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Vector Competence Analyses on Aedes aegypti Mosquitoes using Zika Virus
Published on: May 31, 2020
Mechanical transmission of dengue virus by Aedes aegypti may influence disease transmission dynamics during outbreaks
Hsing-Han Li1, Matthew P Su2, Shih-Cheng Wu3
1National Mosquito-Borne Disease Control Research Center, NHRI, Miaoli, 350401, Taiwan; National Institute of Infectious Diseases and Vaccinology, NHRI, Miaoli, 350401, Taiwan; Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, 92093, USA.
Background:
Dengue virus outbreaks are increasing in number and severity worldwide. Viral transmission is assumed to require a minimum time period of viral replication within the mosquito midgut. It is unknown if alternative transmission periods not requiring replication are possible.
Methods:
We used a mouse model of dengue virus transmission to investigate the potential of mechanical transmission of dengue virus. We investigated minimal viral titres necessary for development of symptoms in bitten mice and used resulting parameters to inform a new model of dengue virus transmission within a susceptible population.
Findings:
Naïve mice bitten by mosquitoes immediately after they took partial blood meals from dengue infected mice showed symptoms of dengue virus, followed by mortality. Incorporation of mechanical transmission into mathematical models of dengue virus transmission suggest that this supplemental transmission route could result in larger outbreaks which peak sooner.
Interpretation:
The potential of dengue transmission routes independent of midgut viral replication has implications for vector control strategies that target mosquito lifespan and suggest the possibility of similar mechanical transmission routes in other disease-carrying mosquitoes.
Funding:
This study was funded by grants from the National Health Research Institutes, Taiwan (04D2-MMMOST02), the Human Frontier Science Program (RGP0033/2021), the National Institutes of Health (1R01AI143698-01A1, R01AI151004 and DP2AI152071) and the Ministry of Science and Technology, Taiwan (MOST104-2321-B-400-016).
Insights
Dengue virus can spread through mechanical transmission, bypassing mosquito replication. This new route could lead to larger, faster outbreaks, impacting control strategies.
Area of Science:
- Virology
- Epidemiology
- Vector-borne Diseases
Background:
- Dengue virus outbreaks are increasing globally in frequency and severity.
- Traditional dengue transmission models assume a necessary replication period within the mosquito.
- The possibility of dengue transmission without mosquito replication remains unexplored.
Purpose of the Study:
- To investigate mechanical transmission of dengue virus.
- To determine the minimum viral load required for symptomatic infection in mice.
- To develop a new transmission model incorporating mechanical transmission.
Main Methods:
- Utilized a mouse model to study dengue virus transmission.
- Assessed mechanical transmission by exposing mice to mosquitoes immediately after feeding on infected mice.
- Developed a mathematical model to evaluate the impact of mechanical transmission on population-level outbreaks.
Main Results:
- Mice bitten by mosquitoes that had fed on infected hosts, even briefly, developed dengue symptoms and mortality.
- Mechanical transmission, when included in models, indicated potential for larger and earlier dengue outbreaks.
- This suggests a significant, previously underestimated transmission pathway.
Conclusions:
- Dengue virus can be transmitted mechanically, independent of replication in the mosquito.
- This finding has critical implications for vector control, particularly strategies focusing on mosquito lifespan.
- Mechanical transmission may occur in other mosquito-borne diseases, necessitating broader research.
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