‘Mosquito Toilet’ Built By New Jersey Scientists Reveals Virus Never Before Reported In The Americas

Poop From Backyard Pests Carried West Nile, Rare Viruses, And 35 Kinds Of Parasites

A single backyard collection of mosquito waste in New Jersey turned up the first known evidence of a Hedwig-like virus in the Americas, along with several others that may be entirely new to science. Scientists at Rutgers University made the find with a device one of them describes in blunter terms than most research papers allow.

“What we did, colloquially, was build a mosquito toilet,” said Dana Price, an associate professor at the Rutgers Center for Vector Biology and a lead author of the study, which was published in the journal Microbiology Spectrum.

Price’s mosquito toilet is a 3D-printed funnel coated with a water-repellent spray so slick that droplets bead up and slide straight into a collection tube. Of the two batches of fifty wild Culex mosquitoes tested, the 2022 group turned out to be the richer sample: its waste alone yielded a complete genome of West Nile virus, matching a strain previously tied to New York, plus partial gene segments matching Hedwig virus, a virus that had only ever shown up in Europe. Both years’ waste also carried a complete genome of Culex mosquito virus 1, the most abundant virus in the entire study, previously recorded only in California and Germany.

Mosquito surveillance in the United States has long meant trapping insects by the thousands, sorting them by species, pooling them and grinding them up, all while keeping the samples cold enough that their genetic material does not fall apart. Standard lab tests then hunt for one suspected pathogen at a time. Sequencing everything in a few drops of waste flips that logic around, as Price put it: “If you don’t look for it, you won’t find it. But what if you don’t know what to look for?”

Turning mosquito poop into a disease-tracking tool

Mosquitoes that feed on sugar empty their guts often, and they produce far more waste, roughly 1.5 microliters at a time, than saliva, which they release in volumes hundreds of times smaller. Waste also carries much less mosquito tissue than a crushed insect does, which means less mosquito DNA crowding out whatever virus a lab is trying to find.

Catching those droplets has been the sticking point. Earlier setups relied on swabs, large treated cards, or paper cones sprayed with hardware-store waterproofing, and none of them held up well outdoors or captured everything the insects released. Rutgers researchers printed a rigid funnel instead, sanded the inside smooth, coated it twice with an industrial water-repellent spray and cured it in an oven, so almost nothing stuck to the walls on the way down.

Fieldwork was modest by design. Researchers pulled 50 wild Culex pipiens mosquitoes from a gravid trap in an urban yard in New Brunswick in September 2021, and another 50 from the same yard in September 2022. Each group went into a screened container set over the funnel, with a cotton pad soaked in sugar water tinted with red food coloring on top. After 18 hours, each collection tube held 45 to 55 microliters of red-tinted liquid, about one drop from an eyedropper.

Reading the genetic material left behind

Genetic material pulled from those tubes went through shotgun metagenomic sequencing, which reads nearly everything present rather than screening for one target. Computers then stitched millions of fragments back together and compared them against reference databases. Older detection methods can only find viruses researchers already suspect are there; this one can turn up organisms nobody thought to look for.

A quick barcode check on the same data found that the mosquitoes were overwhelmingly Culex pipiens, consistent with what field staff had identified by eye, though the researchers caution that database gaps can produce misleading matches in this kind of species check. Even with that caveat, getting a species read alongside pathogen screening from one sample, with no microscope work required, is part of what makes the waste attractive as a surveillance material.

A surprising mix of new and rare viruses

Some of what turned up was familiar. Marma virus has been recorded in Culex mosquitoes across Europe, Mexico and the United States, and Wuhan mosquito virus 6 is so widespread that scientists suspect it belongs to a small core set of viruses mosquitoes carry nearly everywhere.

Hedwig virus was a different story. First described in Europe from snowy owls that were also infected with West Nile virus, and named for Harry Potter’s owl, it had never been reported anywhere in the Americas. Six genetic fragments from the 2022 sample matched Hedwig and its close relative Asum virus closely enough that the authors call it the first report of Hedwig-like viruses from this hemisphere. Whether those viruses sicken birds, help West Nile along, or simply ride alongside it is unknown, and the Rutgers work does not settle the question.

“We didn’t even look for it specifically,” Price said. “We just looked for everything, and we found Hedwig in there.”

Most directly relevant to public health was the West Nile genome itself, recovered at high depth from the 2022 sample and confirmed by a separate lab test that came back positive for that sample while the 2021 sample tested negative. Small genetic differences in that sequence matched NY07, a West Nile variant identified in New York, which means the method can sometimes pin down not just the virus but the version of it circulating at a site.

“What came out was an entire viral genome,” Price said. “Rather than just positive or negative, we have genetic data.”

Several sequences matched nothing in the databases closely enough to be assigned a name. Researchers flagged a partiti-like virus, a picorna-like virus and a possible new virus associated with the single-celled parasites living inside the mosquitoes as candidates for species never described before, pending more sampling. Most viruses in the samples appear to infect insects or the microbes inside them rather than people, and a few insect-specific viruses of that kind have been shown to interfere with a mosquito’s ability to transmit West Nile, dengue or Zika.

One find matters for reasons that have nothing to do with mosquitoes at all. Biggievirus Mos11, recovered in full from both samples, encodes an unusually small gene-editing enzyme in the CRISPR family, one the paper’s authors say has already been explored for genome-editing use because its small size makes it easier to get into cells.

Mosquito poop as an early warning system

Close to 30% of emerging infectious disease events worldwide are spread by biting insects and other arthropods, and that share has been climbing. Waste screening also reached past viruses: the same droplets carried genetic matches to a broad range of trypanosomatids, single-celled parasites in the same broad family as the organisms behind sleeping sickness, with 35 distinct reference matches in the analysis. Nearly all of those hits traced back to one early-branching type that is not known to infect people, so the parasite haul says more about how much undocumented diversity waste can capture than about any new disease risk.

Scale is the caveat worth keeping in view. Two samples, 100 mosquitoes, one yard, and the insects were carried into the funnel by hand in a laboratory rather than captured by a working field trap. Because several mosquito species can share a collection point, waste alone cannot always tie a particular virus to a particular species, and small non-mosquito insects could slip past screening and muddy a sample. Finding viral genetic material in waste also cannot prove a mosquito was infected, since some of it may have simply passed through the gut.

Price’s team is now building toward a trap that collects insects and their waste together, with sequencing and analysis eventually happening on site. “The pie-in-the-sky idea is a device that we place in a forest somewhere, and it’s constantly just beaming back data to us,” he said.

Two nights of mosquito droppings from one New Jersey yard produced evidence of a virus lineage never before reported in the hemisphere, along with several viruses possibly new to science. Few broad mosquito virus surveys have ever been run in North America, which leaves open the possibility that these organisms are not rare so much as unlooked for. “The more data we generate, the more we start to wonder if everything is everywhere,” Price said. “Although we don’t yet know how much of everything is everywhere, it may be a lot more than we realize.”

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