Wrongfully accused: research acquits mosquitoes as carriers for Lyme disease

The verdict is in! Scientists have cleared mosquitoes of any responsibility in the spread of Lyme disease, and say ticks are solely to blame for the pervasive disease.

Many patients of Lyme disease do not recall being bitten by a tick before onset of symptoms, which has long-fueled speculation about other possible carriers. Mosquitoes became the obvious suspects since they are known to be carriers of a variety of other diseases. A team of international scientists including FIU’s Fernando Noriega, say not so fast. Their research, published in Parasites and Vectors, says the bacteria that causes Lyme disease is typically found in tissues and rarely found in high concentrations in the bloodstream. Mosquitoes’ fast-eating habits prevent them from taking up the bacteria. Ticks, on the other hand, are slow eaters, which allows them to acquire the bacteria as it migrates from tissues.

“Our results show that mosquitoes do not have the biological capacity to efficiently acquire and maintain the bacteria that cause Lyme disease, and that they are unable to transmit them naturally or mechanically,” said Noriega, emeritus professor of biology and researcher in FIU’s Biological Sciences Institute. “This study provides compelling evidence against Lyme disease transmission by mosquitoes and reinforces Ixodes ticks as the only competent vectors, which is critical for targeted public health interventions and accurate risk communication.”

Further acquitting mosquitoes, the scientists also say mosquitoes have an enzyme in their guts that naturally destroys the bacteria that causes Lyme disease. So even if a mosquito bites an infected animal and the bacteria sneaks through, the bacteria would be destroyed during digestion.

“The need for scientific investigation and eliminating suspects is key in tackling vector-borne diseases,” said Matthew DeGennaro, director of the Biomolecular Sciences Institute and neurogeneticist specializing in mosquito behavior. The institute is dedicated to finding treatments, cures and methods of prevention for diseases including those transmitted by mosquitoes, ticks and other vectors.