"What is the most dangerous animal in the world?”

The answer might surprise you, according to Chad Cross and Louisa Messenger, professors with the UNLV School of Public Health.

“In terms of the number of associated diseases and deaths that are transmitted by them … it’s the mosquito,” Cross says.

Cross and Messenger teach parasitology and medical entomology courses focusing on diseases that can be transmitted, especially to humans, by insects. Bugs pose a larger public health risk than people perceive, the scientists say. “About 17% of all of our infectious diseases are transmitted by some kind of insect,” Messenger says.

From the morphology lab at UNLV, Messenger displays a collection of triatomine bugs, better known as kissing bugs. The beetle-like specimens vary in size, with most about the size of a thumbnail. Although they could easily be mistaken for harmless, the bugs actually spread a parasite that causes Chagas disease, which affects the heart and can develop into lifelong and threatening complications if left untreated.

“It’s probably the leading cause of infectious heart disease in the world. It’s one of those ones that you don’t think about when you think about infectious diseases. But, it’s getting this parasite that is a really big problem, because these bugs can live in peoples’ houses,” Messenger says. “[They’re] not so much an important public health problem in the U.S., because a lot of the time these bugs are found out in the wild. But down in Central and South America, these bugs are found infesting human homes.”

So far, they’ve collected more than 300 specimens from five states in one of the citizen science initiatives to come out of UNLV’s Parasitology and Vector Biology labs. Rather than collect the bugs themselves, they scout out contributors on iNaturalist, a user-based online database of living things.

“Basically, anyone who had reported seeing one of these bugs in the last few months this year, we reached out to directly,” Messenger says “And we said, ‘If you see some in the future, would you be willing to collect for us? We’ll pay your postage. We’ll send you some tools. Just keep us posted.’ We’ve had more than 15 contributors.”

Vector biology, or the study of the transmission of infectious diseases from insects to humans or animals, and parasitology are important for educating and informing the public of risks and whether precautionary action or controls are needed; for example, doing “blood meal analysis” to find out whether kissing bugs have been feeding on humans, pets or livestock, and studying bed bugs to develop best practices for hotels to prevent and monitor them.

Through citizen science initiatives, Cross and Messsenger are looking to get the entire community involved in these types of studies and make them participants in public health as it relates to insects. In one such initiative, the community can participate in mosquito surveillance by collecting their DNA. It sounds complicated, but one of their students is perfecting an easy, efficient way for anyone to do that.

“If you’ve ever watched Forensic Files, they catch people because we leave DNA behind everywhere we go. Insects do the same thing. They shed; they defecate in the water, leave the saliva in the water,” Cross explains. “And so what we can do is go out into the environment, take a sample of water … and on the end of that syringe goes a little filter., and you just pass the water through that filter two or three times. And in that filter now will be DNA from things which have been living in that water, including mosquito eggs, mosquito larvae, adult mosquitoes who have landed in that water, for example.”

That DNA can be analyzed in UNLV’s Parasitology and Vector Biology molecular lab to determine whether mosquitoes are present, and what species of mosquito have been in that water. Knowing the areas where mosquito larvae are present can help the Southern Nevada Health District’s mosquito surveillance identify the best areas to sample for adult mosquitoes that can then subsequently be tested for viruses like West Nile and Zika.

What’s more, Messenger says this type of sampling is accessible on multiple levels. “We’re then looking to set up another citizen science initiative where we can give out these kits. They’re less than a buck, the syringe and the filter,” Messenger says. “We’re looking to give them to communities and families and say, ‘Have you got any standing water in your back garden or in your swimming pool that you’re worried about? Send us the water samples.’ It takes about a minute to collect.”

Not only does the community get to be involved in its own public health experience, but also, sampling could become more comprehensive and less labor intensive. “Hopefully we should be able to get several thousand samples that will cover all of Clark County. … We can get anybody–whole schools, whole classes, submitting samples. So then, people know what lists of mosquitoes are breeding in their environment [and whether] they need to take any precautions or controls,” Messenger says.

“Public health is all about how your world impacts you, and how you impact your world,“ Cross says. “The citizen science initiative that we’re doing and trying to involve people in any way that we can, I think is hugely important not just for students, but just for the community at large to have an appreciation for the world around them.”

Anyone interested in participating in UNLV Parasitology and Vector Biology’s citizen science initiatives can get in touch with Dr. Cross and Dr. Messenger on their website paravec.sites.unlv.edu or by emailing [email protected].

–Shannon Miller

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