Epidemiological and molecular studies on Echinococcus granulosus from free-roaming dogs in Southeast Iran

Global distribution and definitive host range of Echinococcus species and genotypes: A systematic review

Echinococcus species (spp.) are regarded as neglected cestodes causing several potential zoonoses of global public health. This systematic review critically appraises the worldwide distribution of Echinococcus spp. and genotypes (Echinococcus spp.: recognized species in the genus; genotypes: variants identified within E. granulosus sensu lato.) in definitive hosts. We analyzed 82 studies from major databases, comprising 24 individual host species, including canids, felids, and a hyenid species. Canids, particularly dogs, were the most studied group among the host species, with E. granulosus sensu stricto (G1-G3) being the most frequently reported. E. granulosus s.s. was distributed across five major continents, while other Echinococcus spp. and genotypes exhibited an uneven continental distribution. The highest overlap of species existed among Asia, Europe, and Africa. Among the reported host species, 4.2 % were endangered (e.g. Lycaon pictus), 12.5 % species were vulnerable (e.g. Panthera leo, Panthera pardus, and Acinonyx jubatus), and 4.2 % were near threatened (e.g. Speothos venaticus). Overall, our review highlights the significance of canids, particularly dogs, as the core focus of scientific investigations, with E. granulosus s.s. being the most widely distributed species across five major continents, emphasizing the urgent need for continued research and public health efforts.

Environmental contamination with feces of free-roaming dogs and the risk of transmission of Echinococcus and Taenia species in urban regions of southeastern Iran

BACKGROUND

Dogs are the most important definitive hosts of zoonotic taeniid helminths worldwide. Different Echinococcus and Taenia species of domestic and wild carnivores pose a potential risk to human population. High populations of free-roaming dogs (FRDs) in urban areas of Iran and widespread contamination of the environment with dog feces is a potential source of infecting people living in the urban regions with cystic echinococcosis (CE). Our knowledge on the risk of CE transmission in the urban settings in the endemic regions is limited. The present study surveyed the species and genotypes of E. granulosus sensu lato and other taeniids by examining feces of free-roaming dogs in the urban areas in the city of Kerman, southeastern Iran.

METHODS

The city was divided into 100 consecutive blocks of which 25 blocks were randomly selected. Fecal samples of FRDs were counted, mapped and fresh samples were collected. Then Zinc chloride flotation, and sequential sieving was performed, and the samples were examined under an inverted microscope. Single individual taeniid eggs were isolated, partial nad1 gene was amplified and sequenced to identify species and genotypes.

RESULTS

In total 5607 fecal samples of dogs were mapped and 83 fresh samples were collected. Taeniid eggs were detected in nine fecal samples (10.8%) from seven out of the 25 city blocks (28.0%). Echinococcus eggs were found in four samples (4.8%) from three city blocks, two samples containing E. granulosus sensu stricto (2.4%), two samples containing E. canadensis G6/7 (2.4%). In addition, three samples contained eggs of Taenia hydatigena (3.6%), and one sample of Taenia serialis (1.2%).

CONCLUSIONS

This study documented the potential risk of CE transmission to humans resulting from the feces of dogs roaming freely in urban areas.

Gastrointestinal parasites of dogs and foxes in the Zanjan province of Iran: With an emphasis on Echinococcus species

Canids harbor many zoonotic parasites and play an important role in the spread of parasites in the human environment. Estimation of parasitic infection among canids as definitive hosts may help competent authorities design efficient control programs. This study was conducted to determine the prevalence of intestinal parasites in dogs and foxes with an emphasis on Echinococcus spp. A total of 500 fecal samples of dogs and 30 fecal samples of foxes were studied in the summer, autumn, and winter of 2021 in the Zanjan province using the formalin-ethyl acetate concentration technique, followed by multiplex PCR. The overall prevalence of gastrointestinal parasite infection was estimated to be 19.05%. The prevalence was 24.8%, 10.2%, and 26.7% in stray, shelter dogs and foxes, respectively. No parasites were found among pet and guard dog samples. PCR results on Taenidae eggs showed that 2.4% of samples were positive for Echinococcus granulosus and none contained E. multilocularis. Noteworthy is that E. granulosus was identified only in stray dog samples. The higher prevalence of E. granulosus infection in stray dogs in this province emphasizes the importance of monitoring the food sources consumed by these animals.

Global distribution of Echinococcus granulosus genotypes in domestic and wild canids: a systematic review and meta-analysis

The current systematic review and meta-analysis demonstrate the genotypic distribution of canine echinococcosis worldwide. Studies published from the inception until 21 May 2021 were screened, relevant articles were selected and the random-effect model was used to draw forest plots with 95% confidence intervals (CIs). Totally, 44 articles were included, mostly examined dogs (37 records), followed by wolf (8 records), jackal (7 records), fox (3 records), pump fox (3 records) and coyote (1 record). Echinococcus granulosus sensu stricto (G1–G3) and G6/7 cluster of Echinococcus canadensis were the most common genotypes among canids. Most studies were conducted in Asia and Europe with 17 and 15 datasets, respectively. Exclusively, Iran possessed the highest number of studies (10 records). Meta-analysis showed that the pooled molecular prevalence of echinococcosis was 33.82% (95% CI 24.50–43.83%). Also, the highest and lowest prevalence of canine echinococcosis was calculated for South America (66.03%; 95% CI 25.67–95.85%) and Europe (19.01%; 95% CI 9.95–30.16%). Additionally, there were statistically significant differences between the global prevalence of echinococcosis in canines and publication year, continent, country, sample type, host and molecular test. These findings will elevate our knowledge on the poorly known canine echinococcosis worldwide.

Prevalence and Molecular Characterization of Echinococcus granulosus Sensu Lato Eggs among Stray Dogs in Sulaimani Province-Kurdistan, Iraq

The main goal of this study was to estimate the prevalence of Echinococcus granulosus among stray dogs, as well as its potential impact on the environmental contamination in the Kurdistan-Iraq using microscopic examination and the Copro-PCR method. The presence of taeniid eggs was recorded in 400 dog faeces collected from the four different regions in the Sulaimani Governorate. The parasite eggs were recovered from fresh and aged faecal samples of the dogs using two isolation techniques, a flotation method (Sheather’s solution, modified; specific gravity: d = 1.27) and a sedimentation method (formal-ether) in which the sediments from dog faeces were collected. Both methods were used for Copro-PCR to detect the presence of Echinococcus species egg through DNA using common primers designed to amplify a partial gene of cytochrome oxidase subunit 1 (COX₁). The results of the microscopic examination showed a higher prevalence rate, i.e., 97 (24.25%) of E. granulosus among stray dogs generally in Sulaimani Governorate. The prevalence of E. granulosus among stray dogs according to the district area was 40, 24, 23, and 20.8% in Rzgari, Kalar, Sulaimani, and Halabja, respectively. The positive samples (n = 50) were selected for molecular confirmation, the DNA was extracted from the sediment of the positive samples and 40 (80%) samples were successfully amplified by polymerase chain reaction. The sequences show that all samples belong to the Echinococcus granulosus sensu lato (G₁–G₃), with slight genetic variation. It was concluded that the sediment of dog faeces can be used for DNA extraction, which is a new method that increases the sensitivity of the test, and the amount of DNA yield would be higher than the routine method, which directly uses faeces of the dogs. In addition, the molecular diagnosis was more sensitive than the microscope examination for the presence of E. granulosus eggs. The prevalence of E. granulosus in both the final hosts and the intermediate hosts must be regularly monitored.

Cystic Echinococcosis: Knowledge, Attitude, and Practices (KAP) among Surgically Operated Cases in Fars Province, Southern Iran

Introduction

Cystic echinococcosis (CE) is a neglected zoonotic disease caused by Echinococcus granulosus with major health and economic burden. The information on how the community members perceive the disease is crucial in order to recommend an effective preventive and control plan. The current study is aimed at finding out knowledge, attitude, and practices (KAP) of surgically operated cases of hydatid cyst in educational hospitals of Shiraz in Fars Province, southern Iran, toward the CE.

Methods

A cross-sectional survey was conducted among 180 CE patients who underwent surgery due to CE. Using a well-designed questionnaire, a telephone-based survey was carried out to collect the data. The contents of the questionnaire included basic personal information and questions related to the participants' knowledge, attitude, and behavioral patterns toward CE. Univariate and then multivariate linear regression analyses were used to identify factors associated with the KAP. Unstandardized regression coefficients (β) and odds ratios (ORs) and their 95% confidence intervals (CIs) were used to quantify the associations between variables and KAP.

Results

A total of 180 CE patients with a mean age of 35.64 (±17.59) years were recruited. The mean score of participant's knowledge was 8.7 (SD = 2.8, range: 0-17), whereas these scores were 1.3 (SD = 0.7, range 0-2) for attitude and 1.2 (SD = 1.0, range 0-4) for practice. Findings of the study demonstrated that 20 of the participants (11.1%) had good knowledge towards CE, 82 (45.6%) demonstrated a positive attitude, and 57 (47.5%) without having dogs demonstrated a good practice towards CE (score = 2/2), while from 60 dog owners, only 7 (11.6%) participants demonstrated good practice (score 3 and 4/4). Factors that were associated with knowledge were age (OR = −0.49, P value = 0.001) and educational level (OR = 0.668, P value = 0.001), where higher age was associated with lower knowledge and also higher educational levels were associated with higher knowledge regarding hydatid cyst. Regarding attitude, only living location had a significant association with participants' attitude where those who were living in urban areas demonstrating a more positive attitude towards CE (OR = 0.261, P value = 0.022). The practice of the participants was grouped into dog owners and participants with no dogs, in which among participants who did not own a dog, those living in urban areas demonstrating weaker practice towards CE (OR = −0.491, P value>0.001). Moreover, a lack of counseling of patients after the surgery on how to prevent reinfection was noticed.

Conclusion

Findings of the study revealed that the CE patients in southern Iran had poor knowledge and attitude toward the disease, and their practice may help in maintaining the disease in the community. Health education is highly needed to increase community awareness and to prevent and control this neglected parasitic infection in the area.