Chapters 18 & 19 Supplement to diseases already covered. –Previously covered in depth and not included here: Viruses –HIV –Influenza (including avian and

Chapters 18 & 19

• Supplement to diseases already covered.– Previously covered in depth and not included here:

• Viruses– HIV– Influenza (including avian and swine)

• Bacterial diseases– Tuberculosis– Lyme disease– The Plague– MRSA

• Protozoan diseases– Malaria

• Fungal diseases– Tinea diseases– Aspergillosis– Ergot poisoning

Viral Diseases of the Skin

• Herpes simplex– DNA virus– Signs

• Cold sores• Fever blisters• Herpetic ulcers• Herpetic whitlow

– Two different viruses• HSV-1: labial herpes• HSV-2: genital herpes

Fig. 18.1 The cold sores (fever blisters) of herpes simplex

Courtesy of Dr. Hermann/CDC


• Measles (rubeola)– RNA virus– Transmitted by respiratory droplets– Rarely seen in US any more– Signs

• Hacking cough

• Sneezing

• Nasal discharge

• Eye redness

• Sensitivity to light

• High fever

• Characteristic red rash that eventually encompasses entire body

– Extremely effective vaccine


• Rubella (German measles)– Different from measles– Caused by rubella virus, not measles virus– Occasional fever– Variable, pale-pink rash

– Begins on face

– Spreads to trunk and extremities

– Congenital rubella– Extremely effective vaccine

• Mumps– Characteristic unilateral salivary gland enlargement– Obstruction of duct out of gland creates painful swelling– Extremely effective vaccine


• Fifth disease (erythema infectiosum)– Caused by parvovirus B19– DNA virus– 5th disease marked by rash

• I is measles

• II is scarlet fever

• III is rubella

• IV is roseola

– Signs• Fiery red rash on cheeks and ears (slapped cheek appearance)

• Rash may spread to trunk and extremities

• Rash fades within several days

• Leaves lacy pattern of red on skin

– No available treatments


• Smallpox– Caused by variola major virus– Scourge of the world– Signs

• Pink-red spots (macules)• Appearance of large fluid-filled vessels• Vesicles become deep pustules• Pustules break open and emit infectious

pus • If person survives, pustules leave pitted

scars (pocks)

– Extremely lethal– Extremely effective vaccine

• Developed originally by Jenner in 1798 (first “vaccine”)

– Eradicated worldwide• Officially 1980• Last case observed 1977 in Somalia

– Risk of smallpox as bioterrorism agent

Fig. 18.3a Smallpox lesions

Courtesy of World Health Organization; Diagnosis of Smallpox Slide Series/CDC


• Warts– Caused by papilloma viruses– Small DNA viruses– Many types of warts

• Cutaneous warts

• Plantar warts

• Genital warts

– Linked to cervical cancer

– Effective vaccine for genital warts

Viral Diseases of the Respiratory Tract

• Adenovirus infections– DNA viruses– Large family– Usually result in common cold

• Rhinovirus infections– RNA viruses– Major cause of common cold (beyond adenoviruses)– Over 100 subtypes– Usual signs

• Headache• Dry, scratchy throat• Runny nose• Variable cough• Little to no fever

– No vaccines– No antiviral drugs– Infection and signs usually short-lived and tolerable

Viral Diseases of the Nervous System

• Rabies– Carried in wild animals

• Raccoons

• Squirrels

• Skunks

• Bats

– RNA virus– Fatal to all animals, including humans– Transmission from infected animal into skin wound

• Saliva

• Urine

• Blood

– Incubation period of days to years

Viral Diseases of the Nervous System• Yellow fever

– RNA virus– Transmitted by bite of infected mosquito– Causes liver damage that leads to jaundice (hence, “yellow”)– Signs

• Gums bleed• Bloody stools• Bloody vomit • Death by rupture of capillaries: internal bleeding• High mortality

– Vaccine exists for high risk groups

• Polio– RNA virus– Paralytic disease– Acquired from contaminated drinking water– Extremely effective vaccines

• Salk: inactivated virus• Sabin: attenuated virus

– Global eradication effort

Viral Diseases of the Visceral Organs

• Viral hemorrhagic fevers– All caused by RNA viruses– Different diseases caused by different viruses

• Ebola and Marburg

• Sin Nombre hantavirus (hantavirus pulmonary syndrome)

• Dengue

• Yellow fever

• Crimean-Congo hemorrhagic fever

• Omsk fever

• Rift Valley fever

• Lassa fever

– Signs• Complete breakdown of capillaries

• Uncontrollable hemorrhaging, usually ending in death

Airborne Bacterial Diseases

• Streptococcal disease– Streptococcus pyogenes

• Strep throat• Childbed fever• Necrotizing fasciitis

(flesh-eating disease)• Scarlet fever

– Streptococcus mutans• Tooth decay• Rheumatic heart disease

– Enterococcal illnesses• GI tract infection

– Treatment• Antibiotics

Fig. 19.1 Streptococci

Reprinted with permission from the American Society for Microbiology (Tao, L., Tanzer, J.M and MacAlister, T.J.; J. Bacteroil, 1987 June; 169(6): 2543-2547.)

Reprinted with permission from the American Society for Microbiology (Fluckiju, U. and Fischetti, V.A.; Infect. and Immun, 1998 March; 66(3): 974-979.) Photo courtesy of Doctor Vincent A. Fischetti.

Courtesy of Vincent A. Fischetti, Ph.D., Head of the Laboratory of Bacterial Pathogenesis at Rockefeller University


• Diphtheria– Caused by Corynebacterium diphtheriae– Prevented by toxoid vaccination

• Pertussis– Also known as whooping cough– Caused by Bordetella pertussis– Disintegrating cells and mucus accumulate in airways – Debris causes labored breathing– Prevented by toxoid vaccination– Re-emerging as problem in Eastern Europe


• Bacterial meningitis– Disease of meninges, membranes that cover brain– Most severe is meningococcal meningitis

• Caused by Neisseria meningitidis

• Accompanied by

– Pounding headache

– Stiff neck

– Numbness in extremities

• Starts as upper respiratory infection

• Toxins can spread from bloodstream and cause rapid death

• Transmissible as aerosol or through shared utensils or cups

– Childhood meningitis• Typically caused by Haemophilus influenzae or Streptococcus

pneumoniae

• Vaccine available for both causes


• Legionairre’s disease– Caused by Legionella pneumophila

• Grow in standing water

– Cooling towers

– Industrial air-conditioning unit

– Humidifiers

• Hard to grow in laboratory

– Signs• Fever

• Dry cough with little sputum

• Potentially fatal lung infection


• Bacterial pneumonia– Microbial disease of the bronchial tubes and lungs– Infection usually results in significant fluid infiltration into lungs– Can be caused by many agents, including Streptococcus

pneumoniae– Signs

• High fever• Sharp chest pains• Difficulty breathing• Rust-colored sputum (from blood in lungs)

– Walking pneumonia• Also called primary atypical pneumonia• Not as severe (low to no fever, no blood in lungs)• Caused by Mycoplasma pneumoniae

– Treatment of both with antibiotics

Foodborne and Waterborne Bacterial Diseases

• Botulism– Caused by Clostridium botulinum

• Spore-forming obligate anaerobes

– Botulism toxin as bioterrorism agent• 1 pint of pure material could eliminate world population• 1 ounce would kill all the people in the United States

– Toxin produced by spores that germinate• Canned foods

– Signs• Blurred vision• Slurred speech• Labored breathing• Flaccid paralysis

– Botox as cosmetic agent– Once toxin enters bloodstream, only treatment is antitoxin


• Staphylococcal food poisoning– Caused by Staphylococcus aureus– Signs similar to most food poisoning

cases• Diarrhea• Vomiting• Other signs of gastrointestinal distress

• Salmonellosis– Caused by various Salmonella

species– Sources may be poultry,

contaminated animals, eggs– Signs similar to most food poisoning

cases

Fig. 19.6 Salmonella

© S

cimat/P

hoto Researchers, Inc.

Courtesy of D

r. W.L. D

entler


• Typhoid fever– Caused by Salmonella typhi– Spread by not washing hands during food preparation

• Typhoid Mary

– Signs• Deep intestinal ulcers

• Bloody stools

• In a few days, mounting fever

• Lethargy

• Delirium

• If left untreated, frequently fatal

– Antibiotic treatment


• Shigellosis– Sometimes called

bacterial dysentery– Caused by four different

species of Shigella– Signs

• Intense abdominal cramps

• Small-volume, bloody, mucoid stools

– Shiga toxins

• Cholera– Caused by Vibrio

cholerae– Severe watery diarrhea

may lead to death due to dehydration

Fig. 19.8 Vibrio cholerae

Courtesy of Louisa Howard, Dartmouth College, Electron Microsocpe Facility

Courtesy of Janice Carr/CDC


• E. coli diarrheas– Sometimes called

• “Hamburger disease”

• Traveler’s diarrhea

– Caused by subset of Escherichia coli• Enterohemorrhagic E. coli (EHEC)

– O157:H7

• Enteropathogenic E. coli (EPEC)

• Enterotoxigenic E. coli (ETEC)

• Enteroinvasive E. coli (EIEC)

• Enteroaggregative E. coli (EAggEC)

– Spread from contaminated animal feces• Water supplies

• Raw ground meat

Soilborne Bacterial Diseases• Anthrax

– Sometimes called wool sorter’s disease

– Caused by Bacillus anthracis• Spore-forming Gram-positive

bacteria– Spread by

• Aerosol inhalation of spores• Ingestion of spores• Entrance of spores into open

wounds– Spores germinate and vegetative

cells make fatal toxin– Signs

• Organs fill with black, bloody fluid

• Black, crusty, boil-like lesions• Violent dysentery with bloody

stool• Frequently fatal

– Potential as bioterrorism weapon– Antibiotic therapy

Fig. 19.10 Bacillus anthracis

Courtesy of CDC/James H. Steele

© Phototake/Alamy Images

© Phototake/Alamy Images

Soilborne Bacterial Diseases

• Tetanus– Also called lockjaw– Caused by Clostridium tetani

• Spore-forming obligate anaerobes

– Acquired from environment• Soil-contaminated nail

• Piece of glass

• Dirty needle

• Thorns

– Spores germinate under skin– Vegetative cells produce tetanus toxin

• Rigid paralysis

• Can lead to death

– Tetanus toxoid vaccine

Sexually Transmitted Diseases

• Syphilis– Caused by spirochete Treponema pallidum– Spirochetes penetrate skin and cause disease– Three stages

• Primary syphilis– Chancre– Disappears after 2-6 weeks

• Secondary syphilis– Systemic lesions– Fever– Rash– Patchy loss of hair on head

• Tertiary syphilis– Gumma– Paralysis– Insanity

Sexually Transmitted Diseases

• Gonorrhea– Also called “the clap”– Caused by Neisseria gonnorhoeae– Can cause pelvic inflammatory disease and sterility– Treatment with antibiotics

• Chlamydia– Caused by Chlamydia trachomatis– Frequently no signs of infection in males– Female signs and symptoms

• Slight vaginal discharge

• Inflammation of cervix

• Burning pain upon urination

– Can result in scarring of Fallopian tubes and sterility

Contact and Miscellaneous Bacterial Diseases

• Leprosy– Also called Hansen’s disease– Caused by Mycobacterium leprae

• Acid-fast bacillus that resists desiccation

– Spread by multiple skin contacts or aerosol droplets– Signs

• Disfigured skin and bones

• Twisted limbs

• Curled fingers

• Loss of sensation in extremities

• Loss of extremities

– Leper colonies

Contact and Miscellaneous Bacterial Diseases

• Conjunctivitis and trachoma– Conjunctivitis

• Also called pinkeye

• Caused by many different bacteria, including Haemophilus aegyptius

• Spread by aerosol droplets from close contact

• Effective antibiotic therapy

– Trachoma• Caused by Chlamydia trachomatis

• Also eye infection, like pinkeye

• Spread by contaminated fingers, towels, etc.

Needs figure of pinkeye

Documents

Chapters 18 & 19 Supplement to diseases already covered. –Previously covered in depth and not included here: Viruses –HIV –Influenza (including avian and