Enterotoxigenic Escherichia coli (ETEC) are a cause of diarrhea and diarrheal deaths in children living in developing countries. They are also a cause of travelers' diarrhea.
Vaccine developments have focused on protective immunity against surface colonization factors (CFs) and the heat-labile enterotoxin.
However, although vaccines that induce immunity to heat-labile toxin offer protection against diarrhea from ETEC, the benefit of including CF antigens remains unclear.
In this study, investigators from Scandinavia estimated the protection that natural ETEC infections induce against new infections.
|The estimated protection attributable to surface colonization factors was -1%.|
The team followed up 200 neonates from Guinea-Bissau until they were 2 years old. Most of these children were breastfed throughout the study.
They collected stool samples from the children every week, regardless of whether they had diarrhea.
The team calculated the measure of protection using Cox regression analysis to estimate the change in infection rates after a primary ETEC infection.
They determined the protection which could be attributed to CFs, toxins, and other factors that could be shared by ETEC with the same toxin-CF profile.
The researchers found that ETEC infections induced a 47% protection against new ETEC infections with the same toxin-CF profile. However, they determined that the corresponding protection attributable to CFs was -1%.
Infection with heat-labile toxin-positive ETEC conferred a 45% protection against symptomatic infections with ETEC positive for this toxin.
Dr Hans Steinsland's team concluded, "For breastfed children living in endemic areas, other antigens are substantially more important than CFs for induction of protective immunity against ETEC infection".