Status of intestinal parasitic infections among rural and urban populations, southwestern Iran

Objective: To evaluate the prevalence and risk factors of intestinal parasitic infections in the urban and rural areas of Shushtar County, southwest Iran. Methods: A total of 1 008 fecal samples were analyzed by direct smear examination, formalin-ether concentration, and Ziehl-Neelsen and trichrome staining; furthermore, PCR was used to distinguish Trichostrongylus and hookworm species based on 28S rRNA gene. Results: Totally, 16.0% cases tested positive, either with a pathogenic or a non-pathogenic parasite. Protozoa were detected in 14.0%, helminths in 1.0%, protozoa and helminth co-infections were detected in 0.3%, and co-infections of two protozoa were detected in 0.7% of cases. The most common protozoa and helminths were Giardia duodenalis (7.7%) and Trichostrongylus spp. (0.5%), respectively. Among five microscopy Trichostrongylus positive cases, Trichostrongylus culbriformis was successfully identified in three isolates by sequencing. In the rural areas, the prevalence of parasitic infection was higher (9.8%) than that in the urban areas (6.2%). A significant association was found between educational level, type of drinking water, animals contact, hand-washing, and clinical symptoms. Conclusions: This study indicates that intestinal parasitic infections remain as a public health priority in Shushtar County. It seems that drinking water and environmental sanitation are the main risk factors of parasitic infections in rural areas

Multilocus genotyping of Giardia duodenalis in Southwestern Iran. A community survey.

Giardia duodenalis is one of the main enteric pathogens associated with diarrheal disease. In developing countries, giardiasis is a major public health concern, particularly in children under five years of age. This study aimed to evaluate the occurrence and genetic diversity of G. duodenalis causing human infections in Shushtar County, Southwestern Iran. Individual faecal specimens were collected from 1,163 individuals (male/female ratio: 0.9; age range 2-75 years) with (n = 258) and without (n = 905) gastrointestinal symptoms living in rural and urban settings during the period 2017-2018. Conventional (sucrose flotation and microscopy) methods were used for the initial detection of G. duodenalis cysts in faecal specimens. Microscopy-positive samples were confirmed by PCR amplification and sequencing of the small subunit rRNA (ssu rRNA) gene of the parasite. A multilocus genotyping (MLG) scheme targeting the triose phosphate isomerase (tpi), the glutamate dehydrogenase (gdh), and the beta-giardin (bg) genes was used for genotyping purposes. Giardia duodenalis cysts were detected in 7.7% (90/1,163) of samples by microscopy, of which 82 were confirmed by ssu-PCR. Successful amplification and sequencing results were obtained for 23.2% (19/82), 9.8% (8/82), and 8.5% (7/82) of the confirmed samples at the tpi, gdh, and bg loci, respectively. MLG data for the three loci were available for two samples only. Out of the 24 samples genotyped at any loci, 50% (12/24) were identified as assemblage A and the remaining half as assemblage B. Overall, AII was the most prevalent sub-assemblage detected (41.7%, 10/24), followed by BIII (25.0%, 6/24), discordant BIII/BIV (5/24) or AII/AIII (2/24) sequences, and BIV (1/24). No significant correlation was demonstrated between a given assemblage/sub-assemblage and the occurrence of clinical symptoms. No genotypes adapted to animal hosts other than humans (e.g. assemblages C-F) were found circulating in the investigated human population, suggesting that transmission of human giardiasis in this Iranian region is primarily of anthroponotic nature. Further molecular-based studies are needed to confirm and expand these results, and to ascertain the presence and public health relevance of the parasite in environmental (e.g. drinking water) samples.This study was funded by the Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz (Iran) under grant OG/9731 to MB. Additional funding was obtained from the Health Institute Carlos III (ISCIII), Ministry of Economy and Competitiveness (Spain), under project PI16CIII/00024 to DC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.S