Tick fever threatens to spread to U.S. from Mexico

A new kind of tick is causing an epidemic of Rocky Mountain spotted fever in Mexico, and it's threatening to spread to the U.S., researchers said Wednesday.

Rocky Mountain spotted fever is already dangerous, and the new carrier is more likely to bite people than the ticks that usually spread it, the team of U.S. and Mexican researchers said.

As ticks in general become more common as the climate warms, they're a bigger threat, they added.

"Rocky Mountain spotted fever, caused by the bacteria Rickettsia rickettsii, is responsible for more human deaths than any other tick-borne disease in North America," the team wrote in the journal Emerging Infectious Diseases.

Rocky Mountain spotted fever was reported in 4,269 people in the U.S. in 2016, according to the Centers for Disease Control and Prevention. It can kill up to 10 percent of victims, depending on the outbreak.

It's usually spread by the American dog tick and the closely related Rocky Mountain wood tick. But in recent years the bacterial infection has also been spread by the brown dog tick — a completely different species.

How to avoid tick bites
See Gallery
How to avoid tick bites

1. Stay in the middle of the path

When hiking, make sure to stay in the middle of the path. Weeds, grass and trees make it easier for ticks to crawl onto you. Don't venture out to the grass or bushes, where ticks are formidable to be hiding. 

2. Wear long pants and closed toed shoes

Protect your skin. Adding an extra layer makes it more difficult to latch on to you. It's smart to wear pants, long sleeves and hats, especially in the summer.

3. Invest in deer-resistant plants. 

Since ticks feed on and are transported by deer, try looking into deer-resistant plants. French marigolds, rosemary, mint and crape myrtle are just some of the greens deer tend to "overlook". 

See a complete list of the herbs and flowers here

4. Check your dog! 

Dogs can literally bring ticks right to your front door. Prevent ticks by keeping their coats short in the summer. Use your hands to check the fur, stopping if you feel a pea-sized bump. Favorite spots ticks like to hide include the ears, toes and under the tail. 

Dog ticks don't "harbor diseases that sicken people", but you should still be wary. 

5. Yes, repellant can help. 

According to TickenEncounter, spray with DEET does not provide "sufficient" protection. Get spray for your clothes like Permethrin, which instantly kills ticks. 

6. Dry your clothes 

The CDC recommends tumble drying clothes immediately for ten minutes after you've been outside. Ticks can easily "dry out" with high heat, but you should make sure the clothes are completely dry. 

Warning: Ticks can survive the wash. 

7. Tuck your pants into your socks.

This covers the small, easily accessible space in between your pants and ankles. Especially if you are sitting, it makes it easier for ticks to latch on. 

8. Stay in the sun.

Since ticks survive in shady, humid environments, researchers agree that staying in the sun lowers the risk for ticks. According to LiveScience, ticks "can't survive" in places with lower than 80% humidity. 

9. Invest in Permethrin socks

The chemical is successful in protecting against ticks, mosquitoes and other types of bites. Lymedisease.org estimates that permethrin-treated footwear offered 74 times the protection from bites.

10. Mow your lawn

Cut your grass, clean your yard, get rid of any extra firewood or wood chips. 


The researchers were investigating an epidemic of the infection that broke out in the border town of Mexicali starting in 2008. It's already sickened at least 4,000 people, according to Mexican government estimates. Several hundred have died, and at least four people have died in the U.S. after crossing the border, according to this report and others.

"That's a very big epidemic of a fatal disease," said Dr. Janet Foley, an expert in the spread of animal-borne disease at the University of California Davis School of Veterinary Medicine. "There are likely thousands of cases."

The infection is not always easy to diagnose in human blood. If people get a rash and other symptoms of Rocky Mountain spotted fever, the advice is to treat quickly with the antibiotic doxycycline. Other symptoms are similar to those caused by many infections and include fever, nausea and headache.

Working with a team at the Universidad Autónoma de Baja California in Mexicali, Foley and colleagues tested the blood of 16 patients to see if they could find a characteristic signature of the infection.

"I was absolutely startled," Foley said in an interview. The people who had been sickened in Mexicali had a heavy load of the infectious agent in their blood — something that had not been seen in past outbreaks.

Ticks that commonly bite humans.

The epidemic is worrisome because the brown dog tick is more likely to bite people and it adapts easily to living in a house, as opposed to living on wild animals, the researchers said.

"The Rocky Mountain spotted fever epidemic in Mexicali has not been contained and may be spreading to other parts of Baja California and into the United States," the team wrote.

And now it's possible that for some reason, the infection the brown dog tick transmits is more virulent, Foley said.

"We need to study this tick more to understand why it makes people so sick," she said. "This Mexican strain seems more willing to feed on people."

It's a big problem in a poor, crowded city like Mexicali, where many people and many dogs live. Foley said she visited neighborhoods there where dogs were infected with hundreds or even thousands of the ticks.

"It's pretty bad," she said. She described one dog that was homeless but being fed by the community.

"This dog had ticks everywhere. Every millimeter of ear tissue was covered with ticks. They were down her back," Foley said.

12 tick mistakes that are putting your health in danger
See Gallery
12 tick mistakes that are putting your health in danger

Using nail polish

Grandma may have had good intentions when she told you to coat an embedded tick with nail polish. Grandma should have saved her nail polish advice for stopping pantyhose runs (which totally works). The polish may suffocate the bug eventually, but by that time, you may already have been infected with a disease. You need to remove it right away, and according to the CDC, good tweezers are the safest and fastest way. Grab the tick as close to the skin as you can possibly get and pull. A slow and steady hand is best: Take your time to avoid jerking as you don’t want any of the tick’s mouth parts left behind.


Bug burning

Another old wive’s tale that has been totally debunked is that holding a match near the tick will cause it to let go. Wrong again. All this will do is possibly give you a burn and panic the tick so that it regurgitates and increases the risk of infection, reports the New York Times. Check out this video to learn exactly how to remove a tick.


Mowing the lawn

Keeping a well-manicured lawn will help keep ticks at bay; they prefer longer grass. But while a well-tended yard may reduce ticks, it won’t eliminate them. In fact, the Connecticut Agricultural Experiment Station Tick Management Handbook sites a computer simulation demonstrating that landscape management alone resulted in the “prevention of only a moderate number of Lyme disease cases in comparison.” You only need one tick bite to get infected. Don’t stop mowing, but be sure to take other precautions, too. Here are more tick-borne diseases you need to watch out for this summer.


Avoiding DEET

This very effective bug repellent suffers from a perception problem, according to the Los Angeles Times. Its bad rep persists despite many studies and both the CDC and EPA saying it is perfectly safe to use. “In the more than 45 years that DEET has been used in the U.S., reports of adverse effects in humans associated with the dermal application of DEET have been relatively rare, given the billions of applications of the repellent,” says the Agency for Toxic Substances and Disease Registry, part of the U.S. Department of Health and Human Services. Still leery? Look for lower-concentration sprays—30 percent-strength DEET is all you need.

Washing your clothes

You would think a little laundry detergent and hot water would take care of any ticks that have hitched a ride on your clothes. But ticks thrive in moist environments; a ride in the washer can be nothing to the parasite. It’s the dryer that’s a tick’s worst nightmare. The dry heat will kill them. Although it might seem counter-intuitive, dump your clothes in the dryer before washing. Run the dryer on regular heat for a full cycle—not permanent press. Don’t be surprised if you find dried husks of dead ticks in the lint filter.


Hitting the shower

The first thing you probably want to do if ticks are giving you the creepy crawlies is to jump in the shower. And showering is a good thing as it can help wash off any loose ticks, but the keyword here is loose. If a tick has already burrowed in your skin, they won’t come off just by showering. That said, the shower is the perfect place to do a full body for any ticks that may have latched onto you. Take a hand-held mirror in with you so you can check every crevice—from between your toes to your belly button to parts that never see the light of day. These are the 10 things you need to do right now if you’ve been bitten by a tick.

Wearing long clothes

You’ve heard that long-sleeved shirts and pants will keep ticks off, but they have no problem creeping up your ankle and under your pants. New research confirms there is a way to stop ticks—wear clothes treated with the repellent permethrin, according to CBS News report on a new U.S. government study. This insecticide is derived from the chrysanthemum flower, and it’s effective: “All tested tick species and life stages experienced the ‘hot-foot’ effect after coming into contact with permethrin-treated clothing,” said senior researcher Lars Eisen of the U.S. Centers for Disease Control and Prevention. Check out suppliers like Insect Shield: You can send them everything from socks to pants to bandanas, and they’ll treat all your items with permethrin. The treatment lasts through 70 washings.


Testing negative

Unfortunately, you may not be in the clear just because a blood test is negative for Lyme. According to an article in USA Today, if you have symptoms consistent with Lyme, you may want to seek out a Lyme-literate doctor for another opinion. Lyme disease is tricky to diagnose since many of the symptoms—headache, joint pain, or blurred vision—could be passed off as the flu or some other infection. And bulls-eye rashes appear in less than half of all Lyme cases. Don’t miss these 18 other silents signs of Lyme disease.


Squashing it

Not when it comes to ticks. You could end up infecting yourself. If you must kill them, drop them into a container full of alcohol. Take note: You might want to consider bagging that bug to save for testing in case you come down with symptoms.


Drowning them

Jumping in a pool or taking a nice hot bath won’t drown a tick, reports Time magazine. If they’re already attached to your skin, the wetness may encourage them to bore deeper into your skin. Here are 13 more things that ticks don’t want you to know.

Expecting to feel the bite

Most people have no clue they’ve been bitten by a tick. That’s because a tick’s saliva acts like anesthesia, reports Time. And although you may be able to spot an adult tick, it’s much more difficult to see a nymph, which is about the size of a tiny poppy seed. All you need is one of those little ‘poppyseeds’ to burrow in without being removed and they’ll feed for days.



Thinking no wings means no problem

Ticks may not be able to fly, but they get around just fine. According to Time, they don’t need wings for “questing” (how they catch and hold on to their next host): Using their rear legs, they cling to grass or leaves and then stretch out their front legs to jump on their next victim. Make sure you know these 9 tricks tips to avoid getting any tick-borne illnesses.



The Universidad Autónoma de Baja California veterinary team tested dogs in the town and found that more than 80 percent were infected.

"One community I worked in tried to get rid of their dogs," Foley said. "That was so sad. We shouldn't have to go so far."

The key is to stop the ticks from biting dogs, but that can be expensive, as flea spray and flea collars are costly.

It's less of a threat in more affluent communities, where dogs are vaccinated, groomed and licensed, but people can travel with infected dogs.

"It can be a threat as people go back and forth across borders, especially with dogs," Foley said. "The tick is present in the U.S. and is moving northward."

More than 72 million crossings were made by people from Mexico into California in 2015 alone, a CDC team reported.

The CDC says tick-borne diseases are on the rise. "Overall, since 2000, in the United States, the incidence of Rocky Mountain spotted fever has reportedly increased fourfold," Foley's team wrote.

The brown dog tick may be in part responsible but it could be that testing methods have made a difference as well, they said.

Read Full Story