The Indirect Fluorescent Antibody Technique Applied to Dried Blood, for use as a Screening Test in the Diagnosis of Human Trypanosomiasis in Africa

Abstract

Fluorescent antibody tests based on the technique developed by COONS, CREECH and JONES (1941) are widely used for the detection in serum of specific antibodies to infectious micro-organisms. FIFE and MUSCHEL (1959) described an indirect fluorescent antibody technique (1FT) for the serodiagnosis of Chagas's disease. Trypanosoma cruzi cultured on a diphasic blood agar medium was used as the antigen and, as this had to be kept moist, the entire technique was carried out in test tubes. A modification of this technique has been shown by SADUN et al. (1963) to be of value in the serodiagnosis of human trypanosomiasis. Thin blood smears from rats infected with T. CTUzi, T. gambiense and T. rhodesiense were used as antigen, and this resulted in a test which could be rapidly carried out on glass slides with serum collected from suspected cases of disease. ANDERSON et al. (1961) described a technique for the diagnosis of schistosomiasis by immunofluorescence, making use of blood samples dried on filter paper, and SADUN et al. (1963) showed that dried blood samples could be also used in the diagnosis of human trypanosomiasis. Their technique involved the elution of serum from the dried blood samples contained in plastic tubes, and the subsequent extrusion of the eluate in a carpenter's vice. This technique was somewhat tedious and time-consuming and only a limited number of tests could be carried out at anyone time. A modified technique has now been developed for the diagnosis, by immunofluorescence, of human T. rhodesiense infection. The complete procedure is carried out on glass microscope slides at room temperature, and large numbers of blood samples can be examined in a short period of time.