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Published Date: 2012-05-16 11:52:34
Subject: PRO/AH/EDR> Undiagnosed disease, wombat - Australia: (SA) toxic weed susp.
Archive Number: 20120516.1134446

UNDIAGNOSED DISEASE, WOMBAT - AUSTRALIA (02): (SOUTH AUSTRALIA) TOXIC WEED SUSPECTED
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Date: Tue 15 May 2012
Source: Google News, Agence France-Presse (AFP) report [edited]
http://www.google.com/hostednews/afp/article/ALeqM5iJymsMYA5xKqc6ROz3udl08zKMLA?docId=CNG.a43e1c7494a00df0179192c4bf246bb0.2f1


Balding disease killing Australia's wombats
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A mystery liver disease thought to be caused by introduced weeds is causing hairy-nosed wombats in southern Australia to go bald and die, researchers said Tuesday [14 May 2012].

The illness, which causes the wombat to lose some or all of its fur and then starve to death, is tearing through South Australia's native southern hairy-nosed wombats, threatening entire populations.

Peter Clements from the state's Natural History Society said wildlife rescue workers had discovered "several hundred" sickened animals in the Murraylands region near Adelaide, where up to 85 percent of the population was unwell. "They tend to lose their fur in patches and sometimes in whole," Clements told AFP.

"You can see the bones showing through and they're generally immobile, they just sit there in the sun all day and try to keep warm."

Clements said it was unusual to see the wombat, a nocturnal creature, out during the day and when they were in daylight "we know that they're in trouble."

Initially the animals were thought to have mange, but it became so widespread and severe -- with shiny, healthy skin revealed beneath -- that autopsies were carried out to determine what was causing the illness. University of Adelaide researcher Wayne Boardman said the non-native toxic potato weed appeared to be affecting the wombats' livers, triggering a reaction with ultraviolet light that caused them to lose their fur. Boardman said it was unclear why the herbivorous wombat had suddenly taken to eating the noxious weed but a shortage of their usual grasses and alternative foods due to prolonged local drought could be to blame.

"We have a feeling it might well be a struggle to find enough vegetation, leading them to eat other plants like weeds, and particularly potato weed, which is then having a deleterious effect on the liver," Boardman told ABC Radio.

The creatures were also roaming in areas where they were not usually seen, supporting the theory that there were food shortages and they "have to move out to find vegetation," he added.

Squat and thickly furred, wombats are small burrow-dwelling marsupials that walk on all fours and are bear-like in appearance with a wide muzzle and a flattened head.

They are not a threatened species but Boardman said the population in parts of South Australia state could die out completely if their habitat was not restored to a healthy balance of native plants.

Brigitte Stevens, from the Wombat Awareness Organisation, said it was a "huge and overwhelming" problem.

"Some of them are just lying down... on their side and just eating dirt. You know, they can't even lift their heads," she told ABC.

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[If the potato weed, (likely _Heliotropium europaeum_) contains pyrrolizidine alkaloids, these often have effects on the liver. The damaged liver is unable to remove the chlorophyll breakdown product, phylloerythrin from the blood. The phylloerythrin reacts with sunlight in the skin and produces a condition known as photosensitization. This usually appears as a severe type of sunburn. The wombats are noted to have liver damage and loss of hair. Perhaps their current habitat (not enough sunlight) or their own metabolism prevents the photosensitization reaction. However, they are noted to be thin and in poor condition, which may be reflective of a liver condition.

As to the creatures starving, I am not sure. Liver damage can prevent the removal of other metabolites from the blood. Some of those entities may have an effect on the brain. If there is a neurological effect it may mean they don't recognize their normal food or may not remember how to forage correctly. On the other hand, perhaps their normal forage is unavailable because of an invasion of this plant, other weather conditions affecting the normal forage, or other reasons.

While common names of plants can become problematic, scientific names are more straightforward. Below are 3 different Australian sites relating to _Heliotropium europaeum_ as potato weed and attesting to the issue of toxic effects on the liver and its effects on other livestock.

Australian source 1: http://www.dpi.qld.gov.au/27_11766.htm
Potato weed (_Heliotropium europaeum_)
This plant, also called 'common heliotrope' is an annual weed that infests the wheat-producing areas of southern Australia. It produces toxic pyrrolizidine alkaloids that damage the liver. In 1993, a serious poisoning outbreak occurred in South Australia when 1000-4000 pigs died over 3 months because wheat contaminated with potato weed seed was incorporated into diets at about 0.2-1 per cent. Lower levels slowly damage the liver and severely affect growth without obvious signs. Poisoning outbreaks tend to occur every few years when wet summers favour weed growth and delay wheat harvest. Although a safe feeding level has not been established, a maximum of 0.01 per cent might be an interim guideline (about 100 seeds/kg, as 100 seeds = 0.13 g). QASR [Queensland's Agricultural Standards Regulations] currently has no standard for this seed because it does not grow in northern Australia.

Australian source 2: http://www.dpi.nsw.gov.au/agriculture/pests-weeds/weeds/profiles/common-heliotrope [includes photos of the plant]
Common heliotrope (_Heliotropium europaeum_), also known as caterpillar weed or potato weed, is a summer-growing annual native of southern and central Europe, western Asia, and northern Africa.

Accidentally introduced to South Australia during the 19th century, it is now recorded in all states except the Northern Territory and Tasmania. It is of considerable economic importance as a summer fallow weed, and in grazing situations because of its toxicity to stock. It is widespread in southeastern Australia, infesting over 10 million hectares [24.7 million acres], which is why it is not a declared noxious weed -- complete control and eradication are unlikely.

The earliest recording of common heliotrope in NSW was in the Parkes district in 1899.

Livestock toxicity
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Common heliotrope contains pyrrolizidine alkaloids, commonly referred to as PAs. The types of PAs found in common heliotrope are considered more poisonous than those found in blue heliotrope.

Heliotrope is not very palatable to livestock and consequently tends to be avoided; however, some individuals continue to eat it indiscriminately.

Continual ingestion by livestock of large amounts of heliotrope plants (either fresh or dried) or of their seeds as contaminants in stock feed, can cause liver damage and reduced productivity. Horses, pigs, cattle, sheep, and goats can all be affected, but display decreasing susceptibility with horses being the most susceptible. All affected livestock species may become jaundiced and experience varying degrees of photosensitisation.

Summary of livestock toxicity clinical signs: horses present with clinical signs including weight loss, dull, depressed, uncoordinated, wander aimlessly, can develop respiratory difficulties, reduced productivity, liver damage, and secondary brain damage.

Pigs present with clinical signs including death (most common), reduced productivity, and liver, kidney, and lung damage.

Cattle present with clinical signs including depression, unpredictable bouts of aggression, death, and can have reduced productivity, liver damage, and secondary brain damage.

Sheep and goats present with clinical signs including accumulation of copper, which can cause sudden death when released into the bloodstream, reduced productivity, and liver damage.

Australian resource 3: http://www.dpi.vic.gov.au/agriculture/pests-diseases-and-weeds/animal-diseases/beef-and-dairy-cows/heliotrope-toxicity-in-sheep-and-cattle
_Heliotropium europaeum_ is often referred to as potato weed, blue weed, or common or wild heliotrope. It was introduced into Australia in the 19th century and has established in all states of mainland Australia, apart from the Northern Territory.

Heliotrope is a summer sowing annual herb that thrives on disturbed, bare or open, cultivated ground. It has branched stems, grows up to 300 mm [12 in] high, and is covered with coarse white hairs. The leaves, which are grey-green in colour and oval shaped, are arranged alternately on the stems and have small white flowers.

Seeds germinate in the warm, moist conditions after each late spring or summer rain, and growth is prolific where seedlings are not shaded and there is no competition from perennial plants. Fallow ground is ideal, hence it is more of a problem in wheat/sheep areas than pastoral areas. Heliotrope has enormous seeding potential and the seeds are viable for many years.

This plant contains poisons or toxins known as pyrrolizidine alkaloids. The toxins are present at all stages of growth and in all parts of the plant, including the seed (http://www.dpi.vic.gov.au/agriculture/pests-diseases-and-weeds/animal-diseases/beef-and-dairy-cows/heliotrope-toxicity-in-sheep-and-cattle).

Hopefully the researchers will find the cause of the problem affecting these fascinating creatures. A fact sheet and photographs of hairy nosed wombats may be found at http://www.wombania.com/wombats/hairy-nosed-wombat.htm.

A HealthMap/ProMED-mail map can be accessed at http://healthmap.org/r/2nz9. - Mod.TG]

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