Diseases

Question 1

Human Papillomavirus (HPV)

Answer 1

Type: DNA virus

Disease: genital warts–> cervical cancer (possible)

Pathogenesis:

• virus transmitted by physical contact, binds to epithelial cells
• stimulates cell proliferation–> warts
• viral proteins (E6/E7) binds to tumor suppressor gene product =tumors

Treatment: ca be self-limiting, topical treatments to destroy infected tissue

Question 2

Human Immunodeficiency Virus (HIV)

Answer 2

Type: RNA virus, enveloped

Disease: Lymphadenopathy: enlarged lymph nodes, fever, sweats, myalgia, vomiting, diarrhea

- AIDS: dramatic loss of CD4 cells (>200), immunodeficiency 
- opportunistic

Pathogenesis:

• exposure to blood/blood products
• virus binds to CD4 receptors on T helper cells and macrophages
• virus used reverse transcriptase and HIV integrates to integrate into host DNA
• virus gets latent (asymptomatic)
• when reactivated–>kill CD4 cells–> loss of cell mediated immunity

Treatment: antiretroviral therapy (3 or more drug combinations)

Question 3

Poliovirus

Answer 3

Type: RNA virus

Disease: poliomyelitis: permanent paralysis of muscles

Pathogenesis:

• virus binds to intestinal mucosa
• spreads to lymphatic tissue –> blood –> multiple organs
• if reaches brain of spinal cord –> destroys nerve cells

Treatment:
-none- supportive care, vaccine available (working to eradication)

Question 4

Streptococcus mutans

Answer 4

Type: bacteria, Gram (+) cocci
Disease: dental carries (cavities)
  -holes in tooth enamel, pain
Pathogenesis: 
  -breaks down sucrose into glucose and fructose
  -glucose forms dextran (sticky polysaccharide)
    -allows bacteria to stick to enamel
    -contributes to plaque
  -fructose: fermented into lactic acid
    -erodes tooth enamel 
Food Implicated:
  -sucrose
Treatment/ Prevention
  -brush and floss teeth
  -fluoride helps prevent degradation by lactic acid

Question 5

Helicobacter pylori

Answer 5

Type: bacteria, Gram (-) spiral
Disease: peptic ulcers
  -abdominal cramps, black stool
Pathogenesis 
  -produces high amounts of urease
    -urease converts urea to ammonia
    -ammonia neutralizes stomach acid, allowing for infection
  -bacteria colonize in stomach lining, degrading linings 
   --> ulcers
Treatment/ Prevention
  -bismuth subsalicylate- coats stomach to prevent bacteria from adhering
  -antibiotics

Question 6

Staphylococcus aureus

Answer 6

Type: bacteria, Gram positive cocci 
Disease: Staphylococcal food poisoning
  -vomiting, abdominal cramps, diarrhea, soon after ingestion
Pathogenesis 
  -heat stable enterotoxin 
  -stimulates vomiting and abdominal cramps, shortly after ingestion
Food Implicated
  -high salt, sugar, or protein based foods
  -ex. custards, cream pies, ham
Treatment: 
  -fluid replacement 
  -self-limiting within 24 hours

Question 7

Shigella dysenteriae

Answer 7

Type: bacteria, gram (-) rod
Disease: Shigellosis (Bacillary dysentery)
-dysentery (bad- 20/day)
-Abdominal cramps and fever
Pathogenesis:
-infective dose extremely low (10-100 cells)
-resistant to stomach acidity, replicates in small intestines, infects large intestines
-epithelial cells ingest bacteria, bacteria multiples inside, spread
-shiga toxin: destroys tissue, extremely virulent
Food Implicated:
-contaminated water (fecal-oral route)
Treatment/ Prevention:
-rehydration
-antibiotics: fluoroquinolones

Question 8

Salmonella enterica

Answer 8

Type: bacteria, Gram negative rod
Disease: Salmonellosis- gastroenteritis
-diarrhea, abdominal cramps, nausea, moderate fever (possible)
Pathogenesis:
-infects intestinal mucosa, ingested by epithelial cell
-multiplies in cells –> inflammation –> diarrhea
-produces enterotoxin
Food Implicated
-undercooked poultry products
-ex Chicken, eggs
Treatment/ Prevention:
-fully cook poultry, and apply proper sanitation practices
-rehydration

Question 9

Salmonella typhi

Answer 9

Type: bacteria, gram (-) rod
Disease: Typhoid fever
  -high fever 40C, headache
  -Rose spot rash
  -diarrhea 
Pathogenesis
  -multiplies within phagocytes, spread to multiple organs
  -phagocytes lyse --> bacteremia 
  -recovering patients still shed organism from gall bladder
Food implicated:
  -contaminated water (fecal-oral route)
Treatment/ Prevention:
  -rehydration 
  -antibiotics: doxycycline

Question 10

Vibrio cholerae

Answer 10

Type: bacteria, Gram (-) curved rod
Disease: Cholera
  -rice water stool
  -Severe dehydration (12-20 liters per day)
  -Can lead to shock or death
Pathogenesis:
  -infect small intestines and produce enterotoxin
  -enterotoxin binds to epithelium causing host to secrete Cl-
  -water and other electrolytes follow
Food implicated: 
  -contaminated water (fecal-oral route)
Treatment/ Prevention:
  -intravenous replacement of fluids
  -antibiotics: doxycycline

Question 11

Escherichia coli

Answer 11

Type: bacteria, Gram negative rod (various types)
1. ETEC- enterotoxigenic E. coli
2. EHEC- enterohemorrhagic E. coli (E. coli O157:H7)
Disease ETEC: Traveler’s Diarrhea
-diarrhea from enterotoxin
Food implicated: contaminated water (fecal-oral route)
Treatment: fluids

Disease (EHEC)
  -dysentery inflamed colon
  -hemoltic uremic syndrome: blood in urine, kidney failure
Pathogenesis:
  -enterotoxin, similar to shiga toxin
Food Implicated: 
  -contaminated meats, ground meats Treatment/Prevention: 
   -antibiotics, cook meat thoroughly

Question 12

Bacillus cereus

Answer 12

Type: bacteria, gram positive rod (endospore former)
Disease: gastroenteritis 
  -vomiting and nausea (2-5 hours after ingestion)
  -diarrhea (8-16 hours)
Pathogenesis
  -endospores survive cooking process
  -as food cools, spore germinate and toxins released
  -ingested
Food implicated
  -high carbohydrate foods
  -ex. cereal, rice, pasta
Treatment/Prevention:
  -self-limiting

Question 13

Clostridium perfringens

Answer 13

Type: bacteria, gram positive rod (endospore former)
Disease: mild gastroenteritis 
  -mild upset stomach 
Pathogenesis:
  -endospores resist cooking
  -vegetative cells germinate during serving r inadequate refrigeration 
Food implicated
  -several foods
Treatment/Prevention:
  -self-limiting

Question 14

Clostridium botulinum

Answer 14

Type: bacteria Gram Positive rod (endospore former)
Disease: botulism
-double vision, paralysis, blinding and flashing lights
-death is paralysis of diaphragm
Pathogenesis:
-potent paralytic neurotoxin (tasteless, colorless)
Food implicated:
-canned meats and vegetables
-honey (infant botulism)
Treatment/Prevention
-anti-toxin against specific strain

Question 15

Norovirus

Answer 15

Type: virus, RNA
Disease: diarrhea, vomiting, nausea, stomach pain
Pathogenesis:
-extremel contagious (5 viral particles –> infection)
-virus enters through contaminated foods or air
-infects small intestines –> inflammation
Food implicated: contaminated water (fecal-oral route)
Treatment/Prevention: self-limiting

Question 16

Entamoeba histolytica

Answer 16

Type: Protozoa (sacrodina)
Disease: amoebic dysentery 
Pathogenesis: 
  -ingest cysts
  -low pH of stomach --> excitation
  -trophozoites emerge in small intestines
  -trophozoites multiply/lyses in epithelial lining (feeds on tissue)
Food Implicated:
  -contaminated water (fecal-oral route)
Treatment/Prevention:
  -metronidazole