Preventative Medicine & Pest Control

Question 1

Describe the two aspects of an integrated pest management plan.

What is included in indirect suppression of unwanted species?

What are the five components of direct suppresion?

What do each of those entail and what are some pros and cons of each?

Answer 1

Fowler 7 Ch 8 - Integrated Pest Management

• A pest management program is key to controlling pests in a zoological setting and is required for licensed animal facilities.
• Integrated pest management (IPM) involves analysis of the pest and attempts to use the safest approach to control the population, in keeping with environmental concerns.
• IPM uses a combo of control measures including: exclusion, habitat management, sanitation, removal (trapping, baiting, relocation, euthanasia), and repellants.

INDIRECT SUPPRESSION:

• Focused on education and prevention.
• Preventing pest access to food, water, and shelter along with staff education and regular chemical treatments will provide the best long-term effects with IPM.
• Staff responsibilities:
  
  • cleaning and sanitation in their areas
  • alert pest control staff if identify signs of pest infestation
  • prepare areas for treatment, move animals if needed
  • remove dead and dying pests, monitor bait stations, set traps as recommended

DIRECT SUPPRESSION:

• Focused on trapping and eliminating (mechanical control) pest species.
  
  • Includes: exclusion, baiting, repellants, trapping, removal, euthanasia, relocation
• Exclusion
  
  • Physical barriers
  • Eliminating areas for pests to find shelter indoors and outside
  • Trimming trees/plantings away from perimeters of buildings, preventing access to burrows (mammals) and perching structures (birds)
  • Eliminating access to harborages indoors (false ceilings, hollow walls, gaps around piping, electrical wires)
• Baiting
  
  • Most appropriate with high pest numbers or risk of infectious disease to animals, staff, guests.
  • Big concern with untargeted/secondary toxicity when animals other than intended pest consume bait directly or consume pests that have consumed toxic bait.
  • Unintentional primary toxicity can affect wildlife on zoo grounds: squirrels, chipmunks, voles, waterfowl, passerines.
  • May develop pesticide resistance with prolonged use (ex: coumarin-based rodenticides)
  • Bait stations should be numbered, secured far from animal enclosure to prevent exposure, and carefully monitored for effectivity.
• Repellents
  
  • Noise, light, smell – are safer than baiting but may be less effective and require more staff time and repeated application.
  • There are many products available (ex: pheromones) for natural pest control
  • Little literature available on efficacy and cost/benefit ratio.
• Trapping
  
  • Involves live and lethal capture methods
  • Live trapping allows for removal, translocation, and humane euthanasia of pests
  • Lethal trapping preferred over baiting due to decreased risk of secondary toxicity
  • Benefit of trapping and removing is reducing risk of infectious/zoonotic diseases.
  • Surveillance programs that take blood/tissue from pests can be valuable to ID diseases.

Question 2

Describe the infectious disease risks to collection animals from various pest species:

Rodents

Small Carnivores & Opossums

Deer

Birds

Insects

What regulations govern an integrated pest management plan?

Answer 2

INFECTIOUS DISEASE POTENTIAL:

• Rodents:
  
  • Transmission of many bacterial/viral diseases: lepto, salmonella, plague, lymes, lymphocytic choriomeningitis virus (LCMV), enceph. myocarditis virus (EMCV), hantavirus.
  • Transmission of parasitic diseases: toxoplasmosis in marsupials, lemurs, new world primates with ingestion of cat feces, intermediate hosts (mice, birds), and contaminated cockroaches.
• Small Mammals:
  
  • Rabies vectors (skunks, raccoons, coyotes, foxes
  • Raccoons and domestic dogs prey on zoo species and may carry CDV and rabies.
  • Baylisascaris procyonis (zoonotic roundworm of raccoon) can cause mortality in primates, ratites, psitticines.
  • Feral cat/dogs may transmit parvo, calici, FeLV, feline panleukopenia. Exotic felids have been linked to feral cat exposure.
  • Opossums are reservoir for Sarcocytis neurona and S. falcatula. S. neurona causes EPM and EPM-like disease in other mammals.
    
    • Infection occurs when animals consume opossum feces, contaminated food, or cockroaches contaminated with opossum feces.
• Deer:
  
  • Can damage landscaping and transmit disease: TB (Mycobacterium bovis), Johnes (M. avium paratb), CWD (Chronic wasting disease)
• Birds:
  
  • Feral birds can introduce: M. avium, Chlamydophilia psittici, Salmonella sp., Mycoplasma sp., Newcastle’s disease, and avian influenza.
• Insects:
  
  • Are vectors of disease, transmit fecal borne pathogens, reservoirs of disease, and intermediate hosts.
  • Cockroaches are prolific pests in zoos worldwide

REGULATION OF PEST MANAGEMENT PRACTICES:

• An IPM program should be responsibility of senior management that is knowledgeable about pest management, animal health and disease, state/federal wildlife regulations, legal aspects of pesticide use.
• EPA regulates use of many pesticides used in zoos.
• All pesticide activities should be logged and tracked as part of an IPM program.
• Topical pesticides may also be regulated and require a prescription or pest control log in certain states.
• To become a certified pesticide applicator, an individual must complete training and examination administered by state/local authorities that enforce EPA regulations.

Question 3

There is dilemma of how to manage the effects of feral cats on wildlife.

For TNR to work, what conditions must be met?

What are the effects of cats on wildlife and conservation?

What are some important diseases that feral cats may transmit? Both to people and to wildlife?

What alternatives exist to TNR or euthanasia programs?

Answer 3

FOWLER 9 CHAPTER 18: Feral Cat Dilemma

Kerrie Ann T. Loyd & Sonia Maria Hernandez

Cats and Human Culture

• Cats are believed to be domesticated from the wildcat in the Near East appx. 10,00 years ago
  
  • Originally valued as predators of pests around grain/crop stores; revered as religious figures
• Cats have surpassed dogs as the most popular companion animal in most of North America and Europe

Rise of Feral Cats

• Large feral cat populations may have started in developed countries as people migrated to cities from the countryside in early 20^th century
• Lack of sterilization techniques and prolific nature of cats (queens may have 2+ litters of 4+ cats per year)
• Controversy over biologically effective yet socially acceptable management strategies
  
  • Lethal control - pathogens, poison baiting (used in areas with imminent conservation issues)
  • Fertility control – capturing and socializing/euthanizing; trap-neuter-release (TNR)
    
    • For TNR to work, 75%+ population must be sterilized and immigration rate must be 0
    • Does not impact a cat’s ability to hunt prey
• Stakeholders –animal welfare organizations (TNR) vs cat activists vs wildlife advocates (cat removal)

Cats Hunt – So What?

• Impact on native prey species and competition with native predator species
• Cats have been implicated in 63 species extinctions on islands
• Cats are estimated to kill 3.7 billion birds and 20.7 billion mammals in USA annually
• Due to decline of natural areas and expansion of developed areas, urban/suburban habitats are critical to future protection of biodiversity but may become ecologic traps if harbor non-native predators

Animal Welfare – From Both Sides

• Feral cats have poor QoL (exposed to environmental extremes and sources of trauma/protection)
  
  • PETA supports humane euthanasia; other groups (eg Best Friends Animal Society) support other means
• Cats are a major cause for submission of injured animals to wildlife clinics
• Welfare of individual cats gets extensive attention but welfare of individual wildlife is usually unseen

Public & Wildlife Health Concerns Related to Feral Cats

• Cats are zoonotic reservoirs: Bartonella henselae, Salmonella, Toxocara cati, tapeworms, hookworms, Sarcoptes scabiei, Toxoplasma, Yersinia pestis, rabies (2^nd to bats in cause of human exposure)
• FeLV was transmitted from feral cats to the Florida panther; Toxoplasma was transmitted to sea otters

Management Alternatives to TNR or Euthanasia

• Feral cat numbers are unlikely to decline unless multiple strategies are adopted in combination
• A vigorous trap/removal program is needed
• Strongly enforced licensing, identification and confinement laws are integral
• Continued financial support for animal control agencies and shelters
• Public education program that encourages responsible pet ownership (how/why to keep cats indoors)
  
  • Cat runs/aviaries, flexible cat tunnels, harnesses/leashes, supervised outdoor time, indoor enrichment
• Removing TNR colonies from sensitive habitats where threatened species live
• Enclosed colonies/sanctuaries of TNR cats managed by people (feeding, medical care, socialization, etc)

The Role of Veterinarians in Feral Cat Management

• Reconsider participating in TNR due to the fact that rereleasing cats contributes to negative impacts on wildlife
  
  • TNR is not supported many large groups
• Become involved in local policy and help develop feral cat management strategies
• Educate the public and provide cat owners with viable solutions

Question 4

What are the various methods of vaccinating wildlife?

What safety considerations need to be met?

What factors make a wildlife vaccination protocol efficacious?

What concerns may arise from starting a vaccine protocol or suddenly disconinuing it?

What diseases could potentially be managed in wildlife with vaccines?

Answer 4

Fowler 9 Chapter 44 – Techniques for Vaccinating Wildlife

• Vaccines relatively underutilized in free ranging wildlife – logistical, ethical, legal reasons
• Motivations for wildlife vaccination include
  
  • Control rate of transmission of pathogen with public health significance targeting reservoir population
    
    • Rabies, Mycobacterium bovis, Brucella abortus, swine fever virus
    • Maximize vaccine coverage to evoke immunity reliably & cost effectively
  • Tool to promote conservation of endangered species – raise immune status of threatened population or preventing loss of prey species
    
    • Canine distemper vaccine in Hawaiian monk seals
      
      • Studies show will be more successful prophylactically than as a reaction to outbreak due to time required for protective immunity
    • Racoon poxvirus based recombinant vaccine for Yersinia pestis for prairie dogs, to benefit them and their ecologic dependent the black-footed ferret
    • Maximizing vaccine coverage may slow loss of genetic diversity in a threatened population, but is challenging and may be cost prohibitive
    • Low coverage vaccination strategies may help limit spread of infection and allow for survivors
• Methods of delivery
  
  • Oral
    
    • Meat, packets with flavor matrix palatable to target species
  • Parenteral
    
    • Risk of capture, handling, immobilization
  • Remotely through projectiles
    
    • Darts, bio-bullets
  • Aerosolized sprays
• Safety
  
  • Should not cause disease or have other negative side effects
  • Difficult to do safety trials in threatened target species
  • Must consider safety trial in non target species
• Efficacy
  
  • Challenge studies required to demonstrate protection – ethical challenge
  • Duration of immunity important consideration, likely unable to deliver boosters
  • Oral vaccines must be delivered in a behaviorally acceptable manner and palatable to ensure ingestion
    
    • Biomarkers to quantify rates of vaccine uptake
      
      • Tetracycline – teeth/bone, fluorescent rhodamine dye – UV light
  • Must protect against degradation
  • Appropriate adjuvants to enhance contact/absorption
• Cautionary principles
  
  • Sudden loss of immunity if program discontinued
  • Any perception of failure of wildlife vaccination may have widespread consequences
  • African wild dog vaccination against rabies
    
    • Critics stated immunosuppression related to stress of capture may have activated latent rabies infections
    • Became very difficult to secure permission for captures or vaccinations
    • May have been averted with stageholder engagement, realistic expectations, explore possible consequences
• Future
  
  • Oral Borrelia vaccine for Peromyscus mice
  • Oral delivery of BCG vaccines, baiting for badgers – bovine TB
  • Canine distemper and tigers
  • Tasmanian devil facial tumor disease
  • Fungal disease – chytridiomycosis
  • Cytomegalovirus
    
    • Assumed to be safe and host specific
    • Carry Ebola virus nucleoprotein, protects mice and rhesus macaques
    • Self-disseminating vaccine
    • Containment would be impossible once released
    • Virus can cause human birth defects