An outbreak of rubella in a hilly district of Kangra-Chamba, Himachal Pradesh, India, 2006

Abstract

Rubella is a minor disease that often goes unnoticed and seldom results in significant morbidity and mortality. However, the infection among pregnant women is associated with serious consequences for the fetus. On 5th November, 2006, a local community leader reported cases of fever with rash in three villages of Chamba district to Shahpur hospital. No death was reported. We investigated the outbreak as a suspected outbreak of measles with the objectives of confirming diagnosis, estimating the magnitude of outbreak and formulating recommendations for control and prevention. We defined a case of the rubella as occurrence of fever with rash in any resident of these three villages between 20th October to 9th December, 2006. We line listed the cases and collected information on age, sex, residence, date of onset, symptoms, signs, treatment history, traveling history, vaccination status and pregnancy status. We described the outbreak by time, place and person characteristics. Sera of a sample of case patients were tested for IgM antibodies to measles and later rubella viruses. We identified 61 cases in three villages - 39 cases in Hattli, 17 in Thulel and 5 in Dramman. The overall attack rate (AR) was 8.7%. Sex specific AR for males was 10% and females 7.4%. All case patients were less than 20 years of age and the attack rate was highest in the age group 11-20 years (median age 12 years). The index case was traced in Hattli Bengali slum and occurred on 20th October 2006 where majorities (41%) of the cases were reported. No pregnant woman was found to be affected. The number of cases peaked on 19th November and the last case was reported on 9th December 2006. Of 61 case-patients, 50 (82%) were immunized against measles while proportions of children vaccinated for measles were 96% (672/700) and none of them were immunized against rubella (including two (3%) who had MMR immunization privately). Out of six blood samples tested, all tested negative for measles IgM antibodies but four were positive for IgM antibodies to rubella. Only 36% (22/61) of the cases took the treatment from modern system of medicine. An outbreak of rubella was confirmed and was possibly due to the frequent traveling of Bengali colony patients to other areas for selling the food items. We advised the local health authorities to provide MMR vaccination to the unexposed and energetic IEC in three affected and neighboring villages.