Molecular characterization of two hantavirus strains from different rattus species in Singapore

<p>Abstract</p> <p>Background</p> <p>Hantaviruses cause human disease in endemic regions around the world. Outbreaks of hantaviral diseases have been associated with changes in rodent population density and adaptation to human settlements leading to their proliferation in close proximity to human dwellings. In a parallel study initiated to determine the prevalence of pathogens in Singapore's wild rodent population, 1206 rodents were trapped and screened. The findings established a hantavirus seroprevalence of 34%. This paper describes the molecular characterization of hantaviruses from <it>Rattus norvegicus </it>and <it>Rattus tanezumi</it>, the predominant rodents caught in urban Singapore.</p> <p>Methodology</p> <p>Pan-hanta RT-PCR performed on samples of <it>Rattus norvegicus </it>and <it>Rattus tanezumi </it>indicated that 27 (2.24%) of the animals were positive. sequence analysis of the S and M segments established that two different hantavirus strains circulate in the rodent population of Singapore. Notably, the hantavirus strains found in <it>Rattus norvegicus </it>clusters with other Asian Seoul virus sequences, while the virus strains found in <it>Rattus tanezumi </it>had the highest sequence similarity to the Serang virus from <it>Rattus tanezumi </it>in Indonesia, followed by Cambodian hantavirus isolates and the Thailand virus isolated from <it>Bandicota indica</it>.</p> <p>Conclusions</p> <p>Sequence analysis of the S and M segments of hantavirus strains found in <it>Rattus norvegicus </it>(Seoul virus strain Singapore) and <it>Rattus tanezumi </it>(Serang virus strain Jurong TJK/06) revealed that two genetically different hantavirus strains were found in rodents of Singapore. Evidently, together with Serang, Cambodian and Thailand virus the Jurong virus forms a distinct phylogroup. Interestingly, these highly similar virus strains have been identified in different rodent hosts. Further studies are underway to analyze the public health significance of finding hantavirus strains in Singapore rodents.</p

Intestinal parasitic infections and environmental water contamination in a rural village of northern Lao PDR

A field survey studying intestinal parasites in humans and microbial pathogen contamination at environment was performed in a Laotian rural village to identify potential risks for disease outbreaks. A parasitological investigation was conducted in Ban Lak Sip village, Luang Prabang, Lao PDR involving fecal samples from 305 inhabitants as well as water samples taken from 3 sites of the local stream. Water analysis indicated the presence of several enteric pathogens, i.e., Aeromonas spp., Vibrio spp., E. coli H7, E. coli O157: H7, verocytotoxin-producing E. coli (VTEC), Shigella spp., and enteric adenovirus. The level of microbial pathogens contamination was associated with human activity, with greater levels of contamination found at the downstream site compared to the site at the village and upstream, respectively. Regarding intestinal parasites, the prevalence of helminth and protozoan infections were 68.9% and 27.2%, respectively. Eight helminth taxa were identified in fecal samples, i.e., 2 tapeworm species (Taenia sp. and Hymenolepis diminuta), 1 trematode (Opisthorchis sp.), and 5 nematodes (Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis, trichostrongylids, and hookworms). Six species of intestinal protists were identified, i.e., Blastocystis hominis, Cyclospora spp., Endolimax nana, Entamoeba histolytica/E. dispar, Entamoeba coli, and Giardia lamblia. Questionnaires and interviews were also conducted to determine risk factors of infection. These analyses together with a prevailing infection level suggested that most of villagers were exposed to parasites in a similar degree due to limited socio-economic differences and sharing of similar practices. Limited access to effective public health facilities is also a significant contributing factor

Intestinal parasitic infections and environmental water contamination in a rural village of northern Lao PDR

A field survey studying intestinal parasites in humans and microbial pathogen contamination at environment was performed in a Laotian rural village to identify potential risks for disease outbreaks. A parasitological investigation was conducted in Ban Lak Sip village, Luang Prabang, Lao PDR involving fecal samples from 305 inhabitants as well as water samples taken from 3 sites of the local stream. Water analysis indicated the presence of several enteric pathogens, i.e., Aeromonas spp., Vibrio spp., E. coli H7, E. coli O157: H7, verocytotoxin-producing E. coli (VTEC), Shigella spp., and enteric adenovirus. The level of microbial pathogens contamination was associated with human activity, with greater levels of contamination found at the downstream site compared to the site at the village and upstream, respectively. Regarding intestinal parasites, the prevalence of helminth and protozoan infections were 68.9% and 27.2%, respectively. Eight helminth taxa were identified in fecal samples, i.e., 2 tapeworm species (Taenia sp. and Hymenolepis diminuta), 1 trematode (Opisthorchis sp.), and 5 nematodes (Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis, trichostrongylids, and hookworms). Six species of intestinal protists were identified, i.e., Blastocystis hominis, Cyclospora spp., Endolimax nana, Entamoeba histolytica/E. dispar, Entamoeba coli, and Giardia lamblia. Questionnaires and interviews were also conducted to determine risk factors of infection. These analyses together with a prevailing infection level suggested that most of villagers were exposed to parasites in a similar degree due to limited socio-economic differences and sharing of similar practices. Limited access to effective public health facilities is also a significant contributing factor

Growth inhibition of pathogenic bacteria by sulfonylurea herbicides.

Emerging resistance to current antibiotics raises the need for new microbial drug targets. We show that targeting branched-chain amino acid (BCAA) biosynthesis using sulfonylurea herbicides, which inhibit the BCAA biosynthetic enzyme acetohydroxyacid synthase (AHAS), can exert bacteriostatic effects on several pathogenic bacteria, including Burkholderia pseudomallei, Pseudomonas aeruginosa, and Acinetobacter baumannii. Our results suggest that targeting biosynthetic enzymes like AHAS, which are lacking in humans, could represent a promising antimicrobial drug strategy