Assessing the burden of intestinal parasites affecting newly arrived immigrants in Qatar

Abstract

Background: In the last decades, the enormous influx of immigrants to industrialized countries has led to outbreaks of parasitic diseases, with enteric infections being amongst the most frequently encountered. In its strategy to control such infection, Qatar has established the Pre-Employment Certificate (PEC) program which requires medical inspection before arrival in Qatar and which is mandatory for immigrant workers travelling to the country. To assess the reliability of the PEC, we conducted a survey of intestinal parasites, based on examination of stool samples provided by immigrant workers (n = 2,486) recently arrived in Qatar.

Results: Overall prevalence of helminths was 7.0% and that of protozoa was 11.7%. Prevalence of combined helminths was highest among the western Asians and the highest prevalence of combined protozoan parasites was among workers from North to Saharan Africa. Analysis of temporal changes showed an increasing trend of protozoan infections over the investigated 3 years. A major contribution to this temporal change in prevalence came from Blastocystis hominis as well as from other protozoan species: Giardia duodenalis and Endolimax nana. Analysis of the temporal trend in species richness of the protozoan species showed a significant increase in the mean number of species harboured per subject across this period.

Conclusion: The increase of protozoan infections over recent years raises some concerns. It suggests that screening protocols for applicants for visas/work permits needs to be revised giving more careful attention to the intestinal protozoan infections that potential immigrants may harbor.

Keywords: Blastocystis; Giardia; Helminth; New immigrants; Protozoa; Qatar.

Fig. 1

Change of prevalence of all the parasite species combined, combined helminths and combined protozoa with host age

Fig. 2

Change in abundance with host age of (a) hookworms, combined helminths, B. hominis and G. duodenalis, and b all protozoa combined and all protozoa and helminths combined

Fig. 3

Temporal changes in the prevalence of (a) combined helminths, b combined protozoa and (c) B. hominis. Values along the X-axis are offset slightly to avoid overlap of error bars

Fig. 4

Temporal changes in the mean oocyst/cyst counts (in units of CPG) for combined protozoa, B. hominis, E. nana, E. coli and G. duodenalis. Values along the X-axis are offset slightly to avoid overlap of error bars