General Parasitology and Protozoa
Treatment of Tropical Splenomegaly is
a. Tropical Splenomegaly (Hyperreactive Malarial Splenomegaly)- Chronic or repeated malarial infections produce hypergammaglobulinemia; normochromic, normocytic anemia; and, in certain situations, splenomegaly.
b. Some residents of malaria-endemic areas in tropical Africa and Asia exhibit an abnormal immunologic response to repeated infections that is characterized by massive splenomegaly, hepatomegaly, marked elevations in serum titers of igm and malarial antibody, hepatic sinusoidal lymphocytosis, and (in Africa) peripheral B cell lymphocytosis.
c. This syndrome has been associated with the production of cytotoxic igm antibodies to suppressor (CD8+) lymphocytes, antibodies to CD5+ T cells, and an increase in the ratio of CD4+ T cells to CD8+ T cells.
d. It is believed that these events lead to uninhibited B cell production of igm and the formation of cryoglobulins (igm aggregates and immune complexes).
e. This immunologic process stimulates reticuloendothelial hyperplasia and clearance activity and eventually produces splenomegaly.
f. Patients with hyperreactive malarial splenomegaly (HMS) present with an abdominal mass or a dragging sensation in the abdomen and occasional sharp abdominal pains suggesting perisplenitis.
g. Anemia and some degree of pancytopenia are usually evident, but in many cases malarial parasites cannot be found in peripheral blood smears.
h. Persons with HMS who are living in endemic areas should receive antimalarial chemoprophylaxis: the results are usually good. In nonendemic areas, treatment is advised.
i. Antimalarial drugs are effective therapy for HMS, and the specific choice of drug is dictated by the pattern and prevalence of drug resistance in that geographic area.
j. The treatment should be continued regularly for a prolonged period to be effective. Months may pass before response is noticed, and relapses may occur when therapy is discontinued.
k. Treatment may have to be continued for more than a year, sometimes even longer. Response to therapy is guided by the splenic size, decrease in serum igm levels, improvement of anemia, and general improvement in the well-being of the patient.
l. Chloroquine and proguanil appear to be equally effective, which suggests that the eradication of parasitemia is the common pathway responsible for the response. Pyrimethamine may be an alternative drug.