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australia:mites

mites / sarcoptic mange / scabies in Australia

Introduction

  • mites are microscopic insects which burrow under the skin causing very contagious infections such as scabies in hominid species and sarcoptic mange in animals
  • NB. sarcoptic mange is contagious between animals whereas demodectic mange is not contagious but both cause hair loss and itching
  • it seems that humans were probably the original host of Sarcoptes scabiei and sub-species have evolved with predilections for other animals
    • they now affect over 100 mammalian species (incl. dogs, foxes, pigs, horses, camels, wombats, koalas, bandicoots, wallabies, potoroos, possums) from at least 10 orders and 7 families, and continues to spread into new hosts, classifying it as an emerging infectious disease
    • it is likely to have spread to Australian native animals via invasive red fox populations as well as dogs
      • transmission is via direct contact from an infected animal or from shared usage bedding chamber such as a burrow or den - foxes often use wombat dens
    • of the affected native Australian mammals, sarcoptic mange is of greatest impact to wombats and infection rates can be as high as 70% amongst populations of wombats
      • increased rates of mange disease are often associated with high wombat densities and periods of drought or high stress (e.g. seasonal stress in winter)
      • during outbreaks, mange prevalence in wombats can rise to > 50%, with near 100% mortality (unlike in dogs in whom the condition tends to be self-limiting)
      • mange has driven common wombat populations to the edge of localized extirpation, with documented outbreaks causing > 90% decline in wombat abundance
      • the first clinical signs of mange infection in wombats develop within 1 – 3 weeks of parasite exposure, with more severe signs appearing by 4 – 5 weeks.
      • death usually occurs as a result of secondary bacterial infection around 2 – 3 months after infection.

Species

  • Sarcoptes scabiei var hominis
    • this is the cause of scabies in humans which is an extremely contagious and annoying infestation
  • Sarcoptes scabiei var cani
    • causes sarcoptic mange in animals - mainly dogs and foxes
    • can be spread to wombats and even to humans in close contact (but in this case infection tend to be localised and self-limiting as humans are not the preferred host)
    • it was likely introduced by European settlers and their domestic animals around 200 years ago
  • Sarcoptes scabiei var wombati
    • has a predilection for wombats
australia/mites.txt · Last modified: 2024/01/01 18:14 by gary1

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