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PCR screening of 1,482 murid rodents from 13 genera caught in 18 different localities of Guinea, West Africa, showed Lassa virus infection only in molecularly typed Mastomys natalensis. Distribution of this rodent and relative abundance compared with M. erythroleucus correlates geographically with Lassa virus seroprevalence in humans.

A survey conducted by UNHCR in 2009 in IDP camps in North Kivu shows that access to land is the second factor after security which prevents people from returning to their zone of origin.

Context: Novel antimalarial agents are in demand due to the emergence of multidrug resistant strains. Ginseng, a medicinal plant with antiparasitic activity, contains components that can be used to treat the tropical disease malaria. Objective: Ginsenosides and polysaccharides are active components of ginseng. This study aimed to elucidate the ability of these compounds to inhibit the replication of Plasmodium yoelii in an attempt to determine whether the medicinal uses of ginseng are supported by pharmacological effects. New antimalarial compounds may be developed from ginsenosides and water-soluble ginseng polysaccharides (WGP). Materials and methods: Ginsenosides and ginseng polysaccharides were prepared from ginseng. Antimalarial activities were examined by 4-day tests and repository tests. Macrophage phagocytosis was tested in normal and malaria-bearing mice. Results: Ginseng polysaccharides could inhibit residual malaria infection. After a 6-day treatment, the parasitemia reductions of WGP and acidic ginseng polysaccharide (WGPA) were 55.66% and 64.73% at 200 mg/kg/day, respectively. Ginsenosides showed significant antimalarial activity on early infection. Protopanaxadiol-type ginsenosides caused 70.97% chemosuppression at 50 mg/kg/day, higher than 52.8% of total ginsenosides at the same dose. Discussion and conclusion: Protopanaxadiol-type ginsenosides have remarkably suppressive activity during early infection, while acidic ginseng polysaccharides have significant prophylactic activity against malaria by stimulating the immune system. We propose that the activity of ginsenosides is dependent upon non-specific carbohydrate interactions and that the activity of ginseng polysaccharides is due to immunological modulation. Ginsenosides and ginseng polysaccharides might have a potential application in antimalarial treatments. [ABSTRACT FROM AUTHOR]

Based on empiric surveillance data, the incidence of human Lassa fever (LF) cases in Guinea and other West African countries has been reported to increase during the dry season compared to the rainy season. To investigate possible links with the ecology of the rodent reservoir of the virus, we conducted a 2-year longitudinal survey of Mastomys natalensisin a region of high human Lassa virus (LASV) seropositivity in Guinea. Standardized rodent trapping with similar trapping efforts between seasons was performed in three villages and 53.5 (6011123) of the animals were identified as M. natalensisusing morphometric and molecular criteria. Mean trapping success (TS) of M. natalensiswas always higher inside houses than in proximal cultivations. In the dry season, mean TS increased 2-fold inside houses and decreased up to 10-fold outside (p< 0.0001), suggesting aggregation of rodents inside houses due to restricted food supply. 14.5 (80553) of M. natalensiswere tested positive for Lassa virus by reverse transcription-polymerase chain reaction (RT-PCR; range, 5–30) and prevalence of the virus was two to three times higher in rodents captured in the rainy season than in the dry season (p< 0.05). Inside houses, however, the LASV prevalence fluctuated nonsignificantly with season. These data suggest that in Guinea the risk of LASV transmission from rodents to humans is present both in the rainy and the dry season, reflected by the occurrence of LF cases throughout the year. In the dry season, however, the increased risk of humans encountering Mastomysand their excreta inside of houses may result in an increase of human Lassa fever cases. [ABSTRACT FROM AUTHOR]