Rift Valley fever in Nigeria: infections in humans

Olaleye, O.D.; Tomori, Oyewale; Ladipo, M A; Schmitz, Hans

doi:10.20506/rst.15.3.967

Cited by 33 publications

(19 citation statements)

References 14 publications

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“…This finding affirms our previous report, which highlighted IEP transmission of RVF in livestock [12]. Inter-epidemic sero-positivity to RVF in people has also been previously documented in other parts of Tanzania and Africa [13, 14, 16, 29], with IgM antibodies detected in Nigeria and Chad [14, 29]. The observed sero-prevalence by inhibition ELISA (11.7%) in this study is high compared to studies from other parts of Tanzania during inter-epidemic period with sero-prevalence of 5.2% and 4% in Mbeya and Tanga regions respectively [13, 19], possibly as a result of our sampling of participants from hotspots of RVF circulation in animals.…”

Section: Discussionsupporting

confidence: 92%

Inter-epidemic Acquisition of Rift Valley Fever Virus in Humans in Tanzania

et al. 2015

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BackgroundIn East Africa, epidemics of Rift Valley fever (RVF) occur in cycles of 5–15 years following unusually high rainfall. RVF transmission during inter-epidemic periods (IEP) generally passes undetected in absence of surveillance in mammalian hosts and vectors. We studied IEP transmission of RVF and evaluated the demographic, behavioural, occupational and spatial determinants of past RVF infection.MethodologyBetween March and August 2012 we collected blood samples, and administered a risk factor questionnaire among 606 inhabitants of 6 villages in the seasonally inundated Kilombero Valley, Tanzania. ELISA tests were used to detect RVFV IgM and IgG antibodies in serum samples. Risk factors were examined by mixed effects logistic regression.FindingsRVF virus IgM antibodies, indicating recent RVFV acquisition, were detected in 16 participants, representing 2.6% overall and in 22.5% of inhibition ELISA positives (n = 71). Four of 16 (25.0%) IgM positives and 11/71 (15.5%) of individuals with inhibition ELISA sero-positivity reported they had had no previous contact with host animals. Sero-positivity on inhibition ELISA was 11.7% (95% CI 9.2–14.5) and risk was elevated with age (odds ratio (OR) 1.03 per year; 95% CI 1.01–1.04), among milkers (OR 2.19; 95% CI 1.23–3.91), and individuals eating raw meat (OR 4.17; 95% CI 1.18–14.66). Households keeping livestock had a higher probability of having members with evidence of past infection (OR = 3.04, 95% CI = 1.42–6.48) than those that do not keep livestock.ConclusionThere is inter-epidemic acquisition of RVFV in Kilombero Valley inhabitants. In the wake of declining malaria incidence, these findings underscore the need for clinicians to consider RVF in the differential diagnosis for febrile illnesses. Several types of direct contact with livestock are important risk factors for past infection with RVFV in this study’s population. However, at least part of RVFV transmission appears to have occurred through bites of infected mosquitoes.

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Section: Discussionsupporting

confidence: 92%

Inter-epidemic Acquisition of Rift Valley Fever Virus in Humans in Tanzania

et al. 2015

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“…The antibody prevalence observed in this study is in agreement with the results of a surveillance study carried out in the 1980s, when 14.8% of the sera collected in more than 30 locations throughout Nigeria were found to be positive for a hemagglutination-inhibiting antibody against RVFV. 11 In this study a significant difference in the prevalence of antibodies was observed (RVFV rNP-ELISA [14.1%], LASV rNP-ELISA [7.4%] and CCHFV rNP-ELISA [2.4%]), and the highest prevalence was noted for RVFV rNP-ELISA antibody. In addition, more than 12% of the samples tested had NAb activity against RVFV.…”

Section: Discussionmentioning

confidence: 61%

“…In addition, serological studies conducted on human sera have confirmed the existence of the disease in Nigeria. 11 The specific geographical location of Borno State in northeastern Nigeria, which shares international borders with three other African countries (Cameroun, Chad and Niger), makes it vulnerable to the transboundary spread of various diseases, including viral hemorrhagic fevers (VHFs). In addition, Borno State has been reported as the niche for Lassa fever virus (LASV) and possibly other VHFs.…”

Section: Introductionmentioning

confidence: 99%

Development and validation of serological assays for viral hemorrhagic fevers and determination of the prevalence of Rift Valley fever in Borno State, Nigeria

Bukbuk

Fukushi

Tani

et al. 2014

Transactions of the Royal Society of Tropical Medicine and Hygiene

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“…59 In the patients with encephalitis, cerebrospinal fluid may be tested for locally produced IgM. The most popular method of laboratory diagnosis uses serology to detect antibodies, either IgM antibodies in a single serum sample, or a rising titre of IgG antibody in acute and convalescent serum samples.…”

Section: Diagnosismentioning

confidence: 99%