A baseline study of importance of bovines for human Schistosoma Japonicum infections around Poyang Lake, China: Villages studied and snail sampling strategy

An epidemiologic survey among four administrative villages around Poyang Lake, in Jiangxi Province, China (two experimental and two controls) is being conducted to determine if bovine infections are responsible for the persistence of human schistosomiasis transmission on Yangtze River marshlands. A previously published paper presented the experimental design and baseline data for humans and bovines. This paper presents basic data for the four villages using remote sensing, and baseline data for snails that includes geographic information systems and remote sensing technology to classify the areas of bovine grazing ranges and habitats suitable for snails. A new method for sampling Oncomelania snails in China is used to determine the distribution, density, and infection rates of snails throughout the grazing ranges from season to season over a four-year period. Hypothetically, treating bovines should reduce infection rates in snails to below the critical number necessary to maintain infections in man and bovines.

An investigation of contact transmission of methicillin resistant-Staphylococcus aureus

Hand hygiene is critical in the healthcare setting and it is believed that methicillin-resistant Staphylococcus aureus (MRSA), for example, is transmitted from patient to patient largely via the hands of health professionals. A study has been carried out at a large teaching hospital to estimate how often the gloves of a healthcare worker are contaminated with MRSA after contact with a colonized patient. The effectiveness of handwashing procedures to decontaminate the health professionals' hands was also investigated, together with how well different healthcare professional groups complied with handwashing procedures. The study showed that about 17% (9-25%) of contacts between a healthcare worker and a MRSA-colonized patient results in transmission of MRSA from a patient to the gloves of a healthcare worker. Different health professional groups have different rates of compliance with infection control procedures. Non-contact staff (cleaners, food services) had the shortest handwashing times. In this study, glove use compliance rates were 75% or above in all healthcare worker groups except doctors whose compliance was only 27%. (C) 2004 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.

Genome reduction in Leptospira borgpetersenii reflects limited transmission potential

Leptospirosis is one of the most common zoonotic diseases in the world, resulting in high morbidity and mortality in humans and affecting global livestock production. Most infections are caused by either Leptospira borgpetersenii or Leptospira interrogans, bacteria that vary in their distribution in nature and rely on different modes of transmission. We report the complete genomic sequences of two strains of L. borgpetersenii serovar Hardjo that have distinct phenotypes and virulence. These two strains have nearly identical genetic content, with subtle frameshift and point mutations being a common form of genetic variation. Starkly limited regions of synteny are shared between the large chromosomes of L. borgpetersenii and L. interrogans, probably the result of frequent recombination events between insertion sequences. The L. borgpetersenii genome is ≈700 kb smaller and has a lower coding density than L. interrogans, indicating it is decaying through a process of insertion sequence-mediated genome reduction. Loss of gene function is not random but is centered on impairment of environmental sensing and metabolite transport and utilization. These features distinguish L. borgpetersenii from L. interrogans, a species with minimal genetic decay and that survives extended passage in aquatic environments encountering a mammalian host. We conclude that L. borgpetersenii is evolving toward dependence on a strict host-to-host transmission cycle.

Transmission mode and distribution of parasites among groups of the social lizard Egernia stokesii

We explored patterns of infection of three apicomplexan blood parasites with different transmission mechanisms in 46 social groups across seven populations of the Australian lizard, Egernia stokesii. There was higher aggregation of infections within social groups for Hemolivia, transmitted by ticks, and Schellackia, either tick-transmitted or directly transmitted from mother to offspring, than for Plasmodium, with more mobile dipteran vectors. Prevalence was not related to group size, proximity to other groups or spatial overlap with adjacent groups for any of the parasites. However, for Hemolivia, groups with higher levels of relatedness among adults had higher parasite prevalence. Living in social groups leads to higher risk of infection for parasites with low transmission mobility. An unanswered question is why so few lizard species tolerate these risks to form stable social aggregations.

Hematozoa of teleosts from Lizard Island, Australia with some comments on their possible mode of transmission and the description of a new hemogregarine species

Little is known of the blood parasites of coral reef fishes and nothing of how they are transmitted. We examined 497 fishes from 22 families, 47 genera, and 78 species captured at Lizard Island, Australia, between May 1997 and April 2003 for hematozoa and ectoparasites. We also investigated whether gnathiid isopods might serve as potential vectors of fish hemogregarines. Fifty-eight of 124 fishes caught in March 2002 had larval gnathiid isopods, up to 80 per host fish, and these were identified experimentally to be of 2 types, Gnathia sp. A and Gnathia sp. B. Caligid copepods were also recorded but no leeches. Hematozoa, found in 68 teleosts, were broadly hemogregarines of 4 types and an infection resembling Haemohormidium. Mixed infections (hemogregarine with Haemohormidium) were also observed, but no trypanosomes were detected in blood films. The hemogregarines were identified as Haemogregarina balistapi n. sp., Haemogregarina tetraodontis, possibly Haemogregarina bigemina, and an intraleukocytic hemogregarine of uncertain status. Laboratory-reared Gnathia sp. A larvae, fed experimentally on bruslitail tangs, the latter heavily infected with the H. bigemina-like hemogregarine, contained hemogregarine gamonts and possibly young oocysts up to 3 days postfeeding, but no firm evidence that gnathiids transmit hemogregarines at Lizard Island was obtained.