Table 1.

Nosocomial parasites, listed according to their route of infection, with their infective stages, routes of infection, reported frequencies, and selected references.

Pathogen	Infective Stage in Healthcare-Associated Infection (HAI)	Route of Infection in HAI	Reported Frequency	Selected References
Toxoplasma gondii	bradyzoites (infection of donor a long time ago) tachyzoites (recent infection of donor)	solid organ transplantation (SOT; heart, lungs, kidneys)	25–75% in absence of prophylaxis	[6,7]
	oocysts	water	unknown	[8]
Plasmodium spp.	schizonts of the erythrocytic cycle	blood transfusion	1 case/year in non-endemic countries	[9]
		infected needles	very rare	[10,11]
		SOT	unusual	[12]
Babesia spp.	trophozoites	blood transfusion	162 cases in 30 years	[13]
Trypanosoma cruzi	metacyclic trypomastigotes	blood transfusion	800 cases in 2005	[14,15]
		during birth	5% of children of infected mothers	[16]
		contaminated food/water	in Brazil: more infections than classical route (via kissing bugs)	[17]
Leishamania spp.	amastigotes	blood transfusion	~6% of blood samples positive for L. infantum DNA	[18]
Filariae	microfilariae	blood transfusion	very rare	[19]
Strongyloides stercoralis	larvae	SOT	uncommon; 27 reported cases	[20]
Taenia solium	cysticerci	SOT	3 cases	[21,22]
	eggs	food/water person-to-person	unknown	[23]
Schistosoma spp.	eggs	SOT	very few cases	[24]
Fasciola hepatica	adult flukes	SOT	1 case	[25]
Acanthamoeba spp./ Balamuthia mandrillaris	trophozoites	SOT	>10 cases	[26]
		contaminated devices	1 case	[27]
Naegleria fowleri	trophozoites	SOT	not reported to date	[28]
Trichomonas vaginalis	trophozoites	during birth	2 to 17% of neonates of infected mothers	[29]
Giardia spp.	trophozoites and cysts	during birth	rare	[30]
		food/water	4.4–6.75% of diarrhea patients	[31,32]
Cryptosporidium spp.	oocysts	during birth	rare	[33]
		food/ water	often	[34]
		person-to-person	uncommon–rather often	[35,36]
Enterobius vermicularis	eggs	during birth	rare	[37]
		person-to-person	20–30% in pediatric clinics	[38]
Sarcoptes scabiei	mainly impregnated female mites	person-to-person	19 outbreaks in 16 hospitals	[39]
Entamoeba histolytica	cysts	food/water	probably common in clinics with poor sanitation	[40,41]
Maggots	larvae	female flies lay eggs in open wounds/intact skin	low frequency, but constant	[42]
Flies	bacteria/viruses	bacteria/viruses mechanically transported	e.g., 42% positive for Escherichia coli, 96% positive for Pseudomonas spp.	[43,44]
Cockroaches	bacteria/viruses	bacteria/viruses mechanically transported	detected in 70% (German cockroach) and 40% (Oriental cockroach) of hospitals in Poland	[45]
Pharaoh ants	bacteria/viruses	bacteria/viruses mechanically transported	detected in 14% of hospitals in Poland	[46]
Dermanyssus gallinae	mites	bird nests near window provide mites that feed on blood	rare	[47]
Pediculus humanus capitis	adults/nits	close hair contact	30–70% in pediatric clinics	[48]
Pediculus humanus corporis		contact with infested clothing	unknown; (6–30% in homeless people)	[49]
Phtirus pubis	adults	sexual contact; contact with bedding	unknown; (general population: 1.3–4.6%)	[50]
Demodex folliculorum/Demodex brevis	adults	immunosuppression increases number of parasites	56% in heart failure patients	[51]