Outbreak investigation of influenza B in a place for detention and verification Prison A, Ratchaburi Province, Thailand during May 21–June 7, 2019

Abstract

Background: On May 20, 2019, Ratchaburi Hospital was notified for a confirmed influenza B case in a place for detention and verification Prison A, Ratchaburi (Place A). He was a detainee admitted as an inpatient at Ratchaburi Hospital. There were many detainees with suspected influenza. A Joint Investigation Team jointly investigated outbreak during 21 May–7 June 2019.
Methods: This is a cross–sectional study of both descriptive and analytic studies for influenza B outbreak in Place A. The situation of influenza B was analyzed from the epidemiological surveillance report database, interviewing the officers and detainees, active case finding, laboratory examination, environmental study, and review of influenza–like illness from the prison health care center. The analytical study by case–control was carried out to identify possible risk factors. Data were analyzed and preventive and control measures were implemented in the prison.
Results: A total of 81 male influenza cases were identified in Place A during 8–28 May 2019. The morbidity rate was 37.16% (81/218 detainees). The age of cases ranged 18–68 years with a median of 35.3 years. All of cases were detainees; one was inpatient and no one died. All of them had fever and myalgia. Other symptoms were cough, sore throat, rhinorrhea, and sputum with 82.7%, 81.5%, 75.3% and 74.1% respectively. Laboratory finding confirmed of influenza B virus by RT–PCR method 9 from 10 samples. The analytical studies were found the risk factors associated with this outbreak including (i) not covering mouth and nose when coughing and sneezing, (ii) sharing water bottles and glasses with others, (iii) not washing hands before contact with mouth, nose, or eyes and (iv) using the visiting room. The environment study found this place was overcrowded, no patient isolation and using many things together.
Conclusion and discussion: This outbreak was caused by influenza B virus. Factors affecting the outbreak might be no patient isolation at the beginning of outbreak, overcrowded place and poor personal hygiene. Preventive and control measures included patient isolation, screening for suspected influenza cases for all detainees, limiting relatives visiting, sanitizing and administering Oseltamivir. The outbreak was finished; last case was detected on 24 May 2019.