Abstract
BackgroundThe lack of characteristic clinical findings and accurate diagnostic tools has made the diagnosis of enteric fever difficult. We evaluated the classic signs of relative bradycardia and eosinopenia as diagnostic predictors for enteric fever among travellers who had returned from the tropics or subtropics.MethodsThis matched case-control study used data from 2006 to 2015 for culture-proven enteric fever patients as cases. Febrile patients (>38.3°C) with non-enteric fever, who had returned from the tropics or subtropics, were matched to the cases in a 1:3 ratio by age (±3 years), sex, and year of diagnosis as controls. Cunha’s criteria were used for relative bradycardia. Absolute eosinopenia was defined as an eosinophilic count of 0/μL.ResultsData from 160 patients (40 cases and 120 controls) were analysed. Cases predominantly returned from South Asia (70% versus 18%, p <0.001). Relative bradycardia (88% versus 51%, p <0.001) and absolute eosinopenia (63% versus 38%, p = 0.008) were more frequent in cases than controls. In multivariate logistic regression analysis, return from South Asia (aOR: 21.6; 95% CI: 7.17–64.9) and relative bradycardia (aOR: 11.7; 95% CI: 3.21–42.5) were independent predictors for a diagnosis of enteric fever. The positive likelihood ratio was 4.00 (95% CI: 2.58–6.20) for return from South Asia, 1.72 (95% CI: 1.39–2.13) for relative bradycardia, and 1.63 (95%CI: 1.17–2.27) for absolute eosinopenia. The negative predictive values of the three variables were notably high (83–92%);. however, positive predictive values were 35–57%.ConclusionsThe classic signs of relative bradycardia and eosinopenia were not specific for enteric fever; however both met the criteria for being diagnostic predictors for enteric fever. Among febrile returned travellers, relative bradycardia and eosinopenia should be re-evaluated for predicting a diagnosis of enteric fever in non-endemic areas prior to obtaining blood cultures.
Highlights
Enteric fever is a systemic infection caused by human-specific food- and water-borne pathogens, such as Salmonella enterica subspecies enterica serovar Typhi or Paratyphi A, B, or C
We evaluated the classic signs of relative bradycardia and eosinopenia as diagnostic predictors for enteric fever among travellers who had returned from the tropics or subtropics
The positive likelihood ratio was 4.00 for return from South Asia, 1.72 for relative bradycardia, and 1.63 (95%confidence intervals (CIs): 1.17–2.27) for absolute eosinopenia
Summary
Enteric fever (typhoid and paratyphoid fever) is a systemic infection caused by human-specific food- and water-borne pathogens, such as Salmonella enterica subspecies enterica serovar Typhi or Paratyphi A, B, or C. The low isolation rate of the bacteria from blood cultures, at 40–70% [3,4,5], is a concerning issue, in patients with prior antibiotic use. The lack of characteristic clinical findings and userfriendly and accurate diagnostic tools have made diagnosis of enteric fever difficult [6]. Rose spots are comparatively characteristic of enteric fever, whereas they are rarely seen in returned travellers; rose spots reportedly occur in only 4% of patients [7], because they generally develop 1 to 2 weeks after disease onset. The lack of characteristic clinical findings and accurate diagnostic tools has made the diagnosis of enteric fever difficult. We evaluated the classic signs of relative bradycardia and eosinopenia as diagnostic predictors for enteric fever among travellers who had returned from the tropics or subtropics
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