Tick ​​Discovery points out how few answers we have about these bugs in the United States

Last August, Tadhgh Rainey, division manager at the Hunterdon County Division of Public Health Services in Flemington, NJ, received an odd phone call. An assistant in a nearby building enthusiastically explained that a woman had entered their office covered with tiny ticks – much more than what they had seen on a person. "She's really scared – and now we're a little scared, and her pants are in our freezer," said the assistant.

The woman, a local farmer, had shorn her sheep when she realized that she was covered with black spots and crawling and reserved them for the health department. She had spare clothes in her car and gave the health office staff her spotted trousers; they threw them into the laboratory freezer to kill the ticks. Later in the day, Rainey went to his colleague's building, where the staff took the pants off the freezer and shook the sticky ticks in a saucepan. They saved about a thousand – although the ticks were dead, Rainey wanted to keep them for further tests. "I looked at them, I thought to myself," Well, that's a lot of ticks, "recalls Rainey." It was almost exhilarating – at the point where you want to blow up the building, though. "

The ticks collected were larvae, the youngest step in their two-year life cycle, which are too small for humans to see in the smallest detail. Yet, for Rainey, they did not look like common blacklegged ticks in New Jersey, because they do not travel by the thousands and usually do not feed on sheep. Rainey reached out to colleagues but they had no idea what kind of ticks they were. A month and a half later, Rainey met his acquaintance Andrea Egizi, a biologist with the Center for Vector Biology at Rutgers University, at a conference that proposed sequencing ticks DNA. He came back as a perfect match for Haemaphysalis longicornis, a tick species Egizi had never heard of. "The first thing I did was go to Google," she says. "The more I read about it, the more I realized: It could be great." She had confirmed that a species of invasive exotic tick had found its way to the United States, apparently for the very first time.

About 90 species of ticks call the home of the United States but H. longicorniscalled the long-horned tick-the Latin longicornus translates to "long-corned" -n't ever been one of them. It is usually found in East Asia, Australia and New Zealand where it primarily injures livestock by causing considerable blood loss and limiting milk production. The species is not known to transmit Lyme disease. No one seems to know how the longhorn tick found in New Jersey: Neither the farmer nor any of his sheep have ever traveled to these places. Other than Hunterdon County, H. longicornis has also been spotted in three other counties in New Jersey as well as in West Virginia, Virginia, and Arkansas.

We do not know how much we should be worried about the fact that these migrant ticks are now calling the home of the United States. There is no evidence that they have bit humans or harbor diseases, but "pathogens can adapt to new vectors," Egizi says. It is therefore possible that ticks begin to transmit and transmit tick-borne endemic diseases. In Asia, this tick is also known to transmit life-threatening viruses, including those that cause Japanese purple fever and severe fever with thrombocytopenia-conditions that can cause fever, vomiting, and multiorgan failure.

The history of Rainey's long-horned ticks is a "fortuitous discovery of an exotic and dangerous tick that apparently landed here and spread about years ago but that did not not discovered until a few poor sheep have been coated, "says Richard Ostfeld, ecologist at the Cary Institute of Ecosystem Studies, who was not involved in the case of the discovery of ticks with long horns. Among other things, the story highlights the country's dire need to monitor ticks more and more. Scientists also know very little about interventions that actually reduce the risk of tick-borne diseases, and many have not received the funding to fill these gaps. But the discovery of longhorn ticks and other tick-related concerns inspires a necessary boost in the interest and funding of tick research.

Many US states have active mosquito surveillance programs – and have them for a long time. In fact, the US Centers for Disease Control and Prevention were established in 1942 to prevent the spread of malaria. And in 2016, in response to the Zika threat, the CDC launched MosquitoNET, a program in which state or local government employees use traps to capture mosquitoes and then report the location and the species of those that they identify. The CDC provides these entities with recommendations on where, when and how to use traps, and how often to check them; second, it uses their data to regularly update mosquito distribution maps and guide additional monitoring and control efforts. But "at the present time, there is not a single coordinated and coordinated effort for tick surveillance," says Ben Beard, chief of the CDC's Bacterial Diseases Branch in the Division of Diseases at vector transmission.

That's not to say that there is no data at all – it's just that the information is incredibly limited. For example, the CDC online tick distribution map for blacklegged ticks, the only vector of Lyme disease, is based primarily on data from a 2016 study. CDC researchers examined published studies and investigated US counties to determine whether health department employees or other local ticks had identified at least six blacklegged ticks or at least two of three blacklegged ticks. ;last year. If so, the authors categorized the ticks as being "established" there; if at least one tick but fewer than six had been seen this year, they were classified as "declared". The map they created based on these data suggests that blacklegged ticks are present in nearly half of the United States. They also found that these ticks have spread and spread since the last surveillance study conducted in 1998. Yet, the study only provides an overview of the presence of ticks and provides no information on the number ticks, evolution of populations or life stages are the most common (which is important because it is the tick nymphs, and not the larvae or adults, who are the main culprits of the transmission of the disease to humans). Other ticks, such as solitary ticks, also carry diseases, including Rocky Mountain spotted fever, ehrlichiosis and tularemia; Yet we know even less about where these ticks are or how their populations are changing.

The lack of information on where ticks are and their activities is worrying, as the burden of tick-borne diseases in the United States is so high, much higher than for diseases transmitted by mosquitoes. Only 2,149 Americans in 2016 are reported to have been infected with West Nile virus, which the CDC calls the country's "major mosquito-borne disease". (In case of epidemic, however, the number of cases has reached nearly 10,000). Yet, it is estimated that at least 300,000 Americans contract Lyme disease every year, which is contracted only by tick bites.

While mosquito-borne diseases are a growing threat, in part because of climate change, tick-borne diseases are also increasing in the United States for a variety of reasons, including land use and climate change. . According to a May 2011 CDC report, the incidence of tick-borne diseases in the United States more than doubled between 2004 and 2016 and, in some states, the increase was more worrisome. In Maine for example, from 2006 to 2016, the incidence of Lyme disease quadrupled. Although most tick-borne diseases among Americans are believed to be acquired in Canada, many mosquito-borne diseases, including over 90% of Zika, dengue and chikungunya cases, are actually acquired outside the United States.

Knowing where ticks are is only part of the puzzle of tick-borne diseases, but researchers also do not understand many other ecological aspects. In fact, tick researchers disagree on a number of crucial aspects of the ecology of ticks and ticks, including animal hosts – deer or small mammals, including mice and chipmunks – which are the most important for the spread of Lyme disease.

There is another big difference between the US thinking about tick containment and mosquito confinement: state and county governments often intervene to control mosquito populations, but leave tick populations alone. "Local municipalities often have mosquito control districts funded by some sort of taxpayer base," says Beard. "But what's really interesting is that if you have a problem with ticks in your garden, it's usually you who are talking about it. This is not a public problem; This is a burden that weighs on the shoulders of the owners. "

And no clear solution exists for these owners. The CDC recommends that people who face ticks take a number of preventative measures such as using insect repellents and showering after being outside. "We have very little data to support the fact that these interventions actually reduce the human disease," says Beard. Some studies have shown that such interventions can reduce the number of ticks or ticks, but it is unclear if they keep people in better health. . In a double-blind trial published in July 2016, for example, researchers from the CDC and other institutions treated orchards in tick-infested areas with insecticides while treating others with a placebo . Over the next two years, compared to untreated tillers, treated ticks had 63% fewer ticks in the pupa stage – yet, families living in treated homes are no less likely to have the disease. Lyme nor bitten by fewer ticks. because people tend to be bitten by ticks when they are out of their property. "There are a lot of things that kill ticks," says Ostfeld, but "none of them have shown that it did it well enough and in the right places to reduce the number of ticks." 39, incidence of tick-borne diseases.

According to experts, finding such answers would require more financial support. A search of online reporting tools from the National Institutes of Health's research portfolio shows that there are 412 NIH-funded research projects that can be found using the word "mosquito", but only 133 that can be found on "tick". It has also awarded only $ 23 million for Lyme disease research in 2018, but it has almost doubled the research on West Nile virus. Part of this problem could be historical: mosquito-borne diseases have been threatening the United States for centuries, while tick-borne diseases have been considered a threat for only a few decades; The first case of Lyme disease was diagnosed in 1975. Research on Lyme disease tends to be biased towards clinical aspects, such as diagnosis, therapy and pathogenesis, notes Durland Fish, entomologist and professor emeritus at Yale School of Public Health. "It's all about people, not the environment where diseases are contracted," he says.

However, we have reason to feel optimistic. Beard says the CDC is creating a national tick surveillance program, which could be launched in the year; they are still working on the details of how, exactly, it will work. The Ministry of Defense and some private donors have also started to fund research on tick-borne diseases. With a $ 5 million grant from the Steven and Alexandra Cohen Foundation as well as additional funding from the CDC and other sources, Ostfeld and colleagues at Bard College are conducting a randomized controlled trial in the United States. Dutchess County, in the state of New York. has one of the highest rates of Lyme disease in the country – to evaluate the effectiveness of two methods of fighting ticks compared to placebos when they are applied over a four-year period . An intervention consists of checkboxes that are placed outside and attract the hosts of small mammals, such as the mice that feed the young ticks. When the animals enter, they are watered with a small dose of a chemical killing ticks. The other intervention is a mushroom-based natural aerosol, known as Met52, which also kills ticks. The study will evaluate how well these methods, used together or separately, reduce the risk of Lyme disease when they are deployed at the neighborhood scale.

Longhorn ticks are a worrisome reminder of what we still have to learn about these blood-sucking parasites – despite efforts to eradicate them in New Jersey, they have survived very well in the winter. "There is a lot of very important and useful research that has been done – it's not like there were a lot of idlers who did not do anything. It's just that, in my opinion, this is not enough, "says Ostfeld.The invasive and exotic ticks suddenly appear and scientists have no idea where they come from or what to do about them? "The depth of understanding," he says, "leaves something to be desired."