Inapparent infections shape the transmission heterogeneity of dengue

Area of Science:

• Epidemiology
• Infectious Disease Dynamics
• Public Health

Background:

• Transmission heterogeneity is common in infectious diseases, but difficult to measure for vector-borne diseases like dengue virus (DENV).
• Traditional methods inferring heterogeneity from vector abundance may be biased when vector density doesn't correlate with transmission risk.

Purpose of the Study:

• To quantify DENV transmission heterogeneity by analyzing infection distribution within human activity spaces (AS).
• To identify super-spreading units (SSUs) responsible for a disproportionate number of DENV infections during outbreaks.

Main Methods:

• Utilized contact tracing data from two DENV outbreaks (DENV-4 and DENV-2) in Iquitos, Peru.
• Applied negative-binomial distributions and Pareto fractions to analyze infection distribution across AS.
• Investigated factors associated with SSU occurrence, including DENV serotype, infection inapparentcy, mosquito abundance, and host susceptibility.

Main Results:

• Strong evidence of overdispersion in DENV infections across AS, indicating significant transmission heterogeneity.
• Identified SSUs, with approximately 8% of AS contributing to over 50% of all DENV infections.
• SSU occurrence was linked to DENV-2, higher rates of inapparent infections (74%), abundant *Aedes aegypti* mosquitoes, and increased host susceptibility.

Conclusions:

• Dengue virus exhibits marked transmission heterogeneity, challenging traditional control strategies.
• Inapparent infections play a significant role in defining this heterogeneity.
• Effective dengue control requires identifying and prioritizing SSUs for targeted interventions.