Evidence for camels (Camelus bactrianus) as the main intermediate host of Echinococcus granulosus sensu lato G6/G7 in Mongolia

The Diagnostic Challenge of Cystic Echinococcosis in Humans: First Assessment of Underreporting Rates in Mongolia

Cystic echinococcosis (CE), caused by the larval stage of Echinococcus granulosus, is significantly underreported in Mongolia due to geographical remoteness, a lack of early diagnostics, and poor clinical management. This study aimed to provide a more accurate estimate of CE in Mongolia by comparing data from surgical (reported) and diagnosed (unreported) cases and assessing the challenges faced by rural doctors in disease management and surveillance. We collected data on surgical cases hospitalized between 2006 and 2016 and newly diagnosed CE cases in 2016 from eight provinces. Using a quasi-Poisson regression model, we extrapolated the collected data to estimate the number of diagnosed cases for the entire country. Additionally, forty health professionals from all 21 provinces rated local clinical management for CE through a questionnaire. The results reveal that surgical cases (2.2 per year) represent only one-eighth of diagnosed cases (15.9 per year). The laboratory facilities, disease reporting, and cyst classification usage scored below 2. These results highlight the significant underreporting of CE in Mongolia and urge human and animal health experts, along with policymakers, to invest in combating CE, particularly in remote provincial areas. This study also emphasizes the need for standard clinical management involving cyst classification according to the WHO-IWGE and seamless integration of CE reporting and monitoring mechanisms, which can significantly contribute to the national and global burden estimation of CE.

Echinococcus granulosus sensu lato Genotypes in Different Hosts Worldwide: A Systematic Review

INTRODUCTION

The aim of this study was to develop a synthesis of the evidence available regarding verified E. granulosus sensu lato (s.l.) genotypes in different species worldwide.

MATERIAL AND METHODS

A systematic review was performed including studies concerning genotypes of E. granulosus s.l. without language or genotyped method restriction, published between 1990 and 2020. A systematic search was carried out in Trip Database, BIREME, SciELO, LILACS, IBECS, PAHO-WHO, EMBASE, PubMed, Scopus, and WoS. Variables of interest were year of publication, country, number of samples, and hosts; genotypes, molecular marker, haplotypes and molecular biology techniques used. Descriptive statistics were applied.

RESULTS

2411 articles were analyzed, however 135 met the selection criteria, representing 8643 liver and lung samples. Of the samples selected 24% were human, the remaining samples pertained to non-human animal hosts; cattle and sheep prevailed with 28.6% and 26.6% of the studied samples, respectively. The reported evidence is mainly from Iran, Turkey, Argentina, China and Chile; with 50, 11, 6, 6 and 5 studies, respectively, published between 1992 and 2020 [most frequently during 2015-2020 (76/135 studies; 56.3%)]. The mitochondrial gene cox1 was generally sequenced and informative (91.8%). Genotypes most frequently identified were E. granulosus sensu stricto (s.s.) (83.2%).

CONCLUSIONS

Based on this overall evidence, it can be concluded that publications related to genotypes of E. granulosus s.l. are heterogeneous. E. granulosus ss accounts for the vast majority of the global burden of E. granulosus s.l. worldwide. Further studies including larger number of cases and adequate internal validity are required to specify the distribution of genotypes in various host species.

TRIAL REGISTRATION

PROSPERO CRD42018099827.

Three species of Echinococcus granulosus sensu lato infect camels on the Arabian Peninsula

We report on the genetic identity of 36 Echinococcus cysts that were collected during a recent slaughterhouse survey of 810 locally bred camels (dromedaries) in the Eastern Province of the Kingdom of Saudi Arabia. Analysis of a partial nad1 gene sequence showed that the majority (n = 29) belonged to E. granulosus sensu stricto, four to E. canadensis G6/7, and three to E. ortleppi. Eight of the 29 E. granulosus s.s. cysts contained protoscoleces; all other cysts were calcified and non-viable. This is the first report of the presence E. ortleppi from the Arabian Peninsula, a parasite that is typically transmitted via cattle. The results indicate widespread infection of camels with CE in eastern Saudi Arabia and an active role of camels in the lifecycles of at least E. granulosus s.s.. Complete cox1 haplotype analysis of 21 E. granulosus s.s. isolates shows that the majority of variants circulating in eastern Saudi Arabia is distinct from but closely related to haplotypes from neighboring countries in the Middle East, which indicates the presence of this parasite in KSA for a longer period of time. All isolates of E. granulosus s.s. in this study belonged to the G1 cluster, although the G3 genotype has previously also been reported from the Middle East.

The global status and genetic characterization of hydatidosis in camels (Camelus dromedarius): a systematic literature review with meta-analysis based on published papers

Hydatidosis is a potential zoonotic helminthic disease affecting a broad spectrum of mammals, including humans, worldwide. The current review was conducted to investigate the genotypic status and prevalence of hydatid disease in camels across the world. For the purpose of the study, the articles addressing the worldwide prevalence of hydatidosis in camels were searched in several English language databases. The search process resulted in the inclusion of 122 papers. Based on the data presented in the reviewed articles, the pooled prevalence of hydatid disease in camels across the world was measured at 23.75% (95% CI 20.15-27.55). Moreover, the subgroup analysis demonstrated significant differences in the overall prevalence of hydatidosis among camels based on year, geographic area, climate parameters, camel population, gender, infected organ, fertility rate of the cyst and laboratory diagnostic technique. Furthermore, the Echinococcus granulosus genotypes identified in camels with hydatidosis included G1, G2, G3, G1-G3, G5, G6, G7, G6-G7 and G6-G10, with G6 being the most common genotype throughout the world. The data obtained from the current study are central to the better conceptualization of the biological and epidemiological characteristics of E. granulosus s.l. genotypes around the world, which can be helpful in the planning and adoption of more comprehensive control strategies.