[Parasite burden and immune response in kala-azar]

The parasite-burden, which is indicative of the macrophage activity, was determined before treatment in 84 kala azar cases (L. infantum) and compared to non specific immune response parameters (serum IgG, and IgM), to the specific antibody levels as detected by immunofluorescence and IgG and IgM-ELISA, as well as to rheumatoid factor titers. In 57 cases presenting with less than 3 months from the first appearance of symptoms and despite some individual variations, high parasite-burden levels were accompanied with high specific and non specific immune response parameters and inversely. The data suggest that, during kala azar, low and high immune responders could be distinguished in the humans in the way it was demonstrated by Biozzi in mice. Data collected from 27 cases with more than 3 months duration showed a poor correlation. However, at highest antibody levels, some decreasing in parasite-burden was noticed. The prognostic value of the parasite-burden determination is emphasized. Genetic studies of populations would improve control measures.