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

Abstract

Background: Natural 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.

Results: From 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.

Conclusions: To 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.

Keywords: Echinococcus granulosus; Fasciola hepatica; Hydatid cyst localization; Polyparasitism.

Fig. 1

Echinococcus granulosus (EG) and Fasciola hepatica (FH) overall prevalence per age group in inspected cattle (n = 1725). Data shown as percentage of infected/ total examined cattle in the respective categories. *P < 0.05 (Chi-square test)

Fig. 2

Anatomical distribution of hydatid cyst in cattle within age range (a); Fasciola hepatica (FH) co-infection status (b); within age range in animals without FH co-infection (c) and with FH co-infection (d). In a cyst anatomical distribution significantly varied among young (≤ 4 years) (χ² = 7.973, df = 2, P = 0.0186) and old animals (> 4 years) (χ² = 14.80, df = 2, P = 0.0006) and within age groups. In b a significant association was found between cyst location and FH co-infection status, where a significant difference was found in animals with FH co-infection (χ² = 22.30, df = 2, P < 0.0001), and not in animals without FH co-infection (χ² = 1.432, df = 2, P = 0.4883). c No association was found between age range and cyst location in animals absent of FH co-infection, or location within each age group. d In cattle with FH co-infection, a significant association was identified between age range and cyst location as well as among each age group. Data are presented as percentage (%) of the number of animals/ total examined cattle in the respective categories. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. Abbreviation: ns, not statistically significant