Parasitic zoonoses in Papua New Guinea

Relatively few species of zoonotic parasites have been recorded in humans in Papua New Guinea. A greater number of potentially zoonotic species, mostly nematodes, occur in animals but are yet to be reported from humans. Protozoa is the best represented group of those infecting man, withGiardia duodenalis,Cryptosporidium parvum,Cyclospora cayetanesis,Toxoplasma gondii,Sarcocystisspp.,Entamoeba polecki,Balantidium coliand, possibly,Blastocystis hominis. The only zoonotic helminths infecting humans include the trematodeParagonimus westermani, the cestodesHymenolepis nana,H. diminutaand the sparganum larva ofSpirometra erinacea, and the nematodesTrichinella papuaeandAngiostrongylus cantonensisand, possibly,Ascaris suum. Other groups represented are Acanthocephala (Macracanthorhynchus hirudinaceus)), insects (Chrysomya bezziana,Cimexsp.,Ctenocephalidesspp.), and mites (Leptotrombidiumspp. and, possiblySarcoptes scabiei, andDemodexsp.). One leech (Phytobdella lineata) may also be considered as being zoonotic. The paucity of zoonotic parasite species can be attributed to long historical isolation of the island of New Guinea and its people, and the absence until recent times of large placental mammals other than pig and dog. Some zoonotic helminths have entered the country with recent importation of domestic animals, in spite of quarantine regulations, and a few more (two cestodes, one nematode and one tick) are poised to enter from neighbouring countries, given the opportunity. Improvement in water supplies, human hygiene and sanitation would reduce the prevalence of many of these parasites, and thorough cooking of meat would lessen the risk of infection by some others.