Parasitic Infections

Question 1

Which plasmodium is most common which is most dangerous?

Answer 1

P. Falciparum is most dangerous and MC form of malaria because it: Infects RBCs of all ages and causes high levels of parasitemia, Induces formation of knobs on RBC surface that adhere to vessel walls and uninfected
RBCs, causing obstruction and local hypoxia, Can cause severe hemolysis, renal failure, CNS damage, and pulmonary edema

Question 2

Clinical manifestation of plasmodium

Answer 2

Hallmark of all forms of malaria is Fever (occurs after lyses of RBC and release of merozoites)
Three classic stages of infection: 1.Initial “cold stage”: shakes and chills (15-60 min before fever). 2.“Hot stage”: Fever associated w/ lassitude, loss of appetite, and vague joint and bone pains- “flu-like”, May also have tachycardia, hypotension, cough, h/a, back pain, nausea, abd pain, vomiting, diarrhea, and altered consciousness; 3.“Sweating stage”: w/in 2-6 hours. Diaphoresis followed by resolution of fever, profound fatigue and desire to sleep

Question 3

Dx of plasmodium

Answer 3

Focus must be on differentiating falciparum from other forms: Blood smear remains preferred method, but enzyme-linked immunoabsorbent assay (ELISA) and PCR methods now available. In falciparum malaria, signet-ring forms are most abundant on peripheral smear immediately after fever spike

Question 4

Tx of plasmodium

Answer 4

Chloroquine or quinine (chloroquine resistant)

Question 5

Babessiosis

Answer 5

Small nymph form (2 mm in diameter) of deer tick, Ixodes scapularis, carries Babesia from white deer mice to humans. In human RBCs, mature signet ring trophozoite multiplies by binary fission forming characteristic tetrads.
Patients with babesiosis may also have Lyme
disease, because Ixodes scapularis transmits both infections

Question 6

Laboratory results for Babesiosis

Answer 6

Giemsa stain of the peripheral blood remains best way to make diagnosis (Only ring forms are seen) - Tetrad ring forms strongly support diagnosis of babesiosis

Question 7

Tx of Babesiosis

Answer 7

clindamycin

Question 8

Visceral Leshmaniasis

Answer 8

Visceral -Subacute onset p/w increased abd swelling (because of massive splenomegaly and hepatomegaly), intermittent fever, and weight loss that can be mistaken for lymphoma or infectious mononucleosis (Acute onset p/w persistent high fever
mimics bactermia or malaria)
Dx made by biopsy and Giemsa stain showing amastgotes
Tx: Liposomal amphotericin B is only approved therapy

Question 9

Cutaneous Leshmaniasis

Answer 9

Cutaneous- Lesions occur primarily on exposed areas. Dry or moist in appearance, ulcers have sharp, raised boarders; “pizza-like” lesions are common
Dx made by biopsy (always from border of lesions)
Tx: May heal spontaneously

Question 10

Mucosal Leshmaniasis

Answer 10

Mucosal
Organisms invade mononuclear cells in mucosa. Nose most commonly involved, resulting in: Nasal stuffiness, discharge, pain, or epistaxis. Later, nasal septum is destroyed, and nose collapses.
Diagnosis made by biopsy
Treatment with IV or IM pentavalent antimony

Question 11

Chagas

Answer 11

T. cruzi; heart problems and swellings called chagomas. Tx with nifurtimox