Introduction: In outbreak settings, more than one virus may be infecting the given population. In twin or triple outbreak of measles, German measles (rubella), and varicella in highly immunized hilly areas, maximal number of the case patients in all the hilly villages belonged to the older age group. It suggested an obvious shift to the higher age group, warranting second dose opportunity in such case scenario. The clinical presentations of viral diseases are too similar to differentiate. The aim is to clearly categorize the case patients of modified measles, rubella, and atypical measles in outbreak settings.
Results: Four outbreaks are listed. In the first one, sixty case patients were identified from 1026 people in 5 villages. Of these, 41 were diagnosed by clinically, 8 were laboratory confirmed as measles and 11 were epidemiologically linked German measles case patients. Seventy percent of the cases were vaccinated for measles. In second case, we identified 29/35 measles and 6/35 were confirmed as epidemiologically linked unvaccinated chickenpox case patients. In third one, we identified 116 cases in eight villages (112/116 clinically and 04/116 laboratory confirmed). Majority of cases were immunized against measles, but only minor cases for rubella. In fourth case, we identified 505 case patients from mixed outbreaks of varicella, measles and rubella (30/505 clinically, 467/505 epidemiologically linked and 8/505 laboratory confirmed case patients from a study population of 3280). In all the four outbreaks, prima facie, the clinical presentations of both rubella and modified measles were difficult to differentiate.
Discussion: On the basis of outbreak investigation and analytical inference, it has been observed that the symtomatology of modified measles and laboratory confirmed rubella case patients/epidemiologically linked cases are so similar placed that many a time, it becomes much difficult to line list the cases in one section of modified measles or rubella or atypical cases.
Conclusion: Similarities of morphological symptoms between modified measles and rubella is the point of challenge and it causes debate between pediatrician and field epidemiologist to differentiate and classify them.
Keywords: Atypical measles; Kangra; Northern Himachal; modified measles; rubella; triple infection; twin outbreak.