Emerging Infections Microbial Threats to Health in the United States (1992) / Chapter Skim
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B CATALOG OF EMERGING INFECTIOUS DISEASE AGENTS
B CATALOG OF EMERGING INFECTIOUS DISEASE AGENTS
Pages 199-260
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From page 199... ...
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 199
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From page 200... ...
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)
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From page 201... ...
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 D~sTR~suT~oN -in the United States: Atlantic coastal states from Maine to Georgia; upper midwestern states (concentrated in Minnesota and Wisconsin)
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From page 202... ...
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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From page 203... ...
, 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 D~sTR~suT~oN probably worldwide the majority of cases have occurred in North America, Asia, and Europe INcusAT~oN PERIOD AND CoMMuNTcAs~E~TY - 1 to 4 weeks period of communicability is unknown but presumed to be long, based on duration of documented outbreaks 203
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From page 204... ...
AND SYMPTOMS Chlamydia trachomatis 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 APPENDIX B 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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From page 205... ...
difficile toxin in the stool visualization of characteristic pseudomembranes during endoscopy of colon INFECTIOUS AGENT - Clostridium difficile, a toxin-producing bacterium MODE OF TRANSMISS] :ON fecal-oral transmission - acquisition of organism from the environment 205 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)
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From page 206... ...
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 APPENDIX B 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, etch; 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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From page 207... ...
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)
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From page 208... ...
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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From page 209... ...
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 DISEASE(S) AND SYMPTOMS Legionella pneumophila 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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From page 210... ...
210 DIAGNOSIS APPENDIX B changes in mental status occur in 25 to 75 percent of patients complications include renal failure, lung abscesses, and extrapulmonary infection Pontiac fever may represent a reaction to inhaled antigen rather than bacterial invasion; patients recover in 2 to 5 days without treatment isolation of the organism on special media demonstration of organism by direct immunofluorescence stain of involved tissue or respiratory secretions INFECTIOUS AGENT Legionella pneumophila, a bacterium MODE OF TRANSMISSTON aerosol transmission via aerosol-producing devices (especially air cooling systems) person-to-person transmission has not been documented DISTRIBUTION - documented as an important cause of pneumonia in North America, Europe, Asia, and Australia also identified in South America and Africa INCUBATION PERIOD 2 to 10 days for Legionnaires' disease 5 to 66 hours for Pontiac fever TREATMENT for Legionnaires' disease, antibiotics: erythromycin and rifampin PREVENTION AND CONTROL drainage of cooling towers when not in use -hyperchlorination and elevation of hot water temperature have been partially successful in interrupting waterborne outbreaks FACTORS FACIEITATING EMERGENCE - recognition in an epidemic situation
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From page 211... ...
) - direct contact with organism or with soil contaminated with infected animal feces transmission can also occur by inhalation of the organism DISTRIBUTION worldwide INCUBATION PERIOD AND COMMUNICABILITY incubation period is extremely variable (from 3 to 70 days)
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From page 212... ...
are infected, clinically or subclinically, with tuberculosis INCUBATION PERIOD AND COMMUNICABILITY - 4 to 12 weeks - disease is communicable as long as viable bacteria remain in the sputum
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From page 213... ...
aureus can range from a single pustule to septicemia to death, "toxic shock syndrome," a newly emerged disease caused by S aureus is the focus of this summary symptoms of toxic shock syndrome (TSS)
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From page 214... ...
DISEASE(S) AND SYMPTOMS the most common conditions caused by group A streptococcal bacteria are sore throat and skin infection other conditions caused by the bacteria include scarlet fever, rheumatic fever, puerperal fever, septicemia, wound infections, and pneumonia rarely, group A bacteria cause sepsis and streptococcal toxic shock syndrome (which can be fatal)
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From page 215... ...
ingestion of food washed with contaminated water
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From page 216... ...
of short duration (3 to 6 months) and thus is of no practical value in epidemic control avoidance of contaminated food and water, as well as raw and undercooked crabs and shellfish harvested from potentially contaminated water FACTORS FACILITATING EMERGENCE - breakdown of sanitation measures protecting water supplies - in Peru, miscalculation of risks involved in chlorine use (and consequent lack of chlorine use)
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From page 217... ...
illness (e.g., oral fluid replacement) PREVENTION AND CONTROL avoidance of exposure of open skin wounds to seawater careful handling of raw or undercooked seafood by persons with superficial wounds avoidance of raw or undercooked seafood, particularly by immunocompromised persons FACTORS FACILITATING EMERGENCE increased recognition EMERGENT VIRUSES Bovine Spongiform Encephalopathy Agent DISEASE(S)
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From page 218... ...
will probably provide effective control FACTORS FACILITATING EMERGENCE changes in the rendering process: continuous processing and elimination of solvents California Serogroup Viruses (LaCrosse, Jamestown Canyon, California Encephalitis) DISEASE(S ~ AND S YMPTOMS acute, inflammatory viral diseases of short duration involving parts of the brain, spinal cord, and meninges many infections are asymptomatic; severe infections involve acute onset, headache, high fever, stupor, disorientation, tremors, spasticity, and coma case fatality rate is 0.5 percent DIAGNOSIS demonstration of antibodies in blood or cerebrospinal fluid
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From page 219... ...
FACTORS FACILITATING EMERGENCE reforestation poor vector control increasing interface between human activity and endemic areas - discarded tires as a source of mosquito breeding sites Chikungunya Virus DISEASE(S) AND SYMPTOMS Chikungunya fever abrupt onset of fever, headache, myalgias -joint pain, arthritis, hemorrhagic fever disease is usually acute and self-limited DIAGNOSIS isolation of the virus from patient's blood 219
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From page 220... ...
220 INFECTIOUS AGENT Chikungunya virus, a single-stranded RNA virus MODE OF TRANSMISSION bite of an infective Aedes mosquito not directly transmitted from person to person DISTRIBUTION primarily Africa, South Asia, and the Philippines INCUBATION PERIOD -3 to 12 days TREATMENT supportive only PREVENTION AND CONTROL -mosquito control in endemic areas a live, attenuated vaccine is being tested FACTORS FACILITATING EMERGENCE unknown DISEASE(S) AND SYMPTOMS APPENDIX B Crimean-Congo Hemorrhagic Fever Virus Crimean-Congo hemorrhagic fever -abrupt onset of fever, headache, chills, photophobia, myalgia, and abdominal pain nausea, vomiting, and diarrhea may be present; rash is common infection to death ratio is estimated at 25:1 in pregnant women, infection is severe and often results in death DIAGNOSIS isolation of the virus from cerebrospinal fluid, blood, or other tissues INFECTIOUS AGENT Crimean-Congo virus, an RNA virus
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From page 221... ...
/dengue shock syndrome (DSS) sudden onset of fever, headache, joint and muscle pain - nausea, vomiting, abdominal pain, and rash may be present fever typically lasts 3 to 7 days; convalescence may be prolonged - initial phase of DHF/DSS may be similar to the above, but is followed by hemorrhagic phenomena, bleeding from multiple sites, and vascular collapse
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From page 222... ...
DISEASE(S) AND SYMPTOMS - sudden onset of fever, headache, joint and muscle pain, followed by sore throat, diarrhea, abdominal pain, vomiting, and rash
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From page 223... ...
Marburg: scattered human cases have occurred in central, eastern, and southern Africa; cases reported in Germany were a result of handling material from infected African green monkeys imported from Uganda INCUBATION PERIOD AND COMMUNICABIEITY for both virus infections, 5 to 10 days both viruses can persist in humans for at least 2 months TREATMENT -supportive only PREVENTION AND CONTROL avoidance of contact with infected persons and their blood, other tissues, and body fluids strict isolation of infected persons FACTORS FACILITATING EMERGENCE virus-infected monkeys shipped from developing countries via air
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From page 224... ...
MODE OF TRANSMISSION contact with infective material (feces, urine, saliva, tissue, etc.) of rodents contact is usually by aerosol transplacental transmission has been documented; other person-toperson spread has not been reported DISTRIBUTION hantaviruses are found on all continents - endemic and epidemic disease in China, Korea, and the Commonwealth of Independent States Hantaan virus is widely distributed in eastern Asia Puumala virus is common to Scandinavia and western Europe INCUBATION PERIOD 4 to 42 days; average is 12 to 16 days TREATMENT supportive only recent studies show that ribavirin may shorten illness and reduce mortality
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From page 225... ...
INFECTIOUS AGENT Hepatitis B virus, a double-stranded DNA virus MODE OF TRANSMISSION virus enters body through a break in the skin or through mucous membranes -transmission via contaminated needles, transfusions of blood or blood products, sexual contact -transplacental transmission DISTRIBUTION worldwide INCUBATION PERIOD AND COMMUNICABILITY 45 to 180 days, average 60 to 90 days blood containing the virus has been shown to be infective many weeks before the onset of first symptoms and to remain infective during the acute clinical course of the disease -chronic carriers are infectious TREATMENT supportive only 225
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From page 226... ...
but more prolonged - strong tendency to progress to chronic hepatitis and liver disease, which can be asymptomatic -the most common form of posttransfusion hepatitis DIAGNOSIS diagnosed by exclusion of hepatitis A, B and delta viruses and other causes of liver injury blood tests are now available for clinical use INFECTIOUS AGENT exact viral agent is unknown - agent appears to be a flavivirus MODE OF TRANSMISSION - percutaneous exposure to contaminated blood and plasma derivatives - the role of sexual activity in transmission is not well defined DISTRIBUTION -worldwide - common among dialysis patients, hemophiliacs, health care workers, and drug addicts INCUBATION PERIOD AND COMMUNICABILITY 20 to 90 days (mean: 50)
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From page 227... ...
jaundice can be present no evidence of a chronic form DIAGNOSIS liver function tests - exclusion of other etiologies of hepatitis (especially hepatitis A) by serologic tests INFECTIOUS AGENT virus is not yet fully characterized - virus-like particles have been detected in the feces of infected patients MODE OF TRANSMISSION - ingestion of contaminated water (most outbreaks have been linked to fecal contamination of water)
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From page 228... ...
228 DISTRIBUTION may be widespread - majority of outbreaks have been reported from Asia, Africa, the Commonwealth of Independent States, and Mexico INCUBATION PERIOD AND COMMUNICABILITY · 30 to 40 days - period of communicability is unknown; may be similar to hepatitis A APPENDIX B TREATMENT supportive only PREVENTION AND CONTROL educational programs stressing importance of sanitary disposal of feces, careful hand washing after defecation and before handling food FACTORS FACILITATING EMERGENCE -agent and disease are newly recognized Human Herpesvirus-6 DISEASE(S) AND SYMPTOMS sudden onset of fever (fever lasts 3 to 5 days)
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From page 229... ...
lest In t. he spring INcusAT~oN PERIOD AND CoMMuN~cAs~TY incubation period is 10 days TREATMENT - supportive only PREVENTION AND CONTROL - none FACTORS FACILITATING EMERGENCE newly recognized Human Immunodeficiency Virus (HIV)
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From page 230... ...
or tissues (transplantation) of an infected person transmitted from mother to fetus routine social or community contact with HIV-infected persons carries no risk of transmission DISTRIBUTION worldwide - more than 200,000 reported cases of AIDS in the United States as of January 1992; approximately 1 million additional persons asymptomatically infected with HIV - worldwide, 8 to 10 million persons infected with HIV-1 by June 1990 - HIV-2 is currently endemic only in West Africa, although cases have appeared in Europe, South America, North America, and other parts of Africa cases were initially clustered among male homosexuals, intravenous drug users, prostitutes, and transfusion recipients distribution patterns have changed in the past 10 years and continue to change (fewer cases of transfusion-induced HIV disease, more cases of infection acquired from heterosexual sex, more cases of transplacental transmission)
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From page 231... ...
caution by health care workers in handling, using, and disposing of needles and other sharp instruments, and wearing of latex gloves when coming into contact with bodily fluids of any patient FACTORS FACILITATING EMERGENCE urbanization changes in lifestyles/mores increased intravenous drug abuse - international travel - medical technology (transfusions) Human Papillomavirus (HPV)
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From page 232... ...
and by contact with contaminated floors - genital warts are sexually transmitted - virus can be transmitted from mother to infant during birth DISTRIBUTION worldwide INCUBATION PERIOD AND COMMUNICABILITY 1 to 20 months; average is 2 to 3 months period of communicability is unknown but is probably at least as long as visible lesions persist TREATMENT freezing of warts with liquid nitrogen application of salicylic acid or podophyllin to remove warts - interferon has been shown to be effective in the treatment of genital warts surgical removal or laser therapy is required for laryngeal and cervical warts PREVENTION AND CONTROL avoidance of direct contact with lesions use of a condom during sexual intercourse FACTORS FACILITATING EMERGENCE possibly increases in sexual activity Human Parvovirus B19 DISEASE(S) AND SYMPTOMS Erythema infectiosum classic infection in childhood is characterized by erythema of cheeks (slapped cheek appearance)
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From page 233... ...
-fever and abdominal symptoms may occur -arthritis is frequently reported - disease ranges from subacute to rapidly lethal (median survival for ATLL is 8 months)
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From page 234... ...
and by sexual contact transplacental transmission is possible DISTRIBUTION virus is present on all continents - cases of HTLV-1 infection have clustered in the Caribbean, southwestern Japan, parts of Central and South America, Africa, Italy, and the southern United States HTLV-2 is commonly found in intravenous drug abusers INCUBATION PERIOD AND COMMUNICABIEITY -incubation period is several years and may be as long as 20 years communicability is unknown TREATMENT -response of ATLL to conventional chemotherapeutic regimens has been poor corticosteroids are helpful in some cases PREVENTION AND CONTROL avoidance of sexual or blood contact with an infected person screening of donated blood for the virus (types 1 and 2) FACTORS FACILITATING EMERGENCE medical technology (transfusion)
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From page 235... ...
are responsible for annual epidemics and regional outbreaks MODE OF TRANSMISSION airborne spread among crowded populations in enclosed spaces transmission also occurs by direct contact with mucus of an infected person (influenza virus can persist for hours in dried mucus) transmission from animal to human has been demonstrated rarely D~sTR~suT~oN worldwide in temperate regions, influenza outbreaks occur during colder months in tropical regions, influenza occurs year round
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From page 236... ...
AND SYMPTOMS Japanese encephalitis virus disease clinical features range from inapparent to fatal mild infections involve fever, headache, and myalgias severe disease involves high fever, nausea, vomiting, and altered consciousness hyperthermia, seizures, paralysis, and coma can occur convalescence is prolonged; up to 80 percent of survivors experience necrologic sequelae with optimal care, case fatality rate is 10 percent (as high as 40 percent in young children and in persons over 65 years of age) DIAGNOSIS isolation of the virus from cerebrospinal fluid or blood isolation of viral antibodies from the blood and cerebral spinal fluid INFECTIOUS AGENT Japanese encephalitis virus - pigs are important amplification hosts for the virus
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From page 237... ...
AND SYMPTOMS Lassa fever gradual onset of fever, malaise, headache, dizziness, and sore throat - nausea, vomiting, and diarrhea are common in severe cases, hypotension, shock, and seizures may result acute illness lasts 7 to 31 days, with an average of 12 days DIAGNOSIS isolation of virus from blood, urine, or throat washings serological tests (ELISA or IFA) INFECTIOUS AGENT Lassa virus, an arenavirus named after a town in Nigeria 237
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From page 238... ...
238 MODE OF TRANSMISSION APPENDIX B contact with excrete of infected rodents deposited on surfaces such as beds and floors, or in food transmission also occurs via contact with blood, secretions, or excretions of an infected person transplacental transmission can occur DISTRIBUTION widely distributed over West Africa, especially Nigeria, Sierra Leone, and Liberia INCUBATION PERIOD AND COMMUNICABILITY 8 to 14 days person-to-person transmission may occur during the acute febrile phase when virus is present in the throat TREATMENT antiviral agents: ribavirin mechanical ventilation and renal dialysis may be required PREVENTION AND CONTROL - avoidance of contact with rats and infected persons strict isolation of infected persons FACTORS FACILITATING EMERGENCE unknown DISEASE(S) AND SYMPTOMS Measles fever, conjunctivitis, coryza, cough, and Koplic spots on the buccal Measles Virus mucosa - red blotchy rash beginning on forehead and neck, later spreading to trunk and limbs DIAGNOSIS usually made on clinical and epidemiological grounds INFECTIOUS AGENT - measles virus
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From page 239... ...
AND SYMPTOMS Gastroenteritis, epidemic diarrhea vomiting, diarrhea, headache, and low-grade fever lasting 2 to 3 days disease often occurs in outbreaks involving people of all age groups DIAGNOSIS -identification of the agent in the stool by electron microscopy and/or immunologic assay (RIA and ELISA)
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From page 240... ...
DISTRIBUTION -worldwide in developing countries, disease is more common in children; in the United States, disease typically occurs in older children and adults INCUBATION PERIOD AND COMMUNICABILITY typical incubation period is 1 to 2 days disease is communicable up to 2 days after diarrhea stops TREATMENT -supportive only (e.g., oral fluid replacement) PREVENTION AND CONTROL - effective preventive measures are undetermined possibly avoidance of alleged vehicles of transmission FACTORS FACILITATING EMERGENCE increased recognition DISEASE(S)
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From page 241... ...
from an infected animal; bites around head, face, or hands carry highest risk of infection mucous membrane exposure to saliva of an infected animal DISTRIBUTION worldwide; causes an estimated 30,000 human deaths per year, mostly in developing countries INCUBATION PERIOD AND (:OMMUNICABlEITY 1 to 2 months period of communicability for animals includes week before clinical signs and throughout the course of the disease TREATMENT immediate and thorough cleansing of bite wound administration of rabies immune globulin (RIG) around wound and intramuscularly to prevent infection, and vaccine intramuscularly to prevent infection -the only treatment for disease is supportive; more than 99% of patients with symptomatic infection die PREVENTION AND CONTROL pre-exposure vaccination is recommended for persons whose occupations or travel will place them at risk for exposure to rabid animals vaccination of dogs and cats - isolation and destruction of infected animals FACTORS FACILITATING EMERGENCE -changing movements of reservoir host species absence or failure of rabies control programs
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From page 242... ...
DIAGNOSIS virus isolation from the blood demonstration of virus antibodies in the cerebrospinal fluid or acute serum INFECTIOUS AGENT - Rift Valley fever virus MODE OF TRANSMISSION bite of an infective mosquito contact with infected animals or their tissues possible transmission via unpasteurized milk not directly transmitted from person to person DISTRIBUTION widespread in Africa; initially described in Rift Valley in Kenya INCUBATION PERIOD 3 to 5 days TREATMENT supportive only PREVENTION AND CONTROL an inactivated vaccine is available for persons at high risk of infection (veterinarians, laboratory personnel) in endemic areas a candidate live, attenuated vaccine is under development -immunization of animals - mosquito control FACTORS FACILITATING EMERGENCE - importation of infected mosquitoes and/or animals - creation of mosquito habitats through dam building and irrigation
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From page 243... ...
, which lasts from days to months - a maculopapular rash on the trunk and limbs commonly follows the onset of arthritis; rash resolves within 7 to 10 days fever is frequently present, lasting 6 to 7 days in 25 percent of cases, rheumatic symptoms continue one year or longer DIAGNOSIS isolation of virus from serum detection of virus antibodies in serum INFECTIOUS AGENT Ross River virus MODE OF TRANSMISSION bite of an infective mosquito transplacental transmission may occur · not directly transmitted from person to person virus reservoir is probably the kangaroo D~sTR~suT~oN - Australia, Tasmania, Papua New Guinea, Indonesia, and several South Pacific islands INCUBATION PERIOD · 3 to 1 1 days TREATMENT supportive only PREvENT~oN AND CoNTRor -mosquito control FACTORS FACILITATING EMERGENCE - importation of infected mosquitoes and/or travel by infected people creation of mosquito habitats through dam building and .
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From page 244... ...
MODE OF TRANSMISSION primarily fecal-oral - fecal-respiratory transmission may also occur DISTRIBUTION worldwide INCUBATION PERIOD AND COMMUNICABILITY incubation period is 1 to 2 days virus shedding occurs throughout duration of illness and continues for several days following the disappearance of symptoms TREATMENT supportive only (e.g., oral fluid replacement) PREVENTION AND CONTROL effective preventive measures are uncertain avoid exposure of infants to persons with acute gastroenteritis - passive immunization by oral immunoglobulin has been effective in protecting low-birth-weight newborns a number of oral vaccines are in various stages of development FACTORS FACILITATING EMERGENCE - increased recognition
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From page 245... ...
can accompany severe cases - most infections are fairly mild; symptoms last 3 to 5 days - in patients with encephalitis, illness typically lasts 3 to 7 days DIAGNOSIS isolation of the virus or of viral antibodies in the blood sometimes based on epidemiological grounds (in areas that have experienced a recent equine epizootic) INFECTIOUS AGENT -Venezuelan equine encephalomyelitis virus virus is maintained in rodents transmission cycle involves horses, which serve as the major source of virus to infect mosquitoes MODE OF TRANSMISSION bite of an infective mosquito transmission also occurs transplacentally and in laboratories via inhalation not directly transmitted from person to person - no evidence of aerosol transmission from horses to humans D~sTR~suT~oN disease is enzootic and epizootic in tropical South America, Central America, the Caribbean, southern North America, and Mexico INcusAT~oN PERIOD 2 to 5 days TREATMENT - supportive only PREvENT~oN AND CoNTRor - mosquito control - a live, attenuated vaccine is available for laboratory workers and other adults at high risk of infection
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From page 246... ...
AND SYMPTOMS Yellow fever clinical features range from inapparent to fatal typical attacks are characterized by abrupt onset, fever, chills, headache, muscle pain, nausea, and vomiting as disease progresses, jaundice, hemorrhagic complications, and renal failure may occur pulse may be slow despite high fever the case fatality rate among indigenous populations of endemic regions is less than 5 percent; this rate may exceed 50 percent among nonindigenous groups and in epidemics recovery is slow but complete in survivors DIAGNOSIS isolation of virus from the blood demonstration of viral antigen in the blood or liver tissue by ELISA INFECTIOUS AGENT Yellow fever virus MODE OF TRANSMISSION - bite of an infective mosquito - not directly transmitted from person to person DISTRIBUTION - disease is endemic in tropical South and Central America and in Africa - potential for outbreaks exists in other areas where vector mosquito is found (including the United States) INCUBATION PERIOD range is 3 to 14 days; usually 1 to 6 days
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From page 247... ...
. 247 obstruction, ulceration, and bleeding in the gastrointestinal tract are possible DIAGNOSIS recognition of the 2 to 3 cm.
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From page 248... ...
nymphal Ixodes ticks (carried by deer mice) are vectors; adult ticks live on deer MODE OF TRANSMISSION -bite of a nymphal Ixodes tick not directly transmitted from person to person occasional transmission by blood transfusion has been reported
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From page 249... ...
AND SYMPTOMS Candidiasis fungal infections usually confined to the superficial layers of skin or mucous membranes: oral thrush, intertrigo, vulvovaginitis, paronychia, or onychomycosis ulcers may be formed in the esophagus, gastrointestinal tract, or bladder - dissemination in the blood may produce lesions in other organs (kidney, spleen, liver, lung, endocardium, eye, or brain) DIAGNOSIS microscopic demonstration of yeast cells in infected tissue or body fluid fungal culture
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From page 250... ...
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)
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From page 251... ...
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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From page 252... ...
AND SYMPTOMS Cryptosporidium (:ryptosporidiosis 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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From page 253... ...
AND SYMPTOMS Giardiasis Giardia lamblia 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 focally contaminated food or water
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From page 254... ...
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 necrologic changes DIAGNOSIS - requires electron microscopy of biopsy specimen
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From page 255... ...
AND SYMPTOMS Malaria Plasmodium 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, pulmo
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From page 256... ...
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
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From page 257... ...
AND SYMPTOMS Pneumocystis carinii Pneumocystis carinii pneumonia progressive dyspnea, tachypnea, and cyanosis pneumonia is often fatal in malnourished, chron 257 rically 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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From page 258... ...
disease INCUBATION PERIOD AND COMMUNICABILITY unknown; symptoms typically appear 1 to 2 months after onset of .
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From page 259... ...
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, PREVENTION AND CONTROL disposal of feces in a sanitary manner avoidance of skin-soil contact in endemic areas FACTORS FACILITATING EMERGENCE - international travel 1mmunosuppresslon DISEASE(S)
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From page 260... ...
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)
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Key Terms
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