Friday, May 16, 2003
CANADIAN RESEARCHERS SAY THEIR
RESEARCH RULES OUT CHICKEN AND PIGS
AS SARS RESERVOIRS.
BUT IS THEIR WORK RELIABLE?
In Today's Washington Post, Rob Stein reports on some conclusions by Canadian researchers about their ability to infect chickens and pigs with the SARS-related coronavirus. According to Stein, "In yet another finding, scientists in Canada said a series of experiments has shown that pigs and chickens cannot be infected with the SARS virus. That indicates the animals were probably not the original source of the virus and would not provide a "reservoir" in which the virus could hide and reemerge if public health measures succeed in stamping out the epidemic in humans . . .Chickens and pigs were considered the most likely animals to play a role in the epidemic. Both species can be infected by related viruses, and people live in close proximity to both species in southern China, where the epidemic began."
A World Health Organization SARS researcher, Dr. Kaus Stohr, told Epstein "We were all speculating about animal reservoirs. These tests show that these animals, pigs and chickens, do not appear to play a role in any stage of the evolution of this virus. The virus does not like them. That makes them a very inefficient host for the virus."
Until we see the published research (if it is ever published) there is no way to judge the quality of the research. It would be tragic if Chinese researchers didn't at least look for the SARS-relarted coronavirus in pigs in the SARS-affected areas of China. We'd love to know what porcine cell lines the Canadian researchers tried to grow the SARS-related coronavirus in. Did they try and infect live pigs? If they didn't do all of the above, we still don't know if pigs can be ruled out in this epidemic. No role in any stage of the evolution of the SARS-related coronavirus? That's awfully strong. Stay tuned.
P.S. What is an "inefficient host"? Is that a host that is just a little bit pregnant? Why didn't Stohr just say chickens and pigs are not hosts for this virus, period?
RESEARCH RULES OUT CHICKEN AND PIGS
AS SARS RESERVOIRS.
BUT IS THEIR WORK RELIABLE?
In Today's Washington Post, Rob Stein reports on some conclusions by Canadian researchers about their ability to infect chickens and pigs with the SARS-related coronavirus. According to Stein, "In yet another finding, scientists in Canada said a series of experiments has shown that pigs and chickens cannot be infected with the SARS virus. That indicates the animals were probably not the original source of the virus and would not provide a "reservoir" in which the virus could hide and reemerge if public health measures succeed in stamping out the epidemic in humans . . .Chickens and pigs were considered the most likely animals to play a role in the epidemic. Both species can be infected by related viruses, and people live in close proximity to both species in southern China, where the epidemic began."
A World Health Organization SARS researcher, Dr. Kaus Stohr, told Epstein "We were all speculating about animal reservoirs. These tests show that these animals, pigs and chickens, do not appear to play a role in any stage of the evolution of this virus. The virus does not like them. That makes them a very inefficient host for the virus."
Until we see the published research (if it is ever published) there is no way to judge the quality of the research. It would be tragic if Chinese researchers didn't at least look for the SARS-relarted coronavirus in pigs in the SARS-affected areas of China. We'd love to know what porcine cell lines the Canadian researchers tried to grow the SARS-related coronavirus in. Did they try and infect live pigs? If they didn't do all of the above, we still don't know if pigs can be ruled out in this epidemic. No role in any stage of the evolution of the SARS-related coronavirus? That's awfully strong. Stay tuned.
P.S. What is an "inefficient host"? Is that a host that is just a little bit pregnant? Why didn't Stohr just say chickens and pigs are not hosts for this virus, period?
Wednesday, May 14, 2003
WHERE DID SARS COME FROM?
PIGS INCREASINGLY LOOK LIKE
THE PRIME SUSPECTS
On May 1, Science published the genome analysis of the SARS-associated coronavirus. The abstract noted a moderate similarity to a human coronavirus labeled "HCoV-OC43." That corononavirus has an interesting track record."HCoV-OC43" is the coronavirus that Japanese researchers found in pigs in a study that indicated that coronaviruses pass back and forth promiscuously between people and pigs. This certainly increased the possibility that the SARS coronavirus is circulating in pigs in China and also the possibility that it could move from people to pigs in countries where only the people are infected. The fact that we don't have conclusive evidence on this matter is very odd, and the reason for that is probably very political. Until someone does some trustworthy research, it is not out of the realm of possibility that SARS is in the food supply in China, given the early high incidence of SARS in foodhandlers there. There still is a great deal of confusion about how SARS is being transmitted there and in Taiwan, which also has a high pig population and a great deal of pork consumption.
On May 13, Maggie Fox of Reuters reported on a possible German SARS breakthrough that again brought pigs into the picture. According to Fox, researchers in Germany said that "they had found a weakness in the SARS virus and that a drug being tested against the common cold could be modified to battle the deadly illness."
The weakness involved a protease (an enzyme necessary for viral replication) that resembles the protease on a pathological coronavirus that infects pigs. The finding seems to only increase the probability that the SARS-related coronavirus can infect pigs.
Where the pig-SARS connection is concerned, the real smoking gun may have appeared in an anecdote in a story published yesterday. Gady A. Epstein, of the Baltimore Sun Foreign Staff, wrote a fascinating story about a farmer in the Chinese area where SARS is thought to have originated. Epstein found a farm where what sounds like SARS-like epidemic in pigs may have occurred. Epstein interviewed a woman named Zheng Haocai who lives with her husband on a farm south of Guangzhou. Her shack of a farmhouse is "cobbled together out of aluminum, lumber, tarpaper and plastic sheeting." According to Epstein, "Zheng is unable to afford feed for her pigs, so they eat factory and restaurant garbage, served out of blue plastic barrels of unidentifiable dark sludge that she buys for $2.50 a barrel."
In what could turn out to be the most important reporting on SARS to date, Epstein writes that "at feeding time, her chickens join the feast, pecking near the porkers and, in the end stall, among a handful of pigs set apart from the others. This small group, Zheng said, had recovered from a strange virus that struck dozens of her pigs with flu and diarrhea a few months ago." And Epstein reports that the woman said, "This year we've had a lot of pigs get sick, and even when I give them medicine, they don't get better."
Epstein also reported that "a few feet from the pen lies an open box filled with empty syringes, used medicine bottles and torn packets of fever remedies that Zheng used with little success. Out of a group of 80 pigs she bought this year, she said, half died." Epstein reported that the woman said, "They got fever and didn't want to eat."
Hopefully, somebody at the CDC and WHO will read Epstein's story.
PIGS INCREASINGLY LOOK LIKE
THE PRIME SUSPECTS
On May 1, Science published the genome analysis of the SARS-associated coronavirus. The abstract noted a moderate similarity to a human coronavirus labeled "HCoV-OC43." That corononavirus has an interesting track record."HCoV-OC43" is the coronavirus that Japanese researchers found in pigs in a study that indicated that coronaviruses pass back and forth promiscuously between people and pigs. This certainly increased the possibility that the SARS coronavirus is circulating in pigs in China and also the possibility that it could move from people to pigs in countries where only the people are infected. The fact that we don't have conclusive evidence on this matter is very odd, and the reason for that is probably very political. Until someone does some trustworthy research, it is not out of the realm of possibility that SARS is in the food supply in China, given the early high incidence of SARS in foodhandlers there. There still is a great deal of confusion about how SARS is being transmitted there and in Taiwan, which also has a high pig population and a great deal of pork consumption.
On May 13, Maggie Fox of Reuters reported on a possible German SARS breakthrough that again brought pigs into the picture. According to Fox, researchers in Germany said that "they had found a weakness in the SARS virus and that a drug being tested against the common cold could be modified to battle the deadly illness."
The weakness involved a protease (an enzyme necessary for viral replication) that resembles the protease on a pathological coronavirus that infects pigs. The finding seems to only increase the probability that the SARS-related coronavirus can infect pigs.
Where the pig-SARS connection is concerned, the real smoking gun may have appeared in an anecdote in a story published yesterday. Gady A. Epstein, of the Baltimore Sun Foreign Staff, wrote a fascinating story about a farmer in the Chinese area where SARS is thought to have originated. Epstein found a farm where what sounds like SARS-like epidemic in pigs may have occurred. Epstein interviewed a woman named Zheng Haocai who lives with her husband on a farm south of Guangzhou. Her shack of a farmhouse is "cobbled together out of aluminum, lumber, tarpaper and plastic sheeting." According to Epstein, "Zheng is unable to afford feed for her pigs, so they eat factory and restaurant garbage, served out of blue plastic barrels of unidentifiable dark sludge that she buys for $2.50 a barrel."
In what could turn out to be the most important reporting on SARS to date, Epstein writes that "at feeding time, her chickens join the feast, pecking near the porkers and, in the end stall, among a handful of pigs set apart from the others. This small group, Zheng said, had recovered from a strange virus that struck dozens of her pigs with flu and diarrhea a few months ago." And Epstein reports that the woman said, "This year we've had a lot of pigs get sick, and even when I give them medicine, they don't get better."
Epstein also reported that "a few feet from the pen lies an open box filled with empty syringes, used medicine bottles and torn packets of fever remedies that Zheng used with little success. Out of a group of 80 pigs she bought this year, she said, half died." Epstein reported that the woman said, "They got fever and didn't want to eat."
Hopefully, somebody at the CDC and WHO will read Epstein's story.
