Epidemiology, Clinical Spectrum, and Serotype Distribution of NS1-Confirmed Dengue Cases in Andhra Pradesh, India: A...

Dengue is a major public health concern in India, showing marked seasonal variation and diverse clinical manifestations. Long-term regional data are essential for improving early diagnosis and guiding public health interventions. This study assessed decade-long epidemiological trends, clinical spectrum, and dengue virus serotype distribution among NS1-confirmed dengue cases in Andhra Pradesh, India.

We conducted a retrospective observational study of 30,086 clinically suspected dengue cases tested for dengue NS1 antigen at a tertiary-care center in Andhra Pradesh, India, between January 2015 and December 2024. Demographic characteristics, urban-rural residence, temporal trends, clinical manifestations classified according to the WHO 2009 dengue classification, and dengue virus serotypes were analyzed. Associations were assessed using chi-square tests, and selected comparisons of clinical manifestation categories were performed using proportion-based analyses.

Among 30,086 suspected cases, 3,899 (13.0%) were NS1-positive. Positivity was higher among males (2,142; 13.6%), children aged ≤18 years (2,235; 20.7%), and rural residents (1,679; 14.7%). Dengue transmission showed consistent post-monsoon peaks from August to October, with a marked decline in 2020 during COVID-19-related movement restrictions. Severe dengue with hemorrhagic manifestations was the most common clinical category (1,734; 44.47%), followed by systemic manifestations (727; 18.64%), neurological involvement (690; 17.68%), gastrointestinal warning signs (307; 7.87%), and hepatic involvement (160; 4.10%). Neurological manifestations were significantly more frequent than gastrointestinal or hepatic involvement. Serotyping of 300 NS1-positive samples showed predominance of dengue virus serotype 3 (111; 37.0%), followed by serotype 2 (70; 23.3%), with mixed serotype infections (28; 9.3%).

This decade-long analysis highlights pronounced seasonality, a substantial pediatric burden, rural predominance, evolving dengue virus serotype circulation, and a notable contribution of neurological manifestations to dengue morbidity in southern India. Strengthened pre-monsoon vector control, early syndromic recognition particularly of neurological involvement, and continued molecular serotype surveillance are essential to reduce dengue-related morbidity in endemic regions.