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Azmuda N.,University of Dhaka | Azmuda N.,University of Bergen | Rahman M.Z.,University of Dhaka | Rahman M.Z.,University of Bergen | And 5 more authors.
APMIS | Year: 2012

An environmental bacterial isolate, Iso10, previously found to show serological cross-reactivity with type-specific Shigella boydii 15 antisera was subjected to further molecular and serological analyses that revealed interspecies transfer of the O antigen gene cluster. Western blot analysis of Iso10 cell surface extracts and purified lipopolysaccharides demonstrated strong cross-reactivity with S. boydii 15-specific monovalent antisera and a lipopolysaccharide gel banding profile similar to that of S. boydii 15. Biochemical and phylogenetic analyses identified the Iso10 isolate as Escherichia fergusonii. O antigen gene cluster analyses of Iso10, carried out by restriction fragment length analysis of the amplified ~10-kb O antigen-encoding gene cluster, revealed a profile highly similar to that of S. boydii 15, confirming the presence of the S. boydii 15 somatic antigen in Iso10. To the best of our knowledge, this is the first report of interspecies transfer of O antigen-encoding genes between S. boydii and E. fergusonii, and it has implications for our understanding of the role of lateral gene transfer in the emergence of novel Shigella serotypes. © 2012 The Authors APMIS © 2012 APMIS. Source

Ruiz-Moreno D.,University of Michigan | Pascual M.,University of Michigan | Pascual M.,Howard Hughes Medical Institute | Emch M.,University of North Carolina at Chapel Hill | Yunus M.,Center for Health and Population Research
BMC Infectious Diseases | Year: 2010

Background: The spatio-temporal patterns of infectious diseases that are environmentally driven reflect the combined effects of transmission dynamics and environmental heterogeneity. They contain important information on different routes of transmission, including the role of environmental reservoirs. Consideration of the spatial component in infectious disease dynamics has led to insights on the propagation of fronts at the level of counties in rabies in the US, and the metapopulation behavior at the level of cities in childhood diseases such as measles in the UK, both at relatively coarse scales. As epidemiological data on individual infections become available, spatio-temporal patterns can be examined at higher resolutions.Methods: The extensive spatio-temporal data set for cholera in Matlab, Bangladesh, maps the individual location of cases from 1983 to 2003. This unique record allows us to examine the spatial structure of cholera outbreaks, to address the role of primary transmission, occurring from an aquatic reservoir to the human host, and that of secondary transmission, involving a feedback between current and past levels of infection. We use Ripley's K and L indices and bootstrapping methods to evaluate the occurrence of spatial clustering in the cases during outbreaks using different temporal windows. The spatial location of cases was also confronted against the spatial location of water sources.Results: Spatial clustering of cholera cases was detected at different temporal and spatial scales. Cases relative to water sources also exhibit spatial clustering.Conclusions: The clustering of cases supports an important role of secondary transmission in the dynamics of cholera epidemics in Matlab, Bangladesh. The spatial clustering of cases relative to water sources, and its timing, suggests an effective role of water reservoirs during the onset of cholera outbreaks. Once primary transmission has initiated an outbreak, secondary transmission takes over and plays a fundamental role in shaping the epidemics in this endemic area. © 2010 Ruiz-Moreno et al; licensee BioMed Central Ltd. Source

Yunus F.M.,BRAC Research and Evaluation Division | Rahman M.J.,Sanitation and Hygiene Research Group | Alam M.Z.,University of Texas at Arlington | Hore S.K.,B Chronic Disease Epidemiology and Genetics Research Group | And 2 more authors.
BMC Public Health | Year: 2014

Background: Chronic exposure to arsenic is associated with neoplastic, cardiovascular, endocrine, neuro-developmental disorders and can have an adverse effect on women's reproductive health outcomes. This study examined the relationship between arsenic skin lesions (a hallmark sign of chronic arsenic poisoning) and age of natural menopause (final menopausal period) in populations with high levels of arsenic exposure in Bangladesh. Methods. We compared menopausal age in two groups of women - with and without arsenic skin lesions; and presence of arsenic skin lesions was used as an indicator for chronic arsenic exposure. In a cross-sectional study, a total of 210 participants were randomly identified from two ongoing studies - participants with arsenic skin lesions were identified from an ongoing clinical trial and participants with no arsenic skin lesions were identified from an ongoing cohort study. Mean age of menopause between these two groups were calculated and compared. Multivariable linear regression was used to estimate the relationship between the status of the arsenic skin lesions and age of natural menopause in women. Results: Women with arsenic skin lesions were 1.5 years younger (p <0.001) at the time of menopause compared to those without arsenic skin lesions. After adjusting with contraceptive use, body mass index, urinary arsenic level and family history of premature menopause, the difference between the groups' age at menopause was 2.1 years earlier (p <0.001) for respondents with arsenic skin lesions. Conclusions: The study showed a statistically significant association between chronic exposure to arsenic and age at menopause. Heavily exposed women experienced menopause two years earlier than those with lower or no exposure. © 2014 Yunus et al.; licensee BioMed Central Ltd. Source

Root E.D.,University of Colorado at Boulder | Giebultowicz S.,University of North Carolina at Chapel Hill | Ali M.,Data Management | Yunus M.,Center for Health and Population Research | Emch M.,University of North Carolina at Chapel Hill
PLoS ONE | Year: 2011

Background: Traditional vaccine trial methods have an underlying assumption that the effect of a vaccine is the same throughout the trial area. There are, however, many spatial and behavioral factors that alter the rates of contact among infectious and susceptible individuals and result in different efficacies across a population. We reanalyzed data from a field trial in Bangladesh to ascertain whether there is evidence of indirect protection from cholera vaccines when vaccination rates are high in an individual's social network. Methods: We analyzed the first year of surveillance data from a placebo-controlled trial of B subunit-killed whole-cell and killed whole-cell-only oral cholera vaccines in children and adult women in Bangladesh. We calculated whether there was an inverse trend for the relation between the level of vaccine coverage in an individual's social network and the incidence of cholera in individual vaccine recipients or placebo recipients after controlling for potential confounding variables. Results: Using bari-level social network ties, we found incidence rates of cholera among placebo recipients were inversely related to levels of vaccine coverage (5.28 cases per 1000 in the lowest quintile vs 3.27 cases per 1000 in the highest quintile; p = 0.037 for trend). Receipt of vaccine by an individual and the level of vaccine coverage of the individual's social network were independently related to a reduced risk of cholera. Conclusions: Findings indicate that progressively higher levels of vaccine coverage in bari-level social networks can lead to increasing levels of indirect protection of non-vaccinated individuals and could also lead to progressively higher levels of total protection of vaccine recipients. © 2011 Root et al. Source

Fuehrer H.-P.,Medical University of Vienna | Fuehrer H.-P.,Malaria Research Initiative Bandarban | Habler V.E.,Medical University of Vienna | Habler V.E.,Malaria Research Initiative Bandarban | And 11 more authors.
International Journal for Parasitology | Year: 2012

In spite of the high prevalence of malaria in Bangladesh and other southern Asian countries, there remains a substantial shortage of knowledge about the less common human malaria parasites. Recent studies indicate that Plasmodium ovale is made up of two species, namely Plasmodium ovale wallikeri and Plasmodium ovale curtisi. Genus- and species-specific nested PCR analyses of the ssrRNA gene was used to detect P. ovale infections among 2,246 diagnostic samples. Plasmodium ovale infections were further differentiated by nested PCR of the potra gene and multilocus sequence analysis of the cox1, porbp2 and the ssrRNA genes. Both P. ovale curtisi and P. ovale wallikeri occur sympatrically in the Chittagong Hill Tracts, Bangladesh and all patients presented with a mild or asymptomatic symptom complex at the time of diagnosis. The pathogens can be differentiated by nested PCRs targeting the ssrRNA and potra genes, and display dimorphism in multilocus sequence analyses. We believe that we report the first evidence of sympatric P. ovale curtisi and P. ovale wallikeri in southern Asia within a relatively confined study area of less than 5,000km 2. High rates of mixed infections, the emergence of "new" human malaria parasite species and the evidence of zoonotic capability call for optimised diagnostic strategies for a new era of eradication. © 2012 Australian Society for Parasitology Inc. Source

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