Diarrhea Across Species: Diagnostics and Management

Outbreak

more cases than expected for that defined population, place, and period

True or false: to be classified as an outbreak, a pathogen must be identified

false! does not require a

known pathogen

Risk or attack proportion

new cases divided by animals at risk

Case fatality proportion

deaths divided by identified cases

Cohort-specific risk

compare pens, rooms, sources, age classes, or feed groups.

Who should ideally be tested during disease outbreaks?

the early (freshly sick), untreated, clinically representative cases

What animals should be tested with systemic or invasive diease?

severely affected animals

What animals should be not be relied upon when completing diagnostic tests?

-chronically affected animals

-samples collected over several treatment courses

-environmental positives without animal level clinical correlation

Why would a single positive PCR result not always be used as a final diagnosis?

While PCR is very sensitive, a single one time PCR from an individual animal sampled from a large group does not necessarily mean that is the issue going on; need multiple positives to confirm

When should dogs/cats be tested for diarrhea?

-Consider IH fecal float for most cases of diarrhea

-Parvo test every young puppy/dog with diarrhea and incomplete vaccine history

-Consider advanced testing when patient is unresponsive to treatments

When should diarrhea be tested for in piglets?

When mortality and morbidity rates begin changing (usually herds have 3% incidence rate and mortality less than 0.5%)

When should diarrhea be tested for in grower/finisher swine?

-When treatments are not effective

-Rapidly spreading, or persistent diarrhea

-Wasting pigs, unthriftiness, uneven growth

-Increase in mortality, necropsy driven

When should diarrhea be tested for in calves?

Consider if it is a herd level concern (greater than 20% affected)

When should diarrhea be tested for in cows?

-Increased incidence of deaths with unknown cause

-Changes in production

When should diarrhea be tested for in foals?

any sick foal with diarrhea (0-3 months)

When should diarrhea be tested for in adult horses?

Diarrhea that lasts longer than a day accompanied by: fever, lethargy, loss of appetite, colic, dehydration, dry mucous membranes

Three tiers of the diagnostic hiearchy:

1.) immediate population assessment

2.) etiologic investigation

3.) cause

Diagnostic Hierarchy: immediate population assessment

-History, examination, hydration and perfusion assessment.

-Temperature and systemic-illness screen.

-Morbidity, mortality, onset, and location.

-Feed, water, housing, movement, vaccination, and treatment review.

-Point-of-care tests (where they will change immediate actions.)

Diagnostic Hierarchy: etiologic investigation

-Fecal PCR or antigen testing for plausible viruses, bacteria, and protozoa.

-Fecal flotation, centrifugation, direct smear, or organism-specific testing.

-Bacterial culture and susceptibility where systemic disease or a meaningful isolate is suspected.

-CBC, biochemistry, blood gas, lactate, and blood culture in selected systemic patients.

-Necropsy, histopathology, intestinal contents, and fresh/fixed tissues.

Three types of population medicine diagnostic:

1.) feces

2.) blood

3.) tissue

Examples of tests run with feces

1.) fecal smear/stain

2.) fecal flotation

3.) PCR

4.) culture

Examples of tests run with blood

1.) PCR

2.) Virus isolation

3.) CBC/CHEM

4.) ELISA

Examples of tests run with tissues

1.) smears

2.) cultures

3.) histopath

4.) virus isolation

Diagnostic Hierarchy: cause

cohort comparisons and risk factor analysis (comparing groups with different exposures to identify factors associated with an increased or decreased risk of disease)

advanced diagnostics a step further than blood/fecal/tissue sampling, such as feed and water testing for a specific suspected exposure, environmental sampling for biosecurity issues, etc

How much feces should be collected for diagnostic sampling?

at least 2 grams or more

How long are fecal samples able to be held?

2 days

Fecal samples are ideally collected before __________ is initiated

treatment

Fecal swabs with suffice for what age group and species?

neonate swine and poultry

Fecal swabs must be kept _______ during transport using transport media

moist

What transport media for fecal swabs is used for bacteria?

What transport media for fecal swabs is used for viruses?

bacteria: amies

viruses: universal

For a necropsy, what three things should be be collected?

1.) feces

2.) fresh tissues

3.) fixed tissues

fresh tissues for a necropsy are collected from four places:

1.) small intestine

2.) large intestine

3.) spleen

4.) intestinal contents

fixed tissues for a necropsy are collected from five places:

1.) small intestine

2.) large intestine

3.) forestomachs

4.) liver

5.) mesenteric lymph nodes

When choosing treatment options for a disease, what question should you NOT begin with?

Which drug kills this organism?

*instead focus on what is causing the disease, who is sick, is there evidence it is a treatable agent, etc.

Therapy for viruses

-Fluids, nutrition, nursing

-isolation from other animals

-vaccination and exposure reduction

Therapy for bacteria

-fluids and NSAIDS

-antibiotics when indicated

-toxin and source control

Therapy for helminths

-deworm w/ labeled anthelminthic

-pasture/environment management

Therapy for protozoa

-environmental cleanup and hygiene to prevent additional spread

-coccidia receive Coccidiostat

-Crypto receive supportive care

Therapy for nutritional/toxic

-remove or correct the exposure

-restore fluids and nutrition

Are bacteria or viruses more resistant to disinfectants?

viruses

Four disinfectants commonly used for surface disinfection in outbreaks:

1.) halogens

2.) peroxygen compounds

3.) phenols

4.) quaternary ammonium compounds

Example of a halogen

chlorine

Halogens can also be used to treat what?

water

Examples of peroxygen compounds

rescue, Virkon-S

Examples of Phenols

One-stroke, Tek-Trol

Examples of Quaternary Ammonium Compounds

Roccal-D, D-256

Diarrhea is a __________, not an etiologic diagnosis

syndrome

Species, age, time, place, and severity usually rank pathogens better than ________ appearance

fecal

Instead of automatically medicating everyone, population treatment

means...

deciding who receives which intervention