Prevalence of parasitic infections in migrants: do official symptom-driven guidelines apply to the current situation?

In recent years, migration has become a significant challenge in Western countries. Migrant populations, coming from hyper-endemic areas, may present parasitic infections that remain latent and asymptomatic even for years, eventually leading to severe complications. Italian guidelines have been established to perform screening guided by the presence of symptoms and/or hypereosinophilia. Parasitological screening was conducted in a migrant population to carry out preventative measures. All migrants were asked to report any symptoms suggesting parasitic infections and list any previous treatment received. Travel data were recorded. Parasitological examination of stools and urine were conducted in all patients regardless of symptoms. In all, 208 consecutive patients were enrolled in our outpatient clinic from November 2016 to August 2017. Thirty-four patients were excluded due to the previous assumption of albendazole or because they did not exhibit suitable samples. Prevalence of parasitic infections was 33/174 (18.9%). A statistically significant difference for the prevalence of parasitic infections was not found between patients who were asymptomatic and without hypereosinophilia compared to those who presented symptoms and/or hypereosinophilia (27/151 [17.9%] vs. 6/23 [26.0%]; p=0.39). By contrast, a statistically significant difference was found for the length of time between arrival in Italy and parasitological examinations (4/51 [7.8%] migrants who arrived in Italy more than six months prior to screening vs. 29/123 [23.6%] migrants who arrived within six months; p= 0.016). Our results did not demonstrate any significant differences in prevalence of parasitic infections between symptomatic or hypereosinophilic and asymptomatic migrants. Thus we feel it inappropriate to support recent guidelines recommending parasitological examinations only in migrants with symptoms and/or hypereosinophilia. By contrast, it would appear important to perform parasitological screening in migrants as soon as possible after their arrival. Since such infestations, if untreated, could result in chronic diseases and complications, and could be transmitted in the host countries, our results have potential implications for public health.