Epidemiology of Shigellosis in the Peruvian Amazon

Johns Hopkins University, Baltimore MD

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Abstract

DESCRIPTION (provided by applicant): Shigellosis is the principal cause of clinical dysentery and a frequent cause of morbidity and mortality in children in impoverished regions. Due to the rapid spread of multiple antibiotic resistant strains and the lack of an available vaccine the morbidity and mortality from shigellosis is likely to increase worldwide. In the initial period of IRSDA support the determination of age-specific incidence rates of shigellosis, risk factors for disease development, antibiotic resistance profiles and regional serotype data to define the burden of drug resistant Shigella and serotype distribution of isolates in a highly endemic area was completed. ERIC-PCR was compared to the gold standard PFGE for the molecular typing of a subset of isolates and was found to be have a nearly equal discriminatory index to PFGE and was simpler, faster, and more affordable therefore more appropriate for use in endemic areas. Isolates from sentinel children under longitudinal surveillance and their contacts studied in a nested case control study to determine the mode of interfamilial spread was limited by the low yield of cultures. The identification of Shigella nearly exclusively by PCR in environmental sources including flies, drinking water, surface waters, and hand washings necessitate the identification and evaluation of a typing method that does not require primary isolation by culture to fully understand the transmission dynamics of shigellosis. The present supplemental application will address the relevance of these sources using a combined approach including PCR detection, epidemiologic analysis of the risk of proximity to these PCR positive but culture negative sources and a space-time analysis of sources of infection in order to optimally understand the ecology and transmission dynamics of this important pathogen. The collaborative research group that is assembled to conduct this study is an established international group of epidemiologists, physicians, biostatisticians, and molecular biologists with a proven track record in the training of junior scientists in an international setting. The proposed project will further strengthen these international research ties in the process of the continued training of a promising physician-scientist.