Flagellates

Question 1

Giardia lamblia

Answer 1

*Giardia
Most commonly diagnosed intestinal disease in the U.S.
Signs/Symptoms: Often asymptomatic. But can also present with GI distress, including greasy, fatty diarrhea, abdominal pain, nausea and vomiting.
Pathogenesis: Infection usually results from drinking contaminated water. Infects duodenum.
Diagnosis: Presence of cysts or trophozoites in stools or ELISA test to measure Giardia antigen.
Treatment: Metronidazole (Flagyl).

Question 2

Trichomonas vaginalis

Answer 2

Most common protozoal urogenital infection in humans.
Signs/Symptoms: Females - yellow, malodorous discharge; Males (less common) - white discharge.
Pathogenesis: sexually transmitted.
Diagnosis: detection of trophozoites in vaginal or urethral secretions.
Treatment: Metronidazole (Flagyl).

Question 3

Leishmania species

Answer 3

Three clinical types: cutaneous, mucuocutaneous, visceral.

Estimated 12,000,000 current infections globally.

Question 4

Visceral leishmaniasis

Answer 4

Signs/symptoms: Enlarged spleen and liver; jaundice. Most have minor symptoms.
Pathogenesis: Sandflies. Initially infects macrophages, which migrate to spleen, liver and bone marrow where parasite multiples.
Diagnosis: Liver, spleen or bone marrow biopsy needed for definitive diagnosis, but serological tests can be suggestive.
Treatment: Pharmacological treatment difficult because of drug toxicity. Pentavalent antimonials first choice.

Question 5

Mucocutaneous leishmaniasis

Answer 5

Signs/symptoms: lesions at mucosal-dermal junctions of nose and mouth; can spread to mucosal tissue, “obliterating” nasal septum and oral cavity. High incidence of secondary infection, sometimes leading to death.
Pathogenesis: sandflies
Diagnosis: tissue samples taken from ulcers examined in lab.
Treatment: Pharmacological treatment difficult because of drug toxicity. Pentavalent antimonials first choice.

Question 6

Cutaneous leishmaniasis

Answer 6

Signs/symptoms: ulcerating skin sores.
Pathogenesis: Sandflies.
Diagnosis: tissue samples taken from ulcers examined in lab.
Treatment: most cases heal spontaneously. Pharmacological treatment difficult because of drug toxicity. Pentavalent antimonials first choice.

Question 7

Trypanosoma brucii species

Answer 7

Causes African Sleeping Sickness.
Signs/symptoms: Flu-like symptoms. Lethargy. Sleepiness.
Pathogenesis: Transmitted by the bite of the tsetse fly. Ultimately infects central nervous system causing inflammation. Fatal without treatment.
Diagnosis: Microscopic examination of blood, cerebrospinal fluid, or lymph aspirates for protozoa.
Treatment: Early: Suramin or pentamidine. Late (with CNS involvement): Melarsoprol (HIGHLY toxic. 5-15% of people die from treatment alone).