New Tool Identifies Aedes Mosquito Exposure in People

NIAID-developed Test Could Be Used to Find Hot Spots for Disease-spreading Mosquitoes

Not all mosquitoes are the same. Some carry pathogens that cause diseases in the people they bite. Scientists at NIAID developed a new tool to help identify geographic hot spots for Aedes mosquitoes, a type of mosquito that can spread diseases such as dengue, Zika and chikungunya. The tool uses a marker from blood serum to identify people bitten by Aedes mosquitoes. Monitoring for this marker in blood samples could help find sites where disease-carrying mosquitoes live, allowing for targeted interventions against dengue and other diseases.

Nearly half of the world's population lives in areas affected by dengue, a viral disease spread by Aedes mosquitoes, primarily of the species Aedes aegypti and Aedes albopictus. The disease symptoms include fever, head and body aches, nausea and rash, and severe cases of dengue can be fatal. Each year, between 100 and 400 million people develop the disease, resulting in approximately 40,000 deaths. In places where dengue is common, it is often a major cause of illness. However, vaccines against dengue are not widely available throughout the world. For these reasons, mosquito control is an important strategy for preventing the disease in these regions.

When a person or animal is bitten by a mosquito, saliva from the mosquito is injected into the skin. The saliva is what causes the bite to itch-and it can also contain pathogens such as viruses and parasites that cause disease. The immune system reacts to a mosquito bite, producing antibodies against the proteins contained in mosquito saliva. People who have been bitten by Aedes mosquitoes carry antibodies against these proteins in their blood. Although a mixture of mosquito salivary gland proteins can be used in the lab to test whether a person has been bitten by Aedes mosquitoes, the test can be expensive, time-consuming, and difficult to standardize among different labs.

A team of researchers led by Dr. Fabiano Oliveira in NIAID's Laboratory of Malaria and Vector Research aimed to develop a test suitable for large-scale monitoring of Aedes mosquito exposure in people. The researchers tested blood serum from children in Cambodia who had enrolled in a study conducted by the NIAID International Center for Excellence in Research, Cambodia. The researchers compared the levels of several mosquito saliva proteins in the blood of children who had and had not developed dengue. They found that most of the children who had developed the mosquito-borne disease had higher levels of antibodies against two proteins, AeD7L1 and AeD7L2, which are from the saliva of the Ae. aegypti mosquito. Based on these findings, the scientists developed a test that uses lab-produced versions of the proteins. They found that the test could detect antibodies produced by Aedes mosquito bites without detecting exposure to other types of mosquitoes, such as some Culex and Anopheles species.

The researchers note that the new test could be a valuable tool for public health programs, such as for identifying where mosquito control measures could have the greatest effect in areas with limited access to resources. However, they say that additional development is needed to ensure that the test produces consistent results in different populations, including adults. They note that the test uses reagents that are inexpensive, could be standardized among different labs, and would need only a drop of blood for analysis, making it a promising means to help prevent the spread of dengue and other mosquito-borne diseases.

Reference:

S. Chea and L. Willen, et al., "Antibodies to Aedes aegypti D7L salivary proteins as a new serological tool to estimate human exposure to Aedes mosquitoes." Frontiers in Immunology, May 1, 2024. [DOI: 10.3389/fimmu.2024.1368066]