Invasion biology meets parasitology: a case study of parasite spill-back with Egyptian Fasciola gigantica in the invasive snail Pseudosuccinea columella.

The liver fluke Fasciola gigantica is a trematode parasite of ruminants and humans that occurs naturally in Africa and Asia. Cases of human fascioliasis, attributable at least in part to F. gigantica, are significantly increasing in the last decades. The introduced snail species Galba truncatula was already identified to be an important intermediate host for this parasite and the efficient invader Pseudosuccinea columella is another suspect in this case. Therefore, we investigated snails collected in irrigation canals in Fayoum governorate in Egypt for prevalence of trematodes with focus on P. columella and its role for the transmission of F. gigantica. Species were identified morphologically and by partial sequencing of the cytochrome oxidase subunit I gene (COI). Among all 689 snails found at the 21 sampling sites, P. columella was the most abundant snail with 296 individuals (42.96%) and it was also the most dominant species at 10 sites. It was not found at 8 sites. Molecular detection by PCR and sequencing of the ITS1-5.8S-ITS2 region of the ribosomal DNA (rDNA) revealed infections with F. gigantica (3.38%), Echinostoma caproni (2.36%) and another echinostome (7.09%) that could not be identified further according to its sequence. No dependency of snail size and trematode infection was found. Both high abundance of P. columella in the Fayoum irrigation system and common infection with F. gigantica might be a case of parasite spill-back (increased prevalence in local final hosts due to highly susceptible introduced intermediate host species) from the introduced P. columella to the human population, explaining at least partly the observed increase of reported fascioliasis-cases in Egypt. Eichhornia crassipes, the invasive water hyacinth, which covers huge areas of the irrigation canals, offers safe refuges for the amphibious P. columella during molluscicide application. As a consequence, this snail dominates snail communities and efficiently transmits F. gigantica.

Zoonoses from cats: with special reference to Egypt.

A zoonosis is an animal disease that is transmissible to humans. Humans are usually an accidental host that acquires disease through close contact with an infected animal, who may or may not be symptomatic. Children are at highest risk for infection because they are more likely to have close contact with pets. Cats are responsible for transmission of an extensive array of bacterial, fungal, and parasitic zoonotic pathogens. The route of transmission can be through the saliva (e.g., bites or contaminated scratches), feces, respiratory secretions, direct contact, or by the cat acting as a vehicle and source of tick or flea exposure. Although cats have been implicated in transmission of zoonosis to their owners, risk of transmission from contact with cats is low and may be further reduced by simple precautions. There is a need for education on zoonotic disease prevention practices for pet-owning households with individuals at higher risk of infection, and to educate future veterinarians during their early years in veterinary school about the risks associated with their future jobs. Also, zoonotic disease awareness training is a valuable service to animal shelter workers.

Zoonoses from dogs with special reference to Egypt.

A zoonosis is an animal disease that is transmissible to humans. Humans are usually an accidental host that acquires disease through close contact with an infected animal, who may or may not be symptomatic. Children are at highest risk for infection because they are more likely to have close contact with pets. Dogs are responsible for transmission of an extensive array of bacterial and parasitic zoonotic pathogens. The route of transmission can be through the feces, urine, saliva (eg, bites or contaminated scratches), or respiratory secretions of the animal, or by the dog or cat acting as a vehicle and source of tick or flea exposure or reservoir for vector borne disease. Although dogs have been implicated in transmission of zoonoses to their owners, risk of transmission from contact with dogs is low and may be further reduced by simple precautions.