Study links disease spread with mosquito diets
Mosquitoes' feeding habits come from learned behaviour and evolutionary adaptations.
A new study has linked mosquitoes’ feeding preferences to localised disease transmission, particularly when the outbreaks are unexpected.
Researchers from the Roslin Institute say that the insect’s habit of returning to a species for blood meals may be contributing to the spread of insect-transmitted disease – even if the species is rare.
The mosquitoes’ feeding habit, which is known as vector fidelity, is noted in some of the adults. It is believed to have developed through a combination of learned behaviour and evolutionary adaptations, such as odour and heat cues.
To explore how these feeding patterns might influence disease transmission, scientists examined a mathematical model.
As an example, the team used the spread of Japanese encephalitis virus (JEV). The model hoped to discover why there were outbreaks in regions where animals associated with virus spread were scarce.
Some animals, including pigs, are able to pass JEV back to susceptible mosquitoes after contracting it. These mosquitoes are then able to infect other animals and people.
However other species, such as cattle, are not able to return the virus to a mosquito.
Researchers say that areas with more cattle and fewer pigs should have a low disease spread. However in many places, including parts of Bangladesh and India, outbreaks are still occurring.
The findings from the Roslin Institute’s mathematical model now links the mosquitoes’ feeding habits to these outbreaks.
Where mosquitoes have a preference for feeding on pigs, return visits would help maintain the spread, even if the pigs are outnumbered by the cattle. Meanwhile, occasional feeding on cattle would continue to sustain the spread to the wider population.
The theory is based on a well-established infectious disease modelling framework. While it has not been tested in the field, researchers say it highlights factors which are rarely considered in disease prevention.
Anthony Wood, postdoctoral research fellow at the Roslin Institute, said: “If preference among mosquitoes for the species they feed on plays a real-world role, separating species that can enable the cycle of infection from other livestock could help reduce risk.
“Our results suggest that even small biases in mosquito feeding habits could have a big impact on transmission dynamics, so understanding and managing these behaviours could be important for disease control.”
The full study can be found in the journal PLOS Neglected Tropical Diseases.
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