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Lyme disease, which infects approximately 300,000 people each year in the United States, is the most prevalent disease in the country. But the most deadly disease spread by ticks in the United States is actually the spotted fever of the Rocky Mountains.
According to a 2012 study by the American Journal of Tropical Medicine and Hygiene, between 1999 and 2007, RMSF killed about 14 people in the United States each year.
The Rocky Mountain Spotted Fever takes its name from the place where it was discovered over a century ago and the spotted rash that often occurs when it damages the vessels blood under the skin.
But today, the disease (along with other tick-spotted fevers) is evident everywhere in the United States and not just in the Rocky Mountains. And even though a rash occurs in 90% of cases, it often only appears after the onset of more vague and flu-like symptoms. In some cases, waiting for the rash to occur to treat an FPSR can be fatal.
"Spotted fever in the Rocky Mountains is a disease that is changing very rapidly; It's a very dangerous disease, "says Naomi Drexler, MP, an epidemiologist in the Division of Vector-Driven Diseases at the Centers for Disease Control.
Here are answers to several key questions about the SPF, what you need to know about this life-threatening disease, and how to protect yourself.
What is the danger of RMSF?
Spotted fever in the Rocky Mountains is part of a group of diseases called spotted fever rickettsiosis. Lucas Blanton, MD, an assistant professor of internal medicine at the University of Texas Medical Branch at Galveston, explains that the bacteria responsible for these spotted fevers live in organisms such as ticks, fleas and mites, likely to pass them on to the man.
Pacific coast tick-borne tick fever, rickettsia parkeri rickettsiosis (transmitted by the Gulf Coast tick) and rickettsialpox (a rare disease transmitted by mites living on the Pacific coast). mice) are among the other diseases of this group.
Spotted fever in the Rocky Mountains is the most dangerous of all spotted fevers. If it is not treated, the disease can be fatal in 20% or more cases (by comparison, Lyme disease is almost never fatal and the CDC only documented 9 cases Lyme infecting the heart in a fatal way from 1985 to 2018).
Some people, even if they survive the disease, may face serious and permanent problems. Damage to the blood vessels caused by the FFSR can result in necrosis or death of body tissues. This can lead to hearing loss, paralysis, mental retardation, organ damage or amputation. Young children and older adults infected with RMSF have a higher risk of serious illness and death.
With rapid antibiotic treatment, RMSF is much less likely to be fatal. Research suggests that in recent years, the mortality rate of all winter spot fevers has dropped to less than 1% in the United States (although it is about 1.6% in children under 10 years of age) . The researchers suggest that this may be due in part to the increased availability of effective antibiotic treatment and increased awareness of tick-borne diseases, but they also point out that because of the difficulty in distinguish between true RMSF and similar conditions. The percentage mortality rate also includes other less severe fevers.
What is the frequency of RMSF?
Since common testing methods do not distinguish between different types of tick-borne spot fevers, the CDC reports rickettsial cases of spotted fever as a group. And the latest data shows that these diseases are increasing. In 2017, 6 248 cases of rickettsiosis with spotted fever were reported to the CDC compared to 4 269 in 2016 – and only 495 in 2000.
According to the CDC, it is not clear in what proportion these cases are RMSF or other spotted fever. Some scientists suspect that, as with Lyme disease, the number of reported cases underestimates the actual number of cases of spotted fever.
Number of cases of rickettsiosis with US spotted fever reported to CDC, 2000-2017
How can you contract RMSF?
In the United States, you can catch SPRFs from three different tick species: American ticks, Rocky Mountain ticks, and brown ticks (see our visual guide for what it looks like).
The American tick is found mainly in the eastern United States and California, while the Rocky Mountain tick is found mainly in the western United States and southwestern Canada. These two ticks, similar to many other species, live mainly in tall grass, scrub or scrubland or in wooded areas.
The third tick that can transmit RMSF in the United States, the dog's brown tick, is a little different. On the one hand, it is present worldwide and in all 50 states. And unlike other ticks, she can survive inside, infesting areas such as kennels or even homes. "It is not necessary that it be in the forest. He can live his whole life in your home, "says Janet Foley, MD, Ph.D., professor of vector-borne disease ecology at the Davis School of Veterinary Medicine at the University of California.
The brown dog tick, be it larva, nymph or adult, prefers to feed on dogs. This is why, according to an analysis of the journal Parasites & Vectors, owning a dog is a risk factor to be bitten by the brown tick. Brown dog ticks feed if needed, and once the tick is established in or around your house or on your dog, you are more likely to become a host of the pest yourself.
The brown dog tick was only recognized as a vector of the FPRS in the early 2000s, when scientists associated it with epidemics of the disease in Arizona, particularly in Native American communities with many populations. dogs in freedom. According to the CDC, between 2003 and 2018, health officials documented more than 400 cases of the disease in Arizona, killing 25 people.
A CDC program to combat the brown dog tick population in these communities, called "Rodeo Rodeo" (Rodeo Rodeo), involves registering, attaching and providing tick collars for dogs; regularly apply acaricides (tick pesticides) in the yards of participating households (and in the interior of infested homes); Finally, according to a 2014 study in Plos One, free dog sterilization and sterilization significantly reduced tick infestations in dogs and reduced the incidence of FPSM cases. %.
Similar epidemics continue along the border between the United States and Mexico.
What should you do if you think you have RMSF?
Unfortunately, the first symptoms of RMSF are not particularly specific: fever, headaches and muscle aches. Nausea and vomiting are also possible. A rash occurs in 90% of cases, but it often does not appear during the first few days of symptoms. This can be a problem because without a rash, doctors may be more hesitant to diagnose RMSF. In fact, a rash that appears late in the course of the disease is associated with an increased risk of serious illness because it can delay the diagnosis.
When a rash appears, it usually begins with the ankles and wrists and then spreads to the trunk. Eventually, the rash can spread to your palms and to the soles of your feet, but not until the disease is advanced. (A doctor should not exclude the FPRS if a rash does not appear on the palms of the hands or the soles of the feet, warns Blanton.)
Since symptoms can be quite vague at first, whenever you see your doctor with flu-like symptoms, be sure to share any recent trips and outdoor activities that may have put you on the tick path. your own yard, if you live in an area where ticks are common). Only about half of people with RMSF remember having been bitten by a tick. If you know that you have been bitten, talk to the doctor, but keep in mind that you could have been bitten without knowing it.
If your recent symptoms and activities suggest that you may be suffering from RMSF and your doctor has ruled out any other possible explanation, your doctor should prescribe the doxycycline antibiotic, says the CDC. It is very effective against FPSR, and blood tests of the bacteria are only effective for about a week. It's too long to wait to start treatment – the CDC says that doxycycline treatment should be started within the first five days of symptoms to reduce the risk of serious illness and death. (Doxycycline is also the first-line treatment for several other tick-borne diseases, including Lyme disease.)
And remember: despite the term "Rocky Mountain Spotted Fever", your doctor should not wait for a rash to appear before starting treatment if she suspects RMSF.
How to prevent RMSF?
Preventing tick bites is the key to avoiding RMSF. Use an EPA approved insect repellent with a tick protection label, such as one of our top rated products here:
Research also suggests that clothing treated with permethrin may offer protection against ticks. You can buy pretreated clothing or treat your own clothes with a permethrin spray at home.
When you go out in a wooded, brushed or grassy place, it is best to wear pants and long sleeves and put your pants in your socks.
Everyday, after being outside and exposed to ticks, throw your clothes in a hot dryer for 10 minutes to eliminate ticks that may have stopped. And take a shower: this gives you the opportunity to do a thorough examination of the ticks that may have attached to your body and remove all the ticks that could crawl on your skin but have not yet been bitten.
If you find a tick, remove it as soon as possible with tweezers. Blanton says it usually takes at least 24 hours for a tick to send you the RMSF. Therefore, removing ticks early can reduce your risk of getting sick.
Finally, pets can transfer ticks to people and, in the case of brown ticks, can cause tick infestation in your home. Ask your veterinarian for an effective anti-tick product for your dog or cat.
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