Parasitic Protozoa - Flagellated Protozoa

Flagellated Protozoa

Also known as African Sleeping Sickness.
Transmitted by the bite of the tsetse fly (Glossina species).
Symptoms:
- Fever
- Severe headache
- Rash
- Late-stage CNS signs: lethargy, insensitivity to pain, difficulty waking up.
Has rendered millions of square miles in Africa uninhabitable.

Trypanosoma cruzi causes Chagas’ Disease.
Occurs in Central, South America, and Mexico.
Transmitted by Reduviid bug (kissing bug), which typically bites near the mouth or eye.
The bug's feces enter the sore created by the bite, leading to infection, and this sore is called a chagoma.
Causes acute disease in children:
- Fever
- Malaise
- Lymphadenopathy
Irreversible sequelae include cardiac damage, megaesophagus, and megacolon.

Cutaneous (Baghdad Boil):
- Transmitted by sand fly vector.
- Causes crater-like skin lesions that heal spontaneously, leaving permanent scars.
- Affected U.S. troops stationed in Iraq and Afghanistan.
Mucocutaneous:
- Affects mucous membranes and skin.
- Destroys tissue of the nose, mouth, and throat, causing disfigurement.
- Most common in the Yucatan Peninsula of Mexico & Central, South America.
Visceral (Kala-Azar):
- Parasite migrates to internal organs such as the liver, spleen, and bone marrow.
- Fatal if untreated.
- Second-largest parasitic killer in the world (after malaria), with an estimated 500,000 cases each year worldwide.
- Opportunistic in AIDS patients.
- Symptoms: Fever, chills, diarrhea, progressive hepatosplenomegaly, skin hyperpigmentation. Death if untreated.

Lack mitochondria, possibly due to evolving prior to eukaryotes acquiring them or losing the ability to make them.
Usually spindle-shaped with flagella.
Two important human pathogens:
1. Trichomonas vaginalis
2. Giardia intestinalis (lamblia)

Found in the vagina and male urinary tract.
Causes trichomoniasis, a sexually transmitted disease (STD) in females; males are primarily asymptomatic.
Has an undulating membrane and no cyst stage.
Must be transmitted quickly before it dries out.
Usually transmitted by sex; rarely on toilets or towels.
Common STD in the U.S.
Diagnosis: look for motility in wet prep of vaginal discharge.
Treated with Flagyl.

Found in the small intestine of mammals, which shed cysts in feces.
Diagnostic form of disease (Giardiasis) is usually the cyst.
In the duodenum, it exists as a trophozoite (bearded man) and attaches to the intestinal mucosa using sucking disks (rarely found in stools).
Causes diarrhea, malaise, nausea, weakness, weight loss, and abdominal cramps; can also be an asymptomatic carrier (7% of the population).
In daycare settings, 5-15% of children in diapers are infected and easily spread the disease.
Diagnosed with stool exam or string test.

Most common cause of epidemic waterborne diarrheal disease.
Can be a danger to the water supply since cysts can be shed by animals in feces and are resistant to potable water levels of chlorination.
Can infect pools if fecal material enters the pool and chlorine levels are not adequate to kill cysts.
Can be a danger to campers and hikers who drink unfiltered water or swim and swallow water; especially common in areas inhabited by beavers (“Beaver’s Fever”).