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Pathogen Genus species Disease Risk Group Host Range Transmission^ Signs & Symptoms Incubation Fact Micrograph Bacteria Actinomcyces spp. Actinomyces israelii Actinomycosis
Humans, cattle, horses Person-to-person by contact of mouth, aerosols, fomites. Opportunistic pathogen. Chronic bacterial disease localized in jaw, thorax, or abdomen. Characterized by persistent swelling, suppuration and formation of abscesses or granulomas. variable - days to months. Fatality rate of 5-20% if untreated. Opportuinistic pathogen. Bacteria Bacillus cereus Food Poisoning
Humans Ingestion of foods kept at ambient conditions after cooking; emetic form frequently associated with cooked rice. Not communicable from person to person. Opportunistic pathogen; intoxication characterized by two forms: an emetic form with severe nausea and vomiting and a diarrheal form with abdominal cramps and diarrhea. Usually mild and self-limiting ( hrs). 1-6 hours, average 4 hours; diarrheal form 6-24 hours (average 17 hours) Infectious dose is greater than 10e6 organisms by ingestion (>10e5 organisms/g of food). Bacteria Bordetella pertussis Whooping Cough
Humans Direct contact with discharges from respiratory mucous membranes of infected persons by the airborne route. Stage 1: Catarrhal: Irritating cough, lasts 1 to 2 weeks; Stage 2 : Paroxysmal; violent coughs followed by a high pitched inspiratory whoop, lasts 2 to 6 weeks; Stage 3: Convalescent; the cough gradually decreases in frequency and severity, lasts several weeks 6-20 days Common in children worldwide; pertussis is among the most lethal infant diseases- Treatment with dTaP(acellular pertussis vaccine, a preventive vaccine) is now available for adults Bacteria Brucella melitensis Brucellosis
Humans, swine, cattle, goats, sheep, dogs Skin or mucous membrane contact with infected animals, their blood, tissue, and other body fluids.. High and protracted (extended) fever. Infection affects bone, heart, gallbladder, kidney, spleen, and causes highly disseminated lesions and abscess 1-15 weeks Most commonly reported laboratory-associated bacterial infection in man. Bacteria Campylobacter jejuni Traveller's diarrhea
Humans, animals and birds By ingestion of organisms in undercooked food or in unpasteurized milk or water; from contact with infected pets (puppies and kittens), farm animals or infected infants. Acute enteric disease of variable severity; diarrhea, abdominal pain, malaise, fever, nausea and vomiting; prolonged illness in up to 20% of patients; blood in association with mucus. 2-5 days with a range of 1- 10 days (dose dependant) Important cause of diarrheal illness worldwide in all age groups (5-14% of diarrhea in world); common source outbreaks most often associated with foods, unpasteurized milk and unchlorinated water. Infectious dose is 500 organisms or less by ingestion. Bacteria Escherichia coli - Enterotoxigenic (ETEC) Travellers Diarrhea / Gastroenteritis
Humans, most mammals (livestock) Fecal-oral route; fecal contamination of water, food or fomites; poor sanitation and hygiene. Produces a heat labile enterotoxin (ST). Low grade fever, profuse watery diarrhea without blood or mucous; abdominal cramping, vomiting, acidosis, prostration, malaise and dehydration. Self-limiting cholera-like disease in man. 24-72 hours Leading cause of traveller's diarrhea and a major cause of diarrheal disease in underdeveloped nations. Bacteria Escherichia coli - Enteropathogenic (EPEC); Entero dherent (EAEC) Acute Diarrhea
Humans, most mammals (livestock) Fecal-oral route; fecal contamination of water, food or fomites; poor sanitation and hygiene. Produces an enteroxin. Intestinal disease accompanied by watery diarrhea, fever, cramps and vomiting; bloody stool in some cases; serious disease in infants 12-72 hours Highly infectious for infants; Adults by ingestion - 10,000 to 1e10 organisms needed for infection. In developing countries, the EPEC are highly prevalent and are a cause of childhood diarrheal disease and de- hydration associated deaths. Bacteria Escherichia coli - Enteroinvasive (EIEC) Bacillary Dysentery
Humans Fecal-oral route; fecal contamination of water, food or fomites; poor sanitation and hygiene Fever; mucoid, occasionally bloody diarrhea, generally self-limiting; most severe form may result in hypotension with severe toxemia; sometimes associated with food poisoning. 12-72 hours Communicable for duration of fecal excretion (several weeks). Low infectious dose, approx. 10 organisms by ingestion.
Pathogen Genus species Disease Risk Group Host Range Transmission^ Signs & Symptoms Incubation Fact Micrograph Bacteria Escherichia coli - Enterohemorrhagic (EHEC) Hemorrhagic Colitis
Humans, animals (0157- H7 piglets, calves and cattle) Ingestion of contaminated food (undercooked hamburger meat, unpasteurized milk); fecal-oral transmission; person-to-person transmission (extremely high) Low grade fever, cramps, abdominal pain, watery diarrhea followed by bloody diarrhea, leading to hemorrhagis colitis and hemolytic uremic syndrome. In most patients, the disease is self-limited. However, 10% of children and a lessser number of adults may develop HUS (hemolytic uremic syndrome). 2-8 days Communicable for duration of fecal excretion (7- days). Bacteria Francisella tularensis Tularemia (Rabbit Fever)
Wild animals (rabbits) and birds; some domestic animals; humans Inoculation of skin, conjunctiva or mucosa with blood or tissue when handling infected animals; fluids from infected flies or other animals; arthropod bites Presents as an indolent ulcer at site of infection, with swelling of the regional lymph nodes and sudden onset of pain and fever, fever that lasts 3-6 weeks without treatment; inhalation may be followed by a pneumonic disease 1-14 days (usually 2- days) Type B strains have a 5-15% fatality rate; type A strains approximately 35% mortality from pulmonary tularemia Bacteria Listeria monocytogenes Listeriosis
Mammals, birds, fish, crustaceans and insects Transmitted from mother to fetus in utero; direct contact with infectious material or contaminated soil; ingestion of contamin-ated food (vegetables and dairy products A flu-like illness with gastrointestimnal symptoms. Perinatal infections can result in abortion or stillbirth in utero; In adults infection can cause meningitis, endocarditis, septicemia, and disseminated granulomatous lesions. 3-70 days; mean incubation period is 3 weeks. Mothers of infected newborn infants may shed the agent for 7-10 days after delivery; infected patients can shed organism in the stool for months. Bacteria Mycobacterium tuberculosis ; Mycobacterium avium complex Tuberculosis (TB)
Primarily humans, primates, other animals (rodents). Inhalation of aerosols (droplet nuclei); direct invasion of mucous membranes or breaks in skin. TB can be in a latent or active phase. Individuals with latent TB do not have clinical symptoms but show sensitivity on screening. Active disease is present in those with clinical symptoms. An immunocompromised state increases likelihood of developing active disease. MTB can cause several clinical illnesses one of which is pulmonary TB (fatigue, fever, cough with bloody sputum, chest pain). 4-12 weeks from infection to primary lesion or significant tuberculin reaction. Infectious dose is 10 bacilli by inhalation. Tb bacilli can survive for 6-8 months in contaminated sputum outside of the host. Prompt diagnosis and treatment of active disease is important to prevent severe disease of surrounding population. Bacteria Neisseria meningitidis Meningitis
Humans By direct contact, including droplets and discharges from nose and throat of infected persons, more often carriers than cases. Sudden onset with fever, intense headache, nausea and often vomiting, stiff neck, and frequently a petechial rash with pink macules; delirium and coma. 2-10 days Personnel working with high concentrations or large quantities of organisms should be immunized with tetra- valent polysaccharide vaccine (A,C Y,and W-135); Bacteria Nocardia asteroides Nocardiosis
Humans, animals Nocardiosis - Inhalation of contaminated dust; Mycetoma - subcutaneous contamination by a penetrating wound (thorns, splinters); rarely nosocomial post surgical transmission occurs. Fever, cough, chest pain, CNS disease, headache, lethargy, confusion, seizures, sudden onset of neurologic deficit. Chronic disease originating in lungs; 80% of cases present as invasive pulmonary infection, disseminateddisease or brain abscess. 20% as cellulitis. months 10% of pulmonary disorders are fatal; Not directly transmitted from person-to-person. Bacteria Pseudomonas spp. ( Pseudomonas aeruginosa, Pseudomonas capacia ) Respiratory and Urinary Infections, Pneuminia, Bacteremia
Humans, animals and plants Direct contact with contaminated water or aerosols, or contact of mucous membranes with infectious discharges from conjunctivae or upper respiratory tract of infected persons. Skin and soft tissue infections may be mild as in hot tub folliculitis or severe as in necrotizing fasciitis. Pseudomonas can cause a variety of severe clinical illness to include: UTI’s, malignant otitis externa, bone infections, pneumonia, bacteremia, mengingitis, and endocarditis. 24-72 hours Opportunistic pathogen in the immunocompromised host;
Pathogen Genus species Disease Risk Group Host Range Transmission^ Signs & Symptoms Incubation Fact Micrograph Virus Picornaviridae Coxsackie virus Devil's Grip, Hand Foot and Mouth Disease, Vesicular Pharyngitis
Humans Direct contact with nasal and throat secretions from an infected person, fecal-oral route, inhalation of infected aerosols. Abrupt onset of fever, sore throat, anorexia, dysphagia, vomiting and small, discrete vesicular lesions in the oral regions; vesicular stomatitis has more diffuse lesions in the oral region.Group A viruses: aseptic meningitis, colds, acute hemorr- hagic conjunctivitis and acute myocardio- pathies and group B: acute myocarditis and a polio-like paralysis 3-5 days Although people of any age can get infected, the majority of patients identified with Coxsackie infection are children. Pregnant women can pass Coxsackie virus to their newborns. Virus Herpesviridae Epstein-Barr virus (EBV) (=Herpesvirus 4) Infectious Mononucleosis (IM)
Humans Person-to-person by oropharyngeal route via saliva, possible spread via blood transfusion (not important route). Infectious mononucleosis - acute viral syndrome with fever, sore throat, splenomegaly and lymphadenopathy; Burkitt's lymphoma - monoclonal tumour of B cells. IM - 4-6 weeks IM is communicable for up to 1 year or more, 15-20% of EBV antibody-positive adults are oropharyn-geal carriers; tumours are not communicable. Virus Herpesviridae Epstein-Barr virus (EBV) (=Herpesvirus 4) Burkitt's Lymphoma (BL)
Humans Primary infection occurs early in life or involves immunosuppression and reactivation of EBV later. Burkitt's lymphoma - monoclonal tumour of B cells; Burkitt's lymphis a cancer of the lymphatic system (in particular, B lymphocytes). 2-12 years from primary infection Burkitt's lymphoma can be divided into three main clinical variants: the endemic, the sporadic and the immunodeficiency-associated variants which are all associated with HIV and AIDS. Virus Retroviridae Human Immunodeficiency virus (HIV-1 and HIV-2) Acquired Immune Deficiency Syndrome (AIDS)
Humans Person to person through direct exposure to infected body fluids (blood, semen) sexual contact, sharing unclean needles etc.; transplacental transfer can occur. Insidious onset with non-specific symptoms such as lymphadenopathy, anorexia, chronic diarrhea, weight loss, fever, and fatigue 6 months to 7 years: most people seroconvert within 4- 10 weeks. Development of symptoms and progression to AIDS can vary greatly depending on treatment. HIV-1 is the predominant form in the US and HIV-2 in Africa.
Pathogen Genus species Disease Risk Group Host Range Transmission^ Signs & Symptoms Incubation Fact Micrograph Virus Herpesviridae Hepatitis A virus (HAV) Infectious Hepatitis
Humans Person-to-person by fecal-oral route; ingestion of contaminated food (i.e., shell fish) and water. Rare instances of transmission by blood transfusion. Many infections are asymptomatic; abrupt onset with fever, malaise, anorexia, nausea and abdominal discomfort, followed within a few days by jaundice. Mild illness (1- weeks) to severely disabling (6-9 months period), no carrier state. 10-50 days Infectious dose is 10-100 HAV particles. Survives in water and sewage for long periods (days-weeks). No carrier state associated with HAV. Virus Hepadnaviridae Hepatitis B virus (HBV) Serum Hepatitis
Humans Percutaneous or mucosal exposure to infectious body fluids (blood, body fluids, tissues, or cell lines). Direct blood-to-blood contact with an infected person. Mother to child transmission during childbirth. Disease onset is gradual with anorexia, abdominal discomfort, nausea and vomiting, arthralgia and rash, jaundice and mild to moderate fever. Severity ranges from asymptomatic to fatal hepatic necrosis. Incubation period ranges from 45-180 days with HBV serum antigen (Ag) appearing in 2 weeks. 80% of infected individuals will only exhibit acute infection, while 20% will become chronic carriers. HBV vaccine is 95% efficacious pre-exposure. Virus Flaviviridae Hepatitis C virus (HCV) Parenterally transmitted non-A, non-B hepatitis
2 (US) 3
(UK)
Humans Primary route of transmission is via Infected blood. Percutaneous exposure to contaminated blood and plasma derivatives. Anorexia, vague abdominal discomfort, nausea and vomiting, progressing to jaundice (less frequently than in individuals infected with hepatitis B); severity ranges from unapparent cases in approximately 90% of infections to rare fulminating, fatal cases. 2 wks to 6 mo; chronic infect-ion may per-sist for up to 20 years be-fore onset of cirrho-sis or heptoma 75-85% of infected persons become chronically infected and 70% of chronic sufferers go on to develop liver disease. Virus Herpesviridae Herpes simplex viruses Herpesvirus 1 (HSV-1) and Herpesvirus 2 (HSV- 2) Fever Blister, Cold Sore, Genital Herpes
Humans HSV - 1 - contact with saliva of carriers, infection of hands of health care personnel (i. e ., dentist); HSV-2 - usually by sexual contact or direct contact of infected secretions. HSV - 1 - infection of the oral mucosa (face & lips); reactivation of latent infection results in fever blisters or cold sores. HSV- is genital herpes and is associated with aseptic meningitis. Either can infect both oral mucosa or genital tract. 90% of HSV- infections are oral; 85% of HSV - 2 are genital. HSV-1: 7-10 days; HSV-2: 2 -12 days. Virus may be secreted in saliva for up to 7 weeks after recovery and from genital lesions for 7-12 days. 50% - 90% of adults possess antibodies to HSV-1. Deleted "type." Virus Arenaviridae Lymphocytic Choriomeningitis virus Lymphocytic Meningitis
Humans, guinea pigs, hamsters, mice and monkeys Aerosols transmission via dust contaminated with rodent excreta; contam-ination of mucous mem-branes, cuts with infected body fluids; no evidence of person to person spread. Bi-phasic febrile illness; mild influenza-like illness or occasional meningeal symptoms. Symptoms include fever, fatigue, headache, nausea, vomitting and muscular pain 8-13 days Infected mice excrete virus in saliva, urine and feces; man is infected through inhalation of infectious aerosolized particles of rodent urine, feces or saliva, Virus Caliciviridae Norovirus (formerly Norwalk virus) Acute Gastroenteritis (AGE)
Humans Primarily by fecal-oral route; other sources include water, food (part-icularly shellfish and sal-ads), aerosol and fomites. Communicable during the acute stage of the disease. Acute onset with vomiting, non-bloody diarrhea, abdominal cramps; 25-50% of affected persons report myalgias, malaise, headache, nausea and low-grade fever. Illness usually resolves within 24-48 hours. 10-60 hours Norovirus is respons-ible for 50% of all food illnesses.. Virus Paramyxoviridae Respiratory Syncytial virus (RSV) Common cold, Bronchiolitis or Pneumonia
Humans Respiratory secretions; in- halation of large droplets; fomites; direct oral contact; indirectly by hands and eating utensils or other articles freshly soiled by respiratory discharges. Most common cause of common cold-like lower respiratory tract illness in infants and young children; causes common colds in adults; pneumonia in infants, and bronchiolitis in very young babies. Most common cause of viral pneumonia in children < 5 years. 4 to 5 days Infectious dose is 100-640 infectious organisms when administered intranasally. Viral shedding may persist for several weeks after symptoms subside. Virus Poxviridae Vaccinia virus Disseminated Vaccinia
Humans Ingestion, parenteral inoculation, droplet or aerosol exposure of mucous membranes or broken skin with infectious fluids or tissues; recently vaccinated individuals can transmit the vuirus to others from the site of inoculation. Vesicular or pustular lesion, area of induration or erythema surrounding a scab or ulcer at inoculation site; major complications encephalitis, progressive vaccinia (immunocompromised susceptible), eczema vaccinatum - a localized or systemic dissemination of vaccinia virus. 5-10 days Infectious dose is unknown. Smallpox vaccine is indicated for laboratory workers directly involved with vaccinia and vaccinia virus recombinants.
*Images were obtained from the U.S. Centers for Disease Control & Prevention Public Health Image Library (PHIL). 08/
Reference:Current Diagnosis and Treatment of Infectious Disease 2001 by The McGraw-Hill Companies, Inc.
