Transmissibility of acute haemorrhagic conjunctivitis in small-scale outbreaks in Hunan Province, China.

Acute haemorrhagic conjunctivitis (AHC) outbreaks are reported frequently in China. However, the transmissibility of AHC remains unclear. This study aimed to calculate the transmissibility of the disease with and without interventions. An AHC outbreak dataset from January 2007 to December 2016 in different schools was built in Hunan Province. A Susceptible-Infectious-Recovered (SIR) model was adopted to calculate the effective reproduction number (R) of AHC. R was divided into two parts (R and R) where R and R represent the uncontrolled and controlled R , respectively. Based on R and R, an index of effectiveness of countermeasures (I) was developed to assess the effectiveness of countermeasures in each outbreak. During the study period, 34 AHC outbreaks were reported in 20 counties of 9 cities in Hunan Province, with a mean total attack rate of 7.04% (95% CI: 4.97-9.11%). The mean R of AHC outbreaks was 8.28 (95% CI: 6.46-10.11). No significance of R was observed between rural and urban areas (t = -1.296, P = 0.205), among college, secondary, and primary schools (F = 0.890, P = 0.459), different levels of school population (F = 0.738, P = 0.538), and different number of index cases (F = 1.749, P = 0.180). The most commonly implemented countermeasures were case isolation, treatment, and health education, followed by environment disinfection, symptom surveillance, and school closure. Social distance, prophylaxis, and stopping eye exercises temporary were implemented occasionally. The mean value of R was 0.16 (range: 0.00-1.50). The mean value of I was 97.16% (range: 71.44-100.00%). The transmissibility of AHC is high in small-scale outbreaks in China. Case isolation, treatment, and health education are the common countermeasures for controlling the disease.