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Rocky Mountain Spotted Fever

Definition

Rocky Mountain spotted fever (RMSF) is a tick-borne illness caused by a bacteria, resulting in a high fever and a characteristic rash.

Description

The bacteria causing RMSF is passed to humans through the bite of an infected tick. The illness begins within about two weeks of such a bite. RMSF is the most widespread tick-borne illness in the United States, occurring in every state except Alaska and Hawaii. The states in the mid-Atlantic region, the Carolinas, and the Virginias have a great deal of tick activity during the spring and summer months, and the largest number of RMSF cases come from those states. About 5% of all ticks carry the causative bacteria. Children under the age of 15 years have the majority of RMSF infections.

Causes and symptoms

The bacterial culprit in RMSF is called Rickettsia rickettsii. It causes no illness in the tick carrying it, and can be passed on to the tick's offspring. When a tick attaches to a human, the bacteria is passed. The tick must be attached to the human for about six hours for this passage to occur. Although prompt tick removal will cut down on the chance of contracting RMSF, removal requires great care. If the tick's head and body are squashed during the course of removal, the bacteria can be inadvertently rubbed into the tiny bite wound.

Symptoms of RMSF begin within two weeks of the bite of the infected tick. Symptoms usually begin suddenly, with high fever, chills, headache, severe weakness, and muscle pain. Pain in the large muscle of the calf is very common, and may be particularly severe. The patient may be somewhat confused and delirious. Without treatment, these symptoms may last two weeks or more.

The rash of RMSF is quite characteristic. It usually begins on the fourth day of the illness, and occurs in at least 90% of all patients with RMSF. It starts around the wrists and ankles, as flat pink marks (called macules). The rash spreads up the arms and legs, toward the chest, abdomen, and back. Unlike rashes which accompany various viral infections, the rash of RMSF does spread to the palms of the hands and the soles of the feet. Over a couple of days, the macules turn a reddishpurple color. They are now called petechiae, which are tiny areas of bleeding under the skin (pinpoint hemorrhages). This signifies a new phase of the illness. Over the next several days, the individual petechiae may spread into each other, resulting in larger patches of hemorrhage.

The most severe effects of RMSF occur due to damage to the blood vessels, which become leaky. This accounts for the production of petechiae. As blood and fluid leak out of the injured blood vessels, other tissues and organs may swell and become damaged, and:

breathing difficulties may arise as the lungs are affected.
heart rhythms may become abnormal
kidney failure occurs in very ill patients
liver function drops
the patient may experience nausea, vomiting, abdominal pain, and diarrhea
the brain may swell (encephalitis) in about 25% of all RMSF patients (brain injury can result in seizures, changes in consciousness, actual coma, loss of coordination, imbalance on walking, muscle spasms, loss of bladder control, and various degrees of paralysis)
the clotting system becomes impaired, and blood may be evident in the stools or vomit

Diagnosis

Diagnosis of RMSF is almost always made on the basis of the characteristic symptoms, coupled with either a known tick bite (noted by about 60-70% of patients) or exposure to an area known to harbor ticks. Complex tests exist to nail down a diagnosis of RMSF, but these are performed in only a few laboratories. Because the results of these tests take so long to obtain, they are seldom used. This is because delaying treatment is the main cause of death in patients with RMSF.

Treatment

It is essential to begin treatment absolutely as soon as RMSF is seriously suspected. Delaying treatment can result in death.

Antibiotics are used to treat RMSF. The first choice is a form of tetracycline; the second choice (used in young children and pregnant women) is chloramphenicol. If the patient is well enough, treatment by oral intake of medicine is perfectly effective. Sicker patients will need to be given the medication through a needle in the vein (intravenously). Penicillin and sulfa drugs are not suitable for treatment of RMSF, and their use may increase the death rate by delaying the use of truly effective medications.

Very ill patients will need to be hospitalized in an intensive care unit. Depending on the types of complications a particular patient experiences, a variety of treatments may be necessary, including intravenous fluids, blood transfusions, anti-seizure medications, kidney dialysis, and mechanical ventilation (a breathing machine).

Alternative treatment

Although alternative treatments should never be used in place of conventional treatment with antibiotics, they can be useful adjuncts to antibiotic therapy. The use of Lactobacillus acidophilus and L. bifidus supplementaion during and after antibiotic treatment can help rebalance the intestinal flora. Acupuncture, homeopathy, and botanical medicine can all be beneficial supportive therapies during recovery from this disease.

Prognosis

Prior to the regular use of antibiotics to treat RMSF, the death rate was about 25%. Although the death rate from RMSF has improved greatly with an understanding of the importance of early use of antibiotics, there is still a 5% death rate. This rate is believed to be due to delays in the administration of appropriate medications.

Certain risk factors suggest a worse outcome in RMSF. Death rates are higher in males and increase as people age. It is considered a bad prognostic sign to develop symptoms of RMSF within only two to five days of a tick bite.

Prevention

The mainstay of prevention involves avoiding areas known to harbor ticks. However, because many people enjoy recreational activities in just such areas, the following steps can be taken:

Wear light colored clothing (so that attached ticks are more easily noticed).
Wear long sleeved shirts and long pants; tuck the pants legs into socks.
Spray clothing with appropriate tick repellents.
Examine. Anybody who has been outside for any amount of time in an area known to have a population of ticks should examine his or her body carefully for ticks. Parents should examine their children at the end of the day.
Remove any ticks using tweezers, so that infection doesn't occur due to handling the tick. Grasp the tick's head with the tweezers, and pull gently but firmly so that the head and body are entirely removed.
Keep areas around homes clear of brush, which may serve to harbor ticks.

Resources

Organizations

Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. (800) 311-3435, (404) 639-3311. http://www.cdc.gov.

Key terms

Encephalitis — Inflammation of the tissues of the brain.

Macule — A flat, discolored area on the skin.

Petechia — A small, round, reddish purple spot on the skin, representing a tiny area of bleeding under the skin.

fever /fe·ver/ (fe´ver)

1. pyrexia; elevation of body temperature above the normal (37°C).

2. any disease characterized by elevation of body temperature.

blackwater fever a dangerous complication of falciparum malaria, with passage of dark red to black urine, severe toxicity, and high mortality.

boutonneuse fever a tickborne disease endemic in the Mediterranean area, Crimea, Africa, and India, due to infection with Rickettsia conorii, with chills, fever, primary skin lesion (tache noire), and rash appearing on the second to fourth day.

cat-scratch fever see under disease.

central fever sustained fever resulting from damage to the thermoregulatory centers of the hypothalamus.

childbed fever puerperal septicemia.

Colorado tick fever a tickborne, nonexanthematous, febrile, viral disease caused by an arenavirus and seen in the Rocky Mountain area of the United States.

continued fever one that varies only slightly in 24 hours.

Crimean-Congo hemorrhagic fever a hemorrhagic fever caused by the Crimean-Congo hemorrhagic fever virus, transmitted by ticks and by contact with blood, secretions, or fluids from infected animals or humans; it occurs in the Crimea, Central Asia, and regions of Africa.

drug fever febrile reaction to a therapeutic agent, such as a vaccine, antineoplastic, or antibiotic.

elephantoid fever a recurrent acute febrile condition occurring with filariasis; it may be associated with elephantiasis or lymphangitis.

enteric fever any of a group of febrile illnesses associated with enteric symptoms caused by salmonellae, especially typhoid fever and paratyphoid fever.

epidemic hemorrhagic fever an acute infectious disease characterized by fever, purpura, peripheral vascular collapse, and acute renal failure, caused by viruses of the genus Hantavirus, thought to be transmitted to humans by contact with saliva and excreta of infected rodents.

familial Mediterranean fever a hereditary disease usually seen in Armenians and Sephardic Jews, with short recurrent attacks of fever, pain in the abdomen, chest, or joints, and erythema like that of erysipelas; it may be complicated by amyloidosis.

Haverhill fever the bacillary form of rat-bite fever, due to Streptobacillus moniliformis, and transmitted through contaminated raw milk and its products.

hay fever a seasonal form of allergic rhinitis, with acute conjunctivitis, lacrimation, itching, swelling of the nasal mucosa, nasal catarrh, and attacks of sneezing, an anaphylactic or allergic reaction excited by a specific allergen (such as pollen).

hemorrhagic fevers a group of diverse, severe viral infections seen around the world but mainly in the tropics, usually transmitted to humans by arthropod bites or contact with virus-infected rodents; they all have certain common features, including fever, hemorrhagic manifestations, thrombocytopenia, shock, and neurologic disturbances.

humidifier fever malaise, fever, cough, and myalgia caused by inhalation of air that has been passed through humidifiers, dehumidifiers, or air conditioners contaminated by fungi, amebas, or thermophilic actinomycetes.

intermittent fever an attack of malaria or other fever, with recurring fever episodes separated by times of normal temperature.

Katayama fever fever associated with severe schistosomal infections, accompanied by hepatosplenomegaly and by eosinophilia.

Lassa fever a highly fatal, acute, febrile disease seen in West Africa, caused by a virulent arenavirus and characterized by increasing prostration, sore throat, ulcerations of the mouth or throat, rash, and general aching.

metal fume fever a disease of welders and others working with volatilized metals, marked by sudden thirst, metallic taste in the mouth, high fever with chills, sweating, and leukocytosis.

mud fever a type of leptospirosis seen in workers in flooded fields and swamps in Germany and Russia.

nonseasonal hay fever , hay fever, perennial nonseasonal allergic rhinitis.

Oroya fever see Carrión's disease.

paratyphoid fever paratyphoid.

parenteric fever a disease clinically resembling typhoid fever and paratyphoid, but not caused by Salmonella.

parrot fever psittacosis.

pharyngoconjunctival fever an epidemic disease due to an adenovirus, seen mainly in school children, with fever, pharyngitis, conjunctivitis, rhinitis, and enlarged cervical lymph nodes.

phlebotomus fever a febrile viral disease of short duration, transmitted by the sandfly Phlebotomus papatasi, with dengue-like symptoms, seen in Mediterranean and Middle Eastern countries.

Pontiac fever a self-limited disease marked by fever, cough, muscle aches, chills, headache, chest pain, confusion, and pleuritis, caused by a strain of Legionella pneumophila.

pretibial fever an infection due to a serovar of Leptospira interrogans, marked by a rash on the pretibial region, with lumbar and postorbital pain, malaise, coryza, and fever.

puerperal fever septicemia accompanied by fever, in which the focus of infection is a lesion of the mucous membrane of the parturient canal due to trauma during childbirth; usually due to a streptococcus.

Q fever a febrile rickettsial infection, usually respiratory, first described in Australia, caused by Coxiella burnetii.

rat-bite fever either of two clinically similar acute infectious diseases, usually transmitted through a rat bite, one form (bacillary) of which is caused by Streptobacillus moniliformis and the other form (spirillary) by Spirillum minor.

recurrent fever

1. relapsing f.

2. recurrent paroxysmal fever occurring in various diseases, such as malaria.

relapsing fever any of a group of infectious diseases due to various species of Borrelia, marked by alternating periods of fever and apyrexia, each lasting from five to seven days.

remittent fever one that shows significant variations in 24 hours but without return to normal temperature.

rheumatic fever a febrile disease occurring as a sequela to Group A hemolytic streptococcal infections, characterized by multiple focal inflammatory lesions of connective tissue structures, especially of the heart, blood vessels, and joints, and by Aschoff bodies in the myocardium and skin.

Rift Valley fever a zoonotic febrile disease with dengue-like symptoms, due to an arbovirus, transmitted to humans by mosquitoes or by contact with diseased animals; first observed in the Rift Valley, Kenya.

Rocky Mountain spotted fever infection with Rickettsia rickettsii, transmitted by ticks, marked by fever, muscle pain, and weakness followed by a macular petechial eruption that begins on the hands and feet and spreads to the trunk and face, with other symptoms in the central nervous system and elsewhere.

rose fever a form of hay fever caused by grass pollens released while roses or other flowers are blooming.

scarlet fever an acute disease caused by Group A β-hemolytic streptococci, marked by pharyngotonsillitis and a skin rash caused by an erythrogenic toxin produced by the organism; the rash is a diffuse, bright red erythema, and desquamation of the skin begins as fine scaling with eventual peeling of the palms and soles.

Sennetsu fever a febrile disease seen in Japan and Malaysia and caused by Ehrlichia sennetsu, characterized by headache, nausea, lymphocytosis, and lymphadenopathy.

septic fever fever due to septicemia.

South African tickbite fever boutonneuse f.

trench fever a louse-borne rickettsial disease due to Bartonella quintana, transmitted by the body louse, Pediculus humanus corporis, and characterized by intermittent fever, generalized aches and pains, particularly severe in the shins, chills, sweating, vertigo, malaise, typhus-like rash, and multiple relapses.

typhoid fever infection by Salmonella typhi chiefly involving the lymphoid follicles of the ileum, with chills, fever, headache, cough, prostration, abdominal distention, splenomegaly, and a maculopapular rash; perforation of the bowel may occur in untreated cases.

fever of unknown origin (FUO) a febrile illness of at least three weeks' duration (some authorities permit a shorter duration), with a temperature of at least 38.3°C on at least three occasions and failure to establish a diagnosis in spite of intensive inpatient or outpatient evaluation (three outpatient visits or three days' hospitalization).

West Nile fever see under encephalitis.

yellow fever an acute, infectious, mosquito-borne viral disease, endemic primarily in tropical South America and Africa, marked by fever, jaundice due to necrosis of the liver, and albuminuria.

Rock·y Moun·tain spotted fever (r

moun

n. Abbr. RMSF

An acute infectious disease caused by Rickettsia rickettsii that is transmitted by ticks, characterized by muscular pain, high fever, and a skin rash, and is endemic throughout North America.

Rocky Mountain spotted fever (RMSF),

a serious tickborne infectious disease occurring throughout the temperate zones of North and South America, caused by Rickettsia rickettsii. It is characterized by chills, fever, severe headache, myalgia, mental confusion, and rash. Erythematous macules first appear on wrists and ankles, spreading rapidly over the extremities, trunk, and face and usually on the palms and soles. Hemorrhagic lesions, constipation, and abdominal distension are also common. The diagnosis is based on clinical examination and confirmed by laboratory analyses, including immunofluorescent antibody screens, complement fixation test, and Weil-Felix test. Early treatment with doxycycline or tetracycline is important because more than 20% of untreated patients die from shock and renal failure. A diet high in protein is important to avoid hypoproteinemia. Nursing care is especially important to avoid decubitus ulcers and hypostatic or aspiration pneumonia. Immunity follows recovery. Prevention includes the use of insect repellents, the wearing of protective clothing, frequent inspection of the body, and careful removal of wood or dog ticks. No vaccine is available. Care must be taken not to crush ticks, because infection may be acquired through skin abrasions. Also called Mexican spotted fever, mountain fever, mountain tick fever, spotted fever. Compare murine typhus, rickettsialpox. See also boutonneuse fever, scrub typhus, typhus.

Rocky Mountain spotted fever,

n.pr a severe bacterial disease caused by
Rickettsia rickettsii; characterized by the rapid onset of fever, headache, muscle pains, nausea, vomiting, and a characteristic rash. Without accurate diagnosis and antibiotic treatment, this condition can be fatal. The range for this disease is not limited to the Rocky Mountains but extends from Canada throughout the continental United States into Central and South America.

Rocky Mountain spotted fever (RMSP).

Rocky Mountain spotted fever (RMSF),

n a serious tick-borne infectious disease occurring throughout the temperate zones of North and South America, caused by
R. rickettsii, and characterized by chills, fever, severe headache, myalgia, mental confusion, and rash.

Rocky Mountain spotted fever

an infectious disease of small mammals, dogs and humans. It occurs mainly in certain areas within the USA. Called also tick fever, and it is also known by various names according to the geographic area.

Rocky Mountain spotted fever belongs to a group of insect-borne fevers caused by rickettsiae, which attack endothelium. The species, Rickettsia rickettsii, responsible for Rocky Mountain spotted fever is transmitted from rodent by various ticks. The clinical signs associated with infection in dogs are lethargy, anorexia, ocular and nasal discharge, lymphadenopathy and splenomegaly. A thrombocytopenia also occurs. Kennel epizootics have been recorded.

Rocky Mountain spotted fever

Spotted fever Infectious disease An exanthematous disease common in the eastern US from April to October even in large cities–eg, NYC Agent Rickettsia rickettsii Hosts Furry woodland creatures–rodents, et al Vectors Wood–Dermacentor andersoni and dog–D variabilis ticks Clinical 1 wk incubation, followed by a discrete pale, blanchable centrifugal maculopapular rash, which may be very dark, hence the alias, 'black measles', persistent headache, fever, ±coughs, rales, myalgia, malaise, splenomegaly; N&V, abdominal pain; CNS Sx–delirium, stupor, ataxia, meningismus; myocarditis, EKG changes, thrombocytopenia, multiple coagulopathies, renal failure, shock Treatment Tetracycline, chloramphenicol Mortality 3-10%; ↑ in blacks, ↑ > age 40. See Rickettsial infection.