Investigation and Analysis on an Outbreak of Mumps at a Remote Tibetan Primary School

doi:10.3969/j.issn.1001-568X.2019.04.0020

Abstract：OBjECTIVE To investigate and analyze the causes of the epidemic and the effect of the measures, and to provide evidence for the prevention and control. METHODS A case definition was formulated to carry out cases search, and the investigation and disposal for the epidemic was carried on simultaneously. A retrospective cohort study on Vaccine Effectiveness (VE) of Mumps-containing Vaccine (MuCV) was carried out in 3 classes with the largest number of diseases. Blood and throat swab specimens of present cases were collected to detect IgM antibody and virus nucleic acid of mumps virus. RESULTS It was found that the mumps incidence was 11.2％, and 26 cases were identified totally during the outbreak in the primary school. The clinical manifestations were mainly parotid swelling and pain (100.0％), fever (61.5％), sore throat (53.8％), headache (42.3％). There was no case with serious complications. The epidemic curve suggested a model of human to human transmission. The attack rates of male and female students were 12.6％, 8.2％ respectively (χ2=1.163, P>0.05). The incidence rate of Grade Five (20.5％) was the highest in the school, followed by grade one (16.3％) and Grade Two (15.6％). The secondary attack rates in classrooms and dormitories were 8.4％ and 4.0％. The retrospective cohort study showed that73.7％ of the students had one dose of MMR, and the prevalence of students with and no history of immunity was 16.7％ and 30％ respectively, RR=1.8 (95％CI:0.87, 3.72), and VE=44.4％. 10 cases of mumps virus nucleic acid tests were positive. Mumps virus IgM antibody was positive in 6 cases, and negative in 4 cases. CONCLUSION This was a mumps outbreak take place in a remote Tibetan primary school. The epidemic situation was effectively controlled by comprehensive prevention and control measures. It was suggested to strengthen the reporting and management of infectious diseases in schools, and to carry out the second immunization of MuCV before primary school.