Rift Valley Fever during Rainy Seasons, Madagascar, 2008 and 2009

The virus reemerged during an outbreak in Madagascar in 2008

Crimean-Congo hemorrhagic fever serosurvey in at-risk professionals, Madagascar, 2008 and 2009

International audienceBackground: Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic arboviral infection with hemorrhagic manifestation and often a fatal ending. Human become infected mainly through tick bite or by crushing infected tick, by contact with blood or tissues from viraemic livestock or patient. CCHF virus (CCHFV) has been isolated once in Madagascar but data on the epidemiology of the disease in the country are very scarce. Objectives: To investigate the circulation and the geographic distribution of CCHFV infection among at risk population in Madagascar. Study design: A national cross-sectional serologic survey was performed in 2008–2009 among slaughterhouse workers. Results: A total of 1995 workers were included. A recent CCHFV infection was detected in 1 of the 1995 participants (0.5‰; 95% confidence interval [CI]: 0–0.15%), and a past CCHFV infection was detected in 15 participants (0.75%; 95% CI: 0.37–1.13%). Conclusion: Overall, the percentage of CCHFV infection seen in Madagascar among at-risk professionals is very low compared to endemic countries. An assessment of the prevalence in livestock as a sensitive indicator of CCHFV activity must be considered in order to confirm the lack or the weak endemicity of CCHF in Madagascar

Dried-Blood Spots: A Cost-Effective Field Method for the Detection of Chikungunya Virus Circulation in Remote Areas

<div><p>Background</p><p>In 2005, there were outbreaks of febrile polyarthritis due to Chikungunya virus (CHIKV) in the Comoros Islands. CHIKV then spread to other islands in the Indian Ocean: La Réunion, Mauritius, Seychelles and Madagascar. These outbreaks revealed the lack of surveillance and preparedness of Madagascar and other countries. Thus, it was decided in 2007 to establish a syndrome-based surveillance network to monitor dengue-like illness.</p><p>Objective</p><p>This study aims to evaluate the use of capillary blood samples blotted on filter papers for molecular diagnosis of CHIKV infection. Venous blood samples can be difficult to obtain and the shipment of serum in appropriate temperature conditions is too costly for most developing countries.</p><p>Methodology and principal findings</p><p>Venous blood and dried-blood blotted on filter paper (DBFP) were collected during the last CHIKV outbreak in Madagascar (2010) and as part of our routine surveillance of dengue-like illness. All samples were tested by real-time RT-PCR and results with serum and DBFP samples were compared for each patient. The sensitivity and specificity of tests performed with DBFP, relative to those with venous samples (defined as 100%) were 93.1% (95% CI:[84.7–97.7]) and 94.4% (95% CI:[88.3–97.7]), respectively. The Kappa coefficient 0.87 (95% CI:[0.80–0.94]) was excellent.</p><p>Conclusion</p><p>This study shows that DBFP specimens can be used as a cost-effective alternative sampling method for the surveillance and monitoring of CHIKV circulation and emergence in developing countries, and probably also for other arboviruses. The loss of sensitivity is insignificant and involved a very small number of patients, all with low viral loads. Whether viruses can be isolated from dried blood spots remains to be determined.</p></div

Ct Differences in RNA amplification from 15 µl aliquots of whole blood and DBFP.

<p>Ct Differences in RNA amplification from 15 µl aliquots of whole blood and DBFP.</p

Primers and probes used in amplification of Chikungunya RNA as previously described by Laurent et al. 2007 [28] (modifications of primers are indicated in bold).

<p>Primers and probes used in amplification of Chikungunya RNA as previously described by Laurent et al. 2007 <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002339#pntd.0002339-Laurent1" target="_blank">[28]</a> (modifications of primers are indicated in bold).</p

Sensitivity and specificity of test performed on DBFP for the diagnosis of Chikungunya virus infection^a.

a<p>Sensitivity, 93.1% (68/73, (95% CI:[84.7–97.7]); specificity, 94.4% (102/108, (95% CI:[88.3–97.7]); Kappa coefficient, 0.87 (95% CI:[0.80–0.94]).</p

Absence of Rift Valley Fever Virus in Wild Small Mammals, Madagascar

International audienceRift Valley fever virus (RVFV) is a mosquito-borne zoonotic virus in the family Bunyaviridae, genus Phlebovirus, which affects mainly domestic ruminants and humans on continental Africa, Madagascar, and the Arabian Peninsula (1). RVFV is transmitted between ruminants mainly by bites of mosquitoes of several genera (1). Infection can lead to mild symptoms or can cause abortion in pregnant animals and high mortality rates among newborns. Humans are mostly infected by aerosol transmission when handling infected tissues (aborted fetuses or meat), which results in dengue-like illness. Some cases in humans can be in a severe form (hemorrhagic fever and meningoencephalitis), which can be fatal

Human Exposure to Hantaviruses Associated with Rodents of the Murinae Subfamily, Madagascar

International audienceWe conducted a national human serologic study of a hantavirus detected in Madagascar rodents using a commercial kit and a new ELISA targeting the virus. Our results suggest a conservative estimate of 2.7% (46/1,680) IgG seroprevalence. A second single-district study using the new ELISA revealed a higher prevalence (7.2%; 10/139)

An Entomological Investigation during a Recent Rift Valley Fever Epizootic/Epidemic Reveals New Aspects of the Vectorial Transmission of the Virus in Madagascar

A Rift Valley fever (RVF) outbreak occurred in at least five regions of Madagascar in 2021. The aim of this study was to provide an overview of the richness, abundance, ecology, and trophic preferences of mosquitoes in the Mananjary district and to investigate the distribution of mosquitoes that were RT-PCR-positive for RVFV. Three localities were prospected from 26 April to 4 May 2021, using light traps, BG-Sentinel traps baited with an artificial human odor, Muirhead-Thomson pit traps, and indoor pyrethroid spray catches. A total of 2806 mosquitoes belonging to at least 26 species were collected. Of 512 monospecific pools of mosquitoes tested with real-time RT-PCR, RVFV was detected in 37 pools representing 10 mosquito species. The RVFV-positive species were as follows: Aedes albopictus, Ae. argenteopunctatus, Anopheles coustani, An. gambiae s.l., An. mascarensis, An. squamosus/cydippis, Culex antennatus, Cx. decens, Cx. Tritaeniorhynchus, and Uranotaenia spp. Of the 450 tested engorged females, 78.7% had taken a blood meal on humans, 92.9% on cattle, and 71.6% had taken mixed (human–cattle) blood meals. This investigation suggests the potential role of mosquitoes in RVFV transmission within this epizootic/epidemic context and that the human populations at the three study sites were highly exposed to mosquitoes. Therefore, the use of impregnated mosquito nets as an appropriate prevention method is recommended