Two Highly Immunized Hilly Areas versus Double Measles Outbreak Investigations in District Kangra, Himachal Pradesh, India, in 2006

Author (s): 

Surender N Gupta, Naveen Gupta

ABSTRACT

Background: We investigated two sequential outbreaks of measles in seven villages of Kangra, to confirm the diagnosis and
to formulate recommendations for prevention and control.

Methods: We defined a case of measles as occurrence of fever with
rash in a child aged six months to 17 years during the period 3rd September to 23rd November 2006. We collected information
on age, sex, residence, date of onset, symptoms, signs, treatment taken, traveling history and vaccination status. We described
the outbreak by time, place and person. We estimated vaccine coverage and efficacy in the affected villages. We confirmed
diagnosis clinically, serologically and through genotyping of the virus.

Results: We identified 69 cases. Overall attack ratesranged between 4.2% and 6%. All case patients were between 6 years to 11 years of age. Age-specific attack rate in double
outbreaks ranged in between 1.7% and 21.6%, the highest being in the age range 11-17 years. No deaths or complications were
reported. The epidemic curve was suggestive of typical propagated pattern. The first outbreak imported virus after an interschool
game competition (relative risk, 6.44%; 95% confidence interval, 3.81-10.91); followed by the second outbreak, in which people
exchanged foods in the festival in one infected village of the first outbreak (relative risk, 5.3; 95% confidence interval, 1.90-14.77;
P <.001). The calculated immunization coverage (93%) coincided nearly with administrative claims. The vaccine efficacies were
estimated to be 85% and 81% in the first and second outbreaks respectively. Eleven of the 16 case patients were tested for
measles IgM antibodies, while two nasopharyngeal swabs were positive by polymerase chain reaction (PCR) and are genotyped
D4 measles strain. Vitamin A supplementations were only given in four villages.

Conclusion: Measles outbreaks were confirmed
in high–immunization-coverage areas. We recommended (i) second dose opportunity for measles in Himachal Pradesh and (ii)
vitamin A supplementation to all the case patients.

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