Screening the asymptomatic soldiers after a stay in sub-Saharan Africa. A retrospective observational study

Background: Many tropical clinics offer post-travel screening for parasitic infections in asymptomatic travellers. However, literature on attack rates and incidence rates of parasitic infections is scarce. Method: All military personnel returning from a tropical region during the year 2018 were tested for the presence of antibodies against Strongyloides stercoralis, Schistosoma and Entamoeba histolytica. Test results were compared with previous results if available to distinguish recent and old infection. Results: In total, 949 soldiers were included in the study. The median age was years 31 (IQR: 26–41), 96.3% were male. The median duration of stay in the tropics was 35 days (IQR: 14–90). The destination was predominantly central Africa. Serological tests were positive for S. stercoralis in 10 patients (1.1%), Schistosoma in 3 (0.3%), and E. histolytica in 16 (1.7%). The attack rates were 0.84, 0.32 and 1.69 respectively. The incidence rates were 3.99, 1.49 and 7.97 respectively. Conclusions: The risk for parasitic infection in the asymptomatic returning soldiers is low. However, the potentially serious complications of unrecognised parasitic infection can legitimise systematic screening.