An outbreak investigation of measles after the tsunami in Cuddalore district, Tamil Nadu

Abstract

Introduction: Tsunami struck the entire coastline of Tamil Nadu on 26 th December 2004. After tsunami an outbreak of measles was reported by media in Cuddalore district due to overcrowding of people in relief camps. We had to investigate and report within 12 hours upon this outbreak of measles and determine whether it was related to the tsunami. Materials and Methods: Investigation was done by interviewing health care workers, by visiting villages from where measles was reported and confirmed serologically among children, by looking for clustering of cases and probing for possible reasons for the outbreak. Results : By the day the investigation was carried out, 27 cases had been reported. Of these, 13 cases were from a village not affected by tsunami. There was clustering of cases in a single street in this village. Other reported cases were from villages affected by tsunami, but there was no clustering. No cases were reported from relief camps. All the affected children were above 3 years of age and were immunized previously against measles. No data were available on occurrence of measles in previous years, but it was ascertained that cases of measles occurred around the same season. No common source was identified. Interview with the health workers revealed that reconstituted vaccine was used more than 4 h after reconstitution. A faulty technique was used in route of administration in the immunization. Health workers also said that after the age of 1 year a non-immunized child was not given the vaccine. Conclusions: There was a localized outbreak of measles, but was not related to tsunami. Probable source could not be identified. Possible reasons for outbreak were the faulty use of vaccine and technique of administration. This investigation shows that though in some field situations it may not be possible, or even necessary, to carry out a full-fledged epidemiological investigation, following the epidemiological principles can lead to concrete conclusions.