Rocky Mountain Spotted Fever vs Lyme Disease – Differences & Treatment

This article reveals the differences between Rocky mountain spotted fever vs Lyme disease:

Rocky Mountain Spotted Fever (RMSF)

This illness is caused by bacteria which are transmitted by tick bites to humans.

Both adults and children can be affected by RMSF. According to data from the Centers for Disease Control and Prevention, an estimated 5 cases per one million people were reported in the US per year.

Missouri, North Carolina, Arkansas, Tennessee, and Oklahoma account for approximately 60 percent of reported cases.

RMSF is the most serious tick-borne disease in the US. About 0.3 percent of people who become ill with RMSF die from the infection.


Symptoms of RMSF typically appear 2 to 14 days after being bitten by the infected tick. Symptoms may include:

  • confusion or other neurological changes;
  • vomiting;
  • nausea;
  • muscle aches;
  • severe headache;
  • chills;
  • high fever.

A rash will commonly develop 2 to 4 days after the fever begins. The rash is usually found on wrists and ankles and then appears on palms, trunk, and soles.

Also, the rash may become necrotic in about 4 percent of patients or hemorrhagic in about fifty percent.


Some individuals may be left with permanent damage, including:

  • mental disability;
  • paralysis;
  • hearing loss;
  • amputation of legs, fingers, arms, or toes (from damage to blood vessels in these areas).


It is a disease which is caused by a bacterium that is transmitted to humans via the bite of an infected tick, called – Rickettsia rickettsii.

Other causes of spotted fevers in the US include:

  • Rickettsialpox, caused by Rickettsia akari;
  • Pacific Coast tick fever, caused by Rickettsia philipii;
  • Rickettsia parkeri rickettsiosis, caused by R. parkeri.

Risk Factors

RMSF usually occurs during the summer months, with peak periods in June and July due to the fact that during this period ticks are most active.

Plus, people spend more time outdoors.


Clinical diagnosis of the condition is based on:

  • detection of bacterial DNA in a clinical specimen via PCR;
  • detection of the bacterial agent via immunohistochemical staining of biopsies;
  • detection of antibody titers via IFA.


To avoid complications, the treatment needs to be administered as soon as possible.

If the infection is not treated within 5 days of symptom onset, chances of severe complications increase substantially.

Treatment may include antibiotics until a few days after the fever goes away.

Doxycycline should be used for children of any age. For adults, tetracycline (brand name Sumycin) is the preferred treatment.


Common tetracycline side effects may include:

  • vaginal discharge or itching;
  • loss of appetite;
  • sores or swelling in your genital or rectal area;
  • upset stomach;
  • trouble swallowing;
  • diarrhea;
  • “hairy” tongue;
  • vomiting;
  • swollen tongue;
  • sores inside your mouth or on your lips;
  • nausea.

Lyme Disease

Lyme disease, also referred to as borreliosis, is a condition that is transmitted to humans by black-legged ticks. It can damage any organ in the body.

It is the 5th most reported of notifiable diseases in the US, with over 300,000 new cases found every year.

Borreliosis is most common in the Pacific Northwest, the Northeast, and the northern midwestern states.

In the United States, LD usually peaks in May through July, when the ticks that carry the disease are most active.

In the United Kingdom, about half of the cases occur between June and August.


Early signs and symptoms

  • headaches;
  • muscle aches;
  • fatigue;
  • a single bulls-eye rash;
  • vision changes;
  • sore throat;
  • enlarged lymph nodes;
  • fever;
  • chills.

Later signs and symptoms

If untreated, new symptoms might appear in the following months, such as:

  • impaired muscle movement;
  • numbness or weakness in the limbs;
  • temporary paralysis of one side of the face;
  • inflammation of the membranes surrounding your brain;
  • joint pain.


Unrecognized LD or an unsuccessful treatment of LD may lead to a progressive complication called Lyme carditis.


A tick bite can cause LD only if the tick has bitten an infected animal with the pathogenic bacteria.

Four main species of bacteria may cause the infection:

  • Borrelia garinii;
  • Borrelia afzelii;
  • Borrelia mayonii;
  • Borrelia burgdorferi.

Notes – usually, the tick must remain attached for at least 36 hours before transmitting the bacterium into a human. LD is not contagious, therefore, you can’t catch it from another person.

Risk Factors

Most tick bites happen in early summer, late spring, and autumn due to the fact that these are the times of year when most families take part in outdoor activities.

Moreover, you are at greater risk if you live in the Midwest or Northeast regions of the US, where most cases of LD occur.


It is diagnosed based on the detection of antibodies to the causative bacteria in the blood and on the sufferer’s clinical signs of illness.


If your doctor thinks you might have LD, he will prescribe a 3-week course of antibiotics.

Note – it is vital to finish the course of antibiotics, even if you start to feel better.

Rocky Mountain Spotted Fever vs Lyme Disease – Differences

Rocky Mountain spotted fever is a bacterial infection that is transmitted by a tick. The states that are most usually affected are Oklahoma, Arkansas, North Carolina, Missouri, and Tennessee.

The symptoms develop within the first few days of a tick bite, but some people may not experience symptoms for up to 14 days. RMSF is characterized by a sudden onset of moderate to high fever, severe headache, deep muscle pain, fatigue, rash, and chills.

Lyme disease is a bacterial infection that can be spread to humans by infected ticks (most people who are bitten by a tick do not get LD). It can affect the joints, heart, skin, and the nervous system. It is the most common vector-borne infection in the US.


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