Officials have ruled out the prime suspect in the mystery over how a herd of Alberta pigs was infected with the new swine flu virus sweeping the globe.
A spokesperson for Alberta Health and Wellness says blood tests have shown that a carpenter who worked for half a day on the farm before heading home with flu-like illness did not introduce the virus to the herd.
“We’ve determined it wasn’t the carpenter,” says spokesperson Howard May.
The workman, Adrian Blaak, declined to be interviewed about the findings. Previously he’d said he did not believe he had infected the pigs, which were raised on a farm near Rocky Mountain House.
Blaak had just returned from a trip to Mexico when he went to do a job at the farm on April 14. At that point the new H1N1 virus was already circulating in parts of the Mexico, but the world was not yet aware a new flu virus was on the move.
The World Health Organization declared Thursday that the new virus has triggered a pandemic, the first in 41 years.
May says provincial health officials are starting to believe they may never find out how the virus made its way into the herd, the only pigs anywhere in the world to have tested positive for the new virus to this point.
“Since serological (blood) tests indicated the carpenter had not had H1N1, someone else must have brought it in, but it is unlikely we will ever be able to pinpoint exactly who,” says May.
Officials had earlier said several members of the family that owned the farm were sick a couple of days before Blaak worked there briefly.
Others fell ill after the pigs started to display signs of being sick, leading authorities to suggest the virus may have gone from a person to pigs and back to people. Nasal swabs taken from people on the farm tested negative, but blood samples were taken to look for antibodies to the virus.
Whether that work is completed and what the tests showed if it is hasn’t been made public.
Recently the farmer who owned the herd announced he had destroyed his pigs, because he could not sell the animals. The farm had been under quarantine since late April, when the outbreak first came to the attention of the Canadian Food Inspection Agency.
Sporadic tests continued to find evidence of possible ongoing circulation of virus in the herd, says Dr. Jim Clark, the national manager for disease control for CFIA’s animal health division.
Over the course of the weeks of quarantine, testing found diminishing but still present viral DNA, which may or may not have meant infectious viruses were still spreading among the pigs, Clark says.
He says the CFIA’s lab in Winnipeg was only able to isolate live viruses from the pigs when they were sampled at the beginning of the investigation. Genetic sequencing of those viruses showed they are virtually identical to the swine flu viruses circulating in humans.
Clark says CFIA would like to be able to determine how the pigs got infected. But he says the agency isn’t getting much co-operation from human health counterparts responsible for testing the people involved.
“So far we haven’t been able to get a whole lot of information from them,” he says, adding that while he’s not sure why that is, privacy concerns may play a role.
“There’s a need to know from a scientific perspective, to try and I guess to get a complete understanding of the epidemiology behind this, but at the same time not wanting to put this (farm) family under any more duress than they’ve already suffered.”
Clark says he expects there will be other opportunities to learn about how this virus behaves when it gets into pig populations. With continued spread around the world, he suggests, “it’s invariably going to result in the exposure of pigs in other countries and in other places.”
But whether farmers will admit to it is another issue. The family who owned the Alberta herd has reportedly paid a heavy price, financially and personally. Pork sales are down, even though health officials have repeatedly stressed people can’t get swine flu from eating pork.
Though the CFIA has asked swine producers and veterinarians to be on the lookout for possible infection in herds and to submit any unusual flu viruses for further testing, “very little” is coming forward, Clark admits.
“As soon as there’s a disease outbreak, everybody gets real nervous about what might be happening,” he says.
The lengthy quarantining of the Alberta farm — and the unfortunate outcome — may discourage farmers from reporting flu-like symptoms in their pigs. There are a variety of influenza virus subtypes that infect pigs and outbreaks, while common, are not a long-term threat to the health of pigs.
“I think right now the production community is looking and saying ‘OK, when you can tell us what you specifically want to do about the situation, then we might be in a situation to want to submit samples to find out what’s going on,”’ says Clark, who admits he has some sympathy for that position.
“From a purely scientific perspective, I’d love all the samples in the world to be coming in and get as much background information as we can about where this virus may currently be occurring anywhere in the swine population,” he says.
”On the practical side, without having a clearly defined policy that is able to get us out of the situation as quickly as possible and define all the risk factors, I’m saying ‘Well, maybe I don’t really want to know about too many things that are going on right now until we can get more definitive information about what we need to be concerned about.”’