Parasites, Viruses, and Bacteria of GIT

Spirocerca lupi

an esophageal parasite in dogs that migrated from the stomach and form a granuloma between aorta + esophagus

This parasite can cause diffuse hypertrophic gastritis in horses

trichostrongylus (nematode -roundworm)

Helicobacter

A gram-negative spiral bacteria with flagella. Most common bacteria in monogastrics. Found in healthy and unhealthy animals. Common cause of gastritis

Ollulanus tricuspis

Nematode. Direct life cycle. Gastric parasite of cats, usually asymptomatic.

Physaloptera

Nematode that infects GIT. Indirect life cycle. Arthropod IH.

Transmission of ollulanus tricuspis

leave the host in vomitus

Diagnosis and treatment of ollulanus tricuspis

Induction of vomiting then baermann technique. Fecal floats are NOT reliable. Treat with ivermectin or fenbendazole

Diagnosis and treatment of physaloptera

Gastroscopy or visualization in vomitus.

Fibrobacter succinogenes

A cellulolytic bacteria of the rumen that breaks down lignin

Entodinium

A ciliate protozoa that accounts for most of the protozoa population in the rumen

Methanogens

Archaea in rumen that are responsible for producing methane from hydrogen

Siphoviridae

most dominant virus of the rumen that is important in genetic exchange with other rumen microbes

lactobacillus (monogastric)

a bacteria that ferments carbs (lactose) into lactic acid, creating an acidic environment

E. coli (monogastric)

A bacteria that helps with synthesis of vitamin K and B-complex vitamins

Enterotoxigenic E. coli

Causes hypersecretory diarrhea via enterotoxins (cause increase in cAMP, leading to CFTR releasing more Cl). Gram negative, LPS.

Common effect of enterotoxigenic E. coli

Neonatal colibacillosis in piglets (watery diarrhea, enteritis, septicemia, bacteremia)

Heat labile enterotoxigenic E. coli toxin

Affects cAMP leading to hypersecretion of fluids

Shiga toxin-producing E. coli

Causes edema and bleeding in GIT of weaned pigs. Attach to enterocytes and produce shiga toxins that can enter the bloodstream.

Significance of transmissible R plasmids

They harbor antibiotic resistant genes in E. coli, creating need for antimicrobial sensitivity testing

Lawsonia intracellularis

Seen in foals and weaned pigs. Inflammatory. Malabsorptive diarrhea. Gram negative.

Salmonella

Uses a Type 3 secretory system (a needle like structure that projects toxins into host cells) to activate secretory pathways, causing diarrhea. Gram negative: LPS.

Feline panleukopenia

Targets undifferentiated crypt cells. Malabsorption diarrhea

Rotavirus

Destroys small intestine enterocytes on the tip of the villi causing malabsorption. Has a toxin called nsp4 that causes secretory diarrhea

Coronavirus

Causes death of microvilli and blunting of villi (disorder of absorptive enterocytes). Effects both small and large intestine. Malabsorption diarrhea

Mycobacterium paratuberculosis (Johne’s disease)

Malabsorptive diarrhea. Causes submandibular edema. Effects cattle. Causes lesions of the lamina propria (M cells take bacteria into peyers patches and infect macrophages) leading to villous blunting and fusion.

Yersinia enterocolitica

Cause secretory diarrhea. Gram negative, LPS. Enter mucosa through M cells and use Type 3 secretory system to inject toxins. . Produce Yersinia outer proteins (Yops) that interfere with phagocytosis and produce ROS)

Brachyspira hyodysenteriae

seen in weaned pigs. Causes muco-hemorrhagic diarrhea (invade goblet cells and have hemolysins). Gram negative, LPS

Clostridium perfringens

Gram positive bacteria that produce 4 kinds of toxins (alpha, beta, epsilon, iota)

Clostridium perfringens type A

Causes canine hemorrhagic gastroenteritis and necrotic enteritis in chickens

Clostridium perfringens type C

Produces alpha (hemolysis) and beta toxins (vascular necrosis) and causes hemorrhagic enteritis in pigs

Canine Parvovirus

Systemic virus that infects and destroys rapidly dividing cells in crypts of lieberkuhn, lymph tissue, and bone marrow. Causes malabsorption and disrupted gut barrier leading to exudative diarrhea.

What do rotavirus, coronavirus, and norovirus have in common

They are all enteric viruses

Qualities of enteric viruses:

Enter through the fecal-oral route and are usually naked viruses so can persist in the environment

Most common viruses causing milk scours/viral diarrhea in calves:

rotavirus and coronavirus

Cystoisospora

A coccidia found in the small intestine that infects dogs/cats (host specific). Causes watery diarrhea

cystoisospora: right is sporulated/infective stage

eimeria

coccidia of small intestine that infects ruminants causing hemorrhagic diarrhea and CNS signs

eimeria: right is sporulated

giardia duodenalis

Protozoa of small intestine. Causes pale mucus diarrhea. trophozoite is infective stage.

giardia: cyst is infective, trophozoites have flagellum

crytosporidium parvum

Causes yellow watery diarrhea in cattle. protozoa that infects small intestine, zoonotic.

cryptosporidium

Ancylostoma caninum

Causes dark tarry diarrhea. Nematodes with 3 pairs of teeth; infect the small intestine; L3 is infective.

hookworm eggs (ancylostoma)

3 pairs of teeth

ancylostoma caninum

ancylostoma tubaeforme

1 pair of teeth

ancylostoma braziliense

cutting plates

uncinaria stenocephala

bunostomum

strongyloides stercoralis

nematode that infects small intestine, zoonotic. Causes bloody diarrhea

trichostrongylus colubriformis

ostertagia

cooperia

Nematodes that infect small intestine of ruminants. Ostertagia infect abomasum

looks the same as ancylostoma but only infects ruminants

trichostrongyles

tritrichomonas blagburni

infects large intestine of cats causing water diarrhea

tritrichomonas

trichuris vulpis

whipworm that infects large intestine of dogs, infective stage is L1. Causes diarrhea with bright blood