bacterial diseases in humans: unit 3 Chapter 15

Disease terms

pathogen : bacteria or infections agent that causes harm to its host
epidemic : increase in incidence of a disease in a specified population
pandemic : wide spread (worldwide) epidemic
Endemic disease: is always present, usually in low incidence in a population
zoonoses : diseases normally in animals in animals that can infect humans

Notable bacterial diseases

Typhoid fever
pathogen : salmonella typhi
Thought to have caused plague of athens (430 BC)
Modern occurrence: estimated 2019 worldwide incidence 9 M (WHO)
Transmitted through water, food contaminated with human feces
Signs and symptoms: “fever, fatigue, headache, nausea, abdominal pain, and constipation or diarrhea” (WHO)

Notable bacterial diseases

Yersinia pestis
Bubonic plague, the black plague
Historic plagues:
Plague of justinian, 541-750 (eastern mediterranean area)
Black Death (europe) 1346-1362
Plague of london (1600s)
Currently endemic in rodents in SW U.S. (10-20 human cases/year)
Transmitted by infected by fleas, also airborne from pneumonic patients
Symptoms include fever, chills, headache, swollen lymph nodes (bubos) pneumonia, shock, gangrene

Notable bacterial disease

Borrelia burgdorferi and other borrelia spp.
Lyme disease ‘
Has been around for thousands of years, newly-recognized via an epidemic of arthritis in children in old Lyme. CT, in 1970s
Transmitted via infected Ixodes ticks
Signs and symptoms: “bulls eye rash”, fever, chills, headache, muscle/joint pain, swollen joints (esp knees, nerve pain, facial paralysis, stiff neck, dizziness.
Clostridium botulinum
Botulism food poisoning
Sporadic occurrence
Occurs when c. botulinum spores from soil contaminate food that is preserved/stored in anaerobic conditions (e.g. sausages, canning)
Causes “limp” paralysis of muscles. Including diaphragm-extremely dangerous
Prevented by careful food processing procedures
Home canners: use a pressure cooker and follow all the guidelines carefully
Acids and nitrites inhibit c. botulinum growth
Enterohemorrhagic strains of e. Coli (e.g. coli o157:H7)
Cause bloody diarrhea often followed by “hemolytic uremic syndrome”
Hus: destruction of red blood cells/anemia, clotting ability, kidney failure
Foodborne, from raw/undercook foods contaminated with cattle feces
Meat
Vegetables
Listeriosis
Listeria monocytogenes
Common in soil, water natural environment; can contaminate foods
Meats, esp. Processed “lunch meat”
Dairy (unpasteurized)
Deli salads, sprouts, melons
Can grow at normal refrigerator temperatures
Healthy adults may have no symptoms, or mild “flu like” illness
Staphylococcus aureus
Skin infections (infected hair follicles, boils, cellulitis)
Infections of internal organs (pneumonia, urinary tract infections)
Infections of the bloodstream, internal tissues
30% of people carry s. Aureus harmessy on their skin/in their gut
Some strains are highly antibiotic resistant (MRSA, VISA, VRSA)

Problems in combating bacterial infections

Biofilms
Organisms in biofilms highly resistant to antibiotics, disinfectants
Antibiotic resistance
Antibiotic: chemical that supports or inhibits the growth of other organisms
Resistance arises from over overexposure to antibiotics
Humans and livestock
Antibiotic kills off most susceptible bacteria: leaves resistant ones to reproduce without competition
Resistance bacteria may share genes with nonresistant ones
Conjugation
Transformation

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