Echinococcus granulosus hydatid cyst location is modified by Fasciola hepatica infection in cattle

Abstract

BackgroundNatural parasite infection occurs in wild and domestics animals with more than one parasite species at the same time, generating an infection called polyparasitism. Cystic echinococcosis reports are usually based only on infection with Echinoccocus granulosus leaving aside other internal parasitoses that could modulate both the immune response and pathogenesis of the natural infection. Fasciola hepatica is another cosmopolitan parasite in ruminants with a similar distribution to E. granulosus in different parts of the world, but no information of the effect of co-infection with E. granulosus has been described. The aims of this report were to establish E. granulosus prevalence and explore the association of F. hepatica co-infection and natural E. granulosus infections in cattle.ResultsFrom 1725 animals, the prevalence of E. granulosus and F. hepatica was 21.16 and 51.3%, respectively. Considering both infections, older cattle (> 4 years) presented higher prevalence compared to younger animals. In E. granulosus-infected cattle, 5.21% had fertile cysts, 71.78% infertile cysts, and in 23.01% cysts were smaller than 1 cm in diameter. Considering cyst location, 39.72% had lungs cysts, 24.72% had liver cysts and 36.94% had cysts in both organs. Cyst location significantly differed between age groups: 44.68% of younger animals had cysts only in the lungs, while older animals presented hydatid cyst in the lungs and liver simultaneously (44.15%). With E. granulosus infection alone, 30.26% of cysts were found in the lungs, 31.79% in the liver and 37.95% in both organs. Regarding the co-infection of E. granulosus with F. hepatica, the proportion was significantly different (P < 0.05) with most animals having cysts only in the lungs (49.41%) and a lower level of liver infection (15.88%). Analyzing organ cyst distribution and F. hepatica absence/presence ratio within each cyst type, small cysts showed the highest difference in ratio.ConclusionsTo the best of our knowledge, this is the first report indicating that F. hepatica co-infection in cattle could be affecting the instate of hydatid cysts in the liver, displacing toward lung localization, suggesting an antagonistic relationship.

Cattle co-infection of Echinococcus granulosus and Fasciola hepatica results in a different systemic cytokine profile than single parasite infection

“…Although extremely relevant for the comprehension of the host-parasite relationship, there is scarce information in the literature that allows determination of the real effects of polyparasitism in host health [35]. A previous study indicates that polyparasitism between Echinococcus granulosus and Fasciola hepatica is associated with a decrease in Echinococcal cysts found in liver by CE and, an increase in lung Echinococcal cysts, particularly small cysts [36]. There are no differences between B and T cell infiltration in the adventitial layer of both fertile and infertile cysts when the host is co-infected with Fasciola hepatica [37].…”

“…Fasciola hepatica, also a platyhelminth, represents a major infection in cattle named fascioliasis. A study of Echinococcus granulosus and Fasciola hepatica co-infection showed that it can happen in almost 10% of cattle [36]. As with other helminths, Fasciola hepatica infection triggers a mixed Th2/Treg immune response [38].…”

“…Only samples from Echinococcus granulosus sensu stricto were included in the study. Fascioliasis diagnosis was made either by direct visualization of adult parasites in bile ducts or by signs of chronic infection, as previously described [36]. Cattle were considered co-infected when Echinococcus granulosus and Fasciola hepatica were found in the same individual, not necessarily the same organ.…”

New insights of the local immune response against both fertile and infertile hydatid cysts

“…The definitive hosts are dogs and other canids; while ungulates and other mammals act as intermediate hosts [3] such as sheep, goats, cattle, pigs, buffaloes, horses and camels [4]. The most common infection sites in cattle are the liver and lungs [5][6][7]. Within these viscera, a unilocular cyst forms, that will grow gradually from 1 to 5 cm a year [8].…”

“…The reason behind why infertile hydatid cysts are unable to produce PSC remains unclear [24]. In many geographical areas, including Chile [25], cattle has been associated with low fertile hydatid cysts counts (<30%) in both Echinococcus granulosus sensu lato [26][27][28][29] and Echinococcus granulosus sensu stricto [6,22], so it is a suitable model to study cyst infertility mechanisms. Our research team, so far has been working in understanding the causes of infertile hydatid cyst in cattle, identifying both higher apoptosis levels in germinal layer of infertile cysts [24] and different immunoglobulin profiles [30].…”