Chikungunya is a disease caused by a virus, which is transmitted through the bite of the Aedes aegypti mosquito, which may cause symptoms like fever, skin rashes and body pain. According to the Ministry of Health, from January to June this year, more than 48,300 probable cases of the disease were reported in Brazil. The disease is mainly concentrated in the North-Eastern region, which presented the greatest incidence rates, with 48.3 cases per 100 thousand inhabitants. Only the State of Bahia concentrated approximately 45% of the probable chikungunya cases in the country.

An important aspect of the disease is that it is estimated that half of the infected individuals develop debilitating chronical pains in the joints, which affects the life quality and increases the burden on the health systems. Thus, researchers from Fiocruz Bahia carried out a study to identify the relevant clinical and demographic variables in the acute phase of chikungunya, seeking to list a set of features that may indicate the patients who have greater probability of developing chronic arthralgia (long-term pain in the joints). 

This prognosis may be useful to track patients that will need special care and to guide public health policies, in addition to being able to provide the patient with early treatment, thus reducing the overload over the health system. The results of the work coordinated by the researcher of Fiocruz Bahia, Viviane Boaventura, were published in the scientific journal Plos Neglected Tropical Diseases [1].

The study is part of a greater project, named Mitigando o Impacto da Artralgia Crônica Pós-Chikungunya (Mitigating the Impact of Post-Chikungunya Chronic Arthralgia), focusing on the development of pharmaceuticals to treat the disease.

In the beginning of the research, a group of persons diagnosed with chikungunya were evaluated, between 2016 and 2018, in cities in Bahia and Ceará. Later, the findings were validated in another group of patients, in the municipality of Feira de Santana (BA). 

As a result, five features that represent good predictors of chronic arthralgia were detected: female, hypertensive individuals, who have had skin edema and retro-ocular pain during the infection, and older than 26 years old. From this data, the scientists developed a score system, which they called Shera (acronym for Sex, Hypertensive, Edema, Retro-Ocular Pain and Age). The tool is available here [2] and may be used in Portuguese and English. 

According to the researchers, this tool can predict 8 in each 10 individual with chikungunya who will persist with joint pain for at least one year after the beginning of the illness. In addition, the easy score system may be applied in areas with limited access to health services.