Protozoan Diseases A. Basic Properties of Protozoa B. Amebiasis C. Primary Amebic Meningoencephalitis D. Giardiasis E. Trichomoniasis F. Balantidiasis G. Toxoplasmosis H. Malaria I. Cryptosporidiosis J. Pneumocystosis

A.Basic Properties of Protozoa Cellular properties Eukaryotic microorganisms having animal-like cells No cell walls Most have heterotrophic metabolisms A few protozoa (eg Euglena) are photosynthetic

A.Basic Properties of Protozoa Cellular properties (cont.) Many are free-living in soil or aquatic environments; a few are parasitic Single-celled or simple colonial organization Classification based predominately on the mechanism of motility

A.Basic Properties of Protozoa Classification Class Sarcodina Motile by pseudopodia & amoeboid movement Amebas, radiolaria, and foraminifera Examples: Amoeba Entamoeba histolytica Naegleria fowleri

A.Basic Properties of Protozoa Classification (cont.) Class Mastigophora Motile by flagella Examples: Euglena Giardia lamblia Trichomonas vaginalis

A.Basic Properties of Protozoa Classification (cont.) Class Ciliophora Motile by cilia Examples: Paramecium Balantidium coli

A.Basic Properties of Protozoa Classification (cont.) Class Sporozoa A class of parasitic protozoa Most have complex life cycles with both sexual & asexual stages Adult forms are nonmotile Examples: Plasmodium Toxoplasma gondii

A.Basic Properties of Protozoa “Trophozoite” and “Cyst” Some protozoa go through different stages in their life cycle. This is especially true of certain parasitic protozoa. Trophozoite: Actively growing and reproducing stage Cyst: A dormant stage, enclosed in a resistant cyst coat

B. Amebiasis Cause: Entamoeba histolytica A parasitic ameba; class Sarcodina Transmitted via contaminated food & water Cysts are shed in the feces When ingested: Excystation occurs in the intestine Trophozoites grow & reproduce in the intestinal tract

B. Amebiasis Symptoms Abdominal pain Little diarrhea but often blood in the stool (“amebic dysentery”) Possibly of intestinal ulceration; perforation; infection of internal organs such as liver & lungs

C. Primary Amebic Meningoencephalitis Cause: Naegleria fowleri A fresh water, free living ameba No cyst stage Several cases of infections in swimmers Transmission and Symptoms: Transmission through the nasal & sinus passages Infection of the brain & meninges Headaches; delirium; seizures

D. Giardiasis Cause: Giardia lamblia A flagellate of class Mastigophora The trophozoite has four pairs of flagella & two nuclei; giving it a face-like appearance Grows in the intestinal tract Cysts are shed in the feces

E. Trichomoniasis Cause: Trichomonas vaginalis Transmission & Symptoms Flagellate of the class Mastigophora No cyst stage Transmission & Symptoms Transmitted via sexual contact Genital itching Painful urination with a white, mucoid discharge Occasional reduction of sperm count or erosion of the cervix

F. Balantidiasis Cause: Balantidium coli Transmission & Symptoms Ciliated, in Class Ciliophora Trophozoites grow in the intestinal tract Cysts are shed in the feces and may remain embedded in intestinal walls, causing chronic infections Transmission & Symptoms Contaminated water & food Ulceration in intestines Profuse diarrhea

G. Toxoplasmosis Cause: Toxoplasma gondii In Class Sporozoa Both asexual & sexual stages Invasion of several areas of the body, including internal organs & muscle tissue Possibly the most prevalent protozoan parasite of humans

G. Toxoplasmosis Transmission & Symptoms (cont.) Generally mild in non-immunosuppressed persons Severe infections in immunosuppressed persons Pregnant women are in danger of fetal damage or miscarriage

H. Malaria Cause: Plasmodium species In Class Sporozoa Complex life cycle requiring two hosts: a mammal (human) and the mosquito Anopheles

H. Malaria Transmission and Symptoms (cont.) The sexual stage of Plasmodium develops in the human host and is picked up by a mosquito The sexual stage is completed in the salivary gland of the mosquito to complete the cycle Treatment by quinine & other antimalarial drugs

J. Pneumocystosis Cause: Pneumocystis carinii Usually classified as a protozoan of class Sporozoa, but recent evidence suggests that it may be a fungus Transmission and Symptoms Transmitted by airborne contact Usually asymptomatic or with mild respiratory symptoms Causes severe pneumonia in immunocompromised persons A major secondary infection & cause of death in AIDS patients

I. Cryptosporidiosis Cause: Cryptosporidium species In class Sporozoa A common protozoan parasite in humans Transmission and Symptoms Contaminated water Mild diarrhea in non-immunosuppressed persons Severe diarrhea in immunosuppressed persons