Detection of malarial antibodies in man by fluorescent antibody test using Plasmodium gallinaceum as antigen.

The results obtained by the serological testing of 38 malaria cases are reported in this paper. The indirect fluorescent antibody test (FAT) was used. Plasmodium gallinaceum was used as antigen. Antibodies were detected in 84% of the patients. The results were more satisfactory in cases affected by falciparum malaria. These results suggest that the FAT with P. gallinaceum as antigen can be regarded only as a complement to the clinical and laboratory diagnosis of malaria. One of many valuable applications of the Fluorescent Antibody Test (FAT) is the detection and measurement of antibody levels during present or past infec¬ tion with malaria parasites. Such a test is useful for clinical purposes (1, 5, 8) as well as for epidemiological investigations (2. 7. 20). Several papers have been published concerning the use of various Plasmodium species (3, 4. 13) in perform¬ ing the test. Besides homologous parasite antigens (7. 14, 21), which are rather difficult to obtain, primate infecting Plasmodia (1. 4. 13, 17-19) have also been used as antigen for the FAT. Kielmann and others (9—12) reported positive results when using Plasmodium gallinaceum as antigen. This offers many advantages. Whereas working on monkeys can be tedious, the handling of chickens to obtain the antigen is easier and the procedure is far less expensive. This paper relates our own further experience with the serological investi¬ gations by FAT of human malaria using P. gallinaceum as antigen. Materials and Methods Sera of patients: These were obtained from 38 Europeans of both sexes who suffered from malaria after having returned from the tropics. All cases were confirmed by direct peripheral blood investigation, which was parasitologically positive. The first serum sample was taken before standard therapy (chloroquine); further samples were taken during and after treatment. Antigen: P. gallinaceum (the same strain used by Kielmann et al. 9, 11) was taken as antigen. Chicken blood films were made between the 9th and 11th day after infection and were preserved at -20 °C. Indirect immunofluorescence test after Coons: The basic technique used by Ambroise-Thomas (1) and Kifxmann et al. (11) was followed. Antigen was fixed with acetone for 10 minutes before the test was started. Small circles (Ö 6 mm) were drawn over the blood films, on to which the serum dilutions were then * Present address: c/o London School of Hygiene and Tropical Medicine. D.P.T.H. Course. Please address request for reprints to Mrs. V. Suter-Kopp, Basle. 270 Acta Trop. XXX. 3. 1972 Miscellaneum Table 1. Distribution of fluorescence antibodies among different Plasmodium species ** Malaria Number < 20 20 of cases negative Antibody titers (reciprocal) 40 80 160 320 640 Mean values P. falciparum 13 2 4 2 P. vivax 12 3 3(1* 4 P. ovate 1 1