Fasciola hepatica coinfection modifies the morphological and immunological features of Echinococcus granulosus cysts in cattle

Christian Hidalgo,Rodolfo Paredes,Caroll Stoore,Marcela Hernández

doi:10.1186/s13567-020-00799-5

Christian Hidalgo, Rodolfo Paredes + Show 2 more

Open Access

https://doi.org/10.1186/s13567-020-00799-5

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Abstract

Polyparasitism occurs when animals harbour multiple parasites concomitantly. It is a common occurrence but is generally understudied in wild and domestic animals. Fasciola hepatica and Echinococcus granulosus, which are helminths of ungulates, frequently coinfect cattle. The effects of this particular type of polyparasitism are not well documented. The metacestode of Echinococcus granulosus is surrounded by the adventitial layer, which constitutes the host immune response to the parasite. This layer in cattle is produced by a granulomatous reaction and is involved in echinococcal cyst (EC) fertility. Due to the systemic immune-modulating abilities of Fasciola hepatica, coinfection possibly generates a favourable environment for EC growth. A total of 203 Echinococcus granulosus sensu stricto cysts were found in 82 cattle, of which 42 ECs were found in 31 animals coinfected with Fasciola hepatica. The overall infection intensity was 3 cysts per animal. Coinfection with Fasciola hepatica decreased the mean infection intensity to 1.4 cysts per animal. Regarding EC size, coinfection resulted in smaller ECs (15.91 vs 22.09 mm), especially for infertile lung cysts. The adventitial layer of ECs in coinfected animals lacked lymphoid follicles and palisading macrophages, which are generally hallmarks of the granulomatous immune response. The ECs in coinfected animals had organized laminated layers, whereas those in animals without coinfection did not. Although coinfection was not statistically associated with EC fertility, we did not find fertile cysts in the livers of coinfected animals. We concluded that coinfection with Fasciola hepatica and Echinococcus granulosus has a detrimental effect on ECs, particularly infertile cysts.

Highlights

Polyparasitism, which is co-infection with different parasite species in the same host, is a well-documented subject in the medical, veterinary, and zoological literature
A previous study found that 46.57% of E. granulosus-infected cattle harbour both parasites simultaneously [17], which was a higher percentage than that found this report
We found that F. hepatica infection decreases the E. granulosus infection intensity

Summary

Introduction

Polyparasitism, which is co-infection with different parasite species in the same host, is a well-documented subject in the medical, veterinary, and zoological literature. Experiments in rats with Moniliformis moniliformis and Hymenolepis diminuta determined that in single infections, both parasites are localized in the anterior portion of the small intestine, whereas in coinfections, Hymenolepis diminuta is pushed to a posterior segment; interestingly, Hymenolepis diminuta lives longer than Moniliformis moniliformis, and once the latter dies, Hymenolepis diminuta moves to its preferred anatomical place [1]. Another example is nematodes from the Steinernema and Heterorhabditis genera [11]

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