Enteric fever frequently diagnosed in urban Nepal, but rural cases rare

Although rates of enteric fever diagnosis are high throughout Nepal, culture-confirmed cases were rare in rural areas, according to findings published in The Journal of Infectious Diseases.

“Enteric fever, caused by Salmonella typhi or Salmonella paratyphi, is an important cause of morbidity and mortality globally,” Jason R. Andrews, MD, assistant professor of medicine at Stanford University, and colleagues wrote. “More than 10 million cases and 100,000 deaths annually are estimated to occur because of these diseases. However, estimates vary widely, owing to limited geographical and temporal resolution of the underlying data. Most incidence data are from studies in urban areas, which are often targeted for vaccine trials because of high reported case numbers.”

The researchers estimated rates of enteric fever diagnosis over the course of 20 years, from 1994 to 2014, using national reports. Andrews and colleagues also performed a prospective study of 4,309 patients who were treated at four rural and peri-urban health care centers between August 2013 and June 2016, all of whom had a fever for at least 72 hours. Researchers compared the patients’ clinical characteristics with culture-confirmed infections from S. typhi or S. paratyphi, and evaluated associations between culture positivity and age, as well as population density.

The national rate of enteric fever diagnosis was high throughout the study period, with 18.8 cases per 1,000 between 2009 and 2014, the researchers reported. Of those patients who received a clinical diagnosis (n = 2,412), more than half (55%; n = 1,334) were diagnosed with enteric fever. However, Andrews and colleagues wrote that just 4.1% of patients diagnosed with enteric fever had a culture-confirmed typhoidal Salmonella infection. Young adults demonstrated the highest rate of culture positivity (patients aged 16 to 24 years; n = 50 of 928; 5.4%), whereas adults aged older than 50 years (n = 1 of 1,037; 0.1%) and children aged younger than 5 years (n = 2 of 322; 0.6%) had the lowest rates. The researchers reported that higher population density was strongly associated with culture positivity (P < .001).

“We found very high rates of enteric fever clinical diagnosis in rural areas; however, the proportion of culture-confirmed disease was very low and strongly related to population density,” the researchers wrote. “These findings underscore the need to address current practices of widespread antibiotic prescription for presumptive enteric fever in rural areas and to generate higher resolution geographical data on typhoid burden to inform future vaccine implementation strategies.” – by Andy Polhamus

Disclosure: The researchers report no relevant financial disclosures.