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Public health officials may soon be able to detect mosquito viruses in the wild much more quickly and easily, thanks to the insect equivalent of a urine test.
In recent years, researchers have discovered that viruses such as dengue and West Nile can be detected in droppings, or droplets of liquid waste, of infected mosquitoes. Now, a new study in Australia shows that two types of mosquito traps commonly used can be easily modified to collect mosquito waste to be tested for signs of the virus. The results of the study and the details of the changes to the trap are published today in the Journal of Medical Entomology.
It is a proof of concept that brings this technique closer to the regions of the world where mosquito-transmitted viruses pose a threat to public health. "These methods could easily be used around the world because the changes to the mosquito excrement trap can be made relatively easily and cost-effectively," says Dagmar Meyer, Ph.D., a postdoctoral fellow at James Cook University. of Cairns, Queensland, Australia. lead author of the study.
Other methods of detecting mosquito-borne diseases in wild populations include collecting mosquito pools to directly search for viruses or animal blood samples, such as chickens or pigs, which are also stung by mosquitoes and serve as reservoirs for viruses. These two problems are faced with problems, such as intensive work and the need to keep cold storage of samples from the collection through testing on a permanent basis. In 2010, a method was developed to collect mosquito saliva, which could also be tested for signs of viruses, on "nucleic acid conservation cards", which store viral RNA. at room temperature for long periods; the cards were coated with honey to attract mosquitoes.
However, a virus must incubate in a mosquito before it can be detected in its saliva, a period of up to 15 days, but a virus can be detected in the residual liquid of a mosquito in just two or three days. In addition, while a typical mosquito releases less than 5 nanoliters of saliva when feeding, it produces about 1.5 microliters of liquid waste each time it is excreted. This represents approximately 300 times more sample material to work on, baduming it can be collected in the field from mosquitoes caught in the wild.
That's what Meyer and other researchers from James Cook University, the Queensland Department of Health, and the Northern Territory Department of Health sought to find out. They started with mosquito traps during the night and long-term pbadive traps, which attract all mosquitoes by emitting carbon dioxide; Night traps also use a motorized light to attract. Overnight traps consisted of a modified trap container that was attached to standard trap models. The container contained a nutrient coated with honey and a polycarbonate sheet placed at the bottom of the container collected droplets of mosquitoes. The nucleic acid conservation cards were then used to wipe the polycarbonate sheet. The traps for long-term field deployment contained an external source of moisture, allowing mosquitoes to stay alive longer and thus excrete more, thus increasing the possibilities of detecting the virus. The traps also housed honey-coated nutrients and nucleic acid preservation cards were placed directly into the traps to collect droplets of mosquito waste.
The researchers then tested the mosquito waste collected for the presence of West Nile virus, Murray Valley encephalitis virus and Ross River virus, all of which were detected. "Our study, to our knowledge, is the first to have detected arboviruses from mosquito excrements harvested in the field," said Meyer. Ana Ramirez and Scott Ritchie from James Cook University, Andrew van den Hurk from the Queensland Department of Health, and Nina Kurucz from the Northern Territory Department of Health collaborated on the study.
The team of researchers has stated that advances in molecular methods for detecting viral RNA in biological samples in recent years have tested mosquito saliva and mosquito excrement, and that their success in collection and detection of excrement opens the door to the detection of viruses transmitted by mosquitoes. viruses in a "simple, potentially more cost-effective way and allowing earlier and more sensitive detections" compared to other methods. They suggest that future work can continue to optimize trap modifications and compare the effectiveness of the method with other existing methods.
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Material provided by Entomology Society of America. Note: Content can be changed for style and length.
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