Tick season returns with new breeds, new germs, new diseases

photoCDC Photo

Tick season is here and that means it’s time once again for people to protect themselves and their loved ones (including pets) from tick bites.

Ticks have been a problem for a long time, with nearly 60,000 cases of tickborne disease reported last year, and with new tick breeds bringing new germs and diseases to the U.S., they’re likely to continue causing problems. Though no one can predict how bad any particular season will be, reducing exposure to ticks is still the best defense against Lyme disease, Rocky Mountain spotted fever, and other tickborne infections.

The growing tick threat includes newly discovered disease-causing germs, an increasing number of reported tickborne illnesses, expanding geographic ranges for ticks, and a novel tick species now found in the U.S. New tools for preventing tickborne diseases are urgently needed, and everyone should take steps to help protect themselves from tick bites.

Protect yourself against tick bites

Taking steps to protect yourself and your family from getting a tick bite is the best defense against tickborne diseases. CDC recommends that people:

  • Avoid areas with high grass and leaf litter and walk in the center of trails when hiking.
  • Use Environmental Protection Agency (EPA)-registered insect repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone. EPA’s search tool can help you find the product that best suits your needs. Always follow product instructions.
  • Use products that contain permethrin to treat clothing and gear, such as boots, pants, socks and tents or look for clothing pre-treated with permethrin.
  • Treat dogs for ticks. Dogs are very susceptible to tick bites and to some tickborne diseases. They may also bring ticks into your home. Talk to your veterinarian about the best tick prevention products for your dog.
  • Bathe or shower as soon as possible after coming indoors to wash off and more easily find crawling ticks before they bite you.
  • Conduct a full-body tick check using a hand-held or full-length mirror to view all parts of your body upon returning from tick-infested areas. Parents should help children check thoroughly for ticks. Remove any ticks right away.
  • Put dry clothes in a dryer on high heat for 10 minutes to kill ticks after you come indoors. If the clothes are damp, dry thoroughly and then tumble dry on high for 10 more minutes.

New germs identified

Over the past two decades, seven new tickborne germs that can cause illness have been identified in the United States:  Borrelia mayonii, Borrelia miyamotoi, Ehrlichia ewingii, Ehrlichia muris eauclairensis, Heartland virus, Rickettsia parkeri, and Rickettsia species 364D.

New laboratory tests that look for DNA are finding new germs in ticks and people. CDC’s Advanced Molecular Detection (AMD) program has supported research to more broadly detect bacteria that may be causing illness in patients with suspected tickborne disease.

Reported cases have tripled

In 2017, state and local health departments reported a record number of cases of tickborne diseases to CDC. The reported numbers of cases of Lyme disease, anaplasmosis/ehrlichiosis, spotted fever rickettsiosis (including Rocky Mountain spotted fever), babesiosis, tularemia, and Powassan virus disease all increased—from a total of 48,610 reported cases in 2016 to a total of 59,349 reported cases in 2017.

Reported cases capture only a fraction of the overall number of people with tickborne illnesses. Even so, the number of reported cases of Lyme disease in the United States has tripled since the late 1990s.

Range expanding

The geographic range of some ticks that spread germs also continues to increase. One example is the lone star tick, which transmits the pathogens that cause ehrlichiosis, tularemia, and Heartland virus disease. The lone star tick continues to expand from its original territory in the southeastern United States into the northern and mid-western states.

The number of counties with the blacklegged ticks responsible for most cases of Lyme disease, babesiosis, and anaplasmosis in the United States also has more than doubled over the past twenty years.

In addition, the number of counties in the northeastern and upper midwestern United States that are considered high-risk for Lyme disease increased by more than 300% between 1993 and 2012. CDC’s tick surveillance program is tracking changes in where ticks (and germs in ticks) are found to better understand when and where people are at risk for tick bites and tickborne diseases.

Aside from causing infections, recent studies in the United States and other countries suggest that ticks may play a role in causing an allergy to mammalian meat (alpha-gal allergy). CDC is working with healthcare providers and researchers to see if tick bites can cause alpha-gal allergy.

Hungry ticks work harder to find you

Ticks are hardy little brutes that can go as long as a year without a meal.

Now scientists at the University of Cincinnati say the hungrier ticks are, the harder they try to find you or other hosts. The findings could have implications for the spread of tick-borne disease such as Lyme or Rocky Mountain Spotted Fever.

“Starved ticks are more likely to look for a host,” said Andrew Rosendale, lead author of the study and UC adjunct assistant professor of biology. “Other studies have found that starved ticks take larger blood meals. They’re attached to the host longer, which provides a greater opportunity to transmit diseases.”

The study was published in the journal Molecular Ecology.

Ticks drink blood as larvae, nymphs and adults but spend most of their lives on the ground in tall grass, patiently biding their time for a victim and presumably ignoring their rumbling stomachs.

Finding a suitable animal upon which to feed is hard, so ticks must be prepared to wait. And wait. Rosendale, who also works as assistant professor at Mount St. Joseph University, said being able to go long periods without a meal is a tick’s superpower.

Biologists in UC’s McMicken College of Arts and Sciences studied the changing gene expression and physiology of lab-raised dog ticks that were subjected to more than 36 weeks of starvation.

Studies have found that starving animals often take bigger risks, such as hunting more dangerous prey or exposing themselves to predators to forage for food. UC’s research suggests ticks are no exception.

In the wild, adult ticks explore the undergrowth and climb tall grass. They reach out with the claws on their forelegs, a behavior called questing, to snag an animal’s fur or your denim jeans. Then they burrow into their hosts with mouthparts shaped like ratchets that keep them in place.

In the lab, UC researchers stimulated the ticks’ questing behavior by breathing into identical glass cylinders. (Ticks can sense carbon dioxide so they know when a possible meal is close at hand.) Biologists recorded differences in activity between just-fed ticks and starving ones. They found that starved ticks had higher activity levels and increased questing behavior than recently fed ones.

Starved ticks also had marked changes in their physiology and gene expression.

Ticks can go so long between meals because of their slow metabolism.

“In the absence of any host cues, they go into a dormant state where they don’t move around a lot,” UC biology professor Joshua Benoit said.

This helps conserve energy for the ticks’ preferred wait-and-see ambush strategy.

But after three months without food, a tick’s metabolism actually increases significantly — by as much as 100 percent — and remains at this higher rate for weeks in association with its increased activity. In fact, some researchers collect ticks in the wild by placing dry ice in the woods to entice them with the sublimation of carbon dioxide.

Likewise, UC biologists found that genes related to immunity were activated by starvation, which could be another survival mechanism. Animals that feed on blood must have a immune system capable of fighting bacteria and other microorganisms. By activating genes associated with immunity, ticks might be preparing for an imminent meal.

More strangely, UC biologists found that genes associated with a starved tick’s salivary glands were activated. Saliva is known to help ticks drink more blood more quickly, a useful ability when you’re clinging precariously to a moving animal in thick brush. The sticky saliva also helps cement the tick to the host.

“The more they were starved, the more they were priming themselves for that next blood meal,” Rosendale said.

The study was funded by the U.S. Department of Agriculture, UC’s Faculty Development Research Grant and the National Science Foundation. UC graduate Megan Dunlevy and Marshall McCue of the metabolic measurement firm Sable Systems International contributed to the study.

New tick species

A new tick species, Haemaphysalis longicornis (the Asian longhorned tick) has been identified for the first time in the United States. In other countries, bites from longhorned ticks can make people and animals seriously ill. As of April 9, 2019, no harmful germs have been found in the ticks of this species that have been collected in the United States. Research is ongoing.

Reasons complicated

While the exact reasons for the geographic spread of ticks and the diseases they carry are unclear, a number of factors may contribute. For example, the spread of Lyme disease over the past several decades has been linked to changes in land use patterns, including reforestation in the northeastern United States. Suburban development in these areas has increased the spread of these germs because people, ticks, deer, and tick hosts such as mice and chipmunks are in close contact.

Changing climate patterns can alter the natural environment and longstanding ecological relationships. Since vector-borne diseases have strong environmental links, we expect that changes in seasonality and location may occur.  We don’t know what those changes will be, but we know that climate is only one of several very important factors that influence the distribution and occurrence of vector-borne diseases.

Predicting the number of Lyme disease or other tickborne infections, including how an upcoming season will compare with previous years, is complicated. Ticks that spread germs to people can have up to 2- to 3-year lifecycles, and many factors can affect their numbers, including temperature, rainfall, humidity, and the availability of hosts for the ticks to feed on, such as mice, deer and other animals. In any given year, the number of ticks in an area will be different from region to region, state to state, and even county to county.

Numbers of reported tickborne disease cases are also affected by healthcare provider awareness and by testing and reporting practices.

Know about risks in your area

We cannot easily forecast how severe each tick season will be. However, we do know that every year hundreds of thousands of people are bitten by ticks and get sick. Therefore, people should be aware that ticks could be in the areas where they live, work and play. Everyone should take steps to help protect themselves and their loved ones, including pets.

While not all ticks spread the same germs, ticks can be found in every state. However, in the continental United States, some diseases occur more frequently in some areas than others:

  • Reported cases of Lyme disease, anaplasmosis, babesiosis, and Powassan virus disease are concentrated in the Northeast, mid-Atlantic, and upper Midwest, with pockets of lower risk along the West Coast. The range of the tick that transmits Lyme disease also is expanding.
  • Other serious tickborne diseases include Rocky Mountain spotted fever, ehrlichiosis, and Rickettsia parkeri rickettsiosis. More than 60 percent of spotted fever rickettsiosis cases (including RMSF) occur in five states: Arkansas, Missouri, North Carolina, Oklahoma, and Tennessee.

Red meat allergy spreading, ticks blamed

The news about tick-caused red meat allergy just keeps getting worse. Last July (2018), a study found that those with the allergy also have a higher risk of heart disease. Then in September, another study said chiggers could also cause the allergy. And now, new research finds that many more ticks may be capable of causing the allergy than had been previously thought.

Until now it has been believed that in order for a tick to trigger the red meat allergy in humans, the tick would need to have recently fed on the blood of a mammal. But new research from the UNC School of Medicine presented at the American Academy of Allergy, Asthma and Immunology (AAAAI) annual conference in San Francisco shows that may not be so.

The substance responsible for all the trouble is alpha-gal, a sugar found in most mammal blood, except humans. When humans develop an allergic immune response to it, this response can lead to the red meat allergy called alpha-gal syndrome (AGS).

“Our original hypothesis was that humans developed the allergy after being exposed to alpha-gal through a tick that had fed on a deer, dog or other small mammal that has alpha-gal,” said Dr. Scott Commins, associate professor of medicine and pediatrics at UNC School of Medicine. “This new data suggests that ticks can induce this immune response without requiring the mammal blood meal, which likely means the risk of each bite potentially leading to the allergy is higher than we anticipated.”

To be avoided

This makes it more important than ever for humans to steer clear of ticks and chiggers whenever possible, since the number of the little devils capable of causing the problem may be many times greater than scientists had believed.

There is no treatment for AGS, other than avoiding foods and products that cause a reaction — most notably red meat, pork and any other food derived from a mammal, which by the way includes gelatin. Many of those who contract the allergy also suffer cardiac arrhythmia, an irregular heart beat that must sometimes be treated with ablation.

The allergy is not to be taken lightly. The reaction to mammal meat in those affected ranges from mild to life-threatening. Some of those who have previously had mild reactions find themselves in the intensive care unit when they have an unexpectedly severe response.

How they found it

To reach their findings, UNC researchers stripped white blood cells of their Immunoglobulin E (IgE), antibodies produced by the immune system during an allergic reaction. The stripped white blood cells were then primed with plasma from individuals with AGS and without AGS. Then, researchers added to the cells tick salivary gland extract from four species of ticks — Lone Star, Deer, Gulf Coast and American Dog. Some of the ticks had recently fed on blood containing alpha-gal, and some had not.

As researchers expected, saliva from the Lone Star and Deer ticks that recently fed on blood caused a reaction. However, saliva from those same types of tick that had not recently fed on blood also caused a reaction. Saliva from a Lone Star tick that had not recently fed caused reactivity 40 times higher compared to the control. Neither type of saliva from the Gulf Coast nor the American Dog ticks caused a reaction.

Because samples of both blood-fed and non-blood-fed tick saliva in these experiments exhibited a range of reactivity, Commins says, “These results suggest that more tick bites than we initially suspected could pose a risk for developing red meat allergy.”

May raise heart attack risk

You would think that one consolation of becoming allergic to red meat would be improved heart health. No such luck. A new study by the University of Virginia finds a possible link between an allergy to red meat and coronary artery disease.

“This novel finding from a small group of subjects from Virginia raises the intriguing possibility that allergy to red meat may be an under-recognized factor in heart disease,” study leader Coleen McNamara, MD, a professor of medicine at the UVA Cardiovascular Research Center, said in a statement. “These preliminary findings underscore the need for further clinical studies in larger populations from diverse geographic regions and additional laboratory work.”

The findings are of particular interest in the Southeast and Eastern U.S., where the lone star tick, whose bite can sensitize people to the red meat allergen, is most prevalent.

Funded by the National Heart, Lung, and Blood Institute (NHLBI), the Virginia scientists studied 118 patients who underwent intravascular ultrasound along with cardiac catheterization. They analyzed blood samples to screen for antibodies to alpha-Gal (galactose-α-1,3-galactose), a complex sugar that is the main allergen in red meat.

Alpha-Gal antibodies were found in blood samples from 26% of participants, and they had 30% more plaque buildup in their coronary arteries than those who weren’t sensitive to the allergen.

The association was most pronounced in those 65 years of age or younger and remained statistically significant after adjusting for possible confounders, such as diabetes, hypertension, and statin use. In addition, plaques in the arteries of participants sensitive to alpha-Gal tended to be less structurally stable, potentially increasing heart attack or stroke risk.

Scientists have long suspected that allergens can trigger immunological changes associated with plaque buildup, but this study is the first to identify a specific allergen, according to the NHLBI.

About Alpha-gal allergy

Researchers estimate that 1% of individuals in some regions might have a red meat allergy, although as many as 20% might develop alpha-Gal antibodies without allergy symptoms.

The Alpha-gal allergy, as it is formally known, causes a delayed reaction, occurring three to eight hours after eating mammalian meat products — beef, pork, bacon, veal, and other mammals, including apes and, of course, other humans. The reaction includes severe whole-body itching, swelling of the facial and mucous membranes, gastrointestinal upset and even anaphylaxis.

Those afflicted with the allergy don’t have to become vegetarians, as they are still able to eat fish and poultry.

There is some evidence that the allergy may recede over time although it’s reported that some patients have observed symptoms for 20 years or more.

The allergy to alpha-gal was first reported in 2009 by UVA researcher Dr. Thomas Platts-Mills, and his colleague Dr. Scott Commins. Since then, there have been increasing numbers of cases of the meat allergy reported across the U.S., especially as the lone star tick’s territory grows. Previously found predominantly in the Southeast, the tick has now spread west and north, all the way into Canada.

UVA’s new study suggests that doctors could develop a blood test to benefit people sensitive to the allergen. “This work raises the possibility that in the future a blood test could help predict individuals, even those without symptoms of red meat allergy, who might benefit from avoiding red meat. However, at the moment, red meat avoidance is only indicated for those with allergic symptoms,” said researcher Dr. Jeff Wilson of UVA’s allergy division.

The latest study was published in Arteriosclerosis, Thrombosis and Vascular Biology, a journal of the American Heart Association.

Chiggers implicated in red-meat allergy

Chigger bites have long been known to cause red, itchy rashes around the ankles and waistline but now researchers say they may also cause an allergic reaction to red meat. The allergy, known as alpha-gal, has previously been linked to tick bites. It’s relatively rare but seems to be increasing and can cause serious, even fatal, reactions.

“If a patient comes in telling me they ate red meat for dinner and then hours later woke up with anaphylaxis, I suspect an alpha-gal allergy,” said researcher Russell Scott Traister, M.D., Ph.D., assistant professor of pulmonary, critical care, allergy and immunologic diseases at Wake Forest Baptist Medical Center.

“With those symptoms, doctors usually ask if the person has had a tick bite recently. But we started seeing patients with the same symptoms who said they hadn’t had a tick bite, only chigger bites,” Traister said in a news release.

The medical community has known for the past five to 10 years that ticks can cause this allergy, but the studies from Wake Forest Baptist and the University of Virginia are the first to suggest that chigger bites may also may be responsible. The paper is published in the current issue of The Journal of Allergy and Clinical Immunology: In Practice.

Allergy process

The alpha-gal allergy is a reaction to a carbohydrate molecule on mammalian meat — beef, pork, venison, etc. However, unlike most allergic reactions that happen within minutes, a reaction to alpha-gal occurs after three to six hours. The only cure is to avoid all mammalian meat, Traister said.

In addition to case studies seen at Wake Forest Baptist, Traister cited results reported by U.Va. from 311 patients who had answered a questionnaire about exposure to tick or chigger bites before developing an alpha-gal allergy. Of the 301 who reported either tick or chigger bites in the past 10 years, 5.5 percent reported a history of chigger bites, but no tick exposure.

Further studies are needed to determine if the alpha-gal molecule is in the gastrointestinal tracts of chiggers to confirm that they, as well as ticks, can cause mammalian meat allergy.

“In the meantime, we want allergists to be aware that patients may report chigger bites, and based on that fact alone should not dismiss alpha-gal sensitization as a possible diagnosis,” Traister said.

Ticks, worms and brain diseases

Microscopic worms carrying the bacteria that causes Lyme disease, a disease transmitted by ticks, have been found inside the brain tissues of patients who were diagnosed with other, serious neurological problems.  That discovery, by researcher Alan B. MacDonald, MD, has added evidence to his belief that there may be a link between Borrelia bacteria and neurological diseases such as Multiple Sclerosis and Alzheimer’s Disease.

worm with borrelia

Borrelia endosymbionts inside nematode worms in MS CSF Photo: Alan B. MacDonald, MD

“Both the worms and the Borrelia pathogens can cause devastating brain damage,” says Dr. MacDonald. “While patients are wrongly declared free of Lyme and other tick-borne infections, in reality, too often they contract serious neurodegenerative diseases which can kill them.”  Dr. MacDonald thinks that these infections frequently go undiagnosed and untreated because current tests don’t adequately detect the presence of the Borrelia bacteria

Autopsies, reviewed during Dr. MacDonald’s research, revealed Borrelia inside parasitic nematode worms (more commonly called round worms), eggs or larvae in the brain tissue of nineteen patients.  Ten of the patients had MS, five died from the highly malignant brain tumor Glioblastoma multiforme, the cancer that took the life of Sen. Edward Kennedy and four died from Lewy Body dementia, which afflicted comedian Robin Williams.

Dr. MacDonald identified the infected worms using a technique known as FISH, Fluorescent In Situ Hybridization, which involves using molecular beacon DNA probes. FISH identifies pieces of Borrelia’s genetic material which glow under the microscope when there is a 100% DNA match.

Dr. MacDonald, a fellow of the Academy of American Pathologists, conducts his research through the Dr. Paul Duray Research Fellowship Endowment Inc. Dr. MacDonald’s full May, 2016 presentation, to a forum to explore the scientific, economic, and policy challenges posed by the epidemic of Lyme disease and associated tick-borne illnesses, can be seen here: https://vimeo.com/166688480.

Self-cloning Asian longhorned ticks invade New York

Staten Island residents have another reason to apply insect repellent and obsessively check for ticks this spring and summer: the population of a new, potentially dangerous invasive pest known as the Asian longhorned tick has grown dramatically across the borough, according to Columbia University researchers. And the tick–which unlike other local species can clone itself in large numbers–is likely to continue its conquest in the months ahead.

“The concern with this tick is that it could transmit human pathogens and make people sick,” explains researcher Maria Diuk-Wasser, an associate professor in the Columbia University Department of Ecology, Evolution and Environmental Biology, who studies ticks and human disease risk.

In a new study appearing in the April issue of the journal Emerging Infectious Diseases, Diuk-Wasser and colleagues provide the most exhaustive local census of the new species to date–and suggest the Staten Island infestation is far more advanced than previously known.

1,698% increase

The researchers found the species Haemaphysalis longicornis in 7 of 13 parks surveyed in 2017 and in 16 of 32 in 2018. In one park, the density of the ticks per 1000 square meters rose almost 1,698 percent between 2017 and 2018, with the number of ticks picked up in the sample area rising from 85 to 1,529. They also found the ticks on anesthetized deer from the area.

The news comes less than a year after the New York City Department of Health announced the discovery of the first member of the species in the city–a single tick–found on southern Staten Island last August.

The tick, native to Asia and Australia, had been identified in the months prior to the Staten Island sighting in New Jersey, West Virginia, North Carolina and Arkansas and just a few weeks earlier in Westchester County. The Westchester sighting prompted a number of state senators to send a letter urging state health officials to act aggressively to stop the spread of the new species.

Public health officials are particularly concerned because the longhorned tick is notorious for its ability to quickly replicate itself. Unlike deer ticks, the common local variety known for carrying Lyme disease, the female Asian longhorned can copy itself through asexual reproduction in certain environmental conditions, or reproduce sexually, laying 1,000-2,000 eggs at a time. They are typically found in grass in addition to the forested habitats that deer ticks prefer, adding a new complication to public health messaging. The Columbia analysis suggests that the public warnings may have come too late.

“The fact that longhorned tick populations are so high in southern Staten Island will make control of this species extremely difficult,” says Meredith VanAcker, a member of Diuk-Wasser’s lab who collected the data as part of her Ph.D. thesis. “And because females don’t need to find male mates for reproduction, it is easier for the population to spread.”

Threat to human health

The threat these new arrivals pose to human health is still unknown. In Asia, there have been reports of ticks passing on a virus that can cause a number of diseases, including hemorrhagic fever and ehrlichiosis, a bacterial illness that can cause flu-like symptoms and lead to serious complications if not treated.

The arrival of the species on Staten Island adds another unwelcome dimension to the region’s tick woes, which have grown dramatically in recent years. Thanks to an expanding deer population, Lyme disease spread through deer ticks has reached epidemic proportions in some areas of the Northeast. Deer ticks (also called black-legged ticks) are capable of disseminating six other human pathogens.

The first Asian long-horned tick in the U.S. was identified in New Jersey in 2013. A large population was later found on sheep in Mercer County, New Jersey. Diuk-Wasser became aware of the potential danger when a doctor at a Westchester clinic removed a tick from a patient and sent it in for identification. The discovery of the first human bite prompted widespread alarm.

By then, the Columbia team was already in the midst of an extensive “tick census” on Staten Island to determine how the landscape connectivity between urban parks influenced the spread of disease.

The Asian longhorned is easy to miss because it resembles a rare native species of rabbit tick. VanAcker spent months combing areas of Staten Island for ticks, dragging a square-meter corduroy cloth over leaf litter and examining it every 10 to 20 meters Diuk-Wasser, post-doctoral student Danielle Tufts and other members of the Diuk-Wasser lab found huge numbers of them on the bodies of unconscious deer that had been captured and anesthetized by wildlife authorities.

VanAcker found her collections were overflowing with the new species, leading to publication of the current study in Emerging Infectious Diseases. Her work on landscape connectivity, slated to appear in the June issue of the same journal, drives home the difficult decisions facing policymakers as they attempt to arrest the spread of the new species and others like it.

“The easier it is for deer to maneuver through urban landscapes between parks, the more likely the ticks are to spread to new areas,” Diuk-Wasser says. “This suggests that the emphasis on urban wildlife corridors has a previously unappreciated downside for human health.”

Rocky Mountain Spotted Fever is deadly

In Mexicali, Mexico, an uncontrolled epidemic of Rocky Mountain spotted fever, one of the deadliest tickborne diseases in the Americas, has affected more than 1,000 people since 2008.

A binational team of researchers led by the University of California, Davis, has conducted the first comprehensive study to examine risk factors for the disease in Mexicali. Researchers examined dogs, ticks, and surveyed households in 200 neighborhoods. Half of the neighborhoods in the study had diagnosed human cases of the disease. They discovered that, even though citywide only one in 1,000 ticks was infected, there were neighborhoods at very high risk, where almost one in 10 ticks were infected.

“If you live in one of these high-risk neighborhoods and you get five brown dog tick bites, that means you have a pretty good chance of being exposed to Rocky Mountain spotted fever,” said lead author Janet Foley, with the Department of Medicine and Epidemiology at the UC Davis School of Veterinary Medicine.

Rocky Mountain spotted fever is spread by the brown dog tick, which feeds on dogs and people, and thrives in hot, arid climates. Previous studies have shown that poverty, numerous stray dogs and brown dog ticks increased the risk of getting Rocky Mountain spotted fever. In Mexicali, risks were higher along the edges of poorer neighborhoods or outside of the city in rural areas.

Half of the 284 dogs the researchers examined were infested with ticks. Some dogs carried thousands of ticks.

“Almost three-quarters of the dogs we tested had been infected with the agent of Rocky Mountain spotted fever at some point in their life,” said Foley. “That’s astronomical.”

A deadly disease

People with Rocky Mountain spotted fever typically develop symptoms one to two weeks after being bitten by an infected tick. They can develop fever, nausea, headache and muscle pain. As the bacteria infect blood vessel linings, blood begins to pool under the skin, resulting in a rash that can look like red splotches or spots. The longer people wait before seeing a doctor and starting treatment with antibiotics, the greater chance they may die.

The study, published in the American Journal of Tropical Medicine and Hygiene, also gauged people’s knowledge about Rocky Mountain spotted fever. It found 80 percent of residents had heard of the disease, but fewer than half used pesticides to prevent bites.

Ticks could spread north with climate change

Foley said a Rocky Mountain spotted fever epidemic on the scale of that in Mexicali is not as likely in the United States as long as dog ticks are well managed. But as temperatures warm with climate change, there are concerns that the particular human-feeding brown dog tick strain will continue to move north, resulting in more human cases. Some studies have suggested the hotter it gets, the more active and aggressive the ticks become.


Other authors include Emily Pascoe of UC Davis. The binational team included academic researchers, health workers, epidemiologists, veterinarians, agency officials, medical doctors and

New coalition forms to fight ticks

Annapolis, MD; May 20, 2019–As the incidence of diseases transmitted by ticks and mosquitoes in the U.S. continues to rise, a coordinated and strategic response is needed now more than ever–and a diverse set of organizations are aligning to answer the call.

Under the stewardship of the Entomological Society of America, 18 scientific and medical societies, professional associations, and advocacy groups have formed the Vector-Borne Disease Network, a new coalition that will stand ready to advise and support federal policymakers in confronting the challenge of diseases spread by insects and related arthropods.

These illnesses–such as Lyme disease, Zika, or West Nile virus–are transmitted by vector organisms, primarily blood-feeding insects or arthropods. Vectors ingest disease-causing germs when biting an infected human or animal and later inject them into a new host during a subsequent bite.

Between 2004 and 2016, reported human disease cases in the U.S. resulting from bites from arthropods–primarily ticks and mosquitoes–tripled, according to the U.S. Centers for Disease Control and Prevention (CDC). Meanwhile, nine new germs spread by ticks and mosquitoes were discovered or introduced in that same timeframe. (See CDC Vital Signs, May 2018.) Disease vectors pose significant threats to livestock and companion animals, as well. The underlying causes for these trends are varying and complex, and so are the potential solutions. Thus, the Vector-Borne Disease Network will gather the expertise and perspectives of a variety of stakeholders invested in the mission to reduce the public-health and economic risks posed by ticks and mosquitoes.

The founding members of the Vector-Borne Disease Network are:

  • American Mosquito Control Association
  • American Society of Tropical Medicine and Hygiene
  • Association of Public Health Laboratories
  • Association of State and Territorial Health Officials
  • Council of State and Territorial Epidemiologists
  • Entomological Society of America
  • Georgia Mosquito Control Association
  • Midwest Center of Excellence for Vector-Borne Disease
  • National Association of County and City Health Officials
  • National Association of Vector-Borne Control Officials
  • National Environmental Health Association
  • National Pest Management Association
  • Northeast Regional Center for Excellence in Vector-Borne Diseases
  • Pacific Southwest Center of Excellence in Vector-Borne Diseases
  • Puerto Rico Vector Control Unit
  • Society for Vector Ecology
  • Southeastern Regional Center of Excellence in Vector-Borne Diseases
  • Western Gulf Center of Excellence for Vector-Borne Diseases

“Our country can no longer afford to be complacent toward the dangers posed by mosquito- and tick-borne disease,” says Robert K. D. Peterson, Ph.D., president of the Entomological Society of America (ESA) and professor of entomology at Montana State University. “From researchers and public-health officials to policymakers and vector-management professionals, it’s time to roll up our sleeves and tackle this problem together.”

The Vector-Borne Disease Network’s ultimate goal is to reduce human and animal suffering caused by arthropod disease vectors, and its primary focus will be to collectively advocate for strong, dedicated funding at the federal level for:

1. research on tick and mosquito biology, ecology, and disease-transmission risk

2. enhanced tick and mosquito detection and disease diagnosis

3. innovation in disease-prevention and vector-control methods

4. building the nation’s workforce and technical capacity in vector-borne disease research, response, and management.

Stakeholder groups in the Vector-Borne Disease Network are conducting preliminary discussions in 2019 with plans for a coordinated launch of the group’s efforts in late 2019 or early 2020. Additional organizations and nonprofits with related missions are invited to participate. To express interest, contact ESA Director of Strategic Initiatives Chris Stelzig at cstelzig@entsoc.org.


About the Author

Truman Lewis
Truman has been a bureau chief and correspondent in D.C., Los Angeles, Phoenix and elsewhere, reporting for radio, television, print and news services, for more than 30 years. Most recently, he has reported extensively on health and consumer issues for ConsumerAffairs.com and FairfaxNews.com.