Ticks transmit other rickettsiae bacteria that cause spotted fevers similar to but milder than Rocky Mountain spotted fever.
A spotted fever develops when a tick carrying the bacteria that causes the fever bites a person.
The infection causes a fever, fatigue, muscle aches, headaches, and a rash.
To diagnose the infection, doctors do blood tests.
The antibiotic doxycycline is used to treat spotted fevers.
Avoiding tick bites is the best way to prevent the infection.
Rickettsiae are a type of bacteria that can live and multiply only inside the cells of a host organism, such as an animal or person, and cannot survive on their own in the environment. For example, hosts for rickettsiae include domestic livestock such as cows, pets such as dogs, and rodents such as mice. For most spotted fever infections, ticks are vectors (secondary hosts) that carry and spread the bacteria that cause the infection from one animal or human to another (primary host). Ticks may sometimes themselves act directly as the primary hosts without needing another animal or human (for example, Pacific Coast tick fever).
Other spotted fever infections include the following:
African tick bite fever (African tick typhus) (caused by Rickettsia africae bacteria)
Mediterranean spotted fever (boutonneuse fever) (caused by Rickettsia conorii bacteria)
North Asian tick-borne rickettsiosis (caused by Rickettsia sibirica bacteria)
Queensland tick typhus (caused by Rickettsia australis bacteria)
Rickettsialpox (caused by Rickettsia akari bacteria)
Pacific Coast tick fever (caused by Rickettsia philipii bacteria)
Rickettsia parkeri rickettsiosis
This photo shows an adult dog tick, which transmits the bacteria that cause Mediterranean spotted fever (boutonneuse fever).
CDC/Lauren Bishop
Other spotted fever infections occur all over the world (see table ). These infections occur mainly in the spring and summer, when adult ticks are active and people are likely to be in tick-infested areas. In warmer climates, the infections may occur throughout the year. For example, Mediterranean spotted fever can occur year-round in the Mediterranean region because it is transmitted by the brown dog tick and thus may be acquired indoors. (See also Ticks of Dogs.)
Symptoms of Other Spotted Fever Infections
Symptoms of spotted fever infections are similar for all of them, and they are usually milder than those of Rocky Mountain spotted fever.
About 5 to 7 days after a bite, a fever, fatigue, muscle aches, and headache develop. The eyes are red, and people feel generally unwell. A small buttonlike sore covered by a black scab (eschar) develops at the site of the bite. Usually, nearby lymph nodes are swollen. About 4 days after the fever starts, a red rash appears on the forearms and spreads to most of the body, including the palms and soles. Fever typically lasts over a week.
When appropriately treated, these infections are rarely fatal and rarely cause serious problems. Problems are more likely to occur in older adults and in people who are already very ill.
Diagnosis of Other Spotted Fever Infections
A doctor's evaluation
Blood tests
Biopsy and testing of the rash
Doctors base the diagnosis of a spotted fever infection on the person's symptoms (such as a fever, rash, and a black scab), particularly if the person has been in contact with ticks or has been in an area where spotted fevers occur.
To confirm the diagnosis, doctors may take a blood sample and do an immunofluorescence assay to detect antibodies to the bacteria. This test may need to be repeated a few weeks later to detect a rise in antibodies. Or they may take a blood sample and do the polymerase chain reaction (PCR) test to make copies of the bacteria's DNA, so that the bacteria can be detected more rapidly.
Sometimes doctors remove a sample of the rash (biopsy) and test if for antigens produced by the bacteria. See also Tests That Detect Antibodies to or Antigens of Microorganisms.
Treatment of Other Spotted Fever Infections
Antibiotics
Doctors immediately prescribe the antibiotic doxycycline if they suspect a person has a spotted fever even if test results are not yet available. The antibiotic is taken for 5 to 7 days.
Although doxycycline can cause tooth staining in children younger than 8 years old, a short, 5- to 10-day course of doxycycline in children of all ages is recommended by the American Academy of Pediatrics and can be used without causing tooth staining or weakening of tooth enamel.
Prevention of Other Spotted Fever Infections
To prevent these infections, people should take measures to prevent tick bites. (See also the Centers for Disease Control and Prevention: Preventing Tick Bites.)
Preventing tick access to skin includes:
Staying on paths and trails
Tucking trousers into boots or socks
Wearing long-sleeved shirts
Applying repellents that contain diethyltoluamide (DEET), picaridin, IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone to skin surfaces
Treating clothing, shoes/boots, and gear with permethrin
Some repellents can be toxic to children, so DEET should not be used in infants under 2 months of age, and repellents that contain more than 10% DEET should not be used in children under 12 years of age. OLE and PMD should not be used in children under 3 years of age. Permethrin on clothing effectively kills ticks. Frequent searches for ticks, particularly in hairy areas and on children, are essential in areas where infections transmitted by ticks are common.
Ticks should be removed as soon as possible. An engorged tick should be removed with care and not crushed between the fingers because crushing the tick may result in disease transmission. The tick’s body should not be grasped or squeezed. Removal is best accomplished by grasping the tick with curved tweezers as close to the skin as possible and pulling it directly out. The tick’s head, which may not come out with the body, should be removed, because it can cause prolonged inflammation. The area where the tick was attached and the hands of the person removing the tick should be disinfected with soap and water, rubbing alcohol, or hand sanitizer. Petroleum jelly, lit matches, and other irritants are not effective ways to remove ticks and should not be used.
Ticks cannot be entirely eliminated from large areas in the environment. However, the number of ticks may be reduced by taking steps to remove or prevent tick habitats and by making the environment less appealing and accessible to the animals that carry ticks. Ticks are often found in wood piles, leaf litter, tall grasses, and brush, so people can reduce the number of ticks in their yard by clearing such debris from around their home, especially outdoor play areas. Regular lawn maintenance, including frequent lawn mowing, is key to keeping ticks out of recreational areas and yards. People should remove any trash or unused furniture from their yard, and move outdoor equipment, toys, and seating away from shaded yard edges and trees. People can also install a 3-foot wide barrier of wood chips or gravel between their lawn and wooded areas.
To discourage tick-carrying rodents (such as rats, mice, and squirrels) from entering the yard, people should stack firewood in dry, elevated areas. To discourage other tick-carrying animals, such as raccoons, deer, and stray dogs, from entering the yard, people can install a fence.
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