LABORATORY SURVEILLANCE OF MEASLES

Background: The first massive national measles vaccination campaign in Chile was done in 1992. Since then a laboratory surveillance of the d isease has been undertaken at the Instituto de Salud Publica. Aim: To report the results of laboratory surveillance of measles between 1992 and 1995. Material and Methods: Paired serum samples from suspected ca ses of measles were received at the Institute. Measles specific IgG wa s determined with indirect immunofluorescence methods. IgG and IgM imm unoenzymatic methods were used as complementary techniques, and rubell a infections were ruled out by hemmaglutination inhibition tests. Resu lts: Sera from 1087 presumptive cases (489 in 1992, 196 in 1993, 180 i n 1994 and 222 in 1995) were analyzed. Only two cases of wild imported measles were confirmed, one in Arica in 1992 and the other in Santiag o in 1993. Five additional post vaccine cases were detected. Eighty ei ght percent of samples in 1992 and 75% in 1994 were seropositive. A hi gh percentage of cases were confirmed as rubella (55% in 1992 and 19% in 1994). Conclusions: Absence of wild measles virus circulation in Ch ile from 1992 to 1995 emphasizes the importance of laboratory surveill ance of the disease.