American trypanosomiasis or Chagas disease is caused by the protozoan Trypanosoma cruzi . Its natural vectors are the reduviid insects, specifically triatomines , variably known as wild bedbugs, assassin bugs, or kissing bugs. It can also be transmitted orally from…
Sixty million people in 36 countries are at risk for infection with Trypanosoma brucei complex, the causative agent of sleeping sickness. Also known as human African trypanosomiasis (HAT) , this disease is restricted to sub-Saharan Africa, the range of the…
The leishmaniases are a diverse group of diseases caused by intracellular protozoan parasites of the genus Leishmania, which are transmitted by phlebotomine sandflies. Multiple species of Leishmania are known to cause human disease involving the skin and mucosal surfaces and…
Trichomoniasis is caused by the protozoan Trichomonas vaginalis. It is the second most common sexually transmitted infection worldwide. Vulvovaginitis is the symptomatic disease form, but T. vaginalis has been implicated in pelvic inflammatory disease, pregnancy loss, chronic prostatitis, and an…
The spore-forming intestinal protozoa Cryptosporidium, Cystoisospora (formerly Isospora ), and Cyclospora are important intestinal pathogens in both immunocompetent and immunocompromised hosts. Cryptosporidium, Cystoisospora, and Cyclospora are coccidian parasites that predominantly infect the epithelial cells lining the digestive tract. Microsporidia were…
Giardia duodenalis Chandy C. John Giardia duodenalis is a flagellated protozoan that infects the duodenum and jejunum. Infection results in clinical manifestations that range from asymptomatic colonization to acute or chronic diarrhea and malabsorption. Infection is more prevalent in children than…
Entamoeba species infect or colonize up to 10% of the world's population, particularly in resource-limited settings. In most infected individuals, Entamoeba histolytica or a related species parasitizes the lumen of the gastrointestinal tract and causes few symptoms or sequelae. Although…
Naegleria, Acanthamoeba, Balamuthia, and Sappinia are small, free-living amebae that cause human amebic meningoencephalitis, which has two distinct clinical presentations. The more common is an acute, fulminant, and usually fatal primary amebic meningoencephalitis (PAM) caused by Naegleria fowleri that occurs…
Parasites are divided into three main groups taxonomically: protozoans, which are unicellular, and helminths and ectoparasites, which are multicellular. Chemotherapeutic agents appropriate for one group may not be appropriate for the others, and not all drugs are readily available (…
The transmissible spongiform encephalopathies (TSEs, prion diseases) are slow infections of the human nervous system, consisting of at least four diseases of humans ( Table 304.1 ): kuru; Creutzfeldt-Jakob disease (CJD) with its variants—sporadic CJD (sCJD), familial CJD (fCJD), iatrogenic…