Eukaryotic Pathogens Fungi Protozoa Not helminths worms in

Eukaryotic Pathogens • • Fungi Protozoa Not helminths (worms) in this lecture Remember these are all eukaryotes, with organelles and many of the same cellular characteristics that humans have. – Makes drug treatment more difficult. 1

Fungi • Review basic fungal biology • Often dimorphic – Yeast in body, mold in culture • Classification of fungal diseases (mycoses) – Superficial, cutaneous, subcutaneous – Systemic and opportunistic – Poisoning and allergies • Treatment – Azole drugs, amphotericin B, others 2

Cutaneous and subcutaneous • Dermatophytes: various genera – Cause skin and nail diseases – Referred to as Tinea (worm) because of the ringlike appearance on scalp. – Cause ringworm, jock itch, athlete’s foot, etc. – Limited to outer layer of skin • Sporothrix schenkii – Acquired from soil and plant material – Infects deeper into skin, but not systemic 3

Systemic Mycoses 4 • Generally acquired by inhalation of spores – Lung infections, may spread beyond into other tissues • Blastomyces (blastomycosis) • Coccidiodes (coccidiomycosis) • Histoplasma (histoplasmosis) – Most common in this area (Ohio and Miss. River valleys) – Many people exposed with asymptomatic cases • Many test positive for exposure

Opportunistic infections • Aspergillus (aspergillosis) – Variety of species, very common in soil, plant materials – Serious infections in immunocompromised – Allergies to A. fumigatus – Poisoning from aflatoxin from A. flavus • Candida (candidiasis)- normal microbiota – Cause of vaginal infections, diaper rash, thrush – Capable of infecting any part of the body – Dangerous in cancer patients, HIV infections, etc. 5

Opportunists-2 • Cryptococcus neoformans – Inhalation of spores – Can infect many parts, but has predilection for CNS – Particularly serious in AIDS • Pneumocystis carinii – Very protozoan like, but is a fungus – Most cases associated with AIDS – Serious lung infections: PCP (P. carinii pneumonia) 6

Protozoans 7 • Group responsible for human diseases are the animal -like protozoa. Old groupings: – Ciliates – Amoebae – Flagellates – Sporozoans (apicomplexans) • Protozoa typically have life cycles – Simple, like vegetative and cyst – Complex, like sporozoans have

Rogue’s gallery-1 • Ciliates – Balantidium coli: present in hog intestines • Source: contaminated water (farm runoff) • Disease: attack of GI tract • Ameobae – Entamoeba histolytica: fecal-oral transmission • Asymptomatic to severe diarrhea – Acanthameoba and Naegleria • Natural waters or through eye (Acanthameoba) • Cause brain infections; rare, fatal. (Naegleria) 8

Rogue’s gallery-2 • Flagellates – Trypanosoma: various species, geographic locations • Cause of African sleeping sickness, spread by bite of tsetse fly: Infection of CNS, causes coma • Cause of Chagas disease, spread by bite of reduviid bug: eventually damages heart tissue. – Leishmania: various species, range of disease severity • Causes leishmaniasis, spread by sandfly • Entered US consciousness after Gulf War 9

Rogue’s gallery-3 • Flagellates continued – Giardia: found in many places including “clean” water • Common cause of diarrhea; 1 -4 weeks. – Trichomonas • Present in genitourinary tract, sexually transmitted – Pain, pus, discharge • A switch: often asymptomatic in men www. ulb. ac. be/sciences/ biodic/Im. Proto 0003. html 10

Rogue’s gallery-4 11 • Sporozoans – Plasmodium: the cause of malaria, several species • Involves mosquito, liver, red blood cells in a complex life cycle. • Features a synchronous bursting of RBCs with fever, delerium, followed by rest and recovery, then cycle • Number one cause of global mortality and morbidity Intracellular plasmodia www. sirinet. net/ ~jgjohnso/plasmodium. html

12 Life cycle of Plasmodium www. sirinet. net/ ~jgjohnso/plasmodium. html

Rogue’s gallery-5 13 • Toxoplasma: kills fetus; many organs in immune compromised. • Part of life cycle involves cats, so pregnant women must stay away from litter box. • Cryptosporidium – Primarily livestock and poultry, acquired fecal-oral through food or contaminated water. – Famous outbreaks (e. g. Milwaukee) of contaminated municipal water supplies. – Diarrhea, but systemic spread as well, highly dangerous to AIDS patients.