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Infectious Disease Epi > Class 3- Diarrheal diseases > Flashcards

Class 3- Diarrheal diseases Flashcards

1
Q

Disease Tests

A
  1. Microscopy
  2. Cell culture
  3. Genetic testing: PCR, Sequencing
  4. Serology: ELISA, Western Blots
  5. Rapid Diagnostic tests
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2
Q

Microscopy

A

Most straight forward test

  • Examine sample under microscope!

Electron Microscope

  • Decreases resolution from .2 micron with light microscope to .0005 microns
  • Has lead to a greater understanding of intercellular pathways and structure
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3
Q

Cell culture

A

Applying specimen to culture plate, with source of nutrient ex. agar

  • Pathogen will survive and populate plate

Can be used for:

  • Drug sensitivity tests
  • Pathogen identification:
    • Virus or bacteria or parasite

Different levels of bio safety level (BSL)

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4
Q

How many BSL are there?

A

Four. 1 is the lowest

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5
Q

Genetic testing

A

Polymerase Chain Reaction (PCR)

  • Primers used determine area of interest

Single nucleotide polymorphisms (SNPs)

  • Mutations in DNA, - Can be used track origin - Determine risk

Sequencing

  • Whole or partial genome experiments
    • Examines entire DNA fragments without necessarily looking for a specific region
    • Great tool for stacking multiple studies
    • Expensive
      • Bps are dyed and captured by dye terminator reader
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6
Q

Serology

A

Enzyme Linked Imunosorben Assay (ELISA) - Indirect and Sandwich

ELISA Great tool for exposure studies

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7
Q

Diarrheal Infections: Fecal Oral Route

A
  1. Cholera – bacterial
  2. Shigellosis – bacterial
  3. Cryptosporidiosis – parasitic
  4. Giardiasis – parasitic
  5. Amebiasis – parasitic
  6. Norovirus (Norwalk)– viral
  7. Rotavirus – viral

*Constant fecal exposure causes constant general inflammation in the body*

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8
Q

Cholera summary

A

Causative agent: Vibrio cholerae

Reservoir- main reservoir is Humans, recent studies have discovered environmental reservoirs

Route- ingestion of water or food that has been directly contaminated with feces Incubation period - a few hours to 5 days!

Primary symptoms- rice water diarrhea, profuse vomiting, nausea. (only cholera causes rice water diarrhea)

Communicability period – as long as stools are positive (two days after recovery)

Cholera is one of the oldest and best understood epidemic diseases. Its strongly linked with consumption of unsafe water and food, poor hygiene, poor sanitation, and crowding

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9
Q

WHO Case definition of cholera

A

Disease unknown in area

  • severe dehydration or death from acute watery diarrhea in a patient over the age of 5

Endemic country

  • acute watery diarrhea with or without vomiting in a patient over the age of 5

Epidemic country

  • acute watery diarrhea with or without vomiting in any patient
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10
Q

Shigellosis

A

Shigella species are broken up into 4 supgroups

Reservoir – Humans

Route – person to person and contaminated food

Incubation – 1 to 3 days

Symptoms- loose stool (usually contains blood), fever, nausea, vomiting and painful stomach cramps.

Communicability- up to 4 weeks after recovery (if untreated) Illness is usually self limiting lasting 4-7 days. Secondary attack rates can be as high as 40% in households

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11
Q

S. dysentary1 Group A

A

Most dangerous sub-species of Shigella High case fatality rate Antibiotic resistant Incubation as high as 1 week.

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12
Q

Cryptosporidiosis

A

Causative Agent: C. parvum – parasitic agent

Reservoir- Human and more than 45 animals

Route- fecal oral Incubation

Incubation- 1 to 12 days, 7 days average

Symptoms- watery diarrhea, abdominal cramping, and vomiting. Symptoms wax and wane over a duration of 30 days in healthy people!

Crypto is NASTY… Outbreaks have also been associated with public sources of drinking water, recreational water sources, and contaminated beverages

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13
Q

Cryptosporidiosis Life cycle

A

Oocyst can survive outside the body for 2-6 months

  • Infected continue to shed oocyst for weeks after recovery.

Hence the importance of WASH: Water, Sanitation, and

Hygiene 1993 Milwaukee outbreak

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14
Q

Giardiasis

A

Causative Agent: Giardia lamblia - Protozoan parasite

Reservoir- Humans and wild/domestic animals

Route – Person- to person (hand to mouth transfer of cysts), ingestion of contaminated sources

Incubation – 3 to 25 days (median 7-10)

Symptoms- frequent loose pale greasy stool, steatorrhea (excess fat in stool). Often asymptomatic

Communicability – entire period of infection

Chlorine does not kill Giardia. Associated with cold streams and water with chances of human/animal fecal matter

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15
Q

Amebiasis

A

Causative Agent: Entomoeba histolytica- protozoan parasites

  • Protozoas is Latin for “first animal”.

Reservoir – humans. Usually chronically ill or asymptomatic cysts carriers

Route – fecal oral

Incubation – 2 to 4 weeks

Symptoms- usually asymptomatic

Communicability- as long as cysts are carried, which can be upwards of years

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16
Q

Norovirus

A

Extremely infectious and contagious

Reservoir: Humans

Route of exposure- probably fecal oral, suspected airborne transmission (through farts). Spreads like wild fire through hospitals, cruises

Incubation- 10-50 hours

Symptoms- Diarrhea, throwing up, nausea, stomach pain. Usually self-limited

Communicability – acute stage and 48 hours after symptoms stop

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17
Q

Rotavirus

A

Reservoirs- Probably human

Route- Oral/fecal

Incubation – 24 to 72 hours

Symptoms- vomiting, fever, and water diarrhea

Communicability – up to 8 days after infection (4-6 days after symptoms)

Susceptibility- Children 6 to 24 months old at highest risk. Why not under 6 months or over 24 months?

18
Q

Foodborne infections

A
  1. Brucellosis- bacterial
  2. Camplyobacter jejuni- bacterial
  3. Escherichia coli – bacterial
  4. Helicobacter pylori – bacterial
  5. Listeriosis - bacterial
  6. Salmonellosis – bacterial
  7. Typhoid fever – bacterial
19
Q

Brucellosis

A

Reservoir- cattle, swine, goats, and sheep

Route- dermal contact with animal fluids, ingestion of unpasteurized milk products

Incubation- 5 to 60 days

Symptoms- intermittent fever, chills, sweating, malaise

Communicability – rare person to person

20
Q

Campylobacter

A

C. jejuni

Reservoir – Poultry and cattle

Route- ingestion of undercooked meat, or contaminated water, person to person transmission is uncommon

Incubation – 2 to 5 days

Symptoms – bloody stool, abdominal pain, fever nausea, vomiting

Communicability – throughout the course of infection usually several days, if untreated 2-7 weeks

One of the most common causes of diarrheal disease in the US

  • FoodNet surveillance indicates 14 cases per 100,000
  • Only takes a few organisms to make some one sick (less than 500)
    • Remember discussion on infectiousness vs. contagiousness
21
Q

Types of E. coli

A
  1. Enterohemorrhagic E. coli (EHEC)
  2. Enteropathogenic (EPEC)
  3. Enterotoxigenic (ETEC)

Lots of different types

  • Different clinical characteristics
  • All transmitted through contaminated food, water, or hands, or direct contact with animals
22
Q

EHEC

A

Enterohemorrhagic E. coli (aka E. coli O157:H7)

This is the nasty/deadly version of e coli.

  • Produce Shiga toxins
    • Can kill adults and children

Primary reservoir: cattle, humans can maintain for person to person

Incubation- 2 to 10 days

Symptom- Hemorrhagic colitis

Communicability- 1 week

23
Q

ETEC

A

Enterotoxigenic E. coli

Causes as many as 380,000 deaths in children under 5

  • Malnourished children are at an increased risk

Reservoir – Humans

Incubation – 12 -72 hrs

Communicability – duration of diarrhea

Symptoms usually last less than 5 days

Leading cause of Traveler’s Diarrhea - Don’t eat salads abroad! - Peel or boil…

24
Q

EPEC

A

Enteropathogenic E. coli

Confined to infants

Route – contaminated formula and weaning foods

Incubation – 9-12 hours

Major agent of infant diarrhea in developing world

25
Q

Helicobacter pylori

A

Reservoir: Humans. Possibly primates

Route: ingestion

Incubation period: 5 to 10 days

Symptoms: Can result in hypochlorhydria. Increases risk of diarrhea but is not a direct cause of diarrhea. Diminishes the stomachs ability to prevent bacteria from reaching intestines. Often asymptomatic.

Common infection in children of developing world. Infected individuals have a 2-6 fold increased risk of gastric cancer

Responsible for peptic ulcers More common in older adults, African Americans, and low SES

26
Q

Listerosis

A

Reservoir – animals, humans, soil, mud, livestock food, silage

Route- ingesting contaminated food. Often raw meats, contaminated milk, ready to cook meats (hot dogs, pate, and deli meats)

Incubation- 2 to 3 weeks. Can be as long as 70 days

Symptoms- only a mild fever. Can cause spontaneous abortion in pregnant women

27
Q

Salmonellosis

A

Reservoir – domestic animals, swine and poultry.

Route – ingestion of animal products contaminated by feces from infected animal or person

  • Culprits – eggs, raw milk, undercooked meat, and contaminated produce

Incubation – 12 to 36 hours

Symptoms – Abdominal pain, diarrhea, nausea, and often vomiting

Communicability- several days to several weeks

28
Q

Typhoid Fever

A

Salmonella typhi

Reservoir- humans

Route – ingesting food and water from contaminated by feces from infected people

Incubation – 8 – 14 days

Symptoms – fever, malaise, nonproductive cough, rose spots on the trunk (only light-skinned people get rose spots)

Communicability – 21 to 28 days

Two types of vaccine

  • live oral vs inactivated

World wide annual incidence 22 million. 200,000 deaths

29
Q

How can we control for Diarrheal disease?

A
  1. Vaccinations
    • Cholera (immunity for about 2 years)
    • Rotavirus (2 doses given during the window of opportunity (first two years of life) decrease mortality rates)
  2. ORT
  3. Zinc treatment
  4. Exclusively Breast feeding
  5. Improved sanitation and hygiene
30
Q

Malnutrition and diarrheal disease

A

When you start to have chronic diarrhea, the intestines begin to straighten/smooth out which provides less area for absorption and increases chance of dehydration

31
Q

Cost effective solutions malnutrition and diarrhea

A
  1. Hand washing with soap
  2. Exclusive breastfeeding for 6 months
  3. Food and nutritional supplements
  4. Food fortification
  5. Clean water
  6. Oral Rehydration therapy
  7. Prenatal care
  8. Education on appropriate nutrition practices.
32
Q

Lack of iodine

A

Influences growth and neurological development Iodine deficiency results in goiter, which stimulates the thyroid gland

People living in mountainous regions or far inland are at a higher risk of deficiency- lack of fish in diet

33
Q

Sources of iodine

A

Seafood

34
Q

Lack of Vitamin A

A

Influences vision - Night blindness - Xeropthalmia: the eye fails to produce tears

Vitamin A deficiency contributes to maternal mortality and poor outcomes in pregnancy

35
Q

Sources of Vitamin A

A

Sweet potatoes

Carrots

Leafy greens

36
Q

Lack of iron

A

The most common of nutritional deficiencies

  • Causes anemia
  • The body’s stores of iron are unable to maintain haemoglobin levels
    • Most at risk: Children and pre-menopausal women
37
Q

Sources of iron

A

meat

spinach

38
Q

Lack of zinc

A

Zinc is vital to protein synthesis and normal growth in children

Zinc deficiency is associated with increased risk of gastrointestinal infections and impaired immunity

Zinc supplementation reduces the duration and severity of diarrhea

39
Q

Sources of zinc

A

beans

nuts

crab/lobster

whole grains

40
Q

“Window of opportunity”

A

Ensuring that children are well-nourished and develop properly beginning at conception and lasting until the children are about 2 years of age.

Nutrition deficits take a enormous toll on maternal health, with important economic consequences

Infectious Disease Epi (11 decks)

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