Mosquito feeding habits could influence disease spread

Some mosquitoes feeding preferences could lead to localised transmission cycles of infectious disease in scenarios where outbreaks would otherwise be unexpected, research suggests. 

Mosquitoes’ occasional tendency to return to the same animal species for repeat blood meals could help sustain the spread of diseases, even when the insects’ preferred species is rare, the team found.

Roslin scientists used a mathematical model to explore the impact of the insects’ feeding pattern on disease transmission. Their approach could be adapted to examine any mosquito-borne disease in which the insects feed on multiple species, such as malaria or West Nile virus.

This feeding pattern, known as vector fidelity, can be noted in some adult mosquitoes and is thought to happen due to learned behaviour and evolutionary adaptations, such as odour or heat cues.

The research team used Japanese encephalitis virus (JEV) as an example to show how this pattern might explain outbreaks in regions where the animals most associated with transmitting the virus are scarce.

Scientists examined the impact of disease spread linked to certain species that mosquitoes feed on. Some animals, such as pigs, can pass JEV back to susceptible mosquitoes, which can then infect other animals or people. Other species, such as cattle, cannot return the virus to mosquitoes.

In theory, areas with many cattle and few pigs should have low disease spread. However, outbreaks still occur in such places, including parts of Bangladesh and India, and such feeding behaviour may explain the persistence of JEV in these regions.

The model showed that if mosquitoes show a preference for feeding on pigs, they can help maintain spread even when pigs are outnumbered by cattle. 

Occasional feeding on cattle can still pass the infection to these animals, sustaining the disease in the wider population.

The study is based on a well-established infectious disease modelling framework, adding mosquito feeding preference to explore its effect on disease spread.

While the work is theoretical and has not been tested in the field, it highlights a factor rarely considered in outbreak prediction, the research team says.

The research was published in PLOS Neglected Tropical Diseases in collaboration with colleagues from the Liverpool School of Tropical Medicine, University of Oxford, University of California, Berkeley. 

The Roslin Institute

Anthony Wood

Roslin's article