The federal organization charged with the responsibility of preventing and controlling infectious diseases for nearly 50 years. Established as the Communicable Disease Center in 1946 in Atlanta, Georgia, the CDC has led efforts to prevent MALARIA, polio, SMALLPOX, TOXIC SHOCK SYNDROME, LEGIONNAIRES' DISEASE, LYME DISEASE, hospital infections, and more recently, HIV/AIDS.
The center's responsibilities have expanded over the years and continue to evolve as the agency addresses other threats to health such as injuries and environmental and occupational hazards.
CDC supports surveillance, research, prevention efforts, and training in the area of infectious diseases through its NATIONAL CENTER FOR INFECTIOUS DISEASES.
In 1946, the mission of the agency was to protect Americans from germs, including TYPHUS, dengue, PLAGUE, malaria, and other infectious diseases. Today, its public mission is more than germs and ranges far beyond the U.S. border. Fighting disease today is a global effort using the talents of public health officials in every country, state, city, and county.
CDC epidemiologists continue to study microbes, from EBOLA in Africa to CRYPTOSPORIDIUM in Milwaukee, but the agency also combats health threats such as gun violence, poverty, and poor nutrition. In so doing, it has been criticized by those who believe the agency should stick to bugs and keep out of social policy.
Today, the CDC maintains 11 centers, institutes, and offices, including the National Center for Infectious Diseases; the National Center for Chronic Disease Prevention and Health Promotion; the National Center for Environmental Health; the National Center for Health Statistics; the National Center for HIV, STD and TB Prevention; the National Center for Injury Prevention and Control; the National Center for Occupational Safety and Health; the Epidemiology Program Office; the International Program Office; the Public Health Practice Program Office; and the National Immunization Program. It has about 6,900 employees in 170 locations in Anchorage; Atlanta; Cincinnati; Fort Collins, Colorado; Morgantown, West Virginia; Pittsburgh; Research Triangle Park,
North Carolina; San Juan; Spokane; and Washington, D.C.
The infectious disease center houses the famed maximum containment lab, one of only six in the world that can handle the most deadly organisms. High-tech filters keep the microbes inside from getting outside, and scientists at the lab wear spacesuits so microbes don't get in. The lab is locked, guarded, and under constant video surveillance. It is here that one of the last two samples of smallpox on earth survives. Smallpox was eradicated in 1977, in large part by activities supported by the CDC.
cephalosporins Antibiotics used to treat infections that occur in a variety of places in the body. They are usually used after other (less expensive) antibiotics have proven unsuccessful or when the infection is unusual. They can be used to treat most common URINARY TRACT INFECTIONS (UTIs) and upper respiratory infections such as PHARYNGITIS or TONSILLITIS. The cephalosporins include cefa-droxil, cefixime, cefuroxime axetil, cefaclor, and cephalexin. As with other antibiotics, some cephalosporins can treat certain bacterial infections better than others.
They can be taken either with food or on an empty stomach; in case of nausea, they should be taken with food or milk. Liquid suspensions should be refrigerated (except for cefixime suspension). Any unused suspension should be thrown away after 14 days.
These drugs should always be taken at the same time of day and for the exact amount of time prescribed, even if the patient feels better. The infection may return if the drug is not taken for the full amount of time. Heart or kidney complications can result if a STREPTOCOCCUS infection is not completely treated.
If the infection is caused by a type of bacteria that responds to cephalosporins, the symptoms should improve within a few days, although sometimes it may take longer to get relief. If the symptoms remain after all the drug is taken or gets worse during the medication period, a physician should be contacted.
Cephalosporins appear to be relatively safe to use during pregnancy. They do pass into breast milk in small amounts. The drugs also may cause diabetics to get a false-positive reading for glucose in the urine if copper sulfate urine test tablets are used.
Side effects Common side effects include mild stomach cramps, nausea, vomiting, and diarrhea that go away with time. Like other antibiotics, cephalosporins may encourage the growth of fungus normally found in the body, causing a sore tongue, mouth sores, or a vaginal yeast infection.
More serious (but rarer) side effects include allergic reactions ranging from itchy, red, or swollen skin rash to severe breathing problems and shock. A patient allergic to penicillin may also be allergic to a cephalosporin.
Specific allergic reaction to cephalosporin can include skin rash, joint pain, irritability, and fever. Another rare side effect is serious colitis, with severe watery diarrhea, stomach cramps, fever, weakness, and fatigue.
cerebrospinal fluid analysis See SPINAL TAP.
cereus A type of food poisoning caused by the Bacillus cereus bacteria, which multiplies in raw foods at room temperature. The B. cereus bacteria produces toxins most often found in steamed or fried rice. It is believed that poisoning with B. cereus is underreported because its symptoms are so similar to other types of food poisoning (especially staphylococcal and CLOSTRIDIUM PERFRINGENS poisoning).
Symptoms This bacterium produces two distinct types of food poisoning: The first features a short incubation period after eating tainted food (usually less than six hours), causing cramps and vomiting, and occasionally a short bout with diarrhea. Almost 80 percent of patients with these symptoms who test positive for B. cereus poisoning have eaten steamed or fried rice at Chinese restaurants.
The second type of B. cereus poisoning is very similar to C. perfringens poisoning; it appears within 8 to 24 hours after ingestion of tainted food and causes abdominal cramps and diarrhea with very little vomiting.
Treatment Treatment of both types of the disease is aimed only at making the patient comfortable. There are no medications which will shorten the course of the disease.
cestode See tapeworm.
Chagas disease A parasitic disease also known as American TRYPANOSOMIASIS transmitted by the bite of blood-sucking insects and rarely by blood transfusions. Named for 19th-century Brazilian physician Carlos Chagas, the disease is endemic in Central and South America, where it is recognized as a serious public health problem. Officials there rank their need to control this disease third, behind MALARIA and SCHISTOSOMIASIS.
More than a quarter of the total population in Central and South America are at risk, with more than a million cases each year. Of these, 45,000 people will die and up to 18 million people may be currently infected. Of these, 3 million may have already developed chronic complications, and more than 3 million are still in the incubation period. The disease is also known as Brazilian trypanosomiasis, Chagas-Cruz disease, Cruz trypanosomiasis, and South American trypanosomiasis.
Cause The disease is caused by the single-celled parasite Trypanosoma cruzi, very similar to those that cause sleeping sickness in Africa. The parasite infects bugs commonly known as "assassin bugs" or "cone-nosed bugs" (redu-viid); when the bugs defecate, the excrement includes the parasite, which can then enter a human through a break in the skin or through a mucous membrane. The parasites live in the bloodstream and can also affect a person's heart, intestines, or nervous system.
Symptoms The disease may occur in an acute or chronic form. The acute form (com mon in children, rare in adults) is marked by a lesion at the site of infection, together with fever, weakness, enlarged spleen and lymph nodes, facial and leg swelling, and rapid heartbeat. This form disappears on its own in about four months, unless complications (such as ENCEPHALITIS) set in.
About 10 to 20 years after the initial acute phase, incurable lesions of the disease develop. In addition, 27 percent of those infected develop a chronic heart disease problem. Six percent have chronic lesions in the digestive tract, and about 3 percent may have neurological problems. Patients with chronic disease become progressively sick and ultimately die, usually as a result of heart failure.
Treatment Nifurtimox is available from the CDC for the treatment of short-term Chagas disease. There is no accepted anti-para-sitic treatment for chronic illness.
Prevention The best prevention is to avoid potential reduviid habitats (mud, adobe, and thatch buildings, especially those with cracks or crevices). If this isn't feasible, infection may be prevented by spraying infested areas with insecticide, using fumi-gant canisters and insecticidal paints, and using bed nets. Housing improvements have also helped. In addition, screening blood donors at blood banks helps to control the spread of the disease via blood transfusions.
In 1991, the health ministers of Argentina, Bolivia, Brazil, Chile, Paraguay, and Uruguay began a program to eliminate Chagas disease by the end of this century. Since then, house infestation has declined 75 to 98 percent in some areas, according to the Pan American Health Organization.
Chagres fever An arbovirus infection transmitted to humans through the bite of the sandfly. The disease, which is rarely fatal, is most common in Central America. It was named after the Chagres River in Panama and is also known as Panama Fever.
Symptoms It is characterized by fever, headache, and muscle pain of the chest or abdomen, with nausea and vomiting, giddiness, weakness, photophobia (sensitivity to light), and pain on moving the eyes. It usually passes within a week.
Treatment Bed rest, fluids, and painkillers.
chancroid A sexually transmitted disease rarely seen in the past 30 years but making a comeback since the early 1980s. In some subtropical and tropical countries, the disease is more common than SYPHILIS. There have been outbreaks in the United States in large cities in California and parts of the south over the past 15 years.
Those most at risk are men under age 24, men and women with multiple sex partners, those with other STDs (especially syphilis), prostitutes and their customers, and those in tropical areas. However, any sexually active person can be infected with chancroid. It is more commonly seen in men than women, especially in uncircumcised males.
Cause Chancroid is caused by Hemophilus ducreyi, a rod-shaped bacterium that grows only in the absence of oxygen (much like GONORRHEA bacteria). The bacteria are transmitted from the draining sores of an infected person during sex. It is more likely to be transmitted to another person with a small cut or scratch in the genital area. The chances of transmission are greater if a person is very active sexually and doesn't practice personal hygiene.
Symptoms Symptoms usually appear within a week of infection. In some women, there may be a small pimple with a reddish base that will gradually fill with pus, opening and hollowing. Eventually, several ulcers usually appear that are very painful and soft. About a week later, the pelvic lymph gland on one side of the groin may become enlarged and painful. Other women don't notice sores but have pain during sex or while urinating. Still others never notice any symptoms, espe cially if ulcers are on the vaginal walls or cervix.
Men experience painful sores under the foreskin or on the underside of the penis that fill with pus and turn into ulcers. About 50 percent of infected men will go on to develop painful, enlarged lymph glands in the groin.
Both men and women are infectious until the lesions are completely healed, which may take up to two weeks. It is not possible to become immune.
Diagnosis The disease is diagnosed by symptoms and negative test results for other more common causes of genital ulcers (such as syphilis or HERPES). About half the time, microscopic examination of the fluid from a draining ulcer will correctly diagnose the infection; a culture of the drainage will provide a correct diagnosis, but the bacteria aren't easy to grow and many labs aren't equipped to do the test.
Treatment Antibiotics for both partners, such as azithromycin or erythromycin, or a shot of ceftriaxone, will cure the disease in about a week. Lesions and ulcers will heal in about two weeks.
Complications Untreated chancroid often causes ulcers on the genitals that may persist for weeks or months. The infection does not harm the fetus of a pregnant woman. However, the lesion does increase the chances of contracting HIV if a person has sex with an HIV-infected partner.
chicken pox (varicella) A common childhood infectious disease characterized by a rash and slight fever. It affects about 4 million children each year in the United States. About 90 percent of cases occur in children under age 10, primarily in winter and spring. Chicken pox is also known as varicella, after the virus that causes the disease (varicella zoster, or VZV). The name varicella dates to the 1700s and derives from the Latin term for "little pox."
Most people throughout the world have had the disease by age 10, and chicken pox is rare in adults. When it does occur after childhood, it is a far more serious illness.
Cause VZV is a member of the family of herpesviruses similar to the herpes simplex virus (HSV); the same virus that causes chicken pox also causes SHINGLES. Once a person has chicken pox, the virus stays in the body in a latent stage, hiding in the nerves of the lower spinal cord for the rest of the person's life. When reactivated (in old age or during times of stress), it can lead to shingles.
Symptoms The VZV virus, which is spread by airborne droplets, is extremely contagious. The incubation period ranges from 10 to 23 days. One to three weeks after exposure, a rash appears on the torso, face, armpits, upper arms and legs, inside the mouth, and sometimes in the windpipe and bronchial tubes, causing a dry cough.
The rash is made up of small red itchy spots that grow into fluid-filled blisters within a few hours. After several days, the blisters dry out and form scabs. New spots usually continue to form over four to seven days. Children usually have only a slight fever, but an adult may experience fever with severe pneumonia and breathing problems. Adults usually have higher fevers, more intense rash, and more complications than children.
The average child will have between 250 and 500 blisters over about five days; the more blisters the child has, the harder the body has to fight to make enough antibodies to destroy the virus. The fight between the virus and the immune system causes fevers, fatigue, and poor appetite. Those who catch the disease from a sibling instead of a classmate usually have a more severe illness, from 300 to 5,000 blisters. This is because the close contact at home causes a much larger amount of virus to enter the system.
The patient is infectious from five days before the rash erupts until all the blisters are completely healed, dried, and scabbed over. This can take from 6 to 10 days after the rash appears.
Complications In children, these may include bacterial infection and, rarely, Reye's syndrome, or in even rarer cases, ENCEPHALITIS. Immunocompromised patients who are susceptible to VZV are at high risk for having severe varicella infections with widespread lesions.
Between 40 and 200 people die every year in the United States; half are previously healthy people and the other half are those with impaired immune systems.
Treatment In most cases, rest is all that is needed for children, who usually recover within 10 days. Adult patients take longer to recover. Acetaminophen may reduce the fever, and calamine lotion, baking soda baths, and oral antihistamines ease the itch. Compresses can dry weeping lesions. Never give aspirin to a child who has flulike symptoms or has been exposed to (or has recently recovered from) chicken pox; aspirin in these cases has been linked to Reye's syndrome.
The drug acyclovir may be prescribed for chicken pox patients who are not pregnant and who have any of the following: chronic skin or lung disorders, required regular administration of aspirin or steroids, overwhelming chicken pox, a compromised immune system (such as AIDS). Unlike the herpes-simplex viruses, VZV is relatively resistant to acyclovir, and doses required for treatment are much larger and must be administered intravenously. While the drug may shorten the length of the illness and lessen symptoms, its high cost and marginal effectiveness have prompted the American Academy of Pediatrics not to recommend it as a routine treatment.
Scratching should be avoided, as it may lead to secondary bacterial infection and increase the chance of scarring.
If possible, don't bring a child with suspected chicken pox into the doctor's office where others will be exposed to the disease; it can be very dangerous to newborns or those with suppressed immune systems. The virus can be spread both through the air and by direct contact with an infected individual. Instead, call the physician on the phone and describe the symptoms, if you suspect it could be chicken pox.
Prevention An infected child should not play with anyone at risk for serious disease from chicken pox, and should be kept away from infants younger than six weeks of age. They should also stay away from crowded public places where high-risk people might congregate.
Passive immunity that offers only temporary protection is available for high-risk susceptible patients via varicella-zoster immune globulin. This can abort or modify infection if administered within three days of exposure. Passive immunization is the administration of antibodies from donor's blood; since a person's blood is completely replaced every three months, the immunity lasts only that long.
There is some disagreement about the value of giving passive immunity to susceptible pregnant women in the first trimester; some fear that while it may prevent symptoms, the virus may still be in the mother's blood and thereby infect the fetus.
Vaccine Active immunization is provided by a vaccination that stimulates the immune system to make protective antibodies that last for life. The chicken pox vaccine is made from a live weakened virus that works by creating a mild infection similar to natural chicken pox, but without the related problems. The mild infection spurs the body to develop an immune response to the disease. These defenses are then ready when the body encounters the natural virus.
The development of a vaccine against the disease has been studied and used in clinical trials with children and adults in the United States since the early 1980s; it has been used in Japan for some time. It protects 70 to 90 percent of children, but it doesn't work well on adults.
In March 1995, the U.S. Food and Drug Administration licensed the vaccine for gen eral use; the American Academy of Pediatrics has recommended the vaccine for all children and teenagers. Children younger than 12 require one dose; children 13 and over require two shots four to eight weeks apart.
Not all physicians agree on the benefits of the vaccine for healthy children, however. While proponents of the vaccine point out that suffering children and parents' considerable lost work time are good reasons to use the vaccine, some researchers are uncertain about how long the vaccine confers immunity. Critics warn that if the vaccine wears off in later life, the adult could then be vulnerable to infection at an age when chicken pox can be serious.
Other experts are concerned about possible side effects of the vaccine. Since the chicken pox virus belongs to the herpesvirus group, there are concerns that the vaccine might cause periodic reactivation of the varicella zoster virus, causing shingles.
Recent reports also note that the vaccine may cause birth defects when given to pregnant women or to women who conceive within three months after vaccination. Doctors already know that having chicken pox while pregnant increases the risk of bearing a child with birth defects. To determine the link (if any) between birth defects and immunization of mothers, the U.S. Centers for Disease Control and Merck (the company that makes Varivax, one of the vaccines) have set up a registry of women who receive the vaccine while pregnant or in the three months before conception. Patients and health care workers should report Varivax vaccinations to this group at 1-800-986-8999. Reports may also be mailed to Merck Research Labs, Worldwide Product Safety & Epidemiology, BLA-31, West Point, PA 19486.
For a free brochure, "What Parents Need to Know About Chickenpox," send a SASE to the National Foundation for Infectious Diseases, 4733 Bethesda Ave., Suite 750, Bethesda, MD 20814.
chiggers The larva of Trombicula mites, which, iri summer, live in tall grass and weeds and can stick to the skin and cause irritation and severe itching. Chiggers are also called harvest mites or red mites. The swelling they cause may turn into an itchy blister that can persist for weeks.
chikungunya fever An infectious disease taken from the Swahili for "that which bends up," in reference to the stooped posture of patients afflicted with the severe joint pain associated with this disease. The disease was first recognized in epidemic form in East Africa in 1952-53.
The virus is found in eastern, southern, western, and central Africa and southeastern Asia, where it has caused illnesses in thousands of people. Epidemics have occurred in the Philippines, Thailand, Cambodia, Vietnam, India, Myanmar (Burma), and Sri Lanka.
Cause The A. aegypti mosquitoes carry the chikungunya virus, which they pass on to humans when they bite. Epidemics are sustained by human-mosquito-human transmission, similar to the way that epidemics of dengue fever and urban yellow fever are maintained.
Symptoms The fever is characterized by sudden onset of chills and fever, headache, nausea and vomiting, joint pain, and rash that lasts up to a week. While chikungunya is often confused with dengue fever, chikungunya has a shorter period of fever, persistent joint pain, and lack of fatalities.
Treatment There is no specific treatment; painkillers can lower fever and ease joint pain.
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