An icddr,b study, which is one of the first analyses of the range of immune responses following typhoid fever in children under-five, has found that young children display the same clinical illness as adults—such as duration of fever and temperature—as well as the same immune responses and antibiotic sensitivity patterns. These novel findings demonstrate that typhoid, contrary to popular belief, can be both severe and common in young children, and underscore the need for accurate diagnosis and treatment to effectively control the spread of the disease in endemic areas.
In the new study, the immune responses in 33 children under five years of age were compared with those of older children (6-17 years of age), adults (18-59 years) and age-matched healthy controls. The scientists used a test of their own design, which they previously developed to identify the activity of specific antibodies secreted by lymphocytes during typhoid fever in older children and adults. They found that children under-five displayed similar lymphocyte antibody levels, suggesting the test can be used to reliably diagnose typhoid fever in young children.A petri dish used for the typhoid/paratyphoid test. Photo ©: icddr,b / Joanna Lovatt
Typhoid fever, a severe systemic disease caused by S. typhi bacteria, is often under diagnosed because, until now, there has been a lack of good diagnostic methods with high sensitivity and specificity. As a result the actual burden of typhoid in Bangladesh is not known, and there is widespread misuse of antibiotics to treat fever. Ultimately, this could contribute to a decrease in the effectiveness of antibiotics and an increase in multi-drug resistant strains of bacteria.
Dr Farhana Khanam, lead author on the study and an assistant scientist in icddr,b’s Centre for Vaccine Sciences, believes that multi-drug resistant typhoid is a very serious threat. “A patient can become a chronic carrier if they are not treated, or if they are treated incorrectly, she says. “And this may have severe implications for their health, such as the risk of intestinal perforation or encephalopathy.” Patients will also continue to transmit the disease and infect others in their community.
In this study, 15% of patients who tested positive for typhoid presented with a multi-drug resistant strain. Although little is known about multi-drug resistant S. typhi in children, the findings of the study suggest that infection with a multi-drug resistant strain may impact clinical severity and outcome.
“Ultimately we are focusing on accurate diagnosis,” she continues, “because to control typhoid you must be able to treat the patients accurately, and to treat the patients accurately you need accurate diagnosis.”
(The study was supported by icddr,b, the US National Institutes of Health, the Fogarty International Center, the Bill & Melinda Gates Foundation and the Swedish International Development Cooperation Agency.)
