Asymptomatic Dengue infections significantly contribute to disease transmission

Understanding asymptomatic dengue infections is essential for treating dengue fever as asymptomatic carriers play a vital role in spreading the infection as per a new study. Knowing the prevalence of asymptomatic carriers helps to levy the necessary control measures in health care centers at various levels. 

The study results were published in the International Journal of Infectious Diseases. 

Dengue infection, caused by DENV-infected female Aedes albopictus and Aedes aegypti mosquitoes, is clinically classified as either dengue with/without warning signs or severe dengue. It is a major public health concern. Asymptomatic dengue constitutes three-quarters of estimated DENV infections each year. Literature shows that asymptomatic infections are about 80% as infectious to mosquitoes as symptomatic dengue cases and about 88% of infections result from asymptomatic individuals. Due to the lack of summarized information on the actual prevalence of asymptomatic dengue cases, researchers from the Indian Council of Medical Research conducted a systematic review and meta-analysis to estimate the global prevalence of asymptomatic dengue infections. 

Cross-sectional studies reporting the prevalence of asymptomatic dengue infections from PubMed, Scopus, and Embase were searched and analyzed. The prevalence of asymptomatic dengue infections was pooled and reported as proportions with a 95% confidence interval (CI). 

Results: 

• There were about 41 studies with 131,953 cases in the analysis.
• The overall pooled prevalence of asymptomatic dengue infections was 59.26%, with 65.52% during outbreaks and 30.78% during non-outbreak periods.
• The pooled prevalence among the acutely infected individuals was 54.52%, whereas, among primary and secondary asymptomatic dengue infections, it was 65.36% and 48.99%, respectively. 
• Thus, a pooled prevalence of asymptomatic dengue was 59.26% due to the elective up/down-regulation of host defense response genes. 

Take-home points: 

• Nearly half of the individuals had asymptomatic dengue infections, especially during outbreak periods. 
• Asymptomatic infections were high during primary dengue infections and among blood donors. 

Further reading: 

Global prevalence of asymptomatic dengue infections - a systematic review and meta-analysis. https://doi.org/10.1016/j.ijid.2023.07.010