Seroepidemiological studies of leprosy in northern Malawi based on an enzyme-linked immunosorbent assay using synthetic glycoconjugate antigen

"A total of 6002 blood samples from total population samples in four separate areas within Karonga District; Northern Malawi; were tested for anti-Mycobacterium leprae antibody using an ELISA based on synthetic glycoconjugate antigen. Results are presented using different criteria for seropositivity. Regardless of the criterion used; the proportion of individuals classified as ""positive"" rose to a peak at 20-30 years of age and then fell; and it was higher at all ages in females than in males. There was no difference in seropositivity levels between individuals with or without BCG scars. Although leprosy cases; in particular those with positive smears; had higher antibody levels than nonleprosy cases; analysis of age- standardized data revealed only weak evidence for a correlation between the prevalence rates of clinical leprosy and of seropositivity within the four areas. There was no evidence for higher seropositivity levels in household contacts of leprosy cases compared to noncontacts. The implications of these results for the epidemiology of leprosy in this population are discussed."

Detection of filarial antibodies in Malayan and Bancroftian filariasis by the indirect fluorescent antibody test, using different filarial antigens.

Indirect fluorescent antibody tests (IFAT) using Wuchereria bancrofti infective larvae as antigen had the highest positivity rates in detecting Malayan and Bancroftian filariasis as compared to IFAT using antigens prepared from 5 other animal filarial species, Brugia pahangi, Dirofilaria immitis, Dipetalonema viteae, Litomosoides carinii and Onchocerca gutturosa. This study also recommends the use of human filarioids as the source of antigen in serological tests. However, before B. malayi and especially W. bancrofti can be easily available from the common laboratory animals. B. pahangi seems to be a suitable source of antigen for use in serological tests for human lymphatic filariasis.

Detection of circulating antigens and immune complexes in feline and human lymphatic filariasis.

Circulating worm antigens were detected in 61% to 81% of sera from Brugia pahangi -infected cats and in 0-93% of sera from humans with malayan of bancroftian filariasis by counter immunoelectrophoresis and a double antibody sandwich enzyme-linked immunosorbent assay, using rabbit antisera to B. pahangi adult worms. In some situations, both antigen tests were as sensitive as antibody tests. However, ELISA was likely to be affected by the presence of antiglobulins, such as rheumatoid factor, in the test sera. Only 10% to 22% of B. pahangi-infected cats (treated with drugs or not) had circulating immune complexes by the conglutinin-binding assay and no sera were positive by C1q-BA. A significantly higher percentage (56%) of B. malayi clinical sera was positive for immune complexes by either C1q- or conglutinin- binding assays as compared to other groups of B. malayi and Wuchereria bancrofti sera (6% to 14%).