New preliminary evidence suggests coronavirus jumped from animals to humans multiple times


Hamish McCallum, Griffith UniversityThe origin of the SARS-CoV-2 virus, which has caused the COVID-19 pandemic, has been hotly debated.

This debate has caused substantial difficulties in the Australia-China relationship, with a call by Foreign Minister Marise Payne for another inquiry into its origin being considered by China as a hostile act.

What’s not in doubt is the closest relatives of the virus are found in bats. How, where and when the virus spilled over into humans is the contentious issue.

One widely supported hypothesis is the spillover occurred in the “wet markets” of Wuhan, where many species of wildlife from across China are held in crowded conditions.

However, there’s no evidence the species of bats in which the closest relatives of SARS-CoV-2 are found were sold through the Wuhan wet markets at any time in the two years before the pandemic. This hypothesis requires the existence of a “bridge host”, another species that becomes infected via spillover from the original bat hosts, and then passes the virus onto humans.

Bridge hosts are well-known in many emerging human diseases. For example, Hendra virus, which my group studies, has flying foxes as its reservoir. Hendra spills over to horses with some frequency. Horses then amplify the virus as a bridge host and can infect humans.

Fortunately, this is extremely rare, with only seven known cases. Tragically, four of those people died. Hendra has never been known to spread directly from flying foxes to humans.




Read more:
I was the Australian doctor on the WHO’s COVID-19 mission to China. Here’s what we found about the origins of the coronavirus


More evidence a lab leak is very unlikely

A second, much more contentious hypothesis is the origin of the pandemic was the result of a “lab leak”.

Wuhan has one of the most sophisticated virological laboratories in China, and the laboratory does work on bat viruses. The suggestion is the virus may have inadvertently been released into the general community via one of the workers. No direct evidence supports this hypothesis.

A new pre-print study, released online this month, provides strong evidence to support the “natural spillover” hypothesis, with results that are hard to reconcile with the “lab leak” hypothesis.

The study is yet to be peer reviewed. But it’s based on a detailed examination of the genetic sequences of two early lineages obtained from people infected in late 2019 and early 2020.

For convenience, these two lineages are called A and B. The two lineages differ by just two nucleotides (letters in the genetic code) at two different key sites in the genetic sequence.

If there was a single lab escape event, the separation into lineages A and B must have happened after the lab escape. We would therefore expect to see a substantial number of intermediate lineages, with the lineage A nucleotide at one site, and the lineage B nucleotide at the other site.

However, if almost all of the genetic sequences obtained from humans are “pure” lineage A or pure lineage B, this suggests there were at least two different spillover events, either directly from bats or via bridge hosts.

And the evolution of the two lineages occurred before humans were infected.

The researchers downloaded all complete genetic sequences for SARS-CoV-2 that had been lodged in a widely used genomic database. Of these sequences, 369 were lineage A, 1,297 were lineage B and just 38 were intermediates.




Read more:
Why it will soon be too late to find out where the COVID-19 virus originated


Genetic sequencing isn’t perfect. Close examination of the 38 intermediates strongly suggested they were more likely to be sequencing errors of pure lineage A or lineage B than to be true intermediates.

The genetic evidence, therefore, suggests very strongly there have been at least two separate spillover events into human populations, one being from lineage A and another being from lineage B.

Did a human bring SARS-CoV-2 to the wet markets?

The data don’t tell us there have been only two spillover events — there may have been more. Nor do they tell us whether these spillovers happened directly from bats, or whether some or all happened via an intermediate bridge host.

A Nature news article suggests this evidence points to the spillover having happened via the wildlife trade, but I think this is taking it a step too far.

While some of the wildlife species sold through the Wuhan wet market can indeed become infected with SARS-CoV-2 (for example raccoon dogs and mink), there’s no evidence any sold through the market were infected.

Many of the earliest human viral sequences (all lineage B) were recovered from the Wuhan seafood market, but wet markets and abattoirs are well-known to be places where the SARS-CoV-2 virus spreads very well from human to human.

So, it may have been a human who brought the virus to the Wuhan seafood market, rather than a species of wildlife.

One thing we do know is this pandemic originated through a human coming in contact with another species infected with the virus.

It’s unknown whether this was a bat or a bridge host, and whether this contact occurred in a wildlife market, or in a bat cave, or somewhere else entirely different.

Nevertheless, as humans encroach more and more on the habitats of wild animals and as wild animals are brought more frequently into close contact with humans, we can expect further spillovers and pandemics to occur.




Read more:
How do viruses mutate and jump species? And why are ‘spillovers’ becoming more common?


The Conversation


Hamish McCallum, Director, Centre for Planetary Health and Food Security, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

World Animal Day: October 4


October 4 is World Animal Day. Find out more at:

http://www.worldanimalday.org.uk/index.asp

http://www.prnewswire.com/news-releases/october-4-is-world-animal-day-october-is-world-animal-month-celebrate-species-around-the-world-with-rare-conservation–103126274.html

What is happening in Australia? Visit:

http://www.worldanimalday.org.uk/2010_events.asp?region=Australia+%26+New+Zealand

JAWS: Massive Shark Lurks of Australia


Evidence has emerged of a massive shark lurking in the waters off Queensland, Australia. The footage below tells the story:

AUSTRALIA: BUSHFIRES AND FLOODS


Australia is a land of extremes. We have bushfires still burning out of control in Victoria and floods across the country in Queensland, New South Wales, the Northern Territory, South Australia and now in Western Australia as well. Somewhere between 15 and 20 percent of Australia is flood affected, while something like 50 percent of the country is still stricken by drought. Some areas have now been in drought for 11 or 12 years.

Flood waters are now beginning to recede across most of the country; however there is still plenty of rain about – especially in Queensland where an active monsoonal trough is still dumping rain on Queensland.

In Queensland authorities have captured the crocodile that took a 5 year old boy in flood waters. The boy’s remains were found inside of the crocodile. The crocodile is not going to be released back into the wild and will probably be sent to a crocodile farm.

The death toll in Victoria’s bushfire disaster now stands at 209, including a fire-fighter who was killed by a falling tree damaged by the fires. The fire-fighter was from interstate and had gone to Victoria to assist in the crisis. He was due to go home the next day.

The police have stated that the death toll is no longer expected to climb much further than 209.

The official damage bill for in the bushfire areas of Victoria is fast approaching $1 billion Australian dollars and is expected to go beyond that.

Police have now arrested a woman who claimed her father was killed in the bushfires after it was discovered she was not related to the man she claimed was her father. The woman was trying to obtain $10 000 in bushfire relief money.

BELOW: Dramatic video footage as a bushfire approaches a house at Anglesea in the early hours of the morning of the 14th February 2009.

AUSTRALIA: BUSHFIRES UPDATE – Saturday 14th February 2009


As Victorians brace themselves for hotter weather this weekend and the possible return to ‘fire weather,’ there are still some 15 major bushfires burning, a further 18 fires burning out of control and about 100 fires considered under control. Each day there are new fires and new threats, though these are not viewed with the same level of concern as the fires last Saturday and Sunday. However, as the weather conditions begin to turn more towards ‘fire weather’ status, each fire will be viewed with increasing concern. Should conditions deteriorate no further, fire-fighters can expect to be fighting these fires for a further 2 to 3 weeks.

Fire-fighters from Canada, New Zealand and the United States have now joined the thousands of Australian fire-fighters in the fight against these bushfires. Though Australia has some of the best-trained and prepared fire-fighters in the world, every bit of help that can be given is appreciated and required.

Authorities are facing growing problems associated with the bushfires and relief efforts, with rubber-neckers (sightseers), looters, arsonists and fraudsters preying on victims and the generosity of most Australians who are doing what they can for the victims. Collection tins have been robbed by a bloke without compassion (captured on security footage as seen below) and one fire-ravaged town has posted signs throughout their community warning that looters will be shot on sight. Another town is issuing citizens special stickers for their cars so locals will know who should be there and who shouldn’t be. It is a tragedy that grows worse by the day, in more ways than one.

1831 homes have now been confirmed destroyed in the bushfire emergency, along with numerous other structures including 2 police stations, three schools, a water treatment plant, a timber mill, a football club, a kindergarten, a church, etc. The damage bill will be enormous.

The death toll currently stands at 181 confirmed dead with many still missing. The death toll will reach 200 plus (possible 300). 7000 people are now homeless. 4 300 further homes remain without power.

ABOVE: Images of Fire Victims

420 000 hectares of bushland, farmland and communities have been reduced to ash by the fires. It is thought that there may be as many as 1 million animal victims of the bushfires.

 

ABOVE: Animal Victims of the Fires

With arsonists being blamed for a number of fires, one fire near Murrindindi is being blamed on a careless person who threw a cigarette from a car window. A farmer says he saw the fire begin on the side of the road near Murrindindi Mill. This fire merged with the Kilmore fire and destroyed Kinglake and Marysville.

ABOVE: Arsonist Arrested

AUSTRALIA: THE NORTH MARINE REGION


Peter Garrett, Australia’s Minister for the Environment, Heritage and the Arts, today released a report on the biodiversity, ecosystems and social and economic uses of the oceans of northern Australia. The report entitled ‘The North Marine Bioregional Profile,’ brings together and explores the available knowledge of the Arafura and eastern Timor Seas, from the Northern Territory/Western Australia border to Torres Strait, including the Gulf of Carpentaria.

The report is expected to assist the government to better understand and protect our marine environment, conserve biodiversity and determine the priorities in our marine conservation efforts. It will also assist industry to better plan and manage their activities in the region.

A Marine Bioregional Plan for the region covered in the report is expected to be handed down in 2010. In total there will be five plans covering Australia’s marine regions.

View The North Marine Bioregional Profile at:
http://www.environment.gov.au/coasts/mbp/north/index.html

RARE BONGO BREEDING PROGRAM GOING WELL


A breeding program for the rare Lowland or Western Bongo (Tragelaphus eurycerus eurycerus) is going well at Australia’s Western Plains Zoo. One month ago a calf (called Djembe, which means drum) was born at the zoo and is doing well. Djembe is the fourth calf born at the zoo.

The calf was born using caesarean section because of difficulties with the birth. Despite fears of the mother rejecting Djembe, which sometimes happens with caesarean births, young Djembe is going well and being cared for by her mother.

The Lowland Bongo is one of the largest African forest antelopes and is in serious decline. It is thought that about 25 000 animals remain in their natural central African habitat.

BELOW: Footage of a Bongo in Captivity