BIOL 251 Microbiology Exam 3 Diseases

Exam 3

Syphilis

Causative Agent: Treponema pallidum

Type of Pathogen: Bacterium (spirochete)

Modes of Transmission:

• Sexual contact

• Transplacental (mother to fetus)

Organs Affected:

• Skin

• Mucous membranes

• Cardiovascular system

• central nervous system

Genital Herpes

Causative Agent: Herpes simplex virus type 2 (HSV-2) — sometimes HSV-1

Type of Pathogen: Virus

Modes of Transmission:

• Sexual contact

• Skin-to-skin contact,

• Vertical (mother to child during childbirth)

Organs Affected:

• Skin

• Mucous membranes of the genital and anal areas

• Nervous system (sensory neurons)

Malaria

Causative Agent:

• Plasmodium falciparum,

• P. vivax

• P. ovale

• P. malariae

• P. knowlesi)

Type of Pathogen: Protozoa (protist)

Mode of Transmission: Bite from an infected female Anopheles mosquito

Animal Reservoir/Vector:

• Mosquitoes

• Primates

Organs Affected:

• Liver

• Red blood cells

• Spleen

• Brain (cerebral malaria)

Bacterial Endocarditis

Causative Agent:

• Staphylococcus aureus

• Streptococcus viridans

• Enterococcus species

Type of Pathogen: Bacteria

Modes of Transmission:

• Oral injury, surgery

• IV drug use

• Existing infections

Organs Affected:

• Heart (especially heart valves)

• Kidneys

• Brain

• Lungs

Lyme disease

Causative Agent:

• Borrelia burgdorferi (in North America)

• Borrelia mayonii (less common)

Type of Pathogen: Bacterium (spirochete)

Mode of Transmission: Bite from infected black-legged tick (Ixodes scapularis or Ixodes pacificus)

Animal Reservoir/Vector:

• Ticks

• Small mammals like white-footed mice

• Deer

Organs Affected: Skin, joints, nervous system, heart

Plague

Causative Agent: Yersinia pestis

Type of Pathogen: Bacterium

Toxins Involved: Yersinia outer proteins (YOPs)

Modes of Transmission:

• Bubonic Plague: Flea bite

• Pneumonic Plague: Respiratory droplets (person-to-person)

• Septicemic Plague: May result from untreated bubonic or pneumonic forms

Animal Reservoir/Vector: Fleas

Reservoir: Rodents

Organs Affected:

• Bubonic: Lymph nodes

• Pneumonic: Lungs

• Septicemic: Blood and multiple organ systems

C. diff

Causative Agent: Clostridioides difficile

Type of Pathogen: Bacterium (spore-forming, anaerobic)

Toxins Involved:

• Toxin A (enterotoxin)

• Toxin B (cytotoxin)

Mode of Transmission: Fecal-oral route, especially in healthcare settings

Organs Affected: Colon

Amoebiasis

Causative Agent: Entamoeba histolytica

Type of Pathogen: Protozoa (protist)

Toxins Involved: Amoebapores and cysteine proteases (damage host tissues)

Mode of Transmission: Fecal-oral route (cysts from contaminated food or water)

Organs Affected:

• Primarily large intestine (ulcers)

• Liver (amoebic liver abscess)

Gonorrhea

Causative Agent: Neisseria gonorrhoeae

Type of Pathogen: Bacterium (gram-negative diplococcus)

Toxins Involved: Lipooligosaccharide (LOS) – promotes inflammation and immune evasion

Modes of Transmission:

• Sexual contact

• Vertical (mother to child during childbirth)

Organs Affected:

• Genital tract

• Rectum

• Throat

• Eyes (conjunctivitis)

Genital Warts

Causative Agent: Human papillomavirus (HPV), types 6 and 11

Type of Pathogen: Virus

Modes of Transmission:

• Sexual contact

• Skin-to-skin contact

Organs Affected:

• Genital and anal regions

• Throat (transmitted orally)

Infectious Mononucleosis

Causative Agent: Epstein-Barr virus (EBV)

Type of Pathogen: Virus (Herpesvirus family)

Modes of Transmission:

• Saliva

• Sexual contact

• Blood

• Organ transplants

Organs Affected:

• Lymph nodes

• Spleen

• Liver

• Throat (tonsillitis)

HIV

Causative Agent: Human immunodeficiency virus (HIV), mainly type 1 (HIV-1), but also type 2 (HIV-2)

Type of Pathogen: Virus (Retrovirus)

Modes of Transmission:

• Blood

• Sexual contact

• Vertical transmission

• Needle sharing

Animal Reservoir/Vector:

• Chimpanzees

• Gorillas

Organs Affected:

• Immune system (particularly CD4 T cells)

• Multiple organs

Blastomycosis

Causative Agent: Blastomyces dermatitidis

Type of Pathogen: Fungus (dimorphic)

Modes of Transmission:

• Inhalation of airborne conidia fungal spores

• Soil

• Decaying organic matter

Organs Affected:

• Lungs (pulmonary form),

• Skin

• Bones

• Genitourinary system

• Brain (rare)

Legionellosis

Causative Agent: Legionella pneumophila

Type of Pathogen: Bacterium (gram-negative)

Toxins Involved: Various, including phospholipases and proteases that damage host cells

Mode of Transmission: Inhalation of aerosolized water droplets contaminated with the bacteria (e.g., from air conditioning systems, hot tubs, or showers)

Organs Affected:

• Lungs (causes pneumonia)

• Other organs in severe cases

Common cold

Causative Agent:

• Most commonly Rhinovirus,

• Coronavirus,

• Adenovirus

• Respiratory syncytial virus (RSV)

Type of Pathogen: Virus

Modes of Transmission:

• Airborne droplets

• Direct contact with contaminated surfaces

• Contact with infected individuals

Organs Affected: Upper respiratory system (nose, throat, sinuses)

Influenza

Causative Agent: Influenza viruses (types A, B, C, and D)

Type of Pathogen: Virus (Orthomyxovirus family)

Modes of Transmission:

• Airborne respiratory droplets

• Direct contact with contaminated surfaces

Animal Reservoir/Vector:

• Wild birds (H5N1);

• Pigs

Organs Affected: Upper & lower respiratory system (nose, throat, lungs)

Pinworms

Causative Agent: Enterobius vermicularis

Type of Pathogen: Helminth (roundworm)

Modes of Transmission:

• Fecal-oral route

• Ingestion of eggs from contaminated surfaces or hands

Organs Affected: Intestinal tract (primarily the colon and rectum)

Hookworms

Causative Agent:

• Ancylostoma duodenale

• Necator americanus

Type of Pathogen: Helminth (roundworm)

Mode of Transmission: Skin contact with contaminated soil, larvae penetrate the skin (usually bare feet)

Animal Reservoir/Vector:

• Dogs & Cats (Ancylostoma).

Organs Affected: Small intestine, may cause anemia and malnutrition

Shiga-toxin-producing E. coli (STEC)

Causative Agent: Escherichia coli (O157:H7)

Type of Pathogen: Bacterium (gram-negative)

Toxins Involved: Shiga toxin (STX), which inhibits protein synthesis in host cells

Modes of Transmission:

• Consumption of contaminated food or water (often undercooked beef)

• Person-to-person contact

Animal Reservoir/Vector: Cattle

Organs Affected:

• GI tract (diarrhea, sometimes bloody),

• Kidneys (hemolytic uremic syndrome)

Helicobacter pylori

Causative Agent: Helicobacter pylori

Type of Pathogen: Bacterium (spiral-shaped, gram-negative)

Toxins Involved:

• Vacuolating cytotoxin A (VacA)

• CagA protein (increases risk of ulcers and cancer)

Modes of Transmission:

• Fecal-oral route

• Oral-oral transmission (potentially from contaminated food or water)

Animal Reservoir/Vector: Primates

Organs Affected: Stomach (gastritis, peptic ulcers, gastric cancer)

Peptic Ulcer Disease

Causative Agent: Helicobacter pylori (most common)

Type of Pathogen: Bacterium (for H. pylori), chemical/physical irritants for NSAID-induced ulcers

Toxins Involved:

• VacA

• CagA

• NSAIDs cause local irritation and inhibit prostaglandin production

Mode of Transmission: Fecal-oral route

Animal Reservoir/Vector: Primates

Organs Affected:

• Stomach

• Duodenum (ulcers, erosions)

Rabies

Causative Agent: Rabies virus

Type of Pathogen: Virus (Rhabdovirus family)

Mode of Transmission: Bite or scratch from an infected animal (usually mammals)

Animal Reservoir/Vector:

• Wild animals (bats, raccoons, skunks, foxes)

• Domestic animals (where vaccination is not common)

Organs Affected: CNS (brain, spinal cord), leading to encephalitis

Arboviral encephalitis

Causative Agent:

• West Nile virus

• Eastern equine encephalitis virus (EEEV)

• Western equine encephalitis virus (WEEV)

• Japanese encephalitis virus (JEV)

Type of Pathogen: Virus (Flavivirus, Alphavirus, and other families)

Mode of Transmission: Bite from an infected arthropod vector (e.g., mosquitoes, ticks)

Animal Reservoir/Vector:

• Mosquitoes

• Ticks

Reservoir:

• Birds (for many arboviruses, like West Nile)

• Horses (for equine strains)

Organs Affected: CNS (brain and spinal cord)

Tetanus

Causative Agent: Clostridium tetani

Type of Pathogen: Bacterium (anaerobic, spore-forming)

Toxins Involved: Tetanospasmin (interferes with neurotransmission, leading to muscle spasms)

Mode of Transmission: Contamination of a wound with spores, often from soil

Animal Reservoir/Vector:

• Soil

• Animal intestines (horses and cattle)

Organs Affected:

• Nervous system (muscle spasms, particularly in the jaw

• Respiratory muscles)

Botulism

Causative Agent: Clostridium botulinum

Type of Pathogen: Bacterium (anaerobic, spore-forming)

Toxins Involved: Botulinum toxin (a potent neurotoxin that blocks neurotransmitter release, causing paralysis)

Modes of Transmission:

• Foodborne botulism: Consumption of food contaminated with botulinum toxin (often improperly canned food)

• Infant botulism: Ingestion of spores (e.g., honey)

• Wound botulism: Contamination of a wound with spores

Animal Reservoir/Vector:

• Soil & dust

• Intestines of animals (fish, poultry, and honeybees)

Organs Affected: Nervous system (causes paralysis, in the face and spreads to the rest of the body)

Typhoid Fever

Causative Agent: Salmonella enterica serotype Typhi

Type of Pathogen: Bacterium (gram-negative, facultative anaerobe)

Toxins Involved: Endotoxin (lipopolysaccharide – LPS) that causes fever and systemic inflammation

Mode of Transmission: Fecal-oral route, usually through contaminated food or water

Organs Affected:

• Intestines

• Liver

• Spleen

• Blood (can lead to septicemia and GI complications)

Cholera

Causative Agent: Vibrio cholerae

Type of Pathogen: Bacterium (gram-negative, curved rod)

Toxins Involved: Cholera toxin (CTX), which causes excessive fluid secretion in the intestines, leading to diarrhea

Mode of Transmission: Fecal-oral route, typically through contaminated water or food

Organs Affected: Intestines