Outbreak investigation of chikungunya disease in Ban Pang Samakkhi, Village no. 16, Pho Thong Sub-district, Pang Silathong District, Kamphaeng Phet Province, April–May 2024

Abstract

Background: On April 19, 2024, a disease investigation team was notified by the epidemiologist from the Kamphaeng Phet Provincial Public Health Office regarding a confirmed case of chikungunya fever in Ban Pang Samakkhi, Village No. 16, Pho Thong Subdistrict, Pang Sila Thong District, Kamphaeng Phet Province. The team subsequently conducted a field investigation to verify the diagnosis and assess the outbreak. Objectives included identifying the chikungunya virus strain involved, defining the extent and distribution of the outbreak, identifying the source of infection, and implementing outbreak control measures.

Methods: A descriptive epidemiological study was conducted. Medical records of patients were reviewed, and the local outbreak situation was assessed. Active case finding was performed in the community and hospitals. Environmental and entomological study: Larval indices, including the House Index (HI), Container Index (CI), and Breteau Index (BI), were assessed, and mosquito species were identified.

Results: A total of 12 cases met the case definition for chikungunya fever, corresponding to an attack rate of 4.36%. These consisted of 8 suspected cases, 1 probable case, and 3 confirmed cases. The attack rate among females (4.02%) was higher than among males (2.38%). The most affected age group was 40–44 years (10.53%), followed by 50–54 years (6.90%). The most common clinical symptoms were high fever (100%) and myalgia (66.67%). Laboratory testing confirmed chikungunya virus RNA in 3 cases, and IgM antibodies were detected in 2 cases by ELISA. Viral strain identification by molecular whole genome sequencing could not be performed due to low viral load. Vector surveillance and larval sampling on April 22, 2024, identified Aedes spp. mosquitoes as the vector. Larval indices were high: HI = 42.86%, CI = 8.15%, and BI = 207.14. Most mosquito breeding containers were stagnant water containers located outside houses.

Recommendations: Local health network staff should strengthen community knowledge, awareness, and self-protection measures against chikungunya fever, particularly through elimination of mosquito breeding sites. Coordination between government and private healthcare providers is recommended to enhance surveillance, case monitoring, and patient information sharing. This will help prevent delays in diagnosis and ensure timely access to medical care.