Parasitic Infections

(Ref : Davidson 23rd ,p -296 )

Explanation: Plasmodium falciparum is a Parasite

Explanation: Amoebiasis is caused by Entamoeba histolytica

Explanation: In endemic regions, a highly sensitive direct agglutination test using stained promastigotes and an equally efficient rapid immunochromatographic k39 strip test have become popular for the Diagnosis of Visceral Leishmaniasis

•Pancytopenia is common.
•Moderate to severe anaemia develops  rapidly and can cause cardiac failure.
•Thrombocytopenia, often compounded by  hepatic dysfunction, may result in bleeding  from the retina, gastrointestinal tract and  nose.
•In advanced illness, hypoalbuminemia may  manifest as pedal oedema, ascites and  anasarca (gross generalized oedema and  swelling).

( Ref : Davidson 23rd ,p - 281 )

The diagnosis of Kala-azar will be based on the  following criteria in a symptomatic case.

History of fever for more than 2 weeks
Residing/ traveling in endemic areas
Any one of the following symptoms and signs:
1.Splenomegaly
2.Weight loss
3.Anemia
And ‘rk39’ test (+) positive.

Red cells infected with malaria undergo haemolysis  which is most severe with P. falciparum that  invades red cells of all ages.
P. vivax and P. ovale preferentially invade younger  cells, and P. malariae normoblasts

Toxoplasma gondii is an intracellular parasite. The sexual phase of the parasite’s life cycle (Fig. 13.40) occurs in the small intestinal epithelium of the domestic cat. Oöcysts in cat faeces are spread to intermediate hosts (pigs, sheep and also humans) via soil contamination. Oöcysts may survive in moist conditions for weeks or months.

Ref : Davidson 23rd ,p - 291

Explanation: Diseases associated with mosquito bite includes Malaria, dengue fever, Chikungunya, filariasis, tularaemia

DEC (see above) is curative, in a dose of 9–12 mg/kg daily, continued for 21 days

Lung fluukes: Paragonimus spp

Reference: Davidson 23rd, Box-11.55

P. falciparum, P. knowlesi and P. malariae have no persistent exoerythrocytic phase but recrudescence of fever may result from multiplication of parasites in red cells that have not been eliminated by treatment and immune processes

Mild falciparum malaria
Preferred therapy
• Co-artemether (CoArtem or Riamet); contains artemether and lumefantrine (4 tablets orally at 0, 8, 24, 36, 48 and 60 hrs)
Alternative therapy
• Quinine (600 mg of quinine salt 3 times daily orally for 5-7 days), together with or followed by doxycycline (200 mg once daily orally for 7 days)
Use clindamycin not doxycycline if the patient is a pregnant woman or young child
or
• Atovaquone-proguanil (Malarone, 4 tablets orally once daily for 3 days)
Pregnancy
• Co-artemether but avoid in early pregnancy
• If not using co-artemether, use quinine plus clindamycin (450 mg 3 times daily orally for 7 days)
Other regimens
• Artesunate (200 mg orally daily for 3 days) and mefloquine (1 g orally on day 2 and 500 mg orally on day 3)

P. vivax and P. ovale may persist in liver cells as  dormant form hypnozoites capable of developing  into merozoites months or years later
Thus the first attack of clinical malaria may occur  long after the patient has left the endemic area, and  the disease may relapse after treatment with drugs  that only kill the erythrocytic stage of the parasite
P. falciparum, P. knowlesi and P. malariae have no  persistent exoerythrocytic phase but recrudescence  of fever may result from multiplication of parasites  in red cells that have not been eliminated by  treatment and immune processes

Diethylcarbamazine (DEC)—6 mg/kg in three divided doses for 2 weeks