High Rates of Enteric Fever Diagnosis and Lower Burden of Culture-Confirmed Disease in Peri-urban and Rural Nepal

Abstract

Background: In South Asia, data on enteric fever are sparse outside of urban areas. We characterized enteric fever diagnosis patterns and the burden of culture-confirmed cases in peri-urban and rural Nepal.

Methods: We used national reports to estimate enteric fever diagnosis rates over 20 years (1994-2014) and conducted a prospective study of patients presenting with a >72-hour history of fever to 4 peri-urban and rural healthcare facilities (during August 2013-June 2016). We compared clinical characteristics of patients with culture-confirmed Salmonella Typhi or Paratyphi infection to those of patients without enteric fever. We used generalized additive models with logistic link functions to evaluate associations of age and population density with culture positivity.

Results: National rates of enteric fever diagnosis were high, reaching 18.8 cases per 1000 during 2009-2014. We enrolled 4309 participants with acute febrile illness. Among those with a provisional clinical diagnosis, 55% (1334 of 2412) received a diagnosis of enteric fever; however, only 4.1% of these had culture-confirmed typhoidal Salmonella infection. Culture positivity was highest among young adults and was strongly associated with higher population density (P < .001).

Conclusions: Enteric fever diagnosis rates were very high throughout Nepal, but in rural settings, few patients had culture-confirmed disease. Expanded surveillance may inform local enteric fever treatment and prevention strategies.

Figure 1.

A, Typhoid/paratyphoid notifications, by district, during 2009–2014. B, Population density, by district. Abbreviation: NA, not available.

Figure 2.

Outpatient department (OPD) visits (open circles; left axis), typhoid/paratyphoid cases reported (solid circles; right axis), and proportion of visits in which typhoid/paratyphoid was reported (gray bars) through the Health Management Information System in Nepal, 1994–1995 through 2013–2014.

Figure 3.

Proportion of patients with acute febrile illness who were blood-culture positive for typhoidal Salmonella organisms, by age. Curve and 95% confidence intervals were produced by a generalized additive model.

Figure 4.

Culture positivity (blue line with shaded 95% confidence intervals) according to population density of the participant’s home locality. Number of study participants living in localities for a given population density is depicted by black histogram (right axis). Curve and 95% confidence intervals were produced by a generalized additive model.