Inter-epidemic Transmission of Rift Valley Fever in Livestock in the Kilombero River Valley, Tanzania: A Cross-Sectional Survey

Sumaye, Robert D.; Geubbels, Eveline; Mbeyela, Edgar; Berkvens, Dirk

doi:10.1371/journal.pntd.0002356

Cited by 87 publications

(126 citation statements)

References 47 publications

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“…Variation in seroprevelences between reports is described to be influenced by age of the animals, season of sampling, timing of sampling (during disease outbreak or during interepizootic), diagnostic test used, inter-mixing of animals under same husbandry practices, administrative localities of camel and virus maintenance and persistence of ecological factors. The sex of the animal was not statistically significantly associated with seropositivity in this study, and this is in agreement with the report of Sumaye et al (2013) and Ahmed et al (2011). However, a small proportion of males compared with females were sampled, which is likely to explain the observed sex-risk difference.…”

Section: Discussionsupporting

confidence: 93%

“…The current theory is that RVFV is maintained in aedine mosquito eggs and epidemics occur following an increase in the mosquito population after abnormally heavy rains (Tchouassi et al 2013), which occur classically every 10 years. Evidence of RVFV exposure has been shown to occur in African buffalo (Syncerus caffer) (Evans et al 2008;Bird et al 2008;LaBeaud et al 2011); giraffe (Giraffa camelopardalis) (Bird et al 2008), humans (Swai and Schoonman 2009;Pepin et al 2010;Heinrich et al 2012), cattle (Sumaye et al 2013) and in sheep (Rostal et al 2010;Fafetine et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Seroprevalence of Rift Valley fever virus infection in camels (dromedaries) in northern Tanzania

Swai

Sindato

2014

Trop Anim Health Prod

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Rift Valley fever (RVF) is an arthropod-borne viral zoonotic disease that affects a wide range of animals including sheep, goats, cattle, camels and humans. Camels have only recently been introduced into Tanzania and, as a result, there is no credible diseases status information concerning this population, estimated to be in the low hundreds. As part of a broader study on camel diseases in different localities of northern Tanzania, serum samples (n = 109) were collected from apparently healthy, non-vaccinated camels during the period June to August 2010 and tested for antibodies specific to RVF virus (RVFV) using the inhibition enzyme-linked immunosorbent assay (ELISA). Overall, herd and individual camel IgG seroprevalence was 78.5 % (11/14) and 27.5 % (30/109), respectively. IgG was found to be most prevalent in camels from Kilindi and Hai districts (45 %, each) and in introduced camels from other areas (37.1 %). The relationship between age and seropositivity showed that the seroprevalence was the highest (84.6 %) in age group of ≥10 years and lowest (11.9 %) in age group of ≤5 years.The results of this study reveal that evidence of camels being exposed to RVFV and that the risk of seropositivity varied according to district, being higher in Kilindi and Hai compared with other districts sampled. The risk of seropositivity increased with increasing animal age and the introduction of camels into the herd. Based on these study findings, continuous disease surveillance of camels for RVFV is indicated.

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Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Seroprevalence of Rift Valley fever virus infection in camels (dromedaries) in northern Tanzania

Swai

Sindato

2014

Trop Anim Health Prod

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“…This figure is close to the findings of 13.1% (n = 1396) seroprevalence reported in cattle in Ijara district, Kenya (Owange et al 2014). It was also high compared to the seroprevalence of 11.3% (n = 970) reported in cattle in the Kilombero river valley in Tanzania (Sumaye et al 2013), but lower than findings of 38.7% in cattle sampled from other areas in Tanzania (Chengula et al 2014). This variation could be because of the differences in sampling techniques, the diagnostic test used or the agro-ecological conditions.…”

Section: Discussionsupporting

confidence: 82%

Seroprevalence of Rift Valley fever in cattle along the Akagera-Nyabarongo rivers, Rwanda

Umuhoza

Berkvens

Gafarasi

et al. 2017

J. S. Afr. Vet. Assoc.

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Rift Valley fever (RVF) virus is caused by a zoonotic arbovirus that is endemic to eastern and southern Africa. It has also been reported in West and North Africa, Madagascar and the Arabian Peninsula. The virus is transmitted by mosquitoes, but people can also become infected while handling blood or other body fluids of animals and humans with RVF. In 2007, there was a large outbreak of RVF in Kenya, Tanzania, Sudan and Somalia. Outbreaks were also reported in South Africa in 2008–2011. The epidemiology of RVF and factors for disease occurrence in Rwanda are neither clear nor documented. Therefore, we conducted a crosssectional study from December 2012 to March 2013 to generate baseline information on RVF in cattle. Purposive sampling of cattle (n = 595) was done in six districts, and serum samples were screened with competitive enzyme-linked immunosorbent assay (ELISA). We performed a statistical analysis on the generated data, and risk factors associated with RVF seroprevalence were determined by a simple logistic regression. Overall, RVF seroprevalence was 16.8% (95% confidence interval [CI] [13.8% – 20.0%]). The highest seroprevalence was recorded in Kirehe district (36.9%) followed by Ngoma (22.3%), and the least was recorded in Nyagatare (7.9%). RVF was more likely to occur in adult cattle (19.9% [odds ratio {OR} = 1.88, 95% CI {0.98–3.61}]) compared to young cattle (10.5% [OR = 0.47, 95% CI {0.26–0.83}]). Pure exotic or cross-breeds were significantly exposed to RVF virus (seroprevalence 22.9% [OR = 4.26, 95% CI {1.82–9.99}]) in comparison to 14.1% (OR = 0.55, 95% CI [0.35–0.86]) in local breeds. Sex differences were not statistically significant. These findings indicated that cattle have been exposed to RVF virus in six districts in Rwanda with a significant risk in adult, exotic or cross-breeds in Kirehe district.

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“…Per year, more than 3000 live ruminants are imported from Tanzania (Chief Veterinary Officer of Comorian Vet services, personal communication), where RVF is endemic [34]. These animals enter the Union, mostly Grande Comore, without any quarantine or clinical examination.…”

Section: Discussionmentioning

confidence: 99%

Evidence for Circulation of the Rift Valley Fever Virus among Livestock in the Union of Comoros

et al. 2014

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Rift Valley fever virus (RVFV) is an arthropod-borne phlebovirus reported to be circulating in most parts of Africa. Since 2009, RVFV has been suspected of continuously circulating in the Union of Comoros. To estimate the incidence of RVFV antibody acquisition in the Comorian ruminant population, 191 young goats and cattle were selected in six distinct zones and sampled periodically from April 2010 to August 2011. We found an estimated incidence of RVFV antibody acquisition of 17.5% (95% confidence interval (CI): [8.9–26.1]) with a significant difference between islands (8.2% in Grande Comore, 72.3% in Moheli and 5.8% in Anjouan). Simultaneously, a longitudinal entomological survey was conducted and ruminant trade-related information was collected. No RVFV RNA was detected out of the 1,568 blood-sucking caught insects, including three potential vectors of RVFV mosquito species. Our trade survey suggests that there is a continuous flow of live animals from eastern Africa to the Union of Comoros and movements of ruminants between the three Comoro islands. Finally, a cross-sectional study was performed in August 2011 at the end of the follow-up. We found an estimated RVFV antibody prevalence of 19.3% (95% CI: [15.6%–23.0%]). Our findings suggest a complex RVFV epidemiological cycle in the Union of Comoros with probable inter-islands differences in RVFV circulation patterns. Moheli, and potentially Anjouan, appear to be acting as endemic reservoir of infection whereas RVFV persistence in Grande Comore could be correlated with trade in live animals with the eastern coast of Africa. More data are needed to estimate the real impact of the disease on human health and on the national economy.

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Inter-epidemic Transmission of Rift Valley Fever in Livestock in the Kilombero River Valley, Tanzania: A Cross-Sectional Survey

Cited by 87 publications

References 47 publications

Seroprevalence of Rift Valley fever virus infection in camels (dromedaries) in northern Tanzania

Seroprevalence of Rift Valley fever virus infection in camels (dromedaries) in northern Tanzania

Seroprevalence of Rift Valley fever in cattle along the Akagera-Nyabarongo rivers, Rwanda

Evidence for Circulation of the Rift Valley Fever Virus among Livestock in the Union of Comoros

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