DISEASES OF THE DIGESTIVE SYSTEM
OVERVIEW
OVERVIEW
Many pathogens enter the body when we ingest water and food.
Defenses of the digestive system are very strong.
Digestive infections are a major cause of morbidity and mortality.
BACKGROUND
The mouth and large intestine are crowded with microorganisms. Part of the normal oral flora
Digestive diseases are usually associated with: Crowding Poor hygiene Contaminated food or water
BACKGROUND
Digestive infections in developed and undeveloped countries are associated with different pathogens.
Developed countries: Campylobacter Salmonella Shigella
Undeveloped countries: Vibrio cholerae
CLASSIFICATION OF INFECTION
Infections in the digestive system are classified in two groups: Exogenous infections – pathogens that come into
the body Endogenous infections – organisms that are part of
the normal microbial flora
EXOGENOUS INFECTIONS
Exogenous infections are brought in with contaminated food or water. C. difficile and other exogenous infections are
frequently acquired in hospital environments. Helicobacter pylori spreads through oral-oral or
fecal-oral contact.
EXOGENOUS INFECTIONS
ENDOGENOUS INFECTIONS
Endogenous infections are caused by organisms that are part of the normal flora. Streptococcus and Enterococcus are examples.
In the right circumstances they can cause: Dental diseases. DISEASES OF the bowel, appendix, and liver. Diverticular abscesses.
ENDOGENOUS INFECTIONS
CLINICAL SYMPTOMS OF GASTROINTESTINAL INFECTIONS
Most common symptoms are: Fever Vomiting Abdominal pain Diarrhea
The central feature in all cases is diarrhea
CLINICAL SYMPTOMS OF GASTROINTESTINAL INFECTIONS
The nature of the diarrhea is used to classify gastrointestinal infections into three categories: Watery diarrhea Dysentery Enteric fever
WATERY DIARRHEA
Caused by pathogenic mechanisms that attack the intestines
Symptoms are usually acute but brief (last 1 to 3 days).
DYSENTERY Caused by organisms that cause damage to the
colonic mucosa Either directly or production of toxins
Contain blood and pus Can be accompanied by cramps, abdominal pain
and little vomiting Not as much fluid loss as in watery diarrhea but
lasts longer Most cases resolve in 3 to 7 days.
ENTERIC FEVER
Systemic infection focused in the gastrointestinal tract.
Prominent features are fever and abdominal pain.
Pathogens spread to biliary (bile) tract, liver, and organs of the reticuloendothelial system.
Most investigated form is typhoid fever.
TYPES OF INFECTION
There are five major types of gastrointestinal infection: Endemic Epidemic Traveler’s diarrhea Food poisoning Nosocomial infections
ENDEMIC GASTROINTESTINAL INFECTIONS
Defined as infections that occur sporadically Some are worldwide. Some are geographically restricted. There can be seasonal variation. They can be age-related.
ENDEMIC GASTROINTESTINAL INFECTIONS
The major pathogens in developed countries are: Campylobacter Salmonella Shigella
Some organisms geographically restricted to warm climates: Vibrio cholerae
EPIDEMIC GASTROINTESTINAL INFECTIONS
Defined as infections involving regional, national, and international populations.
Most common epidemic infections are: Cholera Typhoid fever Shigellosis
All are directly related to failures in public health.
TRAVELER’S DIARRHEA
20-50% of travelers to undeveloped countries will get diarrhea in the first week.
Most studied cases are travelers from the US to Latin America. 50% of cases are caused by enterotoxigenic strains
of E. coli. 10-20% are caused by Shigella. The major source is ingestion of improperly
cooked food.
FOOD POISONING
Food poisoning is usually caused by: Failing to cook food adequately. Allowing undercooked food to sit. Improper storage is an additional factor.
FOOD POISONING
NOSOCOMIAL GASTROINTESTINAL INFECTIONS
Acquired in a hospital and usually traced to: Employees. Contaminated food prepared outside the hospital.
Two major pathogens responsible: E. coli C. difficile
C. difficile accounts for 90% of infections. Symptoms range from mild diarrhea to fulminant
pseudomembranous colitis. Colitis arises either during or after treatment with
antibiotics.
TREATMENT & MANAGEMENT OPTIONS FOR GASTROINTESTINAL INFECTIONS
Treatment involves supportive care with liquid replacement rest.
Infection with E. coli O157:H7 can result in renal failure.
BACTERIAL DISEASES OF THE DIGESTIVE SYSTEM
Most common causes: Escherichia coli (E coli), Salmonella, and
Shigella
Infections causes nausea with or without vomiting, diarrhea and other gastrointestinal symptoms.
May also cause bloody diarrhea, known as dysentery.
BACTERIAL DISEASES OF THE DIGESTIVE SYSTEM
Bacteria from drinking untreated, contaminated water or from eating raw, contaminated produce or undercooked meat, poultry or eggs.
DENTAL AND PERIODONTAL INFECTIONS
Many opportunistic pathogens reside in the mouth.
Most commonly seen infections in the mouth are: Dental caries. DISEASES OF the gum tissue.
In both cases, the major source of infection is plaque.
FORMATION OF DENTAL PLAQUE
Tooth surface is normally covered by pellicle. Bacteria adhere to the pellicle.
Facilitated by bacterial adhesion molecules Initial adherent is usually Streptococcus mutans
FORMATION OF DENTAL PLAQUE
FORMATION OF DENTAL PLAQUE
DENTAL CARIES
DENTAL CARIES (Cavity)
Caries are the single greatest cause of tooth loss.
Several factors are involved in its development. Tooth structure Types of microflora Types of substrate available
Saliva normally protects against carries.
DENTAL CARIES
Organisms that produce acid can cause dental caries. S. mutans is the major cause. Other organisms contribute.
Carbohydrates easily enter the plaque and are readily metabolized.
GINGIVITIS & PERIODONTITIS
There are two forms of plaque-induced periodontal disease. Gingivitis
Inflammatory condition
Limited to the marginal surfaces of the gingival
Does not involve loss of bone
Can be corrected
Will continue as long as dental plaque remains
GINGIVITIS & PERIODONTITIS
There are two forms of plaque-induced periodontal disease. Periodontitis
Infection of the gingival
Results in loss of supportive bone and ligaments
Responsible for most tooth loss in adults
Treatment
Dental Care Take antibiotics only when
prescribed by your dentist. Surgery for more severe cases Visit your dentist every 2 months
SALMONELLA TYPHI
TYPHOID FEVER
TYPHOID FEVER
Affecting an estimated 22 million people each year India, Southeast Asia, Africa, South
America Transmitted by food/water
PREDISPOSING FACTORS
Work in or travel to areas where typhoid fever is endemic
Work as a clinical microbiologist handling Salmonella typhi bacteria
Have close contact with someone who is infected or has recently been infected with typhoid fever
DIAGNOSIS
Blood culture Bone marrow culture
TREATMENT
Chloramphenicol Ciprofloxacin Ampicillin trimethoprim-sulfamethoxazole
VIBRIO CHOLERAE
CHOLERA
CHOLERA
Zero to five cases of cholera are seen in the United States in a given year
Worldwide, it affects 3-5 million and causes 100,000-130,000 deaths a year as of 2010.
Transmitted by food/water
INCIDENCE
Common in developing countries in the tropics and subtropics and most cases occur in Africa
DIAGNOSIS
Blood culture Stool culture “Rice-water sool”
TREATMENT
IV fluids Oral rehydration solution Antibiotics: tetracycline, Doxycline
LEPTOSPIRA INTERROGANS
LEPTOSPIROSIS
LEPTOSPIROSIS
Transmitted by rats and mice most farm animals dogs
India, China, Southeast Asia, Africa, Australia, Central and South America, The Carribean
PREDISPOSING FACTORS
Camping in rural areas People who are working with
animals Sewage workers, farmers
DIAGNOSIS
CBC Creatine kinase Liver enzymes Urinalysis
TREATMENT
Ampicillin Ceftriaxone Doxycycline Penicillin
SHIGELLA
SHIGELLOSIS
SHIGELLOSIS
S. dysenteriae, S. boydii S. sonnei, and S. flexneri
Most cases occur in young children Transmitted by oral-fecal route
PREDISPOSING FACTORS
Living or traveling in areas that lack sanitation
Being a toddler Being a sexually active gay male
DIAGNOSIS
Stool culture
TREATMENT
Sulfamethoxazole Trimethoprim Ampicillin Ciprofloxacin Azithromycin
CAMPYLOBACTER JEJUNI
CAMPYLOBACTERIOSIS
CAMPYLOBACTERIOSIS
2.5 million cases per year in USA In developing countries, older
children and young adults have highest incidence of infection
Transmitted by : Contaminated milk Contaminated food Poultry, livestock or household pets
PREDISPOSING FACTORS
Consumption of poultry and poultry products
Drinking untreated water-consuming unpasteurized milk
DIAGNOSIS
Gram stain Stool culture
TREATMENT
Azitrhomycin
BACILLUS CEREUS
FRIED RICE SYNDROME
FRIED RICE SYNDROME
Common in Northern Europe and Canada
If the rice is not refrigerated properly after being steamed, the bacteria thrives and multiplies rapidly.
Transmitted by food
PREDISPOSING FACTORS
Storage of boiled rice Cooking frequency per dining session
DIAGNOSIS
Isolation of B. cereus organism
TREATMENT
Oral rehydration or intravenous fluid and electrolyte replacement
OTHER BACTERIAL DISEASES
Gastric ulcer Clostridial food poisoning Staphylococcal food poisoning Pseudomembranous colitis
FUNGAL DISEASE OF DIGESTIVE SYSTEM
Mycotoxins are toxins produced by some fungi.
It affects the blood, nervous system, kidneys, or liver.
CLAVICEPS PURPUREA
ERGOT POISONING OR ERGOTISM
ERGOT POISONING OR ERGOTISM
Produced due to fungal contamination of grains Cereal grains
Transmitted by: Ingestion of Claviceps purpurea Ingestion of fungus infected rye
INCIDENCE/PREVALENCE
Open-flowering and male-sterile cereals
Large reservoir of inoculum amongst grasses.
Prevalent throughout Britain
DIAGNOSIS
Stool exam
TREATMENT
Nifedipine
ASPERGILLUS FLAVUS
AFLATOXIN POISONING
AFLATOXIN POISONING They can colonize and contaminate
grain before harvest or during storage.
Peanuts are the crop most often contaminated
Toxin is carcinogenic in humans and can also cause other health effect, particularly liver problems
INCIDENCE
The condition is most common in poorly developed countries.
The American Food and Agriculture Organization estimates that 25% of the food crops in the world are affected by mycotoxins. Of these mycotoxins, aflatoxins are the biggest problem.
DIAGNOSIS
Stool exam Liquid chromatography-tandem mass
spectrometry
TREATMENT
Chemical treatment via ammoniation Reaction with sodium bisulfite
VIRAL DISEASES OF THE DIGESTIVE SYSTEM
Digestive system is an important portal of entry for viruses.
For some it is only an entry point Most common sign of viral infection is
diarrhea.
VIRAL DISEASES OF THE DIGESTIVE SYSTEM
Several groups of viruses cause gastrointestinal infections: Rotavirus Calicivirus Astrovirus Some serotypes of adenovirus Enterovirus
VIRAL DISEASES OF THE DIGESTIVE SYSTEM
Infections all have similar characteristics Brief incubation periods Fecal-oral routes of transmission Vomiting that either precedes or accompanies
diarrhea
VIRAL DISEASES OF THE DIGESTIVE SYSTEM
ROTAVIRUS
ROTAVIRUS
Not discovered until 1973 Now found around the world
Believed to account for 40 - 60% of cases of acute gastroenteritis
Can undergo genetic re-assortment Difficult to deal with immunologically
ROTAVIRUS
Most common cause of severe diarrhea among infants and young children
Outbreaks of rotavirus infections common in infants and children under 2. Adults are usually only minimally affected. Can affect the elderly or institutionalized Usually causes little or no clinical illness
ROTAVIRUS
Rotavirus infections kill more than 1 million infants worldwide each year. In the US there are fewer than 100 deaths
each year. Infection is still a major cause of
hospitalization early in life.
MODE OF TRANSMISSION
Fecal-oral route Contact with contaminated hands,
surfaces and objects Possibly by the respiratory route.
DIAGNOSIS
Enzyme-linked immunosorbent assay (ELISA)
Electron microscopy PCR (polymerase chain reaction)
TREATMENT
Maintenance of hydration low-osmolarity oral rehydration
solution and zinc supplementation
ENTEROVIRUS
ENTEROVIRUS
Enteroviruses are members of the picornaviridae.
Very resistant to acidic environments Humans are the natural hosts.
ENTEROVIRUS
Transmission is by direct or indirect fecal-oral route.
Virus will normally spend 1 to 4 weeks in the oropharynx.
ENTEROVIRUS INFECTION:Pathogenesis
60% of infections occur in children of 9 and younger.
Incubation time is 2 to 10 days. Virus is brought into the host cell by
envelopment in the host membrane.
ENTEROVIRUS INFECTION:Pathogenesis
Enteroviruses are lytic. End result is destruction of host
cell Primary infection in the digestive
system Spreads to other sites
TREATMENT OF ENTEROVIRUS INFECTION
None of the currently available antiviral agents is effective.
HEPATITIS VIRUSES
HEPATITIS VIRUSES
Hepatitis describes any disease that affects the hepatocytes of the liver.
At least 6 different viruses cause hepatitis
HEPATITIS VIRUSES
Humans are the most common natural host. Transmission is usually via the fecal-oral
route. Infections are common where there is crowding
and poor hygiene. Rates of infection are higher in lower
socioeconomic groups. Up to 90% of the population of developing nations
show evidence of previous infection.
HEPATITIS INFECTION:Pathogenesis
Infection often results from poor personal hygiene in food handlers.
Virus is believed to replicate initially in intestinal mucosa
HEPATITIS INFECTION:Pathogenesis
Multiplication in the intestines is followed by spread to liver
Extent of necrosis correlates to the severity of infection.
HEPATITIS INFECTION:Pathogenesis
Immune response is protective. Patients with antibodies cannot be reinfected.
Incubation times vary from 10 to 50 days, followed by: Fever Anorexia Nausea Pain in the abdomen Jaundice
HEPATITIS INFECTION:Pathogenesis
In infected patients with jaundice: Urine becomes dark. Stool can become clay-colored 1 to 5 days before
onset of jaundice.
HEPATITIS INFECTION:Treatment
No drugs are effective – supportive measures are recommended.
There is an active immunization protocol for those who are repeatedly exposed to hepatitis A virus.
Mumps
Oral herpes
Viral gastroenteritis
PARASITIC DISEASES OF THE DIGESTIVE SYSTEM
Several protozoan and helminthic diseases of the human digestive system
Common parasitic diseases are caused by: Giardia Cryptosporidium Whipworms Hookworms
HELMINTHIC DISEASE OF DIGESTIVE SYSTEM
ASCARIS LUMBRICOIDES
ASCARIASIS
ASCARIASIS
Large Intestinal Roundworm The disease is acquired by ingesting
Ascaris eggs. The eggs can remain viable in the
soil for several months or even years.
ASCARIASIS
More than 2 billion people are affected by this infection.
One study indicated that the prevalence of ascariasis in the United States at about 4 million (2%)
PREVALENCE
Perhaps as many as one quarter of the world's population are infected, with a prevalence of 45% in Latin America and 95% in parts of Africa.
MODE OF TRANSMISSION
Ingestion of Embryonated egg through contaminated food or water
DIAGNOSIS
Concentration methods and Direct Fecal Smear: Kato-Katz
TREATMENT
Albendazole Mebendazole Pyrantel pamoate
TRICHURIS TRICHIURA
TRICURIASIS
TRICURIASIS
Infects a human large intestine Found in Tropical Areas There is a worldwide distribution of
Trichuris trichiura, with an estimated 1 billion human infections.
PREVALENCE
50 to 80 percent in some regions of Asia (noted especially in China and Korea) and also occurs in rural areas of the southeastern United States.
Infection is most prevalent among children, and in North America, infection occurs frequently in immigrants from tropical or sub-tropical regions.
MODE OF TRANSMISSION
Fecal-oral contamination
DIAGNOSIS
Stool ova and parasites exam Kato-Katz thick-smear technique Colonoscopy
TREATMENT
Mebendazole Albendazole Ivermectin
ENTEROBIUS VERMICULARIS
ENTEROBIASIS
ENTEROBIASIS
Human parasitic disease and one of the most common childhood parasitic worm
Infection usually occurs through the ingestion of pinworm eggs, either through contaminated hands, food, or less commonly, water.
PREVALENCE
Pinworms are particularly common in children, with prevalence rates in this age group having been reported as high as 61% in India, 50% in England, 39% in Thailand, 37% in Sweden, and 29% in Denmark.
MODE OF TRANSMISSION
Human-to-human By ingesting (swallowing) infectious
pinworm eggs.
DIAGNOSIS
Diagnostic Exam: Scotch Tape Swab
TREATMENT
Mebendazole Albendazole
FASCIOLA HEPATICA
FASCIOLOSIS
FASCIOLOSIS
Human fasciolosis has been reported from countries in Europe, America, Asia, Africa and Oceania. The incidence of human cases has been increasing in 51 countries of the five continents.
In addition, fasciolosis is now recognized as an emerging human disease: the World Health Organization (WHO) has estimated that 2.4 million people are infected with Fasciola, and a further 180 million are at risk of infection
MODE OF TRANSMISSION
Intermediate snail hosts, Domestic herbivorous animals,
DIAGNOSIS
Stool examination ELISA Western blot.
TREATMENT
Nitazoxanide Triclabendazole Bithionol
TAPEWORMS
TAPEWORMS
Taenia Solium - pork Taenia Saginata- beef Diphyllobothrium latum- fish
TAENIASIS
TAENIASIS Most occurrences are found in areas
which lack adequate sanitation Southeast Asia West Africa East Africa
Usually cause no symptoms Some people experience upper
abdominal discomfort, diarrhea, and loss of appetite.
MODE OF TRANSMISSION
Blood to blood contact Eating the raw meat of an animal
infected with tapeworms
DIAGNOSIS
Stool examination Inject gravid proglottid with India ink Scotch tape test for the eggs
TREATMENT
Mebendazole Praziquantel Niclosamide
OTHER HELMINTHIC DISEASE
Schistosomiasis Paragonimiasis Clonorchiasis Strongyloidiasis Cysticercosis Diphyllobothriosis Intestinal capillariasis
PROTOZOAN DISEASE OF DIGESTIVE SYSTEM
Giardiasis Amoebiasis Balantidiasis Isosporiasis Cryptosporidiosis
GIARDIA LAMBLIA
GIARDIASIS
GIARDIASIS
Common cause of gastroenteritis in humans, infecting approximately 200 million people worldwide.
One of the most common water borne gastrointestinal diseases in the United States.
PREVALENCE
Areas with inadequate sanitary conditions
Among people living in developed countries
Tropics and subtropics area
MODE OF TRANSMISSION
Fecal-oral route Personal contact Contaminated water and food By not washing their hands after
touching something contaminated with Giardia cysts
MODE OF TRANSMISSION
DIAGNOSIS
Stool microscopy
TREATMENT
Metronidazole Tinidazole Quinacrine Paromomycin
ENTAMOEBA HISTOLYCTICA
AMOEBIASIS
AMOEBIASIS
A gastrointestinal infection that may or may not be symptomatic and can remain latent in an infected person for several years, amoebiasis is estimated to cause 70,000 deaths per year world wide
Can cause severe diarrhea with blood.
PREVALENCE/ INCIDENCE
Amoebiases occurs worldwide, although much higher rates of incidence are found in the tropics and subtropics. About 5,000 to 10,000 cases are diagnosed each year in the US, leading to about 20 deaths annually.
MODE OF TRANSMISSION
Contaminated food/water Fecal-oral route Anal-oral contact
PREDISPOSING FACTORS
Poor sanitary conditions Commonly affects active homosexual
men Immigrants from developing
countries
DIAGNOSIS
Fecal microscopic analysis
TREATMENT
Metronidazole Paromomycin Amoebicide
BALANTIDIUM COLI
BALANTIDIASIS
BALANTIDIASIS
The first case of Balantidiasis in the Philippines, where it is the most common, was reported in 1904.
Currently, Balantidium coli is distributed worldwide but less than 1% of the human population is infected.
BALANTIDIASIS Symptoms can be local due to
involvement of the intestinal mucosa, or systemic in nature and include either diarrhea or constipation.
MODE OF TRANSMISSION
Contaminated food/water When a patient has diarrhea
combined with a probable history of current exposure to amoebiasis Travel contact with infected persons Anal intercourse.
DIAGNOSIS
Fecal analysis
TREATMENT
Tetracycline Metronidazole Iodoquinol
ISOSPORA BELLI
ISOSPORIASIS
It is found worldwide, especially in tropical and subtropical areas.
Infection causes acute, non-bloody diarrhea with crampy abdominal pain, which can last for weeks and result in malabsorption and weight loss.
ISOSPORIASIS
In immunodepressed patients, and in infants and children, the diarrhea can be severe.
MODE OF TRANSMISSION
Contaminated food/water
DIAGNOSIS
Fecal analysis Typical laboratory analyses include:
Microscopy Morphologic comparison with other
intestinal parasites Bench aids for Isospora
TREATMENT
Trimethoprim-sulfamethoxazole
CRYPTOSPORIDIUM
CRYPTOSPORIDIOSIS
CRYPTOSPORIDIOSIS
Affects the intestines and is typically an acute short-term infection
the main symptom is self-limiting diarrhea in people with intact immune systems.
CRYPTOSPORIDIOSIS
It is found worldwide. It causes 50.8% of water-borne diseases that are attributed to parasites.
The age group most affected is children from 1 to 9 years old.
MODE OF TRANSMISSION
By the fecal-oral route Directly from person to person Contaminated drinking water and
swimming pools and to petting infected animals
Contaminated food
PREVALENCE/ INCIDENCE
0.5 to 2 million undiagnosed cases each year
DIAGNOSIS
Examination of stool samples Stool microscopy
TREATMENT
Nitroxonide Paromonomycin Clarithromycin Azithromycin
OTHER PROTOZOAN DISEASE
Sarcosporidiosis Gum disease
POP QUIZ!
1. CHOLERAA.CAMPYLOBACTER JEJUNIB. VIBRIO CHOLERAE
2. Organisms that are part of the normal microbial floraA. ENDOGENOUS INFECTIONSB. EXOGENOUS INFECTIONS
3. FRIED RICE SYNDROMEA.SHIGELLAB. BACILLUS CEREUS
4. ASCARIASISA. ASCARIS LUMBRICOIDESB. ASCARIS LUMBERICOIDE
5. TAENIA SOLIUMA. BEEFB. PORK
6. TREATMENT FOR ERGOT POISONINGA. NIFEDIPINEB. MEBENDAZOLE
7. Treatment for Ascariasis is SCOTCH TAPE SWAB? Y/N
8. ERGOT POISONING A. CLAVICEPS PURPUREAB. ASPERGILLUS FLAVUS
9. TREATMENT FOR AMOEBIASIS IS NIFEDIPINE?
Y/N
10. A. ROTAVIRUSB. HEPATITIS VIRUS