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wildlife diseases - Coggle Diagram

- - - - prevalence (%) is the percent or proportion of diseased animals in a population at any one time
    - - incidence proportion (0-1) and incidence rate (cases/time eg. 1.5cases/1 wombat-year) relate to number of diseased animals in a population over a defined period of time
      - IR = cases/(people x times observed)
  - - - one that has been in the population for a long time (and there may be few overt signs)
    - - often recently introduced and has a high impact, because the population are naive to it
    - - when an epidemic occurs worldwide (or a very large area)
- - - - causes no disease in bats
      - at least 2 strains
      - all flying fox sp. prob able to carry
      - virus spills from bats to horses to humans
      - transmission through injection of infected material
      - seasonal variation in spill over events, peaks in july
      - shedding may be caused by transient epidemic or episodic shedding
      - dispersing and/or breaking up colonies may result in greater likelihood of shedding and spilling over
    - - vaccinate
        
        vaccinate horses - highly effective
        
        push back due to cost and skepticism
        
        requires yearly booster after initial course
      - separate
        
        separate horses and flying foxes where possible
        
        eg. fencing around trees
      - knowledge
        
        continue research to improve understanding of drivers of spill over events
  - - - poorly understood
      - hotspots for outbreaks = close to water
      - mosquito bites and ulcers typically on periphery in humans + possums
      - M. Ulcerans detected in brushtail and ringtail possum faces in impacted areas: 43% Ringtails and 29% Brushtails
      - high densities of ringtail possums in areas where there have been outbreaks
      - small mammals, environment, insect vector, humans (complex pathway)
  - - - sub-clinical in most placental birds + mammals
      - aus marsupials may be particularly sensitive (big issue in captivity, impacts on wild pops poorly understood)
      - has been reported from many different marsupial sp.; possibly some differences in susceptibility
      - are some strains more pathogenic than others?
      - 2/18 EBBs released onto french island died of toxo within 1 month
  - - - itching, hair loss, skin thickening, skin cracks, leading to secondary infections, blindness and deafness, more diurnal
    - - documented decline with arrival of mange at Narawntapu NP
      - most other declines anecdotal with insufficient data
      - wider population level impacts are unclear
    - - in-field treatment now commonly performed
      - benefits probably mainly at individual animal level
      - burrow flap method very labour intensive
      - new drug available for treatment (fluralaner-bravecto)
      - moxidectin still commonly used
- - - - clinical
        
        Clinical (appearance of clinical signs)
        
        Subclinical (no overt clinical signs, but some underlying impairment eg. of immune function)
      - infectious
        
        infectious (bacteria, viruses, fungi , prions etc)
        
        non-infectious (toxicity, neoplastic/cancer, nutritional, congenital etc)
      - diseases can have welfare implications!
- - - - habitat degradation and destruction
      - urbanisation
      - wildlife trade
      - intensification of ag
- - - - mainland extinction ~3K years ago, isolated in TAS for ~14K years
      - founder effects, pop bottlenecks during periods of low density
      - MHC diversity esp low in east, NW genetically distinct (high MHC diversity)
      - primarily scavengers, but also kill prey
      - very strong jaws
      - will occasionally bite each other when feeding, males fight during mating season
    - - 2 different transmissable cancers
      - transferred through neoplastic cells in saliva during 'biting episodes'
      - start as small legions, develop into humans
      - affects ability to feed, causes blindness, spreads to other organs
      - almost 100% mortality rate w/in months of contraction
      - caused 80% pop decline up to 95% in some local areas
    - - selective culling to remove infected devils didnt work
      - captive breeding - now 700 animals in 44 institutions. Genetic management and population augmentation
      - translocation of healthy devils to maria island 2012
      - forestier peninsula barrier
      - some evidence that devils are becoming resistant
      - vaccine in development
    - - trophic cascades following disease induced decline of apex predator
      - loss of tassie devil leads to increase in invasive mesopredator (feral cat) and decrease in Quolls and bandicoots
  - - - hyperkeratosis (Bd)
      - Ulceration (Bsal)
      - anorexia
      - death
    - - different strains but: global panzootic lineage hypervirulent
      - novel disease: naive populations
      - heterogenous distribitions of hosts, small populations
      - slow disease progression: can transmit before death
      - reservoir hosts: spread disease widely
      - host behaviour: basking frogs better able to shake off disease
    - - ~15% of 214 frog species declined, 6 extinct
      - 7 have managed to avoid extinction
      - at least 10 are vulnerable to extinction