Helminth communities in murid rodents from southern and northern localities in Lao PDR: the role of habitat and season.

The helminth communities of wild murid rodents were investigated in Luang Prabang and Champasak province, Lao PDR. Thirteen species of rodents (404 individuals) were infected by 19 species of parasites (2 trematode, 3 cestode, 14 nematode species). Four of the recorded helminth species (Echinostoma malayanum, Raillietina sp., Hymenolepis diminuta and H. nana) are known to cause potential zoonotic helminthiases of medical importance in the South-East Asian region. Individual helminth infection was significantly higher in the wet season. Habitat significantly influenced individual helminth species richness and individual helminth abudance, with a decrease of individual helminth species richness and individual helminth abundance from forest habitat to agricultural and human settlement habitats. The reduction of helminth diversity and abundance is discussed in relation to the ongoing increase of human influence on habitats in Lao PDR.

Identifying factors associated with treatment delay in leptospirosis: A retrospective study of patients admitted to hospital in Reunion (Indian Ocean) between 2014 and 2015.

BACKGROUND: Leptospirosis is a life-threatening zoonotic disease for which delayed treatment onset has been associated to poor prognosis. The purpose of the study was to identify the determinants of therapeutic delay in hospitalized leptospirosis cases. PATIENTS AND METHODS: We carried out a retrospective multicenter study in the 4 public hospitals of Reunion Island, South Western Indian Ocean. Medical records of confirmed leptospirosis cases occurring in 2014-2015 were reviewed for socio-economic, demographic, geographic and medical data. The primary outcome measure was the therapeutic delay, defined as the time elapsed between the onset of symptoms and initiation of antibiotics. RESULTS: Of the 117 patients included, 107 were men, with an average age of 44.9±15years. The median therapeutic delay was 4 days (interquartile: 2-5 days) and this delay was not found to be associated with severity. The following were found to be at increased risk of having a longer therapeutic delay: cases occurring outside the epidemic period, or rainy season (OR 2.8 [1.08-7.3], P=0.04) and cases with first medical evaluation in primary health care (OR 4.63 [1.43-14.93]; P=0.01) instead of emergency unit. No socio-economic or geographic characteristics were found to be linked to a longer therapeutic delay. CONCLUSION: Although delayed treatment was not associated to disease severity, our results indicate that leptospirosis awareness is needed all year in the subtropical area of Reunion Island and particularly in primary care.

Molecular detection of divergent trypanosomes among rodents of Thailand.

Herpetosoma is a homogenous subgenus of several dozen named species that are often described as morphologically indistinguishable T. lewisi-like parasites. These trypanosomes normally infect rodents and utilize fleas as vectors. Although this trypanosome subgenus is considered non-pathogenic to normal hosts, some of them are on rare occasion reported in association with human disease. Recently, a T. lewisi-like infection was detected in a sick Thai infant, thus the objective of this study was to investigate the prevalence of T. lewisi infections among different rodents indigenous to Thailand in order to identify possible sources of human cases. Blood was collected from a total of 276 rodents trapped from urban and rural areas of three Thai provinces between 2006 and 2007. These samples were processed for DNA isolation and tested with a PCR assay universal for the genus Trypanosoma, followed by internal transcribed spacer 1 (ITS-1) sequence analysis to identify infections in positive samples. Herpetosoma known as T. lewisi-like trypanosomes were present among Rattus (14.3%) and Bandicota (18.0%) rodent species and salivarian trypanosomes closely related to T. evansi were detected in Leopoldamys (20%) and Rattus (2.0%) species. Herpetosoma were prevalent among rodents associated with both human and sylvatic habitats, while three of the four salivaria-positive rodents were from a forest biotope. A Herpetosoma ITS-1 sequence amplified from one of these samples was 97.9% identical to that reported for T. lewisi in an experimentally infected rat and 96.4% identical to the sequence amplified from blood from a Thai infant. Habitats where rodents were collected significantly affect rodent infection, at least for T. lewisi, suggesting that the degree of anthropization may influence the transmission of Trypanosoma spp. These results suggest that multiple Herpetosoma species or strains are enzootic to Thailand, and that Rattus and Bandicota species are possible sources of human exposure to these parasites.

Sizing up human health through remote sensing: uses and misuses.

Following the launch of new satellites, remote sensing (RS) has been increasingly implicated in human health research for thirty years, providing a growing availability of images with higher resolution and spectral ranges. However, the scope of applications, beyond theoretical large potentialities, appears limited both by their technical nature and the models developed. An exhaustive review of RS applications in human health highlights the real implication thus far regarding the diversity and range of health issues, remotely sensed data, processes and interpretations. The place of RS is far under its expected potential, revealing fundamental barriers in its implementation for health applications. The selection of images is done by practical considerations as trivial as price and availability, which are often not relevant to addressing health questions requiring suitable resolutions and spatio-temporal range. The relationships of environmental variables from RS, geospatial data from other sources for health investigations are poorly addressed and usually simplified. A discussion covering the potential of RS for human health is developed here to assist health scientists deal with spatial and temporal dynamics of health, by finding the most relevant data and analysis procedures.

Ebola virus circulation in Africa: a balance between clinical expression and epidemiological silence.

Nearly thirty years after the first epidemics, Ebola virus (EBOV) remains hardly described, its transmission unclear and its reservoir elusive. Soon after the Ebola fever outbreak and virus discovery in 1976 and in order to investigate the distribution of EBOV in Central Africa, several countries including a range of ecological zones were investigated in the early 1980s, using extensive survey: Central African Republic (CAR), Cameroon, Chad, Congo, Gabon and Equatorial Guinea. Since 1992, ELISA antibody test along with a RT-PCR have been used to detect specific virus antibodies and characterize viral RNA. The widely separated geographic locations of outbreaks have suggested that the reservoir and the transmission cycle of EBOV are probably closely associated with the rain forest ecosystem, what is supported by the distribution of antibodies. The fact that outbreaks seldom occur suggests the presence of a rare or ecologically isolated animal reservoir having few contacts with humans and non-human primates. However various serological investigations showed a high prevalence in humans without any pathology reported. This suggests a circulation of both pathogenic and non-pathogenic strains as well as more frequent contacts with man than expected, and could partially explain fifteen years of Ebola fever silence between the emergence and re-emergence of Ebola virus in the Congolese basin. Nowadays, largely enlightened by the study of recent epizootic and epidemic manifestations of EBOV in Gabon and neighboring countries, EBOV natural history starts to be understood as for the fundamentals of epizootic in non-human primates and chains of transmission.

Molecular demonstration of Trypanosoma evansi and Trypanosoma lewisi DNA in wild rodents from Cambodia, Lao PDR and Thailand.

In this study, we investigated the molecular evidence of Trypanosoma evansi in wild rodents from Cambodia, Lao PDR and Thailand. Between November 2007 and June 2009, 1664 rodents were trapped at eight sites representative of various ecological habitats. Of those animals, 94 were tested by direct microscopic blood examination, 633 using the Card Agglutination Test for Trypanosomes (CATT/T. evansi) and 145 by Polymerase Chain Reaction (PCR) with two sets of primers: TRYP1 (amplifying ITS1 of ribosomal DNA of all trypanosomes) and TBR (amplifying satellite genomic DNA of Trypanozoon parasites). Using TRYP1, based on the size of the PCR products, 15 samples from the three countries were positive for Trypanosoma lewisi (two were confirmed by sequencing), and three were positive for Trypanozoon (one was confirmed by sequencing and three by TBR primers); the specificity of the primers failed as rodent DNA was amplified in some cases. Using TBR, six samples were positive for Trypanozoon (one was confirmed by sequencing); as T. evansi is the only species of the Trypanozoon sub-genus possibly present in Asian rodents, these results confirmed its presence in rodents from Thailand (Rattus tanezumi) and Cambodia (R. tanezumi, Niviventer fulvescens & Maxomys surifer). Further investigations are necessary to establish the situation in Lao PDR. None of the 16 samples most strongly positive to the CATT proved to be positive for Trypanozoon by PCR. The merits of the CATT for such studies were not confirmed. Studying the urban and rural circulation of these parasites in rodents will enable an evaluation of human exposure and infection risk, as human infections by T. evansi were recently described in India and by T. lewisi in India and Thailand. As sequencing PCR products is expensive, the development of new molecular and serological tools for rodents would be very useful.