A decade of intestinal protozoan epidemiology among settled immigrants in Qatar

Abstract

BackgroundThe World Health Organization estimates that about 3.5 billion people worldwide are affected by intestinal parasitic infections. Reports have already emphasized the role of immigrants in outbreaks of parasitic diseases in industrialized countries. With the mass influx of immigrants to Qatar, patent intestinal parasitic infections have been observed. Herein, the prevalence of intestinal protozoan infections was analysed in 29,286 records of subjects referred for stool examination at the Hamad Medical Corporation over the course of a decade (2005 to 2014, inclusive).ResultsOverall prevalence of combined protozoan infections was 5.93 % but there were significant temporal trends, age and sex effects and those arising from the region of origin of the subjects. The most common protozoan was Blastocystis hominis (overall prevalence 3.45 %). Giardia duodenalis, Chilomastix mesnili, Entamoeba coli, Entamoeba hartmanni, Endolimax nana, Iodamoeba butschlii, Entamoeba histolytica/dispar, Cryptosporidium sp. and a single case of Isospora were also detected. The prevalence of combined protozoan infections, G. duodenalis and the non-pathogenic amoebae all declined significantly across the decade. That of B. hominis varied between years but showed no directional trend across years and there was no evidence that prevalence of E. histolyitica/dispar changed significantly. Protozoan infections were observed among all regional groups, but prevalence was higher among subjects from the Arabian Peninsula, Africa and Asia compared to those from the Eastern Mediterranean and Qatar. Prevalence was higher among male subjects in all cases, but age-prevalence profiles differed between the taxa.ConclusionThese results offer optimism that prevalence will continue to decline in the years ahead.

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

“…The most prevalent protozoan parasites were B. hominis among north and Saharan African subjects and G. duodenalis among western Asia subjects. In contrast to the generally falling trends in prevalence of intestinal protozoan infections among long-term residents [11], the current data revealed an increasing trend in the short-term over the period 2012–2014 among new arrivals. Comparing the current findings with the previous analysis in 2009 [8], an increase is apparent: from 3.4 to 10.9% for B. hominis among northern Africans and 1.4 to 3.6% for G. duodenalis among western Asians.…”

“…Giardia duodenalis was more commonly encountered among western Asians as observed in earlier work [8, 11]. Analysis of prevalence over a whole decade showed that this species declined with host age [11] but a resurgence of Giardia infection among Asian young male subjects was observed suggesting continued exposure throughout life.…”

“…prevalence of G. duodenalis in northern and Saharan Africans increased from 0.0% in 2012 to 4.2% in 2014; E. nana increased from 3.6% among sub-Saharan Africans in 2012 to 17.1% in 2014 and in the same regional group E. coli increased from 0.0% in 2012 to 4.9% in 2014). We also considered prevalence of G. duodenalis among west Asians, because of earlier reports that subjects from this region showed relatively high prevalence of this species [8, 11]. However, over the period 2012 to 2014, there was no significant increase in prevalence (YEAR x INFECTION, χ 2 2  = 3.8, P  = 0.15), although numerically prevalence was higher in 2014 (4.9%, [CL 95  = 2.59-9.73]) compared to in 2012 (2.8%, [CL 95  = 1.28-5.99]) and 2013 (2.7%, [CL 95  = 1.34-5.16]), and this would also have contributed to the overall increase in the prevalence of protozoan infection over this period.…”

“…Analysis of prevalence over a whole decade showed that this species declined with host age [11] but a resurgence of Giardia infection among Asian young male subjects was observed suggesting continued exposure throughout life. The affected individuals are most likely to be the unskilled construction workers aggregating in overcrowded labour camps where conditions may be cramped and sanitary facilities limited and of a poor standard.…”

“…A subsequent report spanning the decade to 2014 for both helminths [10] and protozoan [11] infections, showed that settled immigrants from Asia, especially those from West Asia/Nepal, were associated with the highest prevalence of intestinal helminth infections (notably hookworms) and also specific intestinal protozoa (e.g. Giardia duodenalis ) [9, 12], even after acquiring residency status in Qatar.…”