Eukaryote agents of disease

1. Eukaryote agents of disease Protists, Fungi and Helminthes

2. Apicomplexa • Plasmodium falciparum • Babesia microti • Cryptosporidium • Toxoplasma gondii

3. Malaria • Several species within the genus, Plasmodium • P. falciparum • P. ovale • P. vivax • Severity and treatability varies by species • Anopheles spp. mosquitoes are vectors and definitive hosts, where sexual reproduction occurs, transmit through injection of saliva • Asexual stage occurs in humans when merozoites/trophozoites reproduce in RBC

4. Cryptosporidium spp. • Cause cryptosporidiosis • Many mammalian reservoirs • Cysts are highly resistant to environmental stress and water treatment (i.e. chlorination) • Cysts passed in feces of host, survive long periods in water where they may be ingested by next host • May also be transmitted by direct fecal-oral route • Causes diarrhea, which may be severe in immunocompromised patients • Massive outbreaks (Milwaukee) can occur when water treatment malfunctions

5. Babesia microti • Causes babesiosis • Often asymptomatic • flu-like symptoms usually not fatal • Difficult to treat • Parasite resemble P. falciparum in RBCs • rodents are main reservoir • Transmitted by black-legged ticks (Ixodes scapularis) to humans

6. Toxoplasma gondii • Causes toxoplasmosis • May be asymptomatic, or resemble low-grade infection resembling mononucleosis • May lead to still births in congenital infections • Contracted through contact with cat feces, or undercooked beef • Many mammals and birds may be infected but cats are definitive hosts

7. Mastigophora • Giardia intestinalis (lamblia) • Trypanosoma cruzi • Trypanosoma brucei gambiense, T.b. rodesiense. • Trichomonas vaginalis • Leishmania spp.

8. Trypanosomes • Chaga’s disease- Trypanosoma cruzi • African Sleeping Sickness • Trypanosoma brucei gambiense • T.b. rodesiense.

9. Leishmania spp. • Visceral leishmaniasis (kala-azar) • Cutaneous leishmaniasis (Baghdad boil, oriental sore other names) • Muco-cutaneous leishmaniasis (espundia) • Transmitted by sand fly

10. Trichomonas vaginalis • Causes trichomoniasis, vaginitis • Symptoms include profuse vaginal discharge • Limited by normal vaginal acidity • Male prostate, seminal vesicles, urethra may be infefcted

11. Giardia intestinalis • One of the most common protozoan parasites in U.S. • Adheres to intestinal epithelium and disrupts absorption of water and nutrients • Fecal-oral route of transmission, especially through water contaminated with feces of humans or reservoirs • Many mammals can be reservoirs

12. Sarcodina • Entamoeba histolytica • Naegleria fowleri • Acanthamoeba castellani

13. Entamoeba histolytica • Amebic dysentery • Severity varies by strain and host • Invade intestinal mucosa and may result in long-term infection and tumor-like masses (amebomas) • Extra intestinal infection may result in liver abcess • Severe cases may result in malnutrition • Many animals may harbor these parasites in their intestines

14. Free-living amebas • Naegleria fowleri may enter through the nose of host from fresh water • Enters NS through olfactory epithelium and into brain where they cause severe tissue damage and hemorrhage • Often fatal after only a few days • Treatment with Amphotericin B is possible if diagnosis is made quickly • Acanthamoeba castellani is Similar to N. fowleri, however, entry may be through ulcers or damaged tissues, such as corneal abrasions associated with contact lenses

15. Fungi • Medical mycology is the study of disease-causing fungi • Can cause infection (Candida etc..) or intoxications (see below) • Many fungi are saprophytes and live primarily off of dead organic matter Intoxicating fungi • Aflatoxins on moldy foods- Aspergillus flavus • Ergotism- Claviceps purpurea • Poor indoor air quality-black mold, Stachybotriys sp.

16. Candida albicans • candidiasis (oral, intestinal, vaginal, cutaneous) • Often called thrush • Vaginitis (yeast infection) • Diaper rash in babies • Can invade many internal tissues and cause toxic reactions (including sepsis)

17. Dermatophytes • Superficial cutaneous mycosescaused by threegenera: Trichophyton spp. Microsporum, and Epidermophyton spp. • Tinea pedis- atheletes foot (feet and hands) • Tinea cruris-jock itch • Tinea corporis (ringworm that actually forms the characteristic ring)- non-hairy surfaces of body • Tinea capitus (ringworm of scalp) • Tinea barbi (ringworm of facial hair) Not scientific names of organisms but names of diseases

18. Other fungal skin diseases • Sporotrichosis- Sporothrixshenckii • Blastomycosis- Blastomyces dermatitidis

19. Fungal respiratory diseases • Coccidiomycosis- Coccidioides immitis • Histoplasmosis- Histoplasma capsulatum • Cryptococcosis- Filobasidiella (Cryptococcus) neoformans • Pneumocystis pneumonia- Pneumocystis carinii • Aspergillosis- Aspergillus spp.

20. Helminthes • Platyhelminthes-flatworms • Cestodes: tapeworms • Trematodes: flukes • Nematoda-roundworms • Filarial worms • Others

21. Tapeworms (cestodes) • Beef tapeworm- Taenia saginata- undercooked beef • Pork tapeworm- Taenia solium- undercooked pork • Cysticercosis results from the ingestion of human feces. Cysticerci form in tissues all around the body including the brain can result in epilepsy and death

22. Other Tapeworms • Broad fish tapeworm- Dibothrocephelus latus (Dyphyllobothrium latum) eating undercooked freshwater fish • Hydatidosis or hydatid disease- Echinoccocus granulosus, dog feces cysts form in tissues including the brain • Vampirolepis (Hymenolepis) nana- most common cestode infection of humans, animal feces • Dipylidium caninum- children accidental hosts by ingesting fleas

23. Blood FlukesSchistosomiasis (bilharzia) • Schistosomamansoni, S. japonicum, S. haemotobium and others • Distributed throughout Africa, South Asia and equatorial South America (S. mansoni) • Female lives within body groove of male, female body adapted for laying eggs in blood vessel. • Eggs pass in human feces and into natural water • Miracidium invades snail (intermediate host) • Cercaria invades human in water • Cercarial dermatitis (swimmers itch)-various genera of schistosomes- an allergic reaction to a parasite that doesn’t normally infect humans

24. Other Flukes • Sheep fluke- Fasciola hepatica • Snail intermediate host • Infective stage on aquatic vegitation • Chinese liver fluke- Chlonorchis sinensis • Snail intermediate host • Second intermediate host commonly Grass Carp • Survive meat preparation other than cooking • Lung fluke- Paragonemus westermani • Acquired through eating raw crabs • Metacercariae bore through GI tract and penetrate the diaphragm and into the bronchioles, eggs transported out of lungs by cilia, swallowed and expelled with feces

25. Nematodes: Hookworm • Main species :Ancelystoma caninum and Necator americanus • Larvae penetrate skin and migrate to circulatory system, then travel to lungs, coughed up and swallowed, adults reside in intestines as blood feeders • Cutaneous larva migrans (creeping eruption) caused by hookworms that can’t get into the blood stream

26. Nematodes: Filarial worms • Onchocerciasis, River blindness • caused by Onchocerca vovulus a filarial worm that migrates to various tissues including the eyes • Transmitted by black flies (Simuliidae: Simulium damnosum) • Loaiasis • Caused by Loa loa, filarial worm, that can end up in the eye but does not result in blindness • Transmitted by deer flies (Tabanidae: some African spp. of Chrysops)

27. Lymphatic Filariasis • Main species that cause LF are Wuchereria bancrofti and Brugia malayi • Several species of mosquitos are vectors including Culex spp. Aedes spp. • Periodic and subperiodic forms of transmission cycle, may also be diurnal or nocturnal • Filarial worms cause inflammation and block the flow of lymph- this can result in elephantiasis

28. Common Nematode infections

29. Other Nematode infections