Epidemiology of Campylobacter Infections among Children in Egypt

Abstract

<i>Campylobacter</i> is a frequently isolated bacterial pathogen among children with diarrhea. Data are lacking on the distribution and spectrum of disease associated with <i>Campylobacter</i> species and <i>Campylobacter jejuni</i> capsular polysaccharide (CPS) types. This information is essential because current vaccine research seeks to target specific CPS types. An effective CPS-conjugate vaccine will need to cover CPS types that are both common and associated with severe disease. The US Naval Medical Research Unit-3 conducted several prospective cohort studies researching diarrheal disease in Egypt from 1995 to 2003. In total, 1,057 children were enrolled and followed to a maximum age of 36 months. We analyzed <i>Campylobacter</i>-positive stool samples that were collected while subjects were symptomatic, along with corresponding clinical data. Of 441 <i>Campylobacter</i> isolates, 322 represented primary infections (189 <i>C. jejuni</i>, 127 <i>Campylobacter coli</i>, six unspeciated). There were 19 <i>C. jejuni</i> CPS types identified; eight accounted for 63.5% of primary <i>C. jejuni</i> infections. We also screened for the presence of the type-6 secretion system (T6SS), a putative virulence determinant. The T6SS was found in 18.0% of <i>C. coli</i> isolates and 57.6% of <i>C. jejuni</i> isolates (<i>P</i> < 0.001), and was not uniformly distributed among CPS types (<i>P</i> < 0.001). Strains with the T6SS were not associated with more severe disease. Clinical presentations across species and CPS types appeared similar. This study adds to the growing epidemiological data and also provides some analysis of the clinical spectrum associated with infection by specific <i>Campylobacter</i> species, <i>C. jejuni</i> capsule types, and possible virulence determinants.