Parasitic Protozoan Infection

What is Giardia intestinalis

Causes Giardiasis; also called traveler’s diarrhea; has world wide distribution

What are the symptoms of Giardia Intestinalis infection in children and adults

Children: delay in physical/mental growth, slow development, malnutrition; adult: weight loss

Giardia Intestinalis infection can cause failure to absorb what nutrients

Fat, lactose, vit A, vit B12

What are the reservoirs of Giardia Intestinalis

Humans, cats, dogs, cows, lamb, beaver, deer

What is are the two stages of Giardia that can be diagnosed

Cyst stage (median body with 1-4 nuclei, axoneme); trophozoite stage (tear drop shape, flagella, axoneme)

Where can trophozoite stage be found for Giardia infection

Ingested food, acute diarrhea

How does Giardia cause malnutrition

Inflammation, lesions, shorten villi

How does giardia evade immune response

Display VSA during early infection

What is Cryptosporidiosis spp

Cause transient diarrheal disease; important are C parvum and C hominis; HIV patients more likely to contract

How is cryptosporidiosis spp diagnosed

Stool microscopy (30% sensitivity which is increased with acid fast); PCR; antigen test; NAAT testing

What is the pathogenesis of cryptosporidiosis spp

Secretory diarrhea (up to 10L a day) from malabsorption, increased intestinal permeability and chlorine secretion

What is the medical ecology of cryptosporidiosis spp

Infect birds and mammals that can infect humans; claves, kids, lambs are sources of infection; animal feces contaminated water

What is Toxoplasma gondii

Obligate intracellular parasite; infect warm blooded animals; immunocompetent humans rarely get serious illness from infection; congenital infection can be devestating

What is mode of transmission for Toxoplasma gondii

Tachyzoites infect liver and then infect macrophage → Macrophage travel throughout body and spread infection

What are the forms of toxoplasma gondii

Tachyzoite (active infection), bradyzoite (latent infection), sporozoite (in feline intestine and soil)

How does toxoplasma gondii escape digestion

Prevent fusion of lysosomal membrane to its vacuole

What is a sign of toxoplasma in patients

Ring enhancing lesion on brain

How can a person contract toxoplasma gondii

Infection by blood/organ transplant; parasitemia 1 year post infection; heart/bone marrow/liver/kidney donor

Sign of congenital toxplasma

toxoplasma ocular disease; episodic flares that destroy retinal tissue

Toxoplasma diag

Microscopy in histological section; PCR test; IgG and IgM; treatment after presumptive diagnosis for AIDS patient

What is Amoebiasis (Entamoeba histolytica)

Causes amoebic dysentery in humans; transmit by oral fecal route; colonizes large intestine wall

Pathogenesis of Entamoeba histolytica

Amebae attach to target cells using galactose and form pore; cell-cell contact synthesis lysosomal enzymes → cell death

Extraintestinal amoebiasis

Commonly hits the liver and lungs; heart and brain are rarer

Entamoeba Histolytica diag

stool exam; serology; imaging test; culture

What is Balantidiasis: Balantidium coli

The ONLY ciliated protozoa; causes dysentery; reservoir host is primate, guinea pig, horse, cattle, pigs, wild boars and rats

What is the pathogenesis of Balantidium coli

Facultative anaerobe and uses carbs for energy; trophozoite has hyaluronidase acting on mucosal epithelium; has protease

Balantidium coli diagnosis

Stool sample, stained section of tissue; trophozoites in watery stool; cyst in formed stool

Trichomoniasis: Trichomonas vaginalis pathogenesis

Secrete molecular Hydrogen; protease cause cell death; TVV cause cervical inflammation; infect people are often asymptomatic; has hydrogenosomems

Clinical disease trichomonas vaginalis infection

20% women are asymptomatic; mild vaginal discomfort and dyapareunia, itching; pH from 4.5 to 5; strawberry cervix

Trichomonas infection diag

Microscopic observation; positive culture; rapid antigen testing; nucleic acid probe test; NAAT

What is African Trypanosomiasis (sleeping disease)

Spread by tsetse flies; also called trypanosoma brucei gambiense/rhodesiense

What is the clinical presentation of trypanosomiasis

Hemolymphatic phase: painless chancre; CNS phase: headache, depression, coma death

What is the difference between trypanosoma b rhodesienses and gambiense

Rhodesiense has rapid onset of CNS symptoms; gambiense has slower involvement of CNS

Trypanosomiasis diag

Wright/Giemsa stain blood smear; CATT; eosinophilic inclusions

What is american trypanosomiasis (Chagas disease)

Tryapanosoma cruzi is cause; cause cardiomyopathy; infect by blood transfusion, organ transplant, ingestion; rat, dog, sloth, bats are reservoir host

American trypanosomiasis pathogenesis

Bind to C3b and C4b complement (no alternate pathway); host immunity depend on IL-12 driven production of NK cells

Congenital Chagas disease

Infected mothers with acute Chagas; lead to acute disease or chronic disease if no treatment

What are clinical signs of Chagas

Romana’s sign, megacolon, cardiomegaly

Chagas diag

Trypomastigote in blood smear; PCR; serology for IgG; histology for amastigote