Random factoid

Avian influenza ("bird flu") is the fourth most common nature oriented news query (scroll down to "News Queries").

In Tasmania, the Devil Now Faces Its Own Hell - New York Times

In Tasmania, the Devil Now Faces Its Own Hell - New York Times

A very interesting article on the mysterious Tasmanian devil facial tumor disease issue.

Very little is known about this disease, but may prove to be disastrous for the conservation of this marsupial. The Times article is very informative.

UPDATE June 4, 2005: In case the NY Times pulls free access to this article, I've reproduced it here:

May 31, 2005
New York Times

In Tasmania, the Devil Now Faces Its Own Hell

By SANDRA BLAKESLEE

LAUNCESTON, Tasmania - Even by the brutish standards of Tasmanian devils, Rosie, Harry and Clyde have led a lamentable life.

A year ago, when the three were each the size of a sesame seed, they wriggled out of their mother's birth canal and undulated their way to her pouch. There, each locked onto a teat and grew like gangbusters.

But tragedy struck. Within months, their mother developed devil facial tumor disease - a mysterious malady that in the last three years has killed nearly half of all the world's devils, marsupials that are found only in Tasmania. Shortly after she died, the baby devils, grown to the size of tiny puppies, were found dangling from their mother's pouch, starving to death.

Rescued and reared by hand, Rosie, Harry and Clyde recently joined six similarly orphaned devils at the Launceston Lakes and Wildlife Park, all in strict quarantine. The fate of their exotic species - Sarcophilus harrisii - may lie in what happens to these rambunctious youngsters in the next 12 to 18 months.

"If they contract the disease, devils may be headed for extinction in the wild," said Nick Mooney, a wildlife biologist with Tasmania's Department of Primary Industries, Water and Environment in Hobart. "If they're free of the disease, we may have reason for hope."

Right now, wildlife experts are struggling to comprehend the nature of the fast moving epidemic. Moving at a rate of 6 to 10 miles a year, it is 100 percent fatal. Only the west coast, isolated by mountain ranges inhospitable to devils, is disease free. Nearly half of the estimated 150,000 devils in Tasmania are now dead.

Devil facial tumor disease is grotesque; the mother of Rosie and her brothers died when grotesque tumors ballooned out of her face and neck, choking off her ability to eat. It is also an extraordinary puzzle. Scientists do not understand its cause, mode of transmission, time from infection until the tumors appear, or potential to infect others.

Their current best guess breaks all the rules of modern biology. Scientists suspect that the disease is caused by a cancer cell that itself moves from one animal to another when they bite one another.

Having declared an emergency, officials are trapping healthy devils for captive breeding in case the disease cannot be stopped. The real devil bears no resemblance to Taz, the Warner Brothers Looney Tunes cartoon character that roars and whirls like a dervish. A real devil is the size of a spaniel, with strong forelimbs, a huge head and a disappointing back end. Geoff King, who lures devils to his ranch in northwestern Tasmania for ecotourists to observe, said they lived solitary, nocturnal lives, coming together to devour carrion. Its bite is as strong as that of a dog four times its weight. "They are nature's cleanup crew," Mr. King said.

Females have lustrous black coats with a purple hue, white stripes on their rump or below the neck, exceptionally long luxurious whiskers and narrow pointy faces. When they get excited, their ears turn blood red. "They are beautiful," Mr. King said.

Males have similar markings along with big boxy heads and heavily scarred faces and rumps. A devil can eat a quarter of its body weight in one feeding. "They're as tough as bloody nails," Mr. King said.

Devils got their name from early European settlers who heard spine-chilling screams and thought that Satan was surely in the backyard. "Devils do make weird noises," Mr. King said. "When they first arrive at a carcass," he said, "they make a recognition signal - whorf? Are you there? Then they start hissing from the stomach. Growls turn to whines and flow into screeches. They sound like a groaning witch."

Devil sex turns up the volume. In March and April, males engage in vicious, blood-soaked combat, said Dr. Menna Jones, a wildlife biologist who also works in the environment department. Females select "big butch dudes," Dr. Jones said, and allow themselves to be dragged by the scruff of the neck into a burrow. There they scream and fight for several days, mating many times for hours at a time. At the end of such bouts, the male thrusts his sperm into the female every two minutes.

Three weeks later, the female gives birth to about 20 or 30 embryos that wiggle through a string of mucus that leads to her pouch, which has only four teats, Dr. Jones said. The first to arrive lock on and survive. All others perish.

By August the pouch gets crowded. When she hunts, the mother leaves her roly-poly little devils in a den. The young are weaned at nine months, emerging from the den in the fall as goofy teenagers. Mom departs.

After six years of scavenging, screeching and seeking mates, devils abruptly die, Dr. Jones said. They are one of the few species in the world with so-called catastrophic mortality. How and why they die this way is not known, she said.

Tasmanians have always taken devils for granted, Mr. Mooney said. Few scientists ever bothered to study them. When the first animal with facial tumors was photographed, in 1996, he said, "people thought, eeew, that looks horrible, but it did not ring alarm bells."

After five more years scientists realized the disease was widespread, Mr. Mooney said. Later surveys show a devastating picture. Spread animal to animal, the disease is now endemic to two-thirds of the island, which is slightly smaller than West Virginia. The disease starts out as a raspberrylike lesion on the gums, palate or under the tongue, Dr. Jones said. Within months, tumors erupt around the mouth, neck and face. A few weeks later, they explode, weeping and oozing, pushing out teeth, eyes or noses, and sometimes invading the rest of the body. "It is a disgusting sight," Dr. Jones said. "Animals starve to death three to six months after the first signs of a tumor.

Here in Launceston, Dr. Stephen Pyecroft is spearheading the government's investigation into what is causing the disease. A virus seemed likely. But so far, Dr. Pyecroft said, every effort to identify a virus has come up empty-handed. A virus has not been ruled out, he added, but scientists are now entertaining other hypotheses.

Since Tasmania has widespread use of agricultural chemicals and pesticides, researchers are looking at 10 toxins to see if devil disease is associated with poisons that can cause tumors.

But the leading theory is that devil facial tumor disease is caused by a transmissible tumor cell, Dr. Pyecroft said. It goes like this: About a decade ago, a random mutation occurred in a single animal in a type of cell involved in hormonal regulation. This devil developed tumors on or near its face. When another devil bit into the tumor, it was infected with tumor cells. With time, tumor cells were passed around in the bloody fray of devil social life, spreading the disease.

In this hypothesis, tumor cells alone are the infectious agent. In nature, this is not supposed to happen, Dr. Pyecroft conceded. Healthy animals exposed to pathogens, including tumor cells, will normally mount an immune response to fight off the infection.

But genetically speaking, devils are virtual clones. With scant variation in their DNA - perhaps from a population bottleneck in the recent past - they may have nearly identical immune systems. Hence they cannot fight off the tumor cells.

Every tumor cell examined so far is the same in every animal, male and female, regardless of area of origin. The chromosomal rearrangements, presumably from the one random mutation, are identical.

Dr. Pyecroft said another disease offered support for the idea that tumor cells could be infectious. That disorder, canine transmissible venereal tumor disease, is passed among dogs during sex or when they lick and sniff infected tissue. The tumors are identical, suggesting that they are passed by contact.

The big difference is that the disease is not fatal in dogs. They mount an immune response and get over it.

Researchers are growing devil tumor cells in petri dishes to explore their basic biology. "We're knocking weird cells on their heads to figure this out," Dr. Pyecroft said.

Meanwhile, Dr. Mooney's team is trapping devils islandwide to determine the extent of the epidemic. They are also in the process of trapping 25 young animals from apparently disease-free areas as an insurance policy. The juvenile devils are being placed in urban and offshore sites to keep them apart from older, wild devils. If after a year or so they show no signs of disease, they will be bred to ensure survival of their species.

Similarly, Rosie, Harry and Clyde are living with other orphans - Donny, Hansel, Gretel, Beatrice, Zilla and Scamp. "We usually don't see the disease until after the animals turn 2 years old," said Heather Hesterman, another biologist on the team. It is possible they might get the disease from their mother's milk or contact with her saliva, Ms. Hesterman said. On the other hand, they may have resistance to it.

Veterinarians will watch the orphans for the next year or so to see what happens.

"We have so many question marks, so little time," Ms. Hesterman said.

Avian influenza (H5N1) in China

There are recent reports of highly pathogenic avian influenza (H5N1) from Qinqhai Nature Preserve in Qinqhai Province, China (west of Xining; see here for a description of the area), a significant extension of the known affected area for this disease.

Previous to this report, the current H5N1 outbreak was thought to be
contained to Southeast Asia (see map).

There are many rumours circulating about this issue, and given the propensity of the media to speculation, it is important to keep in mind what we know and what we don't know.

Why is this important?
The current outbreak of H5N1 avian influenza in Southeast Asia has been making news headlines for over a year now. Millions of domestic poultry have been affected throughout southeast Asia and over 50 humans have died to date. In the last 100 years there have been three pandemics of avian influenza in humans, the most lethal of which occuring in 1918-1919. Well over 20 million people died in that outbreak. Many scientists and health practitioners are warning that it is only a matter of time before the next global influenza pandemic occurs. The current strain circulating in Southeast Asia does not transmit efficiently among humans. However, there is great worry that with continued exposure to humans, the virus may evolve greater transmissibility through mutation or by obtaining genetic material from human influenza viruses.

What we know:

- Disease reports: in its report to the Office International des Epizooties (an international body responsible for fighting infectious diseases), China reported that 519 individuals of 5 species (bar-headed goose (Anser indicus), great black-headed gull (Larus ichthyaetus), brown-headed gull (Larus brunnicephalus), ruddy shelduck (Tadorna ferruginea) and great cormorant (Phalacrocorax carbo)) were found dead at Qinghai Lake Nature Reserve. Although H5N1 avian influenza was initially ruled out as the cause of death, it has subsequently been identified at the site. All these birds are migratory.

- Control measures: There are reports that China has closed all nature preserves to visitors, including Qinqhai NP. Three million doses of vaccine have been shipped to the province, presumably to vaccinate poultry in the area. Further, special clinics have been set up to screen humans with fevers or pneumonia for influenza infection.

Critical information that we don't know:

- We don't actually know what killed these birds. Apparently as many as 100,000 birds congregate on this lake, and so 500 dead birds may not be unusual, and it is possible that avian influenza was isolated from birds that died of something else. Cause-of-death determinations may have been done, but those data are not publicly available presently. If they were not done, it may be too late to determine cause-of-death in this case, but such determinations are a
critical part of any disease outbreak.

- We don't know how many of these 519 birds actually had avian influenza. In some die-offs, detailed investigation is done on a few animals, and then the results of those investigations are extrapolated to the rest of the dead animals.

- We don't know if the virus isolated from these birds is related to
the virus circulating in Southeast Asia. The isolate should be sequenced and the sequence deposited at GENBANK so that comparisons can be made.

- We don't know how or where these birds got infected. H5N1 avian influenza is known to be circulating in domestic poultry in Southeast Asia, but very few wild birds have been found with the virus there. It is possible that one of these five bird species (or one of the many other species that congregate there) brought the virus to the preserve from Southeast Asia. Alternatively, it is also possible that there is an unreported outbreak of H5N1 in domestic poultry in central China from which the wild birds picked up the virus. Transparent reporting
from China on the disease status of their domestic poultry is necessary.

- In the region, there are unsubstantiated reports of human deaths due to an unknown cause. Some bloggers have speculated that these are human cases of influenza, but at this point there is no evidence for or against this theory. The Chinese government is saying there are no
human cases. Again, transparent reporting is necessary.

Why is this a conservation issue?
Avian influenza forms a threat to wild bird conservation on several fronts. First, although most strains of avian influenza relatively benign, H5N1 appears to be able to cause illness and death in wild birds. Second, there may be calls for culling of wild birds to try to control or limit the spread of H5N1, although it is recognized in the wildlife health community that culling of wild birds is not an effective control measure, and that there is no evidence that wild birds play a major role in influenza epidemiology.

The most effective way to prevent transmission of avian influenza between domestic poultry and wild birds is to improve biosecurity around poultry farms. The key goal of improved biosecurity would be to reduce or prevent contact between wild birds and domestic poultry
and their wastes.

H5N1 in Qinghai China Imported from India?

Recombinomics: H5N1 in Qinghai China Imported from India?: "H5N1 in Qinghai China Imported from India?"

Henry Niman's blog on avian influenza is worth a daily read, although he tends towards the paranoic side. Although the blog is full of very good scientific information, I find that he tends to find avian influenza in every nook and cranny, with sometimes only the sketchiest of evidence. For example, India's reported serological evidence of H5N1 exposure in three poultry workers (here and here) , combined with reports of meningitis, immediately leads these Dr. Niman to link disparate stories together.

I'm not saying that migratory geese couldn't have brought H5N1 to Qinghai, but given that they migrate from India, and we have only reports of serological exposure in three poultry workers there from 2002, and no reports of poultry dying, it seems unlikely. Even if unlikely, it is also premature to make conclusions based on limited evidence.

We need genetic typing of the Qinghai H5N1 strain to determine the relatedness to the outbreak in SE Asia. We need to find out if the birds that died at Qinghai actually died of avian influenza using normal pathological methods.

Ultimately, we need more research on the potential role of wild birds in avian influenza epidemiology. This research is necessary to improve biosecurity on all fronts - to protect human, livestock, and wildlife health.

Reuters AlertNet - Philippines culls 500 parrots on bird-flu fears

Reuters AlertNet - Philippines culls 500 parrots on bird-flu fears: "GENERAL SANTOS, Philippines, May 24 (Reuters) - The Philippines culled about 500 parrots imported from Indonesia as part of efforts to prevent the spread of the bird-flu virus from other Southeast Asian countries, officials said on Tuesday."

This story has little information, providing only the following,
- 500 "parrots" were confiscated at the Indonesian border by the Philippine government
- the parrots were held in 14 cages
- the parrots were destined for Europe

It would be interesting to know which species of parrot were confiscated, and if they were actually tested for bird flu. I was only able to find previous reports of H7N1 (not H5N1) in parrots, but that doesn't mean that it couldn't happen.

This is a classic wildlife trade/disease story: 500 parrots, possibly from an avian flu outbreak area, packed into 14 cages, smuggled to Philippines en route to Europe, reminiscent of a recent story. Not sure if there was a bullet to be dodged this time though ...

After Its Epidemic Arrival, SARS Vanishes - New York Times

After Its Epidemic Arrival, SARS Vanishes - New York Times: "Scientists agree that SARS jumped from animals to humans, probably in wildlife markets in the region around Guangzhou, where workers live near the animals they slaughter and sell."

This article highlights the role of the wildlife trade in disease emergence. I would hypothesize that events like SARS emergence will continue happen. Although SARS itself seems to have been controlled, the conditions that led to its emergence still exist, and not just in Asia but globally. Emergence of many of the infectious diseases that have become important in the last century was facilitated by the local, regional, and international trade and consumption in wildlife: HIV/AIDS, Ebola, Marburg, SARS, avian influenza ... and the list goes on. And the scary thing is that there are many other viruses out there that could potentially cross the species barrier into humans. For example, from Peeters et al. (2002) : "These data document for the first time that a substantial proportion of wild monkeys in Cameroon are SIV infected and that humans who hunt and handle bushmeat are exposed to a plethora of genetically highly divergent viruses.". SIV is a closely related virus to HIV that affects primates.

The wildlife trade has long been known to be one of the major threats to biodiversity, but thanks to our increasing ability to get things around the planet very quickly, the international wildlife trade forms a major threat to human health. If conservation doesn't get governments to notice, maybe the threat of another SARS epidemic will.

Re: H5N1 in India

The report is that samples from three poultry workers from 2002 are
"positive" for H5N1, apparently confirmed by the CDC. I'd hold off
judgement just yet as we have yet to see any confirmation from the
CDC. I'm surprised the ProMED moderators took it so seriously at this
stage. Furthermore, no birds are reported to have gotten sick, and
nor have the three poultry workers, so even if it was H5N1, it clearly
wasn't a highly pathogenic form of the virus. This is yet to become a
real story (not to say it won't though).

Damien

CWD in NYS captive deer - slide show

The NY State Department of Environmental Conservation must have had a public meeting last night. They have some new powerpoint slides in pdf form on their web site, and one in particular (called "CWD
Discussion") has some interesting info on movement of deer in and out of the first affected farm.

Although it isn't yet clear how CWD was introduced to the farm. Most deer came from the wild as rehabbed deer, although deer were also brought in from other farms. Regardless of how it got there, the relatively high prevalence on the farm (4/19 or 21%) combined with the high numbers of deer moved off the farm into the wild (over 30 deer since 1997), there was certainly potential for spread of CWD into the wild.

Damien
--

Free-living Canada Geese and Antimicrobial Resistance

A paper to be published in the June issue of the CDC journal Emerging Infectious Diseases shows evidence that free-ranging geese can pick up antibiotic resistant strains of E. coli (in this case likely from a swine production facility) and potentially spread the pathogen into new areas (Free-living Canada Geese and Antimicrobial Resistance | CDC EID).

While this paper is yet another example of "spill-over" of pathogens from domestic animals to wildlife, I am somewhat disappointed the authors chose to emphasize that geese are potential vectors of zoonotic pathogens (and antibiotic resistant pathogens at that). Once again, wildlife that are passive recipients of livestock-originated bacteria become the "bad guy" (in my son's vernacular). Do a quick Google news search to see how this issue is being portrayed in the media.

In my humble opinion, this was an opportunity to emphasize the connectedness between livestock and wildlife health, and perhaps provide impetus to take measures to reduce transmission of bacteria and viruses from livestock to wildlife. Once a livestock disease spills over into wildlife populations, it is difficult or impossible to contain. Take bovine tuberculosis for example. Spread the world over by cattle, it has jumped into wildlife populations at locales in the UK, Australia, USA, South Africa, Tanzania, New Zealand, Canada among others. While we are making great progress reducing bovine tuberculosis in domestic cattle populations, the risk of spill-back from wildlife into livestock becomes more and more important and may prevent TB eradication in domestic livestock. I realize this isn't really a fair comparison as much of the transmission to wildlife occured a long time ago, the issue really demonstrates how difficult it is to get Pandora's box closed again.