case presenting with acute onset of fever, with jaundice appearing within 14 days after the onset of the first symptoms'' (14). The aim of this study was to determine the seroprevalence of YFV in selected health facilities in Western Kenya during the period 2010-2012.A total of 469 human whole blood samples were collected from the following healthcare facilities in Kenya: Andersen Medical Centre (AMC), Endebess Sub District Hospital (END), and Kitale District Hospital (KDH) in Trans Nzoia County; Centre for Infectious and Parasitic Diseases Control Research, Kenya Medical Research Institute (KEMRI) clinic (CIP) lo...

Community-based sero-prevalence of chikungunya and yellow fever in the South Omo Valley of Southern Ethiopia

“…However, the observed overall sero-prevalence (49.5%) of IgG antibody against YFV was low compared to the results of other sero-prevalence studies conducted in YF vaccinated populations in Sudan [32], Brazil [33] and other country [34]. On the other hand, the sero-prevalence against YFV in our study was still higher than the national pooled sero-prevalence of Ethiopia [35] and Western Kenya [19]. These geographic based https://doi.org/10.1371/journal.pntd.0008549.g003…”

“…CHIK outbreaks have been reported from many African countries including Uganda [ 13 ], Kenya [ 14 – 16 ], Sudan [ 17 ] and Tanzania [ 18 ]. Despite the proximity of Ethiopia to these countries, and migration of people across the border between Ethiopia and contingent countries as well as the existence of the potential mosquito vectors ( Aedes bromeliae and Aedes aegypti ) responsible for transmitting CHIKV in the study area [ 9 ], and the repeatedly occurrence of CHIK outbreaks in Kenya [ 14 – 16 , 19 , 20 ], either health facility or community-based survey of CHIKV infection has not been conducted in the present study area.…”

Seroprevalence of yellow fever, dengue, West Nile and chikungunya viruses in children in Teso South Sub-County, Western Kenya

“…We recorded lower YFV seroprevalence than previously reported in children by Kwallah et al (2015), similar to the rates reported in children (Sutherland et al, 2011) and in adults in Western Kenya (Mease et al, 2011;Kwallah et al, 2015) and higher than an earlier study (Geser et al, 1970). The YFV seroprevalence of 0.5% by PRNT in the present study is higher than that in one earlier study (Geser et al, 1970), but lower than that in another (Kwallah et al, 2015). The rates reported in current studies may mean that YFV is spreading locally.…”

“…The differences seen in these studies may be attributed to the different detection methods used at the time (Geser et al, 1970;Vu et al, 2017), different time periods (Geser et al,1970;Vu et al, 2017), different climatic conditions or geographic regions (Kwallah et al, 2015;Mease et al, 2011;Vu et al, 2017), or different environmental, vector, andhost dynamics (Grossi-Soyster et al, 2017;Ngugi et al, 2017;Ndenga et al, 2017;Mwongula et al, 2013;Awando et al, 2013;Kwallah et al, 2015;Ochieng et al, 2015;Vu et al, 2017).…”

Seroprevalence of chikungunya fever virus and O’nyong Nyong fever virus among febrile patients visiting selected hospitals in 2011-2012 Trans Nzoia County, Kenya

“…9 Recent studies conducted in Western Kenya show that Arboviruses are circulating. [10][11][12] ONNV was initially isolated in Northern Uganda from anopheline mosquitoes and human serum during a 1959 epidemic. 13 During 1959-1962, there was an outbreak of ONNV fever that began in northern Uganda and involved an estimated 2 million people in Kenya, Tanzania, and Uganda.…”