Genetic diversity of Echinococcus vogeli in the western Brazilian Amazon

Abstract

Human polycystic echinococcosis is a parasitic infection caused by the larval stage of Echinococcus vogeli, which occurs in rural areas of Central and South America. Until now, little information on the genetic variability of E. vogeli is available. Here, 32 samples from human-excised E. vogeli cysts had a 396-bp sequence of the mitochondrial cytochrome oxidase I (COI) gene sequenced and compared to another 17 COI sequences representing nine Echinococcus species. A Bayesian COI tree revealed that all E. vogeli sequences formed a monophyletic and well-supported clade with an E. vogeli reference sequence. The occurrence of geographically restricted E. vogeli COI haplotypes suggests retention of ancestral polymorphisms with little migration in Acre, Brazil.

Neotropical Echinococcosis: A Review

“…This monophyletic result was more recently confirmed for E. vogeli after studies on its genetic diversity carried out in Western Brazilian Amazon [44,45]. In addition, mitochondrial and nuclear sequence polymorphisms carried out with 38 isolates of E. vogeli from humans and wild animal hosts from Amazonian Regions revealed that E. vogeli is partially synanthropic, with a diverse population near or in association ecologically with humans [44,45]. The use of molecular tools has shown differences in nucleic acid sequences that reflect phenotypic variation, and the phenotypic and genetic characteristics complement the previous observations published by the descriptive parasitologists years ago [20].…”

“…These studies concluded that the origin of the two species of Neotropical Echinococcus appears to be monophyletic; in other words, both share a common ancestor [42,43]. This monophyletic result was more recently confirmed for E. vogeli after studies on its genetic diversity carried out in Western Brazilian Amazon [44,45]. In addition, mitochondrial and nuclear sequence polymorphisms carried out with 38 isolates of E. vogeli from humans and wild animal hosts from Amazonian Regions revealed that E. vogeli is partially synanthropic, with a diverse population near or in association ecologically with humans [44,45].…”

“…It is considered that the number of human cases of neotropical unicystic and EP could be just "the tip of the iceberg" in relation to its real prevalence in Central and South America due to factors such as: (a) most infections occur to farmers, hunters, and rural people who lack medical assistance in those regions; (b) the development of these EP and EU cysts in human tissues or organs is slow and takes time, and during some years, patients are not aware of being parasitized by those polycysts; and (c) under those conditions patients are prone to suffer other infectious or organic diseases, which often might put an end to their lives. Therefore, the total number of human cases only for EP (232 for the year 2008) is perhaps only a small fraction of the real prevalence in South America countries, where there is lack of cumulative reports, of advanced diagnostic methods, and on-time treatment for EP [44]. In other clinical cases, parasitized farmers are able to obtain medical diagnosis and surgical treatment but with fatal results due to the advanced damage to organs such as the liver [21].…”

Occurrence of potential wild hosts of Echinococcus vogeli in the forests of southwestern Brazilian Amazonia

“…There are no other published records of the infection of agouti by E. vogeli in the Amazon region. Most human cases of neotropical echinococcosis recorded in Brazil come from the Amazon region, where the disease is commonly known as "Paca Disease" (D'Alessandro & Rausch 2008, Daipert-Garcia et al 2019). In the state of Amazonas, six cases of the disease were reported (Guimarães et al 2005;Siqueira et al 2013).…”

“…In the state of Amazonas, six cases of the disease were reported (Guimarães et al 2005;Siqueira et al 2013). In the state of Acre, many human cases have been recorded since 1992 (Meneghelli et al 1992, Daipert-Garcia et al 2019, which reflects the continuity of the parasitic cycle of the disease in the Amazon region. Three studies estimated the prevalence of infection in Acre based on serum antibody levels.…”