Monitoring for typhoid through the existing WHO platform

A lack of robust surveillance and data on enteric fever — typhoid and paratyphoid fever — contributes to difficulty in studying, treating, and preventing the disease. Adding surveillance for enteric fever to the existing World Health Organisation (WHO) Invasive Bacterial-Vaccine Preventable Diseases (IB-VPD) network can be done at a modest cost, researchers now report in PLOS Neglected Tropical Diseases.

Enteric fever, caused by Salmonella typhi and paratyphi, affects some 17 million people in low and middle-income countries each year. Most cases occur in Bangladesh, India, and Pakistan. There is currently no global surveillance programme to track enteric fever. The WHO's IB-VPD network currently monitors sepsis, meningitis, and pneumonia in children in countries including those in which enteric fever is endemic.

In the new work, Samir Saha of the Dhaka Shishu Hospital in Bangladesh, and colleagues expanded the IB-VPD surveillance system to capture enteric fever cases in two children's hospitals, sentinel sites of IB-VPD network, in Bangladesh from 2012 through 2016. Inclusion criteria for the surveillance was a fever of at least 102°F for three or more days. The researchers tracked the cases of enteric fever that were diagnosed through the surveillance, those that were missed, and the costs of the expanded programme.

By expanding the monitoring, the researchers enrolled an additional 1,699 patients in the IB-VPD system, of which 22% were positive for microbiological growth. Overall, the surveillance captured 471 laboratory-confirmed cases of enteric fever in children under five during the study period. This represented 96% of all hospitalised typhoid and paratyphoid cases in the hospitals. The additional cost for the integration was US$ 44,974 per year, a 27% increase in the IB-VPD annual expenditure.

"Establishment of a new and stable surveillance platform is time consuming and expensive, and there is a high possibility of failure," the researchers say. "With effective typhoid vaccine (protein conjugated) in sight we recommend that WHO considers the integration of enteric fever surveillance in the present IB-VPD platform.

With such a system in place, areas with known high burden of enteric fever will benefit from better understanding of epidemiological characteristics of the disease and antimicrobial resistance trends for optimal empirical treatment."