about the disease in digestive system

1. Infectious Diseases of the
Digestive System

2. GI Tract

3. U.S. Foodborne-Disease Outbreaks

5. Typhoid Mary
• Human carrier
(and reservoir) of
Salmonella typhi

6. Typhoid Fever and
Salmonellosis

7. Salmonella enterica serovars
• Infect domestic animals
• Eggs and contaminated
meat
• One of the most
prevalent causes of food-
borne illnesses
• Transmission dose as
few as 10 organisms
• Attachment is key
virulence factor

8. Salmonella enterica serovars.
• Gram negative bacillus
• Classification based on serology and
phage susceptibility assays

9. Salmonellosis
• 40,000 cases annually in US
• Invades intestinal epithelial cells
• Nausea, cramps, diarrhea
• Recovery in a few days but may
shed organism for 6 months

12. Campylobacter jejuni
• Small curved
Gram negative
rod
• Lives in large
intestine of birds
and mammals
• Fecal
contamination of
water and foods

13. Campylobacteriosis
• Leading bacterial cause of human
gastroenteritis in the world
• 2.4 million U.S. cases/year
• Undercooked poultry, shellfish,
unpasteurized dairy products,
contaminated water
• Waterybloody diarrhea
• Treated with antibiotics

14. Rotavirus
• virus
• Primary cause of diarrhea
morbidity and mortality
• 1 million cases per year; 70,000
hospitalizations
• Fecal-oral transmission
• Most serious in infants 6-24
months

15. Hepatitis
• Inflammation
of the liver
• Multiple
viruses

16. Hepatitis A Virus
• “Infectious”
hepatitis
• Small RNA virus
• Transmitted by
fecal-oral route
• New effective
vaccine

17. Hepatitis A in US

18. Hepatitis A Worldwide

19. Hepatitis B Virus
• “Serum” hepatitis
• Enveloped DNA
virus
• Can result in
chronic infection
and liver cancer
• Recombinant
vaccine

21. Hepatitis C Virus
• “Serum” hepatitis
• More likely than
HBV to become
chronic
• Also causes liver
cancer
• No vaccine

22. Hepatitis C
• Treated with
Interferon alpha
and ribavirin
• No cure but slows
liver damage

23. Giardia lamblia
• Protozoan
• Cysts survive in
environment
–Insensitive to
chlorine
• Contaminated
water source of
infection

24. Giardiasis
• Shed by wild animals
into water supply as well
as by infected humans
• G. lamblia attaches to
human intestinal wall
• Diarrhea lasting for
weeks
• Treated with anti-
parasitic drugs

25. HELMINTHES
Flat worms and Round worms

27. Hermaphroditic Flukes

34. FLAT WORMS
Phylum Platyhelminthes = Flat worms
Class Cestoda = Tape worms
Scolex contained in egg
holdfast structure with
hooks and suckers
Proglottids major body of
tapeworm
contains both ovaries and
testes = hermaphroditic
Eggs can penetrate intestine of host

36. FIGURE 13-57 Taenia solium scolex (X64).
The Taenia solium scolex has two rings of hooks and four suckers.

43. Hookworms
• Ancylostoma duodenali and Necator
americanus Old world and new world
hookworms differ only in their geographic
location.
Human phase of this worm begins with a
filaform larvae penetrating the skin, enters
circulation, carried to the lungs, coughed up
and swallowed, develops to adulthood in
small intestine. Adult worms lay between
10,000 and 20,000 eggs per day. Daily blood
loss 0.2ml/adult/day. Microcytic hypochromic

45. Biblical worm
• Trichinella spiralis etiological agent
of trichinosis. Infectious larva is
present in the striated muscle of
carnivorous and omnivorous
mammals. Swine most common
organism to transmit to humans.
Encysted larvae live for many
years. Polar bears and walruses
are accounting for new human
infestations in our Alaskan artic
regions.

47. FIGURE 13-68 Trichinella spiralis larva in skeletal muscle (W.M., X260).
The spiral juvenile and its nurse cell are visible in this preparation.

48. Pin worms or Seat worms
• Enterobius vermicularis most common
helminthic infestation in America, 500
million cases annually globally second
globally to Ascaris infestations.
Eggs are ingested mainly fecal-
oral.Egg laden dust can be inhaled.
Autoinfection occurs frequently.
“Scotch Tape Test” from perianal folds
of diagnostic value.

51. Ascaris Lumbricoides
• Large worms 25cm – 45cm in length. Most
common helminth with over a billion infested
a year. Prevalent in areas where sanitation is
poor and human waste is used as fertilizer.
• Ingested egg releases a larva that penetrates
the duodenal wall and carried to the liver and
the heart, enters the pulmonary system,
enters the alveoli where they molt and
mature. They are coughed up, swallowed and
returned to the small intestine. Adults can be
passed out into the feces.

55. Helminth Transmission
• Intestine -->
environment -->
ingested
• Examples:
whipworm

56. Helminth Transmission
• Intestine -->
environment -->
skin penetration
• Example:
hookworms

57. Helminth Transmission
• Intestine -->
environment -->
food animal
muscle -->
ingested
• Example:
tapeworm

58. Helminth Transmission
• Various organs --
> environment -->
ingestion or
penetration
• Example: flukes

59. Treatment of Inflammatory
Bowel Disease with Worms?
• Pig whipworm causes transient, non-
invasive, non-infective human disease
• Improved IBD symptoms