LABORATORY DIAGNOSIS OF ACUTE MEASLES INFECTIONS IN HOSPITALIZED CHILDREN IN ZAMBIA

Laboratory diagnosis of measles infection is rarely performed in devel oping countries and tends to depend on clinical symptoms alone. We eva luated detection of immunoglobulin M (IgM) antibodies for confirmation of acute measles infection in Zambia. In 149 hospitalized children wi th clinical diagnosis of measles, IgM antibodies were detected in 88.6 % (132/149). The IgM-positive rate increased with time after onset of skin rash and all samples were positive after 4 days. In addition to I gM antibody test, virus isolations from throat swabs using B95a cells were also performed. These were positive in only 20.9% (14/67), and bo th IgM and virus isolation in combination increased the positive rate to 92.5% (62/67). Vaccinated children had higher neutralizing (Nt) ant ibody responses and, among IgM-negative patients, all 4 vaccinated chi ldren had high Nt antibodies while all 10 unvaccinated children had ne gative or low Nt results. The IgM antibody test was proved to be a sen sitive method for laboratory confirmation of measles virus infection i n developing countries.