An outbreak investigation of mumps in one primary school in Phanom District, Surat Thani Province, January–April 2018

Abstract

Background: On 23 January 2018, Phanom District Health Office was notified of some cases of mumps in students of one primary school in the district. A joint investigation team conducted to confirm diagnosis and outbreak, determine epidemiologic characteristics, identify risk factors and mode of transmission, recommend preventive and control measures and determine vaccine coverage and efficiency during 23 January–17 April 2018.
Methods: Medical records of the mumps cases were reviewed. Active case finding was carried out in the affected school and community. Serum specimens were collected from 4 suspected cases for detection of mumps IgM antibody by Enzyme-linked immunosorbent assay (ELISA). An environmental investigation was conducted in the affected school. A retrospective cohort study was carried out to determine risk factors. The coverage of MMR vaccine in these students and vaccine efficacy were determined.
Results: 22 mumps cases were detected in this school. Of them, 21 primary school students and 1 teacher. The most common clinical feature was fever (59.09%), followed by swollen and painful salivary glands (45.45%) and pain during chewing/swallowing (39.39%). All the cases had no complications and none died in this outbreak. The 21 students with mumps were 8–11 years old; 15 girls and 6 boys. Mumps was found in 4 classrooms including primary school grade 2–4 (rooms 2/1, 3/3, 4/2 and 4/3). Of the 4 cases with serum examination, 2 were positive for mumps IgM antibody by ELISA. Factors significantly associated with the disease by a retrospective cohort study included having a mumps case in the same house within previous 25 days before illness, sharing a glass, handkerchief/towel, spoon/fork, pencil/pen and sitting in the classroom within 1 meter from the mumps case. The vaccine coverage of MMR in these students was low. The vaccine efficacy of at least 1 dose of MMR was 31.43%.
Conclusions and discussions: The coverage of MMR in these students was low. Factors significantly associated with the disease were closed contact with a mumps case and sharing an object/a utensil. In this outbreak, the calculated vaccine efficacy of MMR was somewhat low.