Outbreak Investigation of Influenza A H1N1 in A Prison, Nakhon Si Thammarat Province, Thailand, March 2020

Abstract

Background: On March 16, 2020, the rapid response team of Pak Phanang District was notified by the Nakhon Si Thammarat Provincial health office that there was a cluster of influenza–like illness in a male prison in Nakhon Si Thammarat province. The team from Pak Phanang District, Office of Disease Prevention and Control 11 and Nakhon Si Thammarat provincial health office investigated the outbreak during 17–20 march 2020.

Objectives: to confirm the outbreak, verify diagnosis, describe epidemiological characteristics, determine associated factors and give recommendation to contain the outbreak.

Materials and Methods: We reviewed a situation of influenza from the Disease Surveillance system, conducted active case finding, interviewed prisoners and jailers, collected throat swab for respiratory pathogen testing by real–time polymerase chain reaction. Case–control study was conducted to determine the associated factors for illness. All patients met with case definition were defined as cases. Control group was sampling from inmates who clearly had no symptom.

Results:  Influenza A H1N1 (2009) outbreak occurred in a male prison in Nakhon Si Thammarat province, between 9–20 March 2020, all patients were inmates. A total of 219 cases (attack rate was 9.63%), 196 were suspected cases and 23 were confirmed cases. Most of patients had fever, myalgia, headache and cough. Factors associated with getting sick from influenza were sleeping in same room with influenza case (aOR 9.62, 95% CI5.92–15.63) , being coughed on(aOR5.30, 95% CI3.49–8.05) , sharing a water glass (aOR 2.35, 95% CI 1.48–3.71) , and sharing a spoon with others (aOR 2.11, 95% CI 1.25–3.55) .

Conclusions:  Separating new inmates from old inmates for at least 7 days to lower the risk of transmitting disease was recommended. Prompt screening, early isolation of sick inmates, stop sharing water glass and spoon should be implemented to control and prevent further outbreak.