Foodborne Giardiasis: Is There Any Relationship Between food Handlers and Transmission of Giardia duodenalis?

Intestinal parasites among food handlers in Iran: A systematic review and meta-analysis

Regarding preparing and serving foods, food handlers have an influential role in the spreading of foodborne infections. Due to the great potential to cause foodborne infections, intestinal parasites (IPs) are considered a significant public health problem in today's societies. In Iran, despite several regional reports, national data on IPs prevalence in food handlers are lacking. The aim of the present study, therefore, is to estimate the pooled prevalence of IPs infections and associated pooled odds ratio of educational level among food handlers in Iran. PubMed, Web of Science, Scopus, Embase, and Google Scholar databases (international) and SID and Magiran databases (national) were systematically searched for studies that reporting the prevalence of IPs in food handlers in Iran, published between 2000 and 2020. Pooled prevalence was estimated using a random-effects model with a 95% confidence interval (CI) and depicted as a forest plot, while heterogeneity was evaluated using Cochran's Q-test. The overall pooled prevalence estimate for IPs was 19.3% (95% CI = 14.9-23.7%). Prevalence of the protozoan parasites (20%, 95% CI = 13.7-26.3%) was significantly higher than that of the helminthic parasites (1.6%, 95% CI = 1.1-2.0%). Giardia lamblia (5.2%), Entamoeba coli (5.0%), and Blastocystis spp. (4.4%), as protozoan parasites, and Ascaris lumbricoides (1.4%), Enterobius vermicularis (0.9%), and Hymenolepis nana (0.5%), as helminthic parasites, were the most commonly reported species. Food handlers with low educational levels were 20% more exposed to IPs infection, compared to those with high educational levels (OR = 1.21, 95% CI = 0.88 to 1.65). The prevalence of IPs infections among food handlers in Iran is significant. Besides taking into account this epidemiologic information, a holistic approach, including periodic stool screening, health education, and treatment of infected food handlers, will help in the control of these infections in Iran.

Molecular Genotyping of Giardia duodenalis in Humans in the Andimeshk County, Southwestern Iran

INTRODUCTION

Giardia duodenalis, one of the most common intestinal protozoa, infects a wide range of vertebrates, including humans and animals.

MATERIALS AND METHODS

In this study, 84 Giardia duodenalis positive stool samples were collected from 3580 patients attending the Imam Ali Hospital and two public health centers in Andimeshk County, southwestern Iran. Stool samples were examined initially by microscopy, and then G. duodenalis was confirmed by SSU rRNA gene and genotypes were determined by amplification of the gdh and β-giardin genes.

RESULTS

The SSU rRNA, gdh, and β-giardin genes were successfully amplified in 89.3%, 58.3%, and 51.2% samples, respectively. Of the positive samples for gdh and β-giardin, 40 isolates were successfully sequenced. Twenty-three isolates belonged to assemblage A, sub-assemblage AII, and 17 belonged to assemblage B. Of the 24 successfully amplified asymptomatic cases, 12 belonged to assemblage A and 12 belonged to assemblage B.

CONCLUSION

The current study found that 64.3% of the patients were asymptomatic. From an epidemiological point of view, the high percentage of asymptomatic patients is important because of their role in the transmission of Giardia. The predominant assemblage was assemblage A, sub-assemblage AII. In general, therefore, it seems that most infections are probably transmitted by anthroponotic pathways in the region.

Giardia: an under-reported foodborne parasite

Foodborne zoonotic pathogens are a serious public health issue and result in significant global economic losses. Despite their importance to public health, epidemiological data on foodborne diseases including giardiasis caused by the enteric parasite, Giardia duodenalis, are lacking. This parasite is estimated to cause ∼28.2 million cases of diarrhoea each year due to contamination of food, but very few foodborne outbreaks have been documented due to the limitations of current detection as well as surveillance methods. The current method for the recovery of Giardia cysts from food matrices using immunomagnetic separation requires further standardisation and cost reduction before it can be widely used. It also should incorporate downstream molecular procedures for genotyping, and traceback and viability analyses. Foodborne giardiasis can be potentially controlled through improvements in national disease surveillance systems and the establishment of Hazard Analysis and Critical Control Point interventions across the food chain. Studies are needed to assess the true prevalence and public health impact of foodborne giardiasis.

Molecular genotyping of Giardia duodenalis in children from Behbahan, southwestern Iran

Giardia duodenalis is an intestinal flagellated protozoan that infects humans and several animal species. Giardiasis causing more than 200 million symptomatic infections globally is one of the most common causes of diarrhea in developing countries. Based on molecular studies mainly targeting the small-subunit (SSU) rRNA gene locus of the parasite, eight assemblages (A to H) have been identified in humans and other animal species. The aim of the current study was to evaluate the frequency and molecular diversity of G. duodenalis in children from rural and urban day care centers from Behbahan, southwestern Iran. This cross-sectional study was based on a concentration method for the microscopic detection of G. duodenalis in stool samples of 450 children, aged 1-7 years, in Behbahan, southwestern Iran. The survey was conducted from December 2015 to May 2016. PCR methods targeting the SSU rRNA and triose phosphate isomerase (TPI) genes of G. duodenalis were used for the identification and genotyping of the parasite isolates. Based on sucrose flotation and microscopy techniques, 2.7% (12/450) of children were infected with G. duodenalis, of which six (50.0%) were males and the other six (50.0%) were females. Overall, 91.7% (11/12) of the infections were detected in children from rural areas. The SSU rRNA and TPI genes were amplified successfully in nine and eight, respectively, of the Giardia-positive samples at microscopy. Among the eight TPI sequences, assemblage A, sub-assemblage AII, was identified in five of the isolates. The sequences of the three remaining samples were untypable. Although no significantly statistical difference between genotype and clinical symptoms was found, five out of the eight isolates identified as assemblage A were obtained in asymptomatic children. Giardia duodenalis infections were more prevalent in children from rural day care schools, and the predominant assemblage was A, sub-assemblage AII. The higher prevalence of giardiasis in rural areas might be related to differences in personal hygiene habits, parents' education level, source of drinking water, and inadequate hygienic toilet facilities in rural areas.