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DHFdihydrofolate or dihydrofolic acid.
fever(fe'ver) [L. febris]
Fever is caused by the release of interleukin-1 (IL-1), interleukin-2 (IL-2), and tumor necrosis factor from white blood cells (esp. macrophages), secretion of acute phase proteins, and redistribution of the blood away from the skin by the autonomic nervous system. The body cools itself and returns its temperature to normal range by diaphoresis (sweating). Elevated temperature caused by inadequate thermoregulatory responses during exercise in very hot weather is called hyperthermia; the set point is not increased. Infections, drugs, tumors, breakdown of necrotic tissue, CNS damage, and collagen diseases are the underlying causes of fevers. Despite common beliefs, fever is not harmful except in patients who cannot tolerate its hypermetabolic effects, some older patients in whom it can cause delirium, and children with a history of febrile seizures.
Patients with fever frequently seek professional medical attention. Fever is often an important indicator of infections or inflammations that may cause significant injury if left untreated. Diagnosing the cause of a fever may lead to specific therapies that limit the duration of an illness, prevent secondary organ damage or even death. The suppression of fever, however, is controversial. Some believe that fever helps to eradicate infecting organisms that cannot survive in a hot environment. Nonetheless, medications such as acetaminophen, aspirin, and other nonsteroidal anti-inflammatory drugs (NSAIDs) can lower body temperatures in febrile patients and are commonly used esp. if the body temperature exceeds 101°F (38.3°C). It is unknown whether using antipyretics results in improvements in survival or decreases in morbidity. In some settings (e.g., the care of the hospice patient with a fever) withholding an antipyretic drug is considered to be inadequate symptom management by most health care providers. In other settings (e.g., in patients with malignant hyperthermia or heatstroke), giving antipyretics represents a standard of care. To date, however, controlled trials of withholding antipyretics in many illnesses have not been performed.
Suppression of fever (by induced hypothermia) is recommended for those who have suffered sudden death, stroke, or persistent seizures; however, proof of the effectiveness of lowering the body temperature of stroke victims is based on laboratory data rather than clinical effectiveness. Suppression of fever in young children with viral and bacterial infections is often a comfort for them; yet some researchers have speculated about adverse effects of this common practice (e.g., whether there is a link suppression of fever and autistic disorders). When the choice is made to suppress a fever, it is probably most comfortable to give antipyretics on a regular basis (every 4 or 6 hr) rather than intermittently. Intermittent dosing of antipyretics may produce alternating bouts of chills and sweats, which most patients find unpleasant. Some patients may never mount a fever; this is particularly true of those over 65, who may have serious treatable infections without elevations of body temperature. In older patients, the first indication of inflammatory or infectious illnesses may be a cough, lethargy, anorexia, or alterations in mental status.
CAUTION!Aspirin and other salicylates are contraindicated as antipyretics or analgesics in children because of their association with an increased risk of Reye's syndrome. Public and parental education should be provided to make certain this knowledge is widely disseminated.
acute pharyngoconjunctival feverAbbreviation: APC
African tick bite fever
Alkhurma hemorrhagic feverAbbreviation: AHFV
The illness is marked by high fevers, dark urine, epigastric pain, vomiting, jaundice, and shock. Physical findings include enlargement of the liver and spleen. Laboratory hallmarks include severe anemia and, occasionally, renal failure.
boutonneuse feverMediterranean spotted fever.
childbed feverPuerperal sepsis.
Congo-Crimean viral hemorrhagic fever
deer fly feverTularemia.
dengue hemorrhagic feverAbbreviation: DHF
Ebola virus hemorrhagic fever
The disease is caused by one of three species of Ebola virus, a Filoviridae virus distinguished by long threadlike strands of RNA. The animal host has not been identified, which limits study of the disease. In each outbreak, the first human infection is believed to be caused by a bite from an infected animal. Subsequent cases are the result of contact with blood or body secretions from an infected person or the reuse of contaminated needles and syringes.
The use of standard barrier precautions prevents transmission, with the addition of leg and shoe covers if large amounts of blood, vomit, or diarrhea are present; negative-pressure isolation rooms are used if available. The spread of Ebola virus between humans by airborne droplets has not been documented, but face masks are recommended if the patient has respiratory symptoms. All equipment must be sterilized before reuse.
The incubation period of 2–3 weeks is followed by sudden onset of high fever, myalgia, diarrhea, headache, fatigue, and abdominal pain; a rash, sore throat, and conjunctivitis may be present. Within 7 days, shock develops, usually associated with hemorrhage; more than 50% of patients die. The patient is infectious after fever appears.
enteric feverTyphoid fever.
epidemic hemorrhagic feverHemorrhagic nephrosonephritis.
familial Hibernian fever
familial Mediterranean fever
Flinders island spotted feverAbbreviation: FISF
Fort Bragg feverPretibial fever.
grain feverSilo-filler's disease.
Haverhill feverRat-bite fever.
Airborne pollens, fungal spores, dust, and animal dander cause hay fever. It is most commonly triggered in the spring by pollen from trees, in the summer by grass pollen, and in the fall by pollen from wildflowers, e.g., ragweed. Nonseasonal rhinitis may result from inhalation of animal dander, dust from hay or straw, or house dust mites.
Seasonal usage of antihistamines, cromolyn, and corticosteroid nasal sprays are the usual therapy in the U.S. Prophylaxis through desensitization is also useful but is less convenient and usually more expensive. Avoiding allergens is also effective but not always possible.
CAUTION!Overuse of corticosteroids may damage the nasal mucosa, and absorption of the drug can cause adverse side effects.
Japanese spotted fever
Korean hemorrhagic feverHemorrhagic nephrosonephritis.
Patients have abrupt onset of high fever that is continuous or intermittent and spiking, with generalized myalgia, chest and abdominal pain, headache, sore throat, cough, dizziness with flushing of the face, conjunctival injection, nausea, diarrhea, and vomiting. Hemorrhagic areas of the skin and mucous membranes may appear on the fourth day. Mortality of those in Africa with this disease varies from 16% to 45%.
Ribavirin given in the first week of illness and continued for 10 days has been very effective in reducing the death rate. This medicine should also be given orally for 10 days prophylactically to those who have been percutaneously exposed to the virus. Patients are isolated in special isolation units that filter the air leaving the room and maintain negative pressure. All sputum, blood, excreta, and objects that the patient has handled are disinfected.
Mediterranean spotted fever
metal fume fever
The onset of symptoms is usually delayed. There are chills, weakness, lassitude, and profound thirst, followed some hours later by sweating and anorexia. Occasionally, there is mild inflammation of the eyes and respiratory tract. The symptoms are more acute at the beginning of the work week than at the end. This is felt to be due to the individual's adapting to the fumes as exposure continues.
Therapy includes analgesics, antipyretics, and rest.
pappataci feverSandfly fever.
Pel-Ebstein feverSee: Pel-Ebstein fever
periodic feverFamilial Mediterranean fever.
phlebotomus feverSandfly fever.
polymer fume fever
puerperal feverPuerperal sepsis.
Query feverQ fever.
Both diseases are treated with penicillin. Therapy is most effective when penicillin is given intravenously for 1 week, then orally for 1 week. Tetanus prophylaxis is also administered.
After a pharyngeal infection with group A streptococci, some patients experience sudden fever and joint pain. Other symptoms include migratory joint pains, pain on motion, abdominal pain, chorea, and cardiac involvement (pericarditis, myocarditis, and endocarditis). Precordial discomfort and heart murmurs develop suddenly. Skin manifestations include erythema marginatum or circinatum and the development of subcutaneous nodules.
Rheumatic fever may occur without any sign or symptom of joint involvement. Two major manifestations (carditis, polyarthritis, chorea, erythema marginatum, subcutaneous nodules) or one major and two minor criteria (fever of at least 100.4°F [38°C], arthralgia, previous rheumatic fever, elevated erythrocyte sedimentation rate or positive C-reactive protein, prolonged P-R interval) are required to establish the diagnosis of acute rheumatic fever.
Prompt and adequate treatment of streptococcal infections with oral penicillin or cephalosporin is given for at least 10 days. Erythromycin or sulfa drugs are substituted in patients with penicillin allergy.
To prevent recurrence of rheumatic fever in a patient who has already been affected by the disease, benzathine benzylpenicillin is given intramuscularly every 3 or 4 weeks. Low-dose oral penicillin, erythromycin, or sulfa drugs are alternatives for compliant patients.
Salicylates, acetaminophen, and NSAIDs are used to lower fever, reduce inflammation, and alleviate pain. Corticosteroids may be needed if the salicylates, acetaminophen, and NSAIDs do not relieve inflammation in patients with carditis. Diuretics and other cardiac medications are prescribed as necessary to treat heart failure. Severe heart valve dysfunction requires surgical correction but usually not until late adolescence or adulthood. Patients known to have carditis who must undergo dental or surgical procedures, esp. those involving instrumentation of the urinary tract, rectum, or colon, should receive additional antibiotic coverage on the day of the procedure and for several days thereafter.
During the acute phase, diversional activities that are not physically demanding are offered; family and friends are encouraged to visit; a tutor ought to be provided to help the child stay current with school work. The child and family are taught about the disease and treatment, and all diagnostic measures are described. The child and family are also taught about signs of recurrent streptococcal infection and of heart failure, which require immediate reporting and treatment. Health care professionals advise the patient about lifestyle and activity modifications, as well as the importance of taking prescribed antibiotics for the full course of treatment and prophylaxis. The child and family are informed about symptoms of hypersensitivity reaction to the antibiotic and are advised to stop the drug and immediately and to notify the primary care provider if a rash, fever, chills, or other signs of allergy develop anytime during the course of therapy. The importance of maintaining a salt-restricted diet and of adhering to treatment with diuretics, digoxin, or afterload-reducing drugs is emphasized for patients with congestive heart failure. The American Heart Association provides educational materials and current protocol for prevention of bacterial endocarditis, which is different from the RF regimen used to prevent recurrence. (800-AHA-USA1; www.americanheartr.org).
Rocky Mountain spotted fever
The organism causes fever, headache, myalgia, and a characteristic vasculitic rash. The rash appears several days after the other symptoms, first erupting on the wrists and ankles, then on the palms and soles. It is nonpruritic and macular and spreads to the legs, arms, trunk, and face. Disseminated intravascular coagulation or pneumonia may be serious complications. Tetracyclines are the drug of choice for treating this disease, but their use in pregnant women is not advised. Chloramphenicol may be substituted.
People living in areas with wood ticks should wear clothing that covers much of their bodies, including the neck, to prevent ticks from attaching to the skin. People who live in or travel to areas where ticks flourish should examine their scalps, skin, and clothing daily. Ticks should be grasped close to the mouthparts (not on the tick's body), as close to their point of attachment to their human host as possible. Pets should be examined regularly for ticks.
San Joaquin valley feverCoccidioidomycosis.
The disease is caused by more than 40 strains of group A, beta-hemolytic streptococci that elaborate an erythrogenic toxin.
After an incubation period of 1 to 7 days, children develop a fever, chills, vomiting, abdominal pain, and malaise. The pharynx and tonsils are swollen and red, and an exudate is present. Initially the tongue is white, with red, swollen papilla (white strawberry tongue); within 5 days, the white disappears, creating a red strawberry tongue. A red pinpoint rash that blanches on pressure with a sandpapery texture appears on the trunk (chest to neck, abdomen, legs and arms, sparing soles and palms) within 12 hr after the onset of fever. Cheeks are flushed, with pallor surrounding the mouth. Faint lines in the elbow creases, called Pastia's lines, are characteristic findings in full-blown disease. Over several days, sloughing of the skin begins, which lasts approx. 3 weeks.
The incubation period is probably never less than 24 hr. It may be 1 to 3 days, and rarely longer.
Scarlet fever is treated with 10 days of penicillin (or erythromycin for those allergic to penicillin). A full course of therapy is vital to decrease the risk of rheumatic fever or glomerulonephritis. In general, patients are taught to isolate the infected child from siblings until they have received penicillin for 24 hr.
Good hand hygiene techniques and proper disposal of tissues with purulent discharge are emphasized. The parents also are advised about the importance of administering the prescribed antibiotic as directed for the entire course of treatment even if the child looks and feels better. Because the child may be irritable and restless, the parents are taught how to encourage the child rest and relax. The child should be kept occupied with age-appropriate books, games, toys, and television.
three-day feverSandfly fever.
Gastrointestinal symptoms may develop within 1 hr of ingestion of S., but they usually subside before the onset of the typhoid fever symptoms. The disease is marked initially by a gradually increasing fever up to 104°F (40°C), anorexia, malaise, myalgia, headache, and slow pulse for about 7 days, followed by remittent fever up to 104°F (40°C) that usually occurs in the evening, a flat, rose-colored, fleeting rash (primarily on the abdomen), chills and sweating, increasing abdominal pain and distention, diarrhea or constipation, generalized lymphadenopathy, abdominal pain, anorexia, weakness, and exhaustion, cough and moist crackles, a tender abdomen with enlarged spleen, and delirium as the bacteria spread through the bloodstream. About 14 days after the infection begins, persistent fever and increased weakness and fatigue are present but usually subside by about 21 days into the illness although relapses may occur. Internal bleeding usually develops due to gastrointestinal ulcers, abscesses, and intestinal perforation; this may lead to hypovolemic shock. Damage to the liver and spleen is common. In approx. 10% of patients, typhoid fever is complicated by pneumonia, thrombophlebitis, osteomyelitis, septic arthritis, cerebral thrombosis, meningitis, myocarditis, or acute circulatory failure, which account for most of the deaths.
TheSalmonella enters the gastroinestinal tract, infects the biliary tract, invades the lymphoid tissues and walls of the ileum and colon, seeds the intestinal tract with millions of bacilli, and then gains access to the bloodstream. The disease is most commonly transmitted via the fecal-oral route through water or food contaminated by human feces, but it can be spread also by vomitus and oral secretions during the acute stage. Unlike S. enteritidis, it lives only in humans. A small percentage of people become carriers after recovering from infection.
Paratyphoid, pneumonia, dysentery, meningitis, smallpox, and appendicitis are among the differential diagnoses. Diagnostic points of value are the presence of rose spots, splenomegaly, leukopenia, the Widal serological test result, blood culture, and examination of feces for the presence of the causative organism. The best means of providing bacterial confirmation is through bone marrow culture. This method is successful even after patients have received antibiotics. See: paratyphoid fever
The disease is treated with ciprofloxacin or other antimicrobials based on organism sensitivity testing for 10 days. Dexamethasone is administered a few minutes before antibiotics are given in patients with shock or decreased levels of consciousness. Travelers should be aware that the most important safeguards are good food handling and water sanitation. The CDC recommends vaccination with typhoid vaccine, which is available in a live attenuated oral and parenteral form and intramuscular form for people traveling to developing countries in Africa, Asia, the Indian subcontinent, Central and South America, and the Caribbean. The oral vaccine is taken in multiple doses, with adults and children over 6 prescribed one capsule every other day for a total of four doses. Each dose should be taken 1 hr before a meal with cool water, and the capsules kept in the refrigerator. The one-dose parenteral vaccine may be used as an option for children 2 to 6, for the immunocompromised, and for those who might not adhere to the oral regimen. Vaccination protects only 50% to 80% of those vaccinated; therefore all travelers should protect themselves by following the adage, “boil it, cook it, peel it, or forget it.” The vaccinations should be completed at least 1 week before the trip; boosters are required every 2 to 5 yrs, depending on the type of vaccine. The vaccinations should not be given to patients who are taking mefloquine for malaria prophylaxis.
Contact precautions (handwashing, patient handwashing, glove and gown for disposal of feces or fecally contaminated objects) are followed until three consecutive stool cultures at 24-hr intervals are negative. Drugs are administered as prescribed, and the patient is observed for signs of complications, e.g., bacteremia, intestinal bleeding, and bowel perforation. During the acute phase, the temperature is monitored, but antipyretics are usually not administered because these mask the fever and can result in hypothermia; tepid sponge baths are also provided to promote vasodilation without shivering. The incontinent patient is cleansed, and high fluid intake (oral or intravenous) is encouraged to maintain adequate hydration. Fluid and electrolyte balance is monitored. Adequate nutrition is maintained. Rest is encouraged and oral hygiene and skin care provided. Abscesses may have to be drained surgically. The caregiver explains the importance of follow-up care and examination to ensure that the patient is not a carrier.
If the patient’s stool cultures are still positive at the time of discharge, he should be careful to use good hand hygiene, esp. after defecating, and should avoid preparation of uncooked foods, e.g., salads, for family members. Those who retain positive cultures (asymptomatic carrier state) should not be employed as food handlers. All cases of typhoid fever should be reported to the state health department. While traveling in endemic areas, people should be careful to buy bottled water or boil tap water for 5 Min before drinking, cooking, or brushing teeth with it; they should avoid ice in beverages and desserts and treats containing ice; eat well-cooked foods that are still steaming hot; avoid raw food, including garden or fruit salads. Before eating fresh fruit, people should wash their hands vigorously, wash the outside of the fruit, then peel the fruit, and they should avoid food sold by street vendors.
fever of unknown originAbbreviation: FUO
viral hemorrhagic feverAbbreviation: VHF
Wolhynia feverTrench fever.
There are two forms of yellow fever: urban, in which the transmission cycle is mosquito to human to mosquito; and sylvan, in which the reservoir is wild primates.
According to the World Health Organization, yellow fever afflicts about 200,000 people a year in Africa and South America, about 30,000 of whom die.
The virus is carried most commonly by the Aedes aegypti mosquito, but the A. vittatus and A. taylori mosquitoes also are important vectors.
After an incubation period of 3 to 6 days, patients develop high fever, headache, muscle aches, nausea and vomiting, and gastrointestinal disturbances such as diarrhea or constipation. In most patients, the disease resolves in 2 or 3 days, but in about 20% the fever returns after a 1 to 2 day remission and is accompanied by abdominal pain, severe diarrhea, gastrointestinal bleeding (producing a characteristic black vomit), anuria, and jaundice (whence the nameyellow fever) caused by liver infection. Rarely, there is progressive liver failure, renal failure, and death.
Yellow fever can be distinguished from dengue by the presence of jaundice, and from malaria by the absence of splenomegaly and low serum transaminase levels. Blood tests can identify the virus and its antigens, to which antibodies are formed in 5 to 7 days. A liver biopsy to isolate the virus is contraindicated because of the risk of bleeding.
As in many viral infections, the white blood cell count and platelet count may be suppressed. The erythrocyte sedimentation rate is rarely elevated. In severely ill patients with jaundice or renal failure, the serum bilirubin and creatinine levels are elevated.
Diagnosis on clinical grounds alone is almost impossible during the period of infection or in atypical mild forms. Yellow fever viral antigen or antibodies may be detected during the acute phase of the illness.
Preventive measures include mosquito control by screening, spraying with nontoxic insecticides, and destruction of breeding areas. Yellow fever vaccine prepared from the 17D strain is available for those who plan to travel or live in areas where the disease is endemic. The vaccine is contraindicated in infants under 4 months old and in women in the first trimester of pregnancy.
No antiviral agents are effective against the yellow fever virus. Fluids are given to maintain fluid and electrolyte balance, acetaminophen to reduce fever, and histamine blockers (e.g., ranitidine) or gastric acid pump inhibitors (e.g., omeprazole) to decrease the risk of gastrointestinal bleeding. Vitamin K is given if there is decreased production of prothrombin by the liver.
A live virus vaccine, which can be obtained only at designated vaccination centers, may be given to adults and children over 9 months old who are traveling to countries where yellow fever is endemic; the vaccine is effective for 10 years, after which a booster is required. Those who are immunosuppressed, pregnant, or allergic to eggs should not receive the vaccine. Travelers must determine if the country they are visiting has regulations about vaccination.
The prognosis is grave. Mortality is 5% in an area where the disease is endemic.