Brucellosis, Rabies, etc

Brucellosis
Brucellosis is a bacterial disease. Well known for its zoonotic potential and its cause of economic losses in livestock.
• Brucella abortus in cattle,
• B. melitensis or B. ovis in small ruminants,
• B. suis in pigs
• B. canis in dogs.
• (B. cetaceae marine animals)

In humans, brucellosis can be caused by B. abortus, B. melitensis, B. suis: rarely the others. It’s a widespread disease, but is fairly well controlled in more developed countries; (ie. U.S)

Gram-negative coccobacillus or short rod bacteria Transmission

transmitted between animals by contact with the placenta, fetus, fetal fluids, semen, and vaginal discharges from an infected animal. Entry into the body occurs by ingestion and through the mucous membranes, broken skin and possibly intact skin. Animals are infectious after either an abortion or full term parturition. Although ruminants are usually asymptomatic after their first abortion, they can become chronic carriers, and continue to shed Brucella in milk and uterine discharges during subsequent pregnancies. This varies somewhat with the different Brucella species.

Some Brucella species have also been detected in other secretions and excretions including urine, feces, saliva, and nasal and ocular secretions. In most cases, these sources seem to be relatively unimportant in transmission. Infected fomites may also play a role. (Infected troughs, etc.)

Clinical Signs Most Common:
• Abortions o Especially late pregnancy
• Placentitis
• Epididymitis
• Orchitis
Also common
• Enlarged lymph nodes
• +/- enlarged spleen , liver
• Lesions on various body parts, especially on aborted young
• Scrotal edema
• Scrotal dermatitis
• Testicular atrophy
• Metritis
• Vaginal discharge

Death rarely occurs, except with fetuses and newborns. Some pups are born live but weak; these pups often die soon after birth. Other congenitally infected pups can be born normal and later develop brucellosis.

Diagnosis (Remember zoonotic potential, so take proper precautions when handling samples!)
• Serology o Agglutination o IFA ( indirect fluorescent antibody)
• Bacteria culture

Treatment
• Antibiotics – potentially long-term o Has had some success in some animals, some relapse
• Quarantining
• Spaying/neutering
• Euthanizing

Control

• Killed by most common disinfectants.
• Autoclaving equipment
• Boil liquids
• Any positive case must be reported to the state of Indiana.
• There is a vaccine for Brucella abortus, but the vaccine isn’t 100% guaranteed.

(Human cases) Brucellosis in the US, for the most part, is considered an occupational disease. However, veterinary medicine is one of the highest occupational occurrences. We see it the most in the US from consuming unpasteurized dairy products

Haemobartonella felis (Feline Infectious Anemia) (Mycoplasma haemofelis)

A parasite of feline red blood cells.

Haemobartonella canis is rare in dogs – if seen, it’s typically after a splenectomy or when and animal is immunocompromised. Fleas consume the blood of infected animals and transfer it to others.

Transmission
Evidence of the flea (Ctenocephalides felis) is involved in the transmission, but we are unsure the exact involvement.

Older male cats are highest risk. (One source) There is a possibility of horizontal transmission via fighting. Queens can transfer to kittens, although we’re not sure the route (transplacental, transmammary, etc.) Can be transferred iatrogenically via blood transfusions.

Pathogenesis

Immune-mediated destruction of RBCs

Clinical Signs
• Anemia o Pale mucous membranes
• Lethargy
• Anorexia
• Weight loss
• Dehydration
• +/- Pyrexia (especially in the acute stages) Diagnosis
• Blood smears o Whole blood not mixed with an anticoagulant
 Organisms often detach from RBCs when in anticoagulant o regenerative macrocytic hypochromic anemia
 appear as cocci in thick areas of the film and as rings or rods in thin areas. o could be misdiagnosed from stain precipitant or Howell-Jolly bodies. o The absence of cell inclusions doesn’t rule out diagnosis
 Should be examined 5-10 days if infection is suspected

Treatment
• Antibiotics (Tetracycline or Doxycycline)
• +/- corticosteroids
• Supportive therapy for anemic patients o Blood transfusions o IV fluids

Control
• Control fleas
• Prevent fighting
• Test felines prior to blood donor programs

Rabies Viral induced neurologic disease of warm-blooded animals.

Transmission

Most common route of transmission is saliva through a bite wound. It can be transferred through open skin, mucous membranes, neurologic tissue, or being aerosolized. All mammals are susceptible to rabies.

Incubation period for dogs and cats is about 10 days to 6 months, with clinical signs typically occurring between 2 weeks-2 months.

Pathogenesis
After being bitten, the virus enters the nerve endings around the bite wound and ascends to the
Brain where is multiplies in the neurons. It travels along nerves to the salivary glands where it appears in saliva.

Blood, urine, and feces are believed not be infective.

Carnivores are more effective vectors than herbivores. Herbivores transmitting the disease are uncommon.

Three phases:
1. Prodromal
• Characterized by changes in behavior. (Aggressive becomes friendly, nocturnal out during the day.)
• People are at the greatest risk of exposure
2. Excitative (Furious)
• Hyperreactive
• Attack unprovoked, attack inanimate objects
• May appear in a stupor
3. Paralytic (Dumb)
• Ascending paralysis from the hind limb eventually leading to respiratory paralysis and death

Clinical Signs (varies depending on the stage)
• Behavioral changes
• Difficulty swallowing
• Hypersalivation
• Laryngeal paralysis o Change in vocalizations
• Extruded penis
• Hind-limb ataxia
• Depression, stupor
• Aggression Diagnosis There is no antemortem definitive diagnosis for rabies.

Treatment Varies somewhat on a case-by-case basis. Any quarantining is at the expense of the owner.

Post-exposure prophylaxis for vaccinated animals
• immediately cleaning and flushing wounds
• vaccination o not believed to help animals that were not vaccinated prior to exposure
• +/- quarantining o Quarantining is to prevent human health, not the animal’s. o Remain “under observation” for 45 days
Post-exposure prophylaxis for un- vaccinated animals
• immediately cleaning and flushing wounds
• strict quarantine up to 6 months
• vaccination prior to release

Animals that have bitten humans but have no known exposure to rabies. Unvaccinated/Expired vaccination.
• quarantined 10 days
• If animals show any potential signs for rabies during this time they are euthanized and tested.

There is no effective treatment once symptoms develop
• Once symptoms occur the disease is almost always fatal within 3 weeks. < 10 reported survived cases (humans) with intensive care in acute stages, and all having received post-exposure vaccinations.

Counties that have rabies eradicated from the country may require lengthy quarantine periods before animals can be imported.

Control

• Vaccination o dogs, cats, ferrets, cattle, sheep and horses
• Bites or exposures should be reported IMMEDIATELY o Human deaths are typically a result of people not knowing they were exposed or didn’t seek medical treatment.
• not eating flesh or drinking milk from a rabid animal
• not handling wild animals
• handle rabies suspects with EXTREME caution o wear appropriate PPE when performing necropsies or handling neurologic tissue
• killed with a variety of disinfectants
• inactivated by heat
• doesn’t survive in the environment well (cool, dark areas)

Animals that make up most reported cases in the US: raccoons, skunks, bats, foxes.