AVS 1113 Safety and Zoonoses Notes

Zoonoses

• Zoonoses (or Zoonotic diseases) are diseases that can be transmitted from animals to humans.
• Historical context: Ancient Greeks recognized rabies could be transmitted by dog bites; Bubonic plague in the 1400s was caused by a bacteria transmitted to humans by fleas carried by infected rats.
• Importance: Identifying potential zoonotic diseases and implementing prevention to protect humans working with animals.

Parasites

• Parasite: an organism that lives on or within another host and derives sustenance from the host.
• Roundworm: common parasite in dogs and cats; can be transmitted to humans in the larval stage; human symptoms can include fever, headache, cough, and poor appetite.
• Hookworms: common parasite in dogs and cats; transmitted to humans in the larval stage; can penetrate the skin and travel under the skin, leaving an inflamed tract.
• Transmission: parasites can be transmitted through contact with soil or surfaces contaminated by feces of infected animals; children are at higher risk as they play in contaminated soil.
• Prevention: keep play areas and sandboxes clean or covered; wash hands after handling animals or their feces.

Toxoplasmosis

• Transmission routes:
  • Eating undercooked contaminated meat or handling uncooked contaminated meat and then touching mouth or food with contaminated utensils.
  • Cat feces as a common source; cats are the primary host.
  • Cats can become infected by eating infected rodents, birds, or other small animals.
• Oocysts:
  • Cats shed oocysts in feces for up to 3 weeks after infection; oocysts contaminate litter boxes and soil.
  • Oocysts take $ext{36--48 hours}$ to become infective.
• Pregnancy implications:
  • In pregnant women, toxoplasmosis can cause severe consequences for the unborn child (nervous system and eyes, miscarriage, preterm birth).
  • Litter box contamination and exposure during pregnancy is a key risk.
• Litter box and handling guidance:
  • Pregnant women should avoid cleaning litter boxes; if unavoidable, litter box should be cleaned daily to prevent oocysts from becoming infective.
  • Use gloves when cleaning litter boxes and wash hands afterwards; wear a mask to prevent inhalation of airborne oocysts.
  • Children’s play areas and sandboxes should be protected from use as a litter box.
• General human infection:
  • Most humans will not develop clinical signs; antibodies may be present which can protect the unborn child if antibodies are present before pregnancy.
  • Immunocompromised individuals can develop symptoms: fever, headache, swollen lymph nodes, cough, sore throat, nasal congestion, loss of appetite, skin rash.

Ringworm

• Ringworm is a skin disease caused by a fungus.
• Animal hosts: dogs, cats, chinchillas, guinea pigs, rats, mice, rabbits; humans can be infected via direct touch or indirectly via contaminated surfaces or objects.
• Symptoms: round, scaly, or encrusted skin lesion.
• Diagnosis and infectiousness: if the lesion is shrinking, the fungus is likely gone; otherwise, remains infectious.
• Prevention: avoid contact with animals with skin rashes; change clothing and wash after contact.
• Treatment: topical antifungal drugs (often also oral medication) for both humans and animals.

Psittacosis (Ornithosis, Parrot fever, Avian Chlamydiosis)

• Can be transmitted by any bird but most common from parrots, parakeets, macaws, cockatiels, turkeys, or ducks (pet birds).
• Transmission: contact with feces of contaminated birds or fecal dust.
• Prevention: purchase birds from reliable sources; testing and quarantine of all new birds.
• In humans: symptoms include coughing, chest pains, fever, chills, weakness, vomiting, and muscle pain.
• Diagnosis and treatment: infection confirmed with a blood test; treated with an antibiotic in both humans and birds.

Cat-scratch fever

• Causative agent: Bartonella henselae infection.
• Transmission: secondary to cat bite or scratch.
• Symptoms: swollen area that heals slowly; lymph nodes may become swollen and tender.
• Severity: usually not serious; treated with antibiotics; seen more in immunosuppressed or elderly individuals.
• Prevention and care: prevent cat scratches and bites; clean wounds promptly; bites should be evaluated by a doctor.

Salmonellosis

• At-risk groups: children and elderly.
• Symptoms: vomiting, diarrhea, abdominal pain; can be serious.
• Onset and duration: symptoms typically appear $12--72 ext{ hours}$ after infection and illness lasts $4--7 ext{ days}$.
• Carriers: carrier animals can appear healthy but carry disease-causing organisms that can infect other animals and humans.
• Animal carriers: dogs, cats, birds, guinea pigs, hamsters, rats, mice, and rabbits can be carriers; pet turtles or other reptiles are common sources of infection.
• Diet and risk: dogs on a raw food diet can be more likely to be carriers.
• Prevention: proper sanitation and husbandry reduce risk; wear gloves when handling animals; wash hands after handling animals.

Streptococcal bacteria

• Transmission: can be transmitted by dogs.
• Susceptibility: children are most susceptible.
• Range of illness: from mild to severe and life-threatening (sore throat or skin infection such as impetigo).
• Prevention: proper hand washing after touching an infected animal; seek medical advice for antibiotics if not improving.

Leptospirosis

• Source: shed in the urine of infected dogs.
• Transmission: by touching the mouth with unwashed hands after contact with infected urine; or absorption through mucous membranes after splashing.
• Precautions in clinical settings: handle suspected leptospirosis in hospitalized dogs with gloves and face shield; consider placement of a urinary catheter if needed.

Animal Bites

• Range of injuries: from minor to serious or fatal.
• Liability: depends on the community.
• Documentation: record if an employee was bitten.
• Infection risk: approximately $5\%$ of dog bites become infected; $50\%$ of cat bites become infected.
• Wound characteristics: puncture wounds are small and difficult to irrigate.
• Rabies status: always determine rabies vaccination status of the biting pet; if unknown, seek medical care for potential rabies immunization.
• Child safety: educate children not to pet unknown animals and supervise children when handling animals.
• Training emphasis: proper handling of animals to prevent worker injury; species-specific review during the semester.

Rabies

• Common reservoirs: bats, foxes, coyotes, skunks, bobcats, ferrets, raccoons; bat exposure is especially common in southern California.
• Domestic animals: generally vaccinated and quarantinable; post-mortem testing may be required in some cases.
• Vaccination: dogs are typically required to be vaccinated; outdoor cats may be vaccinated less often.
• Human exposure: rabies is usually fatal; immediate treatment is essential.
• Post-exposure prophylaxis (PEP):
  • If previously vaccinated: administer $2\ \text{IM boosters}$ if exposed.
  • If not vaccinated: administer $5\ \text{IM injections}$ of rabies vaccine and a single dose of rabies immune globulin (antibodies) over a 28-day period.
• Medical and preventive steps:
  • Vaccination for humans who work around animals should be considered; veterinarians are typically required to be vaccinated.
  • Clean the bite area with soap and water and seek medical attention immediately.
  • Tetanus vaccination is often given after an animal bite.
  • Antibiotic treatment or wound care decisions are made by the medical doctor.
• Prevention steps:
  • Do not feed, touch, or adopt wild animals or stray dogs/cats.
  • Teach children to stay away from stray animals.
  • Keep pets indoors at night; keep trash lids closed; avoid leaving pet food outdoors to discourage scavenging animals.
  • Ensure home has intact screens and no openings for bats or other animals to enter.
• After a pet bite:
  • Wear gloves when handling the pet; isolate the pet from others; arrange booster shot if the pet is vaccinated; report the bite to local animal control.
  • Unvaccinated pets should be isolated for $10--14 ext{ days}$ or longer for observation.
  • There is no ante-mortem rabies test, so monitoring for clinical signs is necessary.

Tick diseases

• Transmission dynamics:
  • An infected animal can bring disease-carrying ticks into the home; the tick itself does not infect the animal, but can bite humans later.
  • Remove ticks from pets carefully using forceps; do not bury the head; clean area afterward.
• Tick behavior: ticks crawl on a person before attaching.
• Common tick-borne diseases:
  • Rocky Mountain spotted fever (Rickettsia rickettsii): carried by several tick species (American dog tick, Rocky Mountain wood tick, brown dog tick, etc.). Symptoms: fever, headache, nausea, vomiting, skin rash. Early diagnosis and antibiotics are important.
  • Lyme disease (Borrelia burgdorferi): common on the North-Eastern US; deer tick (black-legged tick) on the East Coast and Western black-legged tick on the West Coast. Initial rash followed by arthritis-like symptoms; ticks have a 2-year life cycle.
• Tick life cycle (Ixodes scapularis) – summarized:
  • Eggs laid in spring; larvae feed on small mammals; nymphs feed on deer or humans; adults feed and then die; overall cycle spans around 2 years.
  • Notable stages: EGG → LARVAE → Nymph → ADULT; nymphs are a common stage for human infection; adult females lay eggs and die.
• Lyme disease signs:
  • Distinctive skin lesion appearing $3--32 ext{ days}$ after bite; early symptoms include fever, flu-like symptoms, muscle aches, fatigue.
  • If untreated, may progress to chronic fatigue, joint problems, neurological symptoms; can affect humans and animals (dogs, cats).
  • Most dogs and cats do not show symptoms.
• Babesiosis:
  • Causative agent: Babesia microti.
  • Transmission: by black-legged ticks or deer ticks; can also be transmitted via contaminated blood transfusions.
  • Pathology: infects red blood cells causing hemolytic anemia; higher risk for asplenic individuals, immunocompromised, elderly, or those with serious health conditions.

Tapeworms

• Causative parasites: Echinococcus granulosus and Echinococcus multilocularis.
• Epidemiology: rare, originally in Alaska but spreading to the lower US; not the common flea-tlea tapeworm.
• Hosts and transmission:
  • Foxes, coyotes, and mice are natural intermediate hosts; domestic dogs and cats are appearing as well.
  • Humans infected if eggs are ingested; larvae hatch in the small intestine, penetrate the intestinal wall, migrate to the liver, and form a cyst or tumor (alveolar hydatid disease, AHD).
• Clinical consequence: alveolar hydatid disease can be fatal in 50–75% of cases.
• Treatment: surgical removal of the cyst when possible.
• Lifecycle illustrations (summary):
  • E. multilocularis: Definitive host (dogs and other carnivores) harbor adult tapeworms in small intestine; eggs released in feces; intermediate hosts (e.g., small mammals) ingest eggs; oncosphere hatches and penetrates intestinal wall; alveolar hydatid cysts form in liver and may disseminate; diagnostic stages include protoscolex from cyst.
  • E. granulosus: similar lifecycle with sheep/goats/swine as typical intermediate hosts; hydatid cysts form in liver/lungs; definitive hosts are canids; ingestion of eggs leads to cyst formation.

Physical Restraint of Animals

• Purpose: restraint is needed for examination, blood collection, sample collection, or drug administration; aim to prevent injury to the animal and handler; avoid prolonged restraint; stressed animals can deteriorate.

Cat restraint

• Cats can bite or scratch; methods include:
  • Wrap in a blanket or place in a cat bag to examine the head.
  • Remove an unhappy/uncooperative cat from a carrier with care; place a towel over the head; scruff technique can be used with one hand on the rear legs.
  • Do not hold in scruff for too long; use a fishing net or clamshell for uncooperative cats; catch poles should be avoided if possible.
  • Head control: hold head with palm on back to the side of the head; grasp head between thumb and fingers.
  • Muzzles: cat muzzles can help keep the mouth closed and may cover the eyes to calm the cat.
  • Less is often more when restraining a cat.

Dog restraint

• Restraint positions:
  • Sternal recumbency: one arm under the neck with the forearm supporting the head; the other arm around the body to hold the dog close.
  • Lateral recumbency: reach over the animal’s back and grab one front leg and one back leg from underneath; gently lift and guide the dog to the side.
• Examination of ears typical with the dog in sternal recumbency, with a hand on each side of the dog and the other arms securing the muzzle.
• Muzzles (see below) are common, especially for safety.
• Muzzle options: gauze/cloth, tape; can be used to prevent biting.

Dog restraint – muzzle and E-collar

• Muzzle: used to prevent biting; can be homemade (gauze/cloth) or commercially produced.
• Elizabethan collar (E-collar): prevents dog or cat from biting or licking a wound; protects during healing; if using an E-collar, be cautious not to prevent wearing a muzzle when needed.

Rabbit restraint

• Handling: pick up by grasping the scruff of the neck with one hand and lifting up while supporting the rump with the other hand; always support the hind quarters.
• Risks: rabbits can injure you with their hind legs; can injure their spine if they kick hard to escape.
• Environment: avoid smooth surfaces; place on carpet or towel; can be wrapped in a towel or placed in a cat bag for restraint.

Rat and mice restraint

• Risk: can bite; use gloves.
• Handling technique: place the animal flat on carpet or a screen; with the other hand grasp near the base of the tail and use the other hand to grasp loose skin on the neck/shoulders.
• Alternative: use one hand to grasp loose skin over the back and hold in the hand.

Other Risks

• Chemicals and disinfectants: can be dangerous; most often enter the body through the skin; wear gloves when handling chemicals.
• PPE: closed-toe shoes or boots; goggles or face shield when handling chemicals or substances that could injure the eyes; protective coverings when dealing with infectious pets or toxic substances.
• Safety Data Sheet (SDS): required to be on-site and contain properties of the substance.

Safety Guidelines

• Personal protective equipment (PPE): Always wear protective clothing and equipment when required, and wash them after use to prevent contamination.
• Hygiene: wash hands (and face) after completing job to remove chemical residues or potentially infectious organisms; shower if needed to remove chemical residues from the body.
• Hand hygiene: wash hands frequently when working with animals, especially when working with different species or patients; consider wearing gloves and changing gloves between patients.
• Contamination prevention: prevent contamination of other animals and avoid self-contamination.
• Handling and behavior: keep hands away from mouth, eyes, and face to reduce self-contamination; do not eat or drink in contaminated areas; do not store food or drinks in contaminated areas.
• Clothing and equipment: remove uniforms or protective clothing when leaving contaminated areas; do not wash contaminated clothing with regular clothing.
• Labeling and disposal: ensure all chemical containers are correctly labeled; dispose of chemicals and containers following proper procedures or label instructions.
• Training and readiness: students and small animal workers should be instructed on proper handling of small animals; maintain first-aid kits in the work area and know their location.