Ingestion of Cryptosporidium Oocysts by Caenorhabditis elegans

Abstract

Cryptosporidium parvum has been associated with outbreaks of human illness by consumption of contaminated water, fresh fruits, and vegetables. Free-living nematodes may play a role in pathogen transmission in the environment. Caenorhabditis elegans is a free-living soil nematode that has been extensively studied and serves as a good model to study possible transmission of C. parvum oocysts that may come into contact with produce before harvest. The objective of this study was to determine whether C. elegans could serve as a potential mechanical vector for transport of infectious C. parvum and Cyclospora cayetanensis in agricultural settings and whether C. elegans could ingest, excrete, and protect oocysts from desiccation. Seventy to 85% of worms ingested between 0 and 500 oocysts after 1 and 2 hr incubation with oocysts. Most of the nematodes ingested between 101 and 200 oocysts after 2 hr. Intact oocysts and empty shells were excreted by nematodes. Infectivity was determined by the neonatal assay with different treatments of worms (intact or homogenized) or oocysts or both. Adult C. elegans containing C. parvum kept in water were infective for mice. In conclusion, C. elegans adults can ingest and excrete C. parvum oocysts. Caenorhabditis elegans containing C. parvum oocysts can infect mice but does not seem to protect oocysts from extreme desiccation at 23 C incubation of a day or longer. Cyclospora oocysts were not ingested by C. elegans. The role of free-living nematodes in produce contamination needs to be further examined.

Update on Cyclospora cayetanensis , a Food-Borne and Waterborne Parasite

“…Insects, rotifers, and free-living nematodes could also play a role in the dissemination of oocysts, a phenomenon that has been described for Cryptosporidium (67,74,75,90,179) and other food-borne pathogens. The nematode Caenorhabditis elegans can ingest and excrete infectious bacteria (23,98,99) as well as Cryptosporidium parvum oocysts.…”

“…Although the oocysts of Cyclospora are larger and may not be ingested by C. elegans, other, larger species of free-living nematodes could have a significant role in Cyclospora oocyst dissemination. Therefore, the role of free-living nematodes and other mechanical vectors in the contamination of produce and other food crops needs to be examined further (90).…”

Critical processes affecting Cryptosporidium oocyst survival in the environment

“…Caenorhabditis elegans has been shown to ingest oocysts and excrete both intact oocysts and empty oocysts (Huamanchay et al 2004). King et al (2005) observed variation in oocyst FITC staining which they concluded could be a result of partial digestion of the oocyst wall due to predation of oocysts in raw water samples.…”

Overview of Cryptosporidium Presentations at the 10th International Workshops on Opportunistic Protists

“…In France, working with the French Association of Medical Parasitologists (ANOFEL), Guyot et (24,56). Canada geese and seagulls are occasionally mechanic carriers of human-pathogenic Cryptosporidium spp.…”