mites / sarcoptic mange / scabies in Australia

see also:

• March flies
• Mosquitoes in Australia
• "sand flies" / biting midges
• pests in Australia
• ticks in Australia
• https://wildlifehealthaustralia.com.au/Portals/0/ResourceCentre/FactSheets/Mammals/Sarcoptic_Mange_in_Australian_Wildlife.pdf

• 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.

• 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

• belong to the family Trombiculidae and are external parasites of rodents, birds and lizards often found on the edges of rainforests
• the only arthropod with a larval stage (<0.2mm long) that can cause irritation to humans with a itchy red raised patch at the bite site.
  • The chigger larvae do not survive for more than two days on a human host. Chiggers prefer to bite areas where skin is soft and they often congregate under clothing where it is tight against skin (e.g. around the waist or underwear), as well as around the ankles and lower legs.
  • chigger larvae can also transmit an infective agent that causes the potentially lethal rickettsial disease known as scrub typhus in northern Australia (Queensland, Northern Territory and Western Australia) as well as Asia.
• adult (these are <1mm) and nymph stages of the mites pose no public health concern.
• Eutrombicula hirsti and E. samboni (found in the eastern and south-eastern coastal areas from Queensland to South Australia)
• E. sarcina (found in central Queensland)
• E. macropus and Neotrombicula mackayensis (found in north-west Queensland and northern New South Wales)
• Leptotrombidium deliense (found in the coastal north of Queensland and Western Australia).

• several species of bird mite, but the most common species affecting humans is Ornithonyssus bursa
• Individual mites may be difficult to see with the naked eye, but large infestations are clearly visible due to the sheer number of mites, especially when concentrated close to their entry points to dwellings
• most strongly associated with common introduced birds, such as pigeons, starlings, sparrows and Indian mynahs
• mites do bite humans and cause a prickling sensation followed by irritation, rashes and itching but do not infest human skin or clothing

• these can bite humans (but less common an issue compared with bird mites) causing an itchy bite area but do not transmit disease or infect clothing or skin
• Ornithonyssus bacoti

• grass itch mite (Odontacarus australiensis)
• clover mite (Bryobia praetiosa)
• fur mites on cats, dogs, rabbits (Cheyletiella parasitivorax)