The prevalence of some gastrointestinal nematodes and cestodes in Iraqis

This retrospective survey consisted of a spatial and temporal analysis of reported cases of helminths using an available surveillance database from January 2013 to December 2013 taken by the Iraqi Communicable Diseases Control Center (CDC). Data included all provinces of Iraq. The number of patients examined was 2,761,990. The parasites studied and included were divided in to two categories: Nematoda: (Ascaris lumbricoides, Trichuris trichiura, Ancylostoma duodenale, Enterobius vermicularis and Strongyloides stercoralis) and Cestoda (Taenia solium and Hymenolepis nana). Data were arranged according to the geographical distribution of provinces from north to south; provinces were divided into 4 groups according to the database from the CDC (Figure 1).

Figure 1

A map of Iraq showing the four different regions. Northern region: Ninevah, Ta’mim, Suleimaniyah, Erbil, and Dohuk; Middle region: Baghdad, Anbar, Diyala, and Salahuddin; Middle Euphrates region: Babil, Karbala. Najaf, Qadisiyah, and Muthanna; Southern region: Wasit, Dhi-qar, Misan, and Basrah. Permission to use the map granted by MemNav as a courtesy (Source: https://i2.wp.com/www.memnav.com/im/Iraq_map.jpg)

Data for each parasite were arranged according to sex of patients, and seasonal variation from January to December. Data for each parasite were arranged according to age groups as follows: group 1 <1 year old; group 2, from 1 to 4 years old; group 3, from 5 to 14 years old; group 4, from 15 to 45 years old; and group 5, >45 years old. We examined differences in prevalence among sexes, age, and region with a chi square test using the Statistical Package for the Social Sciences (SPSS Inc, Chicago IL, USA). P < 0.05 was considered significant.

The overall prevalence of gastrointestinal helminthiasis was 1.39%. The number of infected individuals was 38,547 of 2,761,990 examined. Enterobius vermicularis infected the highest number of individuals followed by Hymenolepis nana, and Ascaris lumbricoides, with other helminths showing lower numbers of cases (Table 1). Northern and middle Euphrates regions showed lower prevalence of infections with all helminths, compared with the middle and southern regions, which showed a higher prevalence of infections (Table 2). There were significant differences in infection rates between age groups in this survey for all surveyed helminths (Table 3). The maximum numbers of infections for all helminths were seen in two age groups: 5-14 and 15-44 years. The majority of Ascariasis, Ancylostomiasis, Trichuriasis, Strongyloidiasis, and Enterobiasis were noticed in the 5-14 year age group. Most of Hymenolepiasis and Taeniasis were reported in the 15-44 year age group. Age group <1 year showed no worm infection except 799 patients infected with E. vermicularis. The least number of infected cases was seen in: group <1 year for E. vermicularis, age group 1-4 years for Ascariasis, Ancylostomiasis and, Trichuriasis, and age group >45 years for Taeniasis.

Table 3 presents the sex distribution for all surveyed helminths. Results illustrated that the prevalence of infection with helminths in male individuals was higher than in female individuals. No significant (P < 0.05) difference for infection prevalence was found between sexes, although the percentage of infection was higher in male individuals compared with female individuals for the following: Ascariasis, Ancylostomiasis, Trichuriasis, and Taeniasis, while a higher infection prevalence in female individuals was seen for Enterobiasis, Hymenolepiasis, and Strongyloidiasis. An apparent seasonal tendency was recognized in the monthly prevalence of worms in Iraq (from the beginning January to the end of December 2013) as shown in Table 4.

The overall presence of helminthic infections in this survey was 1.39%, this prevalence is considerably lower than previous reports from other surveys in Asia [8]. The prevalence of gastrointestinal helminth infections varies according to geographical location, education, use of raw salads and vegetables, age of patients, socioeconomic criteria, nutritional status, immunological status, and personal hygiene [9]. The most common helminth infections in this survey was Enterobiasis, followed by Hymenolepiasis. E. vermicularis and H. nana are cosmopolitan in distribution, and more common in warm climates. They are the most prevalent helminths worldwide, and easily transmitted directly from person to person, and by autoinfection [10]. These findings were consistent with other reports and showed that the majority of helminthic infections were with E. vermicularis and H. nana [11] and differed from other reports from Asia, which showed that the majority of helminthic infections were with H. nana and A. lumbricoides [12]. Less common helminthic infections found in this survey were with T. saginata and S. stercoralis. This results are consistent with A1-Taie et al. [13] and differed from Raza et al. [11] who had shown that the lowest prevalence was for A. lumbricoides. Some investigators differentiated between domestic (household) and public (public places of work, street, fields, and school) transmission sites [14], these data were not reported in the survey data and this may cause some differences [15]. Most of the helminths included in this survey were reported as having high prevalence in the middle Euphrates and southern districts, except H. nana, which was reported as having high prevalence in northern Iraq. The southern and middle regions showed significantly high prevalence of all helminths. The middle region is more urbanized and Baghdad is located there. Parasitic infections are more prevalent among urban people, particularly during social upheavals and because of migration when urban centers become important loci for the transmission of infectious diseases [16].

The overall prevalence of intestinal parasitosis is greater among 5-14 year olds. This is because at such age school children indicate changes in exposure to conditions that favor the transmission of the infective stages of most of the helminths especially geohelminths; other investigators showed that handwashing habit of the this age group is very poor [17]. This finding is consistent with the result of Arinola and Fawole who showed that the prevalence and intensity of some intestinal helminths were predominant in the same age group [18]. Although there was no significant relationship between sex and helminth infection, most infections were seen in male individuals, this is probably because males are more exposed to unhygienic conditions in fields during outdoor activity [19], especially in a country like Iraq. High prevalence of Enterobiasis is seen in female individuals, also Hymenolepiasis and Strongyloidiasis and this inconsistent with findings by Al-Qadhi et al, who showed that prevalence of E. vermicularis infection was higher in girls than in boys [15]. Finally our findings from the current survey revealed high prevalence of pin worm in the surveyed population and warrants long-term control measures to improve sanitary and living conditions, including treatment of infected individuals. The impact of these measures would be further enhanced via an organized health education programs, which may encourage healthy behavior and lead to a reduction of helminth infections in general and Enterobiasis specifically.