Surge of Chikungunya Cases in Central India, Post-COVID-19 Pandemic

Chikungunya virus (CHIKV) the causative agent of chikungunya fever, has caused several outbreaks in India since its emergence in 2006. However, studies in central India remain limited. In 2024, following the COVID-19 pandemic, a surge in chikungunya cases was reported in the state of Madhya Pradesh, located in central India. This study aimed to evaluate the incidence of chikungunya cases in this region.

This prospective study was conducted in Madhya Pradesh between July 2024 and February 2025. Chikungunya virus infection was confirmed using reverse transcriptase real-time polymerase chain reaction (RT-PCR) to detect viral RNA during the acute phase and in cases of viral co-infection. Patients with an acute onset of high-grade fever (≤7 days from symptom onset) and severe arthralgia or arthritis, with or without a skin rash, were considered to have suspected CHIKV infection according to the case definition by the Government of India. Because of overlapping clinical presentations, patients were also tested for dengue virus (DENV) infection. Demographic and clinical data of CHIKV-positive patients were analyzed. Co-infected samples were further analyzed for viral load using Truenat® Dengue/Chikungunya chip-based real-time duplex PCR test (Molbio Diagnostics Pvt. Ltd., Goa, India). Positive patients were followed for an additional two months.

Of 1878 samples tested, 1105 (58.9%) were positive for CHIKV. The positivity rate was 60.2% ± 0.009 (mean ± standard deviation [SD]) among males and 57.5% ± 0.07 among females. The number of cases in 2024 was significantly higher than in previous years (p<0.001). All age groups were affected. Co-infection with DENV and CHIKV was confirmed by RT-PCR in seven patients who tested positive for both viral RNA. Post-acute clinical complications and recovery patterns differed between children and adults, as well as between mono-infected and co-infected patients.

The true incidence of chikungunya in Madhya Pradesh remains underestimated and underreported. Timely real-time PCR-based diagnosis of CHIKV infection is crucial for an accurate assessment of the disease burden and targeted public health interventions.