Study on epidemiological characteristics of the Japanese Encephalitis in Ha Nam during 2001 - 2006

ABSTRACT

Background: Viet Nam is located in the epidemiological region of Japanese Encephalitis (JE). JE vaccine manufactured in Viet Nam has been used in the national vaccination program since 2003, but there has been no scientific study on the effectiveness of this program in Ha Nam province. Objectives: To investigate the epidemiology of JE and effectiveness of vaccinations in Ha Nam province from 2001-2006. Subjects and method: All residents in Ha Nam province, with the key focus group being JE cases. The retrospective and prospective epidemiological descriptive method was used. Results: The records of 148 cases of JE were collected. Among them, 42.5% (63 cases) were confirmed as JE by MAC-ELISA. The incidence and mortality rate were 1.29/100,000 and 0.12/100,000, respectively. Confirmed JE cases were found annually in all districts of Ha Nam province. However, it has been in decline, especially since the vaccination program was implemented for 1-5 year old children. The disease occurred in the summer with the peak in May and June (80.9% of total cases). Most of the cases were children under 15 years old (98.4%). The highest incidence rate was 6.4/100,000; 5.5/100,000 and 5.3/100,000 in the children aged 5-9, 1-4 and under 1 year old, respectively. Conclusion: The vaccination program appeared effective in reducing the mortality and morbidity of JE among children in Ha Nam province.