B
Catalog of Emerging Infectious Disease Agents

The material in this appendix is provided for those who are interested in more detail on each of the agents considered by this committee to be emerging or reemerging and listed earlier in the report (see Table 2-1). It is a brief summary of information compiled from three sources, listed below, as well as additional data provided by committee and task force members, and other experts. The individual summaries are separated into three sections, corresponding to the categorizations of the earlier charts.

Benenson, Abram S. (ed.) 1990. Control of Communicable Diseases in Man, 15th edition. Washington, D.C.: American Public Health Association.

Mandell, Gerald L.; Douglas, R. Gordon, Jr.; and Bennett, John E. (eds.) 1990. Principles and Practice of Infectious Disease, 3rd edition. New York: Churchill Livingstone.

Wilson, Mary E. 1991. A World Guide to Infections: Diseases, Distribution, Diagnosis. New York: Oxford University Press.

EMERGENT BACTERIA, RICKETTSIAE, AND CHLAMYDIAE

Aeromonas

DISEASE(S) AND SYMPTOMS

Aeromonad gastroenteritis

  • acute diarrhea lasting several days, abdominal pain

  • vomiting, fever, and bloody stools may be present

Cellulitis, wound infection, and septicemia

  • septicemia occurs most often in predisposed patients



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Emerging Infections: Microbial Threats to Health in the United States B Catalog of Emerging Infectious Disease Agents The material in this appendix is provided for those who are interested in more detail on each of the agents considered by this committee to be emerging or reemerging and listed earlier in the report (see Table 2-1). It is a brief summary of information compiled from three sources, listed below, as well as additional data provided by committee and task force members, and other experts. The individual summaries are separated into three sections, corresponding to the categorizations of the earlier charts. Benenson, Abram S. (ed.) 1990. Control of Communicable Diseases in Man, 15th edition. Washington, D.C.: American Public Health Association. Mandell, Gerald L.; Douglas, R. Gordon, Jr.; and Bennett, John E. (eds.) 1990. Principles and Practice of Infectious Disease, 3rd edition. New York: Churchill Livingstone. Wilson, Mary E. 1991. A World Guide to Infections: Diseases, Distribution, Diagnosis. New York: Oxford University Press. EMERGENT BACTERIA, RICKETTSIAE, AND CHLAMYDIAE Aeromonas DISEASE(S) AND SYMPTOMS Aeromonad gastroenteritis acute diarrhea lasting several days, abdominal pain vomiting, fever, and bloody stools may be present Cellulitis, wound infection, and septicemia septicemia occurs most often in predisposed patients

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Emerging Infections: Microbial Threats to Health in the United States DIAGNOSIS identification of the organism in patient's feces or in wound secretions INFECTIOUS AGENT Aeromonas hydrophila, A. veronii (biovariant sobria), A. caviae other species of Aeromonas (A. jandaei, A. trota, A. schubertii, and A. veronii biovariant veronii) have also been associated with human disease the natural habitats of Aeromonas bacteria are water and soil MODE OF TRANSMISSION ingestion of contaminated water entry of organism through a break in the skin DISTRIBUTION presence of organism in clinical specimens has been documented in the Americas, Africa, Asia, Australia, and Europe distribution is worldwide INCUBATION PERIOD undefined; probably 12 hours to several days organism may persist for weeks to months in gastrointestinal tract TREATMENT antibiotics: trimethoprim-sulfamethoxazole, the quinolones, aminoglycosides, and tetracyclines organisms tend to be resistant to penicillins and cephalosporins PREVENTION AND CONTROL proper treatment of drinking water and monitoring of well water predisposed individuals should avoid aquatic environments FACTORS FACILITATING EMERGENCE predisposition (e.g., immunosuppression) improved technology for detection and differentiation increased awareness Borrelia burgdorferi DISEASE(S) AND SYMPTOMS Lyme disease distinctive skin lesion (erythema migrans) at site of tick bite that

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Emerging Infections: Microbial Threats to Health in the United States appears as a red papule and expands in an annular fashion to at least 5 cm. in diameter fatigue, headache, stiffness, myalgia, lymphadenopathy neurologic (10 to 15% of patients) and cardiac (6 to 10% of patients) abnormalities may develop weeks to months after lesion months to years after onset, swelling and pain in large joints may develop and persist for years ("Lyme arthritis") DIAGNOSIS currently based on clinical findings and serologic tests tests are poorly standardized and are insensitive during the first several weeks of infection INFECTIOUS AGENT Borrelia burgdorferi, a spirochete bacterium MODE OF TRANSMISSION bite of an Ixodes tick; transmission does not occur until tick has fed for several hours wild rodents (especially the white-footed mouse) and white-tailed deer maintain transmission cycle; tick depends on deer to reproduce and feeds on mice to become infected no evidence for person-to-person transmission transplacental transmission has been documented DISTRIBUTION in the United States: Atlantic coastal states from Maine to Georgia; upper midwestern states (concentrated in Minnesota and Wisconsin); California and Oregon abroad: Europe, Canada, Japan, Australia, China, and the Commonwealth of Independent States INCUBATION PERIOD erythema migrans appears 3 to 32 days after tick exposure TREATMENT oral antibiotics (tetracycline, doxycycline, amoxicillin, erythromycin) for 10 to 30 days high-dose intravenous penicillin or ceftriaxone is used if neurologic abnormalities develop novel drug regimens are undergoing evaluation

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Emerging Infections: Microbial Threats to Health in the United States PREVENTION AND CONTROL avoidance of tick-infested areas; securing of clothing at entry points (ankles, cuffs, etc.); application of tick repellent to outer clothing host (mice and deer) reduction FACTORS FACILITATING EMERGENCE reforestation and consequent proliferation of deer housing development in wooded areas Campylobacter jejuni DISEASE(S) AND SYMPTOMS Campylobacteriosis, campylobacter enteritis abdominal pain, diarrhea, fever illness typically lasts two to five days prolonged illness and relapses may occur infection is asymptomatic in many cases DIAGNOSIS detection of organism in the stool INFECTIOUS AGENT Campylobacter jejuni, a bacterium other species within the genus Campylobacter have been associated with similar disease MODE OF TRANSMISSION ingestion of contaminated food, water, or milk fecal-oral spread from infected person or animal DISTRIBUTION worldwide organism has a vast reservoir in animals INCUBATION PERIOD AND COMMUNICABILITY incubation period is 2 to 5 days disease is communicable throughout the course of infection TREATMENT rehydration and replacement of electrolytes antibiotic therapy is used in some cases, though it rarely shortens duration of symptoms

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Emerging Infections: Microbial Threats to Health in the United States PREVENTION AND CONTROL chlorination of water proper cooking of foods (particularly poultry) and pasteurization of milk handwashing after animal contact FACTORS FACILITATING EMERGENCE improved recognition of the organism an increase in poultry consumption in recent years Chlamydia pneumoniae (TWAR Strain) DISEASE(S) AND SYMPTOMS TWAR infection, TWAR pneumonia fever, myalgias, cough, sore throat, sinusitis illness is usually mild, but recovery is slow; cough tends to last for more than two weeks DIAGNOSIS isolation of organism from throat or sputum INFECTIOUS AGENT Chlamydia pneumoniae (TWAR), a chlamydia strain name is derived from designation of first two isolates, TW-183 from Taiwan and AR-39 (acute respiratory) MODE OF TRANSMISSION person to person; thought to be acquired by inhalation of infective organisms possibly by direct contact with secretions of an infected person DISTRIBUTION probably worldwide the majority of cases have occurred in North America, Asia, and Europe INCUBATION PERIOD AND COMMUNICABILITY 1 to 4 weeks period of communicability is unknown but presumed to be long, based on duration of documented outbreaks

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Emerging Infections: Microbial Threats to Health in the United States TREATMENT antibiotics: tetracycline or erythromycin PREVENTION AND CONTROL avoidance of overcrowding in living and sleeping quarters FACTORS FACILITATING EMERGENCE increased recognition Chlamydia trachomatis DISEASE(S) AND SYMPTOMS Genital chlamydia urethritis in males, mucopurulent cervicitis in females (opaque discharge, itching, burning upon urination) asymptomatic infection can occur in women, infertility and ectopic pregnancy can result from chronic infection DIAGNOSIS identification of organism on intraurethral or endocervical swab material INFECTIOUS AGENT Chlamydia trachomatis, a bacterium MODE OF TRANSMISSION sexual intercourse DISTRIBUTION worldwide; recognition has increased in the United States, Canada, Europe, and Australia over the past two decades INCUBATION PERIOD AND COMMUNICABILITY incubation period is poorly defined, probably 7 to 14 days or longer period of communicability is unknown TREATMENT oral antibiotics: tetracycline, doxycycline, or quinolone PREVENTION AND CONTROL condom use during sexual intercourse prophylactic treatment of sexual partners

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Emerging Infections: Microbial Threats to Health in the United States FACTORS FACILITATING EMERGENCE probably increased sexual activity Clostridium difficile DISEASE(S) AND SYMPTOMS Clostridium difficile colitis antibiotic-associated colitis pseudomembranous colitis watery diarrhea, bloody diarrhea, abdominal pain DIAGNOSIS detection of C. difficile toxin in the stool visualization of characteristic pseudomembranes during endoscopy of colon INFECTIOUS AGENT Clostridium difficile, a toxin-producing bacterium MODE OF TRANSMISSION fecal-oral transmission acquisition of organism from the environment DISTRIBUTION worldwide an estimated 3 percent of healthy adults carry the organism in the gut INCUBATION PERIOD AND COMMUNICABILITY colitis typically begins during, or shortly after, antibiotic administration (changes in gastrointestinal tract flora due to antibiotic use allow proliferation of the organism and its production of toxins) TREATMENT discontinuation of aggravating antibiotic treatment if possible antibacterial agents: metronidazole, vancomycin, bacitracin PREVENTION AND CONTROL avoidance of unnecessary antibiotic administration FACTORS FACILITATING EMERGENCE immunosuppression increased recognition

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Emerging Infections: Microbial Threats to Health in the United States Ehrlichia chaffeensis DISEASE(S) AND SYMPTOMS Ehrlichiosis fever, malaise, headache, lymphadenopathy, anorexia fever usually lasts 2 weeks meningitis is occasionally reported DIAGNOSIS poor; few laboratories have antigen for immunoflourescence serology by surrogate E. canis antigen INFECTIOUS AGENT Ehrlichia chaffeensis, a rickettsia reservoir is unknown MODE OF TRANSMISSION an undetermined tick transmits the agent (possibly the widely distributed species, Amblyomma americanum) no evidence of person-to-person transmission although other types of Ehrlichia are transmitted to dogs by the brown dog tick, dogs have not been found to be reservoirs of human disease DISTRIBUTION Southern and mid-Atlantic United States INCUBATION PERIOD unknown; possibly 1 to 3 weeks TREATMENT oral antibiotics: tetracycline PREVENTION AND CONTROL avoidance of tick-infested areas; securing of clothing at entry points (ankles, cuffs, etc.); application of tick repellent to outer clothing FACTORS FACILITATING EMERGENCE organism is probably newly recognized possible increase in reservoir and vector populations

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Emerging Infections: Microbial Threats to Health in the United States Escherichia coli O157:H7 DISEASE(S) AND SYMPTOMS Hemorrhagic colitis; hemolytic uremic syndrome DIAGNOSIS identification of antibodies to O157:H7 serotype INFECTIOUS AGENT Escherichia coli O157:H7, a bacterium one of several ''EHEC" (enterohemorrhagic E. coli) strains EHEC bacteria produce potent cytotoxins, called Shiga-like toxins 1 and 2 cattle are believed to be the reservoirs of EHECs MODE OF TRANSMISSION ingestion of contaminated food, typically poorly cooked beef and raw milk transmission by direct contact may occur in high-risk populations DISTRIBUTION probably worldwide most cases have occurred in North America and Europe INCUBATION PERIOD 12 to 60 hours TREATMENT oral replacement of fluids and electrolytes (intravenous if necessary) PREVENTION AND CONTROL proper cooking of meat hand washing proper sewage and water treatment FACTORS FACILITATING EMERGENCE probably spread of a bacterial virus carrying the gene for Shiga-like toxin production into the otherwise unremarkable host, E. coli O157:H7

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Emerging Infections: Microbial Threats to Health in the United States Haemophilus influenzae biogroup aegyptius DISEASE(S) AND SYMPTOMS Brazilian purpuric fever irritation of the conjunctivae of the eyes, followed by edema of the eyelids, photophobia, and mucopurulent discharge high fever appears 3 to 15 days after conjunctivitis, along with vomiting and purpura case fatality rate is 70 percent, with death occurring shortly after onset of systemic symptoms disease was first recognized in 1984 DIAGNOSIS microscopic examination of bacterial culture of conjunctival discharge detection of organism in the blood INFECTIOUS AGENT Haemophilus influenzae biogroup aegyptius, a bacterium MODE OF TRANSMISSION contact with the conjunctival or respiratory discharges of infected persons eye flies are suspected mechanical vectors DISTRIBUTION nearly all reported cases of Brazilian purpuric fever have occurred in southern Brazil (most cases have been in young children) one case was reported from Australia INCUBATION PERIOD AND COMMUNICABILITY incubation period is unknown disease is communicable for the duration of active infection TREATMENT high-dose intravenous antibiotics: ampicillin, chloramphenicol PREVENTION AND CONTROL prompt treatment of patients and close contacts avoidance of exposure to eye flies possibly vector control FACTORS FACILITATING EMERGENCE possibly an increase in bacterial virulence due to mutation

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Emerging Infections: Microbial Threats to Health in the United States Helicobacter pylori DISEASE(S) AND SYMPTOMS dyspepsia, abdominal pain chronic infection may result in peptic ulcer, gastric cancer DIAGNOSIS detection of antibodies in blood by ELISA biopsy and culture INFECTIOUS AGENT Helicobacter pylori, a bacterium (formerly known as Campylobacter pylori) MODE OF TRANSMISSION unknown; some studies suggest a zoonotic origin DISTRIBUTION worldwide INCUBATION PERIOD AND COMMUNICABILITY unknown TREATMENT antibiotics: metronidazole, ampicillin, tetracycline bismuth PREVENTION AND CONTROL none FACTORS FACILITATING EMERGENCE increased recognition Legionella pneumophila DISEASE(S) AND SYMPTOMS Legionnaires' disease, Pontiac fever initial symptoms include malaise, headache, myalgias, fever, chills, and cough fever rises rapidly within 1 day, and may precede the development of pulmonary symptoms

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Emerging Infections: Microbial Threats to Health in the United States INFECTIOUS AGENT species of the fungus, Candida MODE OF TRANSMISSION contact with secretions or excretions of mouth, skin, or vagina of infected persons, or with the feces of infected persons passage from mother to infant during childbirth endogenous spread disseminated candidiasis can originate from indwelling urinary catheters and percutaneous intravenous catheters DISTRIBUTION worldwide the fungus (C. albicans) is often part of the normal human flora INCUBATION PERIOD AND COMMUNICABILITY incubation period is variable infection is presumably communicable while lesions are present TREATMENT topical antifungal agents: imidazole, nystatin oral clotrimazole troches or nystatin suspension is effective for treatment of oral thrush oral ketoconazole is effective for treatment of infected skin and mucous membranes of the mouth, esophagus, and vagina PREVENTION AND CONTROL detection and treatment of infection early to prevent systemic spread detection and treatment of vaginal candidiasis during third trimester of pregnancy to prevent neonatal thrush amelioration of underlying causes of infection (e.g., removal of indwelling venous catheters) FACTORS FACILITATING EMERGENCE immunosuppression medical management (catheters) antibiotic use

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Emerging Infections: Microbial Threats to Health in the United States Crytococcus DISEASE(S) AND SYMPTOMS Cryptococcosis a fungal infection, usually presenting as a subacute or chronic meningitis skin may show acneiform lesions, ulcers, or subcutaneous tumor-like masses infection of lungs, kidneys, prostate, bone, and liver may occur untreated cryptococcal meningitis terminates fatally within several months DIAGNOSIS visualization of fungus on microscopic examination of cerebrospinal fluid tests for antigen in serum and cerebrospinal fluid INFECTIOUS AGENT Crytococcus species, typically C. neoformans, a fungus fungus grows saprophytically in external environment (can be isolated from the soil in many parts of the world) fungus can consistently be isolated from old pigeon nests and pigeon droppings MODE OF TRANSMISSION presumably by inhalation waterborne transmission can also occur not transmitted directly from person to person or between animals and people DISTRIBUTION worldwide infection occurs mainly in adults disseminated or central nervous system cryptococcosis is often a sentinel infection for HIV-infected persons infection also occurs in dogs, cats, horses, cows, monkeys, and other animals INCUBATION PERIOD unknown

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Emerging Infections: Microbial Threats to Health in the United States TREATMENT antifungal agents: amphotericin B is effective in many cases very difficult to cure in persons with HIV disease PREVENTION AND CONTROL careful removal (preceded by chemical decontamination and wetting with water or oil to prevent aerosolization) of large accumulations of pigeon droppings FACTORS FACILITATING EMERGENCE immunosuppression Cryptosporidium DISEASE(S) AND SYMPTOMS Cryptosporidiosis a parasitic infection of the epithelial cells of the gastrointestinal, biliary, and respiratory tracts of man, as well as other vertebrates (birds, fish, reptiles, rodents, cats, dogs, cattle, and sheep) symptoms of infection include watery diarrhea, nausea, vomiting, malaise, myalgias, and, in about half of cases, fever symptoms usually come and go, but subside in fewer than 30 days in most healthy, immunocompetent persons immunocompromised persons may not be able to clear the parasite, with disease becoming prolonged and fulminant and contributing to death DIAGNOSIS identification of oocysts in fecal smears identification of parasites in intestinal biopsies INFECTIOUS AGENT Cryptosporidium, a protozoan parasite MODE OF TRANSMISSION fecal-oral spread from contaminated fingers, food, and water occasional transmission by aerosolized organisms has been reported DISTRIBUTION worldwide; organism has been found wherever sought

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Emerging Infections: Microbial Threats to Health in the United States INCUBATION PERIOD AND COMMUNICABILITY probably 1 to 12 days oocysts, the infectious stage of the parasite, appear in the stool from the onset of symptoms to several weeks after symptoms resolve outside the body, oocysts can remain infective for 2 to 6 months in a moist environment TREATMENT fluid and electrolyte replacement; nutritional support effective, specific therapy has not yet been identified PREVENTION AND CONTROL careful handling of animal excreta hand washing by those in contact with calves and other animals with diarrhea effective water treatment FACTORS FACILITATING EMERGENCE development near watershed areas immunosuppression Giardia lamblia DISEASE(S) AND SYMPTOMS Giardiasis infection of the upper small intestine frequent diarrhea, bloating, abdominal cramps, fatigue, low-grade fever, malaise, and weight loss symptoms typically subside after 2 to 3 weeks, but chronic or relapsing diarrhea may occur DIAGNOSIS identification of cysts or trophozoites in feces or of trophozoites in biopsy material from the small intestine INFECTIOUS AGENT Giardia lamblia, a protozoan parasite MODE OF TRANSMISSION ingestion of cysts in fecally contaminated food or water

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Emerging Infections: Microbial Threats to Health in the United States direct person-to-person spread via hand-to-mouth transfer of cysts from an infected individual (especially in day care centers and chronic care institutions) DISTRIBUTION worldwide; causes both sporadic outbreaks and epidemics INCUBATION PERIOD AND COMMUNICABILITY incubation period ranges from 3 days to 6 weeks; usually 1 to 3 weeks infected persons can be a source of infection for as long as they carry the organism TREATMENT antiparasitic agents: quinacrine, metronidazole, furazolidine PREVENTION AND CONTROL avoidance of drinking untreated surface water disposal of feces in a sanitary manner FACTORS FACILITATING EMERGENCE infection in the animal population (beavers and dogs) capability of the organism to survive in water supply systems that use superficial water immunosuppression international travel Microsporidia DISEASE(S) AND SYMPTOMS Microsporidiosis chronic gastroenteritis, diarrhea, and wasting in patients with HIV disease conjunctivitis, scleritis, diffuse punctate keratopathy, and corneal ulceration have also been reported, primarily in patients with HIV disease other findings include fever, hepatitis, muscle weakness, and neurologic changes DIAGNOSIS requires electron microscopy of biopsy specimen

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Emerging Infections: Microbial Threats to Health in the United States INFECTIOUS AGENT protozoan parasites from the phylum Microspora (phylum consists of about 80 genera, of which at least four cause human disease: Encephalitozoon, Enterocytozoon, Nosema, and Pleistophora) microsporidia typically infect animals and have only recently been recognized as human pathogens MODE OF TRANSMISSION unknown; probably by ingestion of contaminated food or water spores of some species survive up to 4 months in the environment DISTRIBUTION worldwide human infections have been reported from Africa, North and South America, Asia, and Europe the majority of reported patients have been immunosuppressed INCUBATION PERIOD AND COMMUNICABILITY unknown TREATMENT no clearly effective therapy is available some patients have improved with antiparasitic drugs pyrimethamine and metronidazole PREVENTION AND CONTROL unknown at this time FACTORS FACILITATING EMERGENCE immunosuppression parasite is newly recognized Plasmodium DISEASE(S) AND SYMPTOMS Malaria fever, headache, nausea, vomiting, diarrhea, myalgias, and malaise in 30 to 40 percent of acute cases, the spleen is enlarged and liver may be tender respiratory and renal failure, shock, acute encephalopathy, pulmonary

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Emerging Infections: Microbial Threats to Health in the United States and cerebral edema, coma, and death may result from severe cases (especially P. falciparum infections) duration of an untreated primary attack ranges from 1 week to 1 month or longer; relapses of febrile illness can occur at irregular intervals for up to 2 to 5 years chronically infected persons develop hyperreactive malarial splenomegaly or nephrotic syndrome case fatality rates among untreated children and nonimmune adults exceed 10 percent DIAGNOSIS identification of characteristic intraerythrocytic parasites on a blood smear INFECTIOUS AGENT Plasmodium falciparum, P. vivax, P. ovale, and P. malariae protozoan parasites with an asexual cycle in humans and sexual cycle in mosquitoes MODE OF TRANSMISSION bite of an infective mosquito not directly transmitted from person to person transmission by transfusion and transplacental transmission account for a small percentage of infections DISTRIBUTION indigenous malaria persists in about 100 tropical and subtropical countries disease occurs in Africa, Asia, Mexico, Central and South America, the Caribbean, the South Pacific Islands, and in parts of the Commonwealth of Independent States worldwide, an estimated 200 to 300 million infections occur annually, with 2 to 3 million deaths (most are from P. falciparum) chloroquine-resistant P. falciparum strains have been reported from endemic areas in Africa, Asia, and the Americas; continued spread of resistance is expected INCUBATION PERIOD 10 to 30 days, depending on virus strain transmission by transfusion can occur as long as asexual forms of the parasite remain in the circulating blood (for P. malariae, this can be more than 40 years)

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Emerging Infections: Microbial Threats to Health in the United States TREATMENT chloroquine is drug of choice unless resistant P. falciparum is suspected quinine plus tetracycline, pyrimethamine and sulfadiazine/clindamycin, or mefloquine should be used for resistant P. falciparum strains resistance of P. falciparum malaria to all antimalarials has been reported; in these cases, combination therapy and repeated courses of treatment may be necessary PREVENTION AND CONTROL mosquito control chemoprophylactic regimens (be sure to obtain updated information) FACTORS FACILITATING EMERGENCE urbanization changing parasite biology environmental changes drug resistance air travel Pneumocystis carinii DISEASE(S) AND SYMPTOMS Pneumocystis carinii pneumonia progressive dyspnea, tachypnea, and cyanosis pneumonia is often fatal in malnourished, chronically ill, and premature infants, as well as in adults who are immunocompromised DIAGNOSIS demonstration of the organism in material from bronchial brushings, open lung biopsy, and lung aspirates no satisfactory culture method or serologic test is in routine use at present INFECTIOUS AGENT Pneumocystis carinii, a protozoan parasite (with genetic similarities to a fungus)

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Emerging Infections: Microbial Threats to Health in the United States MODE OF TRANSMISSION unknown in man (airborne transmission has been reported in rats) subclinical infection may be common DISTRIBUTION worldwide the disease affects 60 percent of patients with human immunodeficiency virus (HIV) disease INCUBATION PERIOD AND COMMUNICABILITY unknown; symptoms typically appear 1 to 2 months after onset of immunosuppression period of communicability is unknown TREATMENT cotrimoxazole is first choice drug; pentamidine is also used PREVENTION AND CONTROL prophylaxis with cotrimoxazole in immunocompromised patients FACTORS FACILITATING EMERGENCE immunosuppression Strongyloides stercoralis DISEASE(S) AND SYMPTOMS Strongyloidiasis transient rash at site of parasite penetration into the skin coughing and wheezing may develop when parasite passes through lungs abdominal symptoms occur when adult female parasite invades intestinal mucosa abdominal pain, diarrhea, nausea can be chronic and relapsing in the immunocompromised host, infection may become disseminated, resulting in wasting, pulmonary involvement, and death DIAGNOSIS identification of larvae in stool specimens or duodenal aspirates

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Emerging Infections: Microbial Threats to Health in the United States INFECTIOUS AGENT Strongyloides stercoralis, a nematode larvae penetrate skin, enter blood vessels, travel to lungs, migrate up respiratory tree to the pharynx, where they enter the gastrointestinal tract (where the female lays eggs) MODE OF TRANSMISSION penetration of skin or mucous membrane by infective larvae (usually from fecally contaminated soil) free-living form of the parasite can be maintained in the environment (soil) for years transmission also occurs via oral-anal sexual activities DISTRIBUTION worldwide; most common in tropical and subtropical areas INCUBATION PERIOD AND COMMUNICABILITY larvae can be found in stool 2 to 3 weeks after exposure infection is potentially communicable as long as living worms remain in the intestine TREATMENT antiparasitic agents: thiabendazole, albendazole, ivermectin PREVENTION AND CONTROL disposal of feces in a sanitary manner avoidance of skin-soil contact in endemic areas FACTORS FACILITATING EMERGENCE international travel immunosuppression Toxoplasma gondii DISEASE(S) AND SYMPTOMS Toxoplasmosis a systemic protozoan disease, frequently present as an acute mononucleosis-like disease (malaise, myalgias, fever) immunocompromised persons tend to have severe primary infection with pneumonitis, myocarditis, meningoencephalitis, hepatitis, chorioretinitis, or some combination of these

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Emerging Infections: Microbial Threats to Health in the United States congenital toxoplasmosis causes chorioretinitis, fever, jaundice, rash, and brain damage DIAGNOSIS based on clinical signs, as well as on demonstration of the organism in body tissues or fluids INFECTIOUS AGENT Toxoplasma gondii, a protozoan parasite cats and other felines are reservoirs intermediate hosts are sheep, goats, rodents, swine, cattle, chicken, and birds MODE OF TRANSMISSION ingestion of oocysts (on fingers or in food contaminated with cat feces) or cysts in raw or undercooked meat transplacental transmission transmission through blood transfusion and tissue transplantations has been reported not directly transmitted from person to person (except in utero) DISTRIBUTION worldwide prevalence of seropositivity is higher in warm, humid climates and is influenced by presence of cats and by eating habits INCUBATION PERIOD 1 to 3 weeks TREATMENT antiparasitic agents (pyrimethamine plus sulfadiazine) for persons with severe disease no treatment is needed for most healthy, immunocompetent hosts PREVENTION AND CONTROL thorough cooking of meats daily disposal of cat feces and disinfection of litter pans (pregnant women should avoid contact with litter pans) thorough hand washing after handling of raw meat prophylactic treatment for patients with HIV disease FACTORS FACILITATING EMERGENCE immunosuppression increase in cats as pets