**9. Surveillance of chikungunya**

Epidemiological surveillance is the key to detecting cases in a timely manner and a prompt and appropriate response is required with the active participation of all stakeholders. Surveillance activities are carried out to determine whether chikungunya (CHIKV) has entered an area, track the disease that has entered and follow it on an ongoing basis. The forms of CHIKV surveillance activities in Indonesia are: [136, 141].

## **9.1 Case definition**

The case definition of CHIKV used in the surveillance system in Indonesia has been published in the Ministry of Health's National Guidelines for Chikungunya Prevention and Control followed World Health Organization (WHO) criteria [141]. In short, chikungunya cases are classified into three categories, namely: (1). Possible cases, diagnosed on clinical criteria alone as acute fever>38.5° C and severe arthralgia/arthritis which could not be explained by other medical conditions; (2). Probable cases, diagnosed based on clinical criteria as stated and epidemiological criteria (living or visiting epidemic areas); (3). Confirmed cases, diagnosed according to laboratory criteria that showed a positive result for viral isolation, RT-PCR, IgM antibody or a fourfold increase in IgG antibody.
