Heading out to parks, campgrounds and natural areas is one of the pleasures of warmer weather. As beautiful and enjoyable as these outdoor areas may be, they’re also home to millions of tiny insects that could potentially cause infection and illness. And among the most common of these tiny pests are the hard-shelled arachnids we know as ticks.

Ticks live by sucking blood from humans and other animals. In doing so, they can transmit bacteria and other pathogens via their saliva. While tick bites can transmit a host of serious diseases, one of the gravest is Rocky Mountain spotted fever.

What is Rocky Mountain Spotted Fever?

Rocky Mountain spotted fever is a bacterial infection caused by a tiny bacterium called Rickettsia rickettsii. Although the disease is rare – about 250 cases were reported to the CDC between 2003 and 2012 – it is highly lethal. This infection causes death in about 5-10% of those who become infected. And the progression of the disease is also relatively fast; ideally, patients should be treated within five days of the onset in order to decrease their risk of mortality.

Although the disease is rare – about 250 cases were reported to the CDC between 2003 and 2012 – it is very lethal.

RMSF is found far beyond the Rocky Mountains for which it is named. Cases have been reported in nearly every state, as well as throughout parts of Canada and Latin America. In the U.S., the bulk of cases are diagnosed in the central and southern states of Oklahoma, Missouri, Tennessee, Arkansas and North Carolina. It was first diagnosed in 1896 in Idaho’s Snake River Valley. Initially, Rocky Mountain spotted fever was referred to as “black measles” in reference to the skin darkening and discoloration that often occurs in the late stages of the disease.

Which Ticks Carry Rocky Mountain Spotted Fever?

The U.S. is home to about 90 species of ticks, including “hard-bodied” and “soft-bodied” varieties. RMSF is most commonly carried and transmitted by wood ticks and dog ticks. People who hike or spend a lot of time outdoors in wooded areas or open, grassy fields are more likely to come in contact with infected ticks. People who own or care for dogs that spend a lot of time roaming in overgrown or wooded areas are also at greater risk for RMSF.

Rocky Mountain Spotted Fever Symptoms

The symptoms of Rocky Mountain spotted fever can begin appearing anywhere from two days to two weeks from the time of the tick bite. In most cases, the infected tick has long since dropped off by the time the initial symptoms appear. Many patients who become infected aren’t even aware they were bitten by a tick.

In most people, the disease process begins with flu-like symptoms, including headache and fever. Often, these early signs are misdiagnosed, resulting in a delay in care. In addition to fever and headache, other symptoms of RMSF can include:

  • loss of appetite
  • nausea
  • vomiting
  • abdominal cramping
  • muscle aches and pains
  • red, irritated, or inflamed eyes
  • rash, usually occurring within the first few days following a fever (typically appearing as flat, pinkish or purplish patches or hives on the hands, arms and ankles, spreading to the torso)

Not every patient will experience all symptoms, and patients can experience different types of symptoms at varying degrees of intensity. Even the characteristic red rash is absent in some patients.

Diagnosis and Treatment of RMSF

Prompt treatment is important for preventing the most serious side effects of this disease, including both long-term effects and death. Unfortunately, early symptoms can be easily misdiagnosed as flu (especially in patients who don’t have a rash), delaying proper treatment and significantly increasing the risk of mortality. In fact, death can occur within the first eight days after symptom onset, even in otherwise healthy people. This makes early and accurate diagnosis critical; however, this is not without problems.

Because Rocky Mountain spotted fever is closely associated with the “spotted” rash that occurs in about 90% of patients, it is rarely suspected in those 10% who never develop a rash. And since many patients never realize they’ve been bitten by a tick, treating physicians fail to consider tick-borne illnesses as a possible cause of symptoms. Symptoms can also vary significantly from one patient to the next, making it difficult to zero in on RMSF as a specific and distinctly identifiable cause of symptoms. Finally, many physicians only consider the diagnosis of tick-borne illnesses during peak months of the year or in specific geographic regions where ticks are far more prevalent.

Diagnostic tests for RMSF often fail to produce positive results within the first week to 10 days of an infection – the period when treatment is most critical for reducing the risk of serious and long-term side effects and death.

As a result, doctors must rely on their own best judgment to ensure that treatment is initiated as early as possible – ideally within the first five days of symptom onset. If you develop symptoms, it’s also very important to make sure you let your doctor know about any contact you’ve had with wooded or grassy areas, even if you don’t recall being bitten by a tick. Also mention if you have been around dogs that may, in turn, have picked up ticks. Sometimes a blood test can yield clues like a low platelet count or unusual levels of liver enzymes that can help in determining a diagnosis. But if this disease is even suspected, treatment with doxycycline should begin right away to reduce the risk of serious and even fatal side effects. Once treatment is underway, additional comprehensive testing can be performed once the disease has progressed a bit to confirm the diagnosis of RMSF.

After antibiotic treatment begins, fever typically resolves within one to three days. However, people with severe infections may require much longer courses of antibiotics, including intravenous antibiotics to help the medication reach and maintain levels necessary for reducing fever and preventing more serious and long-term damage. In most patients, antibiotic treatment lasts for about two weeks.

Although it may seem like a good idea to have a preventive course of antibiotics if you’ve been bitten by a tick, the Centers for Disease Control and Prevention (CDC) has found no evidence that “pretreatment” with antibiotics can effectively prevent an RMSF infection. In fact, this could actually delay the disease’s onset and interfere with proper treatment. If you have been in areas with a large tick population, be on the lookout for symptoms that could indicate an infection and seek care right away.

RMSF Long-Term Effects

The bacteria that causes Rocky Mountain spotted fever causes damage inside the epithelial cells that line the interior walls of blood vessels. Damaging these cells can cause a serious and long-lasting condition called vasculitis, which can lead to clotting and bleeding disorders affecting the brain and other organs. Vasculitis also interferes with normal circulation, increasing the risk of amputation of the feet, hands and limbs. In most cases, people who develop these severe complications do so within the first few weeks of illness. Those who don’t experience vasculitis symptoms within those first few weeks usually go on to recover, avoiding most long-term health problems associated with RMSF.

Rocky Mountain Spotted Fever Facts

  • Only about one in every 1,000 ticks carry the Rocky Mountain spotted fever bacterium.
  • The bacteria that causes RMSF is named for the man who first identified the disease, Howard Ricketts. After studying RMSF, Dr. Ricketts turned his attention to typhus, another insect-borne infection, and died of the disease at age 39.
  • Nearly all infections occur when the tick is attached for 20 or more hours. If it is removed before those 20 hours have elapsed, it’s far less likely to cause an infection.
  • RMSF infection is more common during the summer months, with peak exposures and subsequent infections occurring in June and July.
  • In addition to becoming infected from a tick bite, people can also become infected with RMSF by crushing an infected tick between their fingers.
  • One of the most recognizable symptoms of Rocky Mountain spotted fever is the red rash found in about 90% of patients. View RMSF rash pictures on the CDC website.
  • Although RMSF can be fatal in any infected patient, lethal outcomes are more common among children under 10 years of age, Native Americans, and people with compromised immune systems, as well as those in whom care is delayed.

How to Avoid Ticks

The best way to avoid ticks and the diseases they carry is to stay away from areas where they are most likely to be found. If you do choose to spend time in the woods and fields, be sure to use repellents with ingredients known to keep ticks at bay:

  • For exposed skin, choose repellent products that contain at least 20% DEET, picaridin or IR3535.
  • For clothing and gear, use products with 0.5% permethrin, or opt for items that have been pretreated with repellents.
  • Follow all application instructions closely.  Consult the Environmental Protection Agency’s guide to help you determine which repellent is best for your needs.

Several commercial products help keep ticks off your dogs, but you should always talk to your vet first before purchasing or applying any of them. Some can have serious and even fatal side effects in some pets. Never use tick repellents on cats.

Dogs are especially susceptible to tick-borne diseases, and they’re also commonly bitten. Perform routine checks on your dogs and other pets, and remove ticks as soon as you find them. Symptoms can take one to three weeks to appear, so watch your pet for unusual changes in behavior that could indicate they’ve become infected, and seek vet care right away.

If you find a tick on your pet or on yourself, grasp it firmly with tweezers as close to the skin surface as possible, then firmly pull upward using steady pressure. Don’t twist, since this can leave portions of the tick under your skin. Once the tick is removed, flush it down the toilet, wrap it tightly in tape, or drown it in rubbing alcohol. Then clean your skin with soap and water or rubbing alcohol. Don’t crush the tick with your fingers – this can release any bacteria it may contain.

Protect Your Property

Ticks can be carried by all sorts of animals, including rodents. Keeping your yard clear of brush and regularly mowing and weeding grassy areas can play an important role in limiting your exposure to ticks. A border of wood chips between wooded and grassy areas can make it more difficult for ticks to invade your lawn area.

Several tick-specific pesticides are also available to keep their populations under control. Be sure to hire a pest company with experience in tick pesticide application to avoid unnecessary and potentially harmful exposures.

Each year in the U.S., millions of people are bitten by ticks, and many don’t even realize it. While the chances of developing an illness as a result of a tick bite may be slim, the outcome can be deadly in those who do become infected.

Limiting your summertime explorations and activities may seem like a bummer, but avoiding exposure to ticks and the bacteria they carry is a critical step in preventing serious diseases like RMSF. Routine checks on yourself, your family, and your pets can protect your loved ones – both human and animal – and help everyone enjoy the great outdoors.


Image source: https://www.onhealth.com/content/1/rocky_mountain_spotted_fever