Table 1.
Main parasitic diseases in HSCT recipients.
| Common name of disease | Organism | Involved sites | Diagnostic specimen/technique | Distibution/Prevalence | Source/Transmission (Reservoir/Vector) |
|---|---|---|---|---|---|
| Amebic meningo-encephalitis |
Naegleria fowleri Acanthamoeba spp. Balamuthia mandrillaris |
Brain, disseminated | Direct examination or Giemsa stain of CSF/brain to identify tissue cysts or trophozoites; Culture; NAAT | Rare but deadly | Nasal insufflations of contaminated warm fresh water, poorly chlorinated swimming pools, hot springs, soil |
| Babesiosis | B. divergens, B. microti | Red blood cells | Giemsa-stained thin blood smear, NAAT of whole blood | Different species have specific distribution: B. divergens (Europe), B. microti (USA) | Tick bites, e.g. Ixodes scapularis Blood transfusion |
| Blastocystosis | Blastocystis spp. | Intestine | Direct microscopy of stool, NAAT | Worldwide: one of the most common human parasites: USA, ~23% of the population; developing regions, 40–100% of the population | Eating food contaminated with feces from an infected human or animal |
| Chagas disease | Trypanosoma cruzi | Colon, esophagus, heart, nerves, muscle and blood | Serology Giemsa-stained thin blood smear NAAT of whole blood or tissue |
Central America, South America: 16–18 million |
Triatoma/Reduviidae - “Kissing bug” (insect vector feeds at night) Blood transfusion, infected mother to fetus, oral ingestion, or transplantation |
| Cryptosporidiosis | Cryptosporidium spp. | Intestine | Direct microscopy of stool, NAAT | Widespread | Ingestion of oocyst (sporulated), some species are zoonotic (e.g. bovine fecal contamination) |
| Cyclosporiasis | Cyclospora cayetanensis | Intestine | Direct microscopy of stool, NAAT | Widespread | Ingestion of oocyst through contaminated food |
| Isosporiasis | Isospora belli | Epithelial cells of small intestine | Direct microscopy of stool, NAAT | Worldwide - less common than Toxoplasma or Cryptosporidium | Fecal-oral route: ingestion of sporulated oocysts |
| Leishmaniasis | Leishmania spp. | Visceral (L. donovani complex): liver, spleen, bone marrow | Giemsa-stained bone marrow aspirate/biopsy, splenic aspirate, and NAAT | Visceral leishmaniasis: Worldwide |
Phlebotomus or Lutzomyia- bite of several species of phlebotomine sandflies. Transfusion, transplantation or by sharing contaminated needles or syringes. Vertical transmission |
| Malaria |
Plasmodium falciparum (80% of cases), Plasmodium vivax, Plasmodium ovale, Plasmodium malariae Plasmodium knowlesi |
Red blood cells, liver, CNS | Giemsa-stained thick and thin blood smears, immunochromatographic assay and NAAT | Tropical - 300 million cases/year | Anopheles mosquito, bites at night Blood transfusions and organ transplantation |
| Strongyloidiasis | Strongyloides stercoralis | Intestine, lung, skin (larva currens) | Identification of larvae by direct microscopy of stool, sputum, CSF or duodenal aspirate; Serology | Worldwide, 100 millions persons | Skin penetration by contacting contaminated soil Auto-infestation |
| Toxoplasmosis | Toxoplasma gondii | Eye, brain, heart, liver | Serology Giemsa stain or NAAT in CSF or tissue |
Worldwide: one of the most common human parasites; estimated to infect between 30–50% of the global population. | Ingestion of uncooked/undercooked pork/lamb/goat with Toxoplasma bradyzoites, ingestion of raw milk with Toxoplasma tachyzoites, ingestion of contaminated water food or soil with oocysts in cat feces |
CFS, cerebrospinal fluid; CNS, central nervous system; NAAT, nucleic acid amplification tests