Rift Valley Fever in Humans and Animals in Mayotte, an Endemic Situation?

Abstract

Retrospective studies and surveillance on humans and animals revealed that Rift Valley Fever virus (RVFV) has been circulating on Mayotte for at least several years. A study was conducted in 2011 to estimate the seroprevalence of RVF in humans and in animals and to identify associated risk factors. Using a multistage cluster sampling method, 1420 individuals were enrolled in the human study, including 337 children aged 5 to 14 years. For the animal study, 198 seronegative ruminants from 33 randomly selected sentinel ruminant herds were followed up for more than one year. In both studies, information on environment and risk factors was collected through a standardized questionnaire. The overall weighted seroprevalence of RVFV antibodies in the general population aged ≥5 years was 3.5% (95% CI 2.6–4.8). The overall seroprevalence of RVFV antibodies in the ruminant population was 25.3% (95% CI 19.8–32.2). Age (≥15), gender (men), place of birth on the Comoros, living in Mayotte since less than 5 years, low educational level, farming and living close to a water source were significantly associated with RVFV seropositivity in humans. Major risk factors for RFV infection in animals were the proximity of the farm to a water point, previous two-month rainfall and absence of abortions disposal. Although resulting in few clinical cases in humans and in animals, RVFV has been circulating actively on the island of Mayotte, in a context of regular import of the virus from nearby countries through illegal animal movements, the presence of susceptible animals and a favorable environment for mosquito vectors to maintain virus transmission locally. Humans and animals share the same ways of RVFV transmission, with mosquitoes playing an important role. The studies emphasize the need for a one health approach in which humans and animals within their ecosystems are included.

Risk factors associated with human Rift Valley fever infection: systematic review and meta‐analysis

“…; Lernout et al . ). The I 2 test result ( I 2 = 63.9%) suggested inconsistency in these studies' measures of association.…”

“…; Lernout et al . ) studies that investigated being male as a possible risk factor found a statistically significant association with RVF infection. ORs were available or able to be calculated for twelve of these thirteen studies, so twelve studies were included in a meta‐analysis (Jouan et al .…”

“…; Lernout et al . ) tested for RVFV IgG seroprevalence, an indication of non‐acute exposure. Older people will, by definition, have greater risk of past exposure than younger cohorts.…”

“…; Lernout et al . ) studies that examined slaughtering an animal found a statistically significant association with RVF infection. Five ORs for this association were included in a meta‐analysis (LaBeaud et al .…”

“…Six (LaBeaud et al 2007(LaBeaud et al , 2008(LaBeaud et al , 2011Anyangu et al 2010;Hassanain et al 2010;Pourrut et al 2010) of the 13 (Jouan et al 1989;Woods et al 2002;Marrama et al 2005;Swai & Schoonman 2009;Al-Azraqi et al 2012;Heinrich et al 2012;Lernout et al 2013) studies that investigated being male as a possible risk factor found a statistically significant association with RVF infection. ORs were available or able to be calculated for twelve of these thirteen studies, so twelve studies were included in a meta-analysis (Jouan et al 1989;Woods et al 2002;Marrama et al 2005;LaBeaud et al 2007LaBeaud et al , 2008LaBeaud et al , 2011Swai & Schoonman 2009;Anyangu et al 2010;Hassanain et al 2010;Pourrut et al 2010;Al-Azraqi et al 2012;Lernout et al 2013). The I 2 test result (I 2 = 63.9%) suggested inconsistency in these studies' measures of association.…”