POSSIBLE NOSOCOMIAL TRANSMISSION OF MEASLES IN UNVACCINATED CHILDREN IN A SINGAPORE PUBLIC HOSPITAL

Monday, 31st of March 2014

[source]Western Pacific Surveillance and Response Journal[|source]

Measles vaccination has been compulsory in Singapore since 1985. Under the National Childhood Immunization Programme, the first dose of the trivalent measles, mumps and rubella (MMR) vaccine is to be administered by the age of two years and the second dose at six to seven years of age. However, in view of the large proportion of reported cases of measles among unvaccinated infants and pre-school children, the MMR immunization schedule was amended effective 1 December 2011, with the first dose to be given at 12 months of age and the second dose at 15 to 18 months of age. Over the past six years, the national vaccination coverage for the MMR vaccine has consistently been maintained at around 95% for the first dose and above 90% for the second dose.

 In this article, the authors report the epidemiological investigations for the outbreak. The report describes a possible nosocomial outbreak of measles occurring within a health care setting. Detailed results, discussion and recommendations are accessible at:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3729085/

 

ABSTRACT

INTRODUCTION: Measles is an acute, highly communicable viral disease, with measles outbreaks usually occurring in settings where there are unvaccinated populations. After being notified of a cluster of five measles cases in a Singapore public hospital in August 2011, the Ministry of Health Singapore conducted an outbreak investigation.

METHODS: Active case detection was conducted, and all notified cases movement history within the hospital were reviewed to determine any common exposures in place and time. Cases were classified as nosocomial if they had contact with other measles cases in the hospital seven to 21 days before onset dates. Laboratory testing included serological and molecular diagnostic methods.

RESULTS: Of the 14 cases, seven cases were nosocomial cases. Investigations identified two wards where cases were epidemiologically linked. Two cases in Ward A were of D8 genotype and genotypically 100% identical, thus confirming a common source of infection. The six cases in Ward B (including one transferred from Ward A) had overlapping periods of admission and three cases were of the same D8 genotype, with a single nucleotide difference.

DISCUSSION: The epidemiological linkages of the cases and laboratory findings suggest nosocomial transmission in Wards A and B. As a result of this investigation, the hospital implemented a new policy of isolating suspected measles cases instead of waiting until they had been laboratory confirmed. This investigation emphasizes the importance of early identification and isolation of suspected measles cases within health care institutions and reinforces the requirement for high measles vaccination coverage of health care workers.