Last week, a child in the Bay Area also tested positive for bird flu without any known exposures.
This week in California, bird flu was also detected in raw milk that was being sold in stores, another first.
Though the risk level of contracting bird flu from drinking milk is unknown, it has been shown to transmit the virus to cats and other animals.
Although the majority of cases in humans have been mild, bird flu historically has a far higher case-fatality rate than the current outbreak.
Last week, bird flu was reported in Hawaii and continued to spread in other countries in Europe like the Netherlands.
Concerns have been raised that the H5N1 virus that causes bird flu is getting closer to changing in a way that would allow it to spread between people after two separate cases were found this month in North American children who had no known contact with infected animals.
Out of the 55 human cases of H5N1 that have been reported since April, all but three have involved farmworkers who have had close contact with dairy cows or poultry, which are being infected by the virus in large numbers. However, three cases in humans have not been traced back to their origin, prompting concerns about whether low-level community spread is taking place.
On Nov. 9. British Columbian authorities announced that a teenager who had no known contact with an infected animal had tested positive for H5N1. A child in the Bay Area tested positive for bird flu last week as well, despite having no known exposures. These two cases come after a third infection in Missouri was reported in September, for which, despite a thorough investigation, health officials were unable to identify the infection’s source.
Stanford University infectious disease specialist Dr. Dot Abraar Karan stated, “The main conclusion is that there is more community spread than is being detected.”. Many red flags are raised when the source of the infection cannot be determined. “”.
Avian influenza A H5N1 viruses (shown in gold) cultivated in MDCK cells (shown in green) are shown in this colorized transmission electron micrograph. (Gado/Getty Images/Smith Collection) In the absence of farm animal exposure, these kids might have contracted the virus by interacting with a virus-carrying wild bird. They might have contracted the virus from a domesticated animal they came into contact with, which is another possibility. However, Bonnie Henry, a public health officer for the province of British Columbia in Victoria, Canada, stated at a press conference that in the case of the Canadian teen, every pet they interacted with tested negative.
Henry stated, “There is a very real possibility that we may not ever determine the source.”.
During a separate press conference today, Henry stated that the teen’s case was a “rare” occurrence and that, following a 10-day incubation period, all of the teen’s close contacts or medical professionals tested negative.
Henry stated, “We have not observed any other transmission, so even if there was a mutation in the young person in the virus here, right now, that would have died off.”. That is comforting, but it only serves to remind us that the influenza virus is subject to sudden changes, so we must remain vigilant. “.”.
“The number and variety of people infected by this virus appear to be rising. “.”.
Although the H5N1 virus has not demonstrated the capacity to spread from person to person, each time it infects a human or a mammal, such as a cow or pig, it increases the likelihood that it will evolve to become more transmissible between humans, potentially leading to a pandemic similar to COVID-19. In an organism infected with both the seasonal flu and bird flu, a process known as viral reassortment may cause genes to swap and mutate, making this a particular concern during the regular influenza season.
In a phone interview with Salon, Karan stated, “It is never easy to determine precisely which set of mutations are needed to cause [human-to-human transmission].”. There are mutations that improve the virus’s ability to locate and enter cells, that enable specific enzymes to replicate the virus more efficiently and aid in its spread, that can make the virus more stable in aerosols, and more. In general, it takes a combination of mutations to have a virus that spreads between people effectively. “”.
According to Jennifer Nuzzo, an epidemiologist and director of the Pandemic Center at Brown University School of Public Health, the world will experience another pandemic if the H5N1 virus gains the capacity to spread effectively between people.
In a phone interview with Salon, Nuzzo stated, “The general trend is that this virus is really expanding its geographic distribution, the number of animal species it is infecting, and the number and types of humans it is infecting seem to be increasing.”.
The rate of H5N1 transmission in cows is unprecedented. According to the Centers for Disease Control and Prevention (CDC), as of this writing, approximately 600 dairy herds had been infected in 15 states, and over 100 million poultry had been affected in 49 states. Bird flu was discovered in raw milk sold in stores this week in California, marking yet another first. It is unknown how likely it is that drinking milk will expose you to bird flu, but it has been demonstrated that milk can spread the virus to cats and other animals. Pigs are referred to as “mixing vessels” because they can contract both human and avian pathogens, which increases the likelihood of viral reassortment. Because of this, the virus was also found in pigs for the first time, which is especially concerning.
Multiple reassortment events in pigs and birds produced the novel H1N1 virus strain during the 2009 swine flu pandemic, resulting in 12,000 fatalities and 60 million cases in the United States. S. The CDC states that it is in its first year of circulation.
The current outbreak has a far higher case-fatality rate than bird flu historically, despite the fact that most human cases have been mild. This is partially due to the fact that the majority of cases in the U.S. prior to this outbreak were brought on by a virus that primarily affects birds. S. The type that primarily affects cows is the one that has caused the current outbreak.
Nevertheless, the Canadian teenager had a severe viral reaction and was admitted to the hospital in critical condition. According to viral genome sequences, the teen contracted the sort of bird flu that usually infects birds. This particular strain of the virus may have undergone a mutation that improved its capacity to adhere to the human respiratory system. The fact that the teen first had an eye infection and then a lung infection, however, may indicate that the virus changed after infecting the young person.
Hensley says, “It supports the theory that the virus may have developed inside that person.”.
Because of their severity, cases like the one in Canada are likely to be detected by surveillance systems. According to Dr. Erin Sorrell, a virologist at the Johns Hopkins Center for Health Security, milder disease is undoubtedly better for human health, but it also makes it more difficult to identify community spread. Seven percent of farmworkers in one CDC study had antibodies that indicated they had previously contracted bird flu, which is significantly higher than the percentage of cases that were actually reported.
“The virus has been able to essentially sustain itself undetected because it is presenting in a mild fashion and initially came out in a very vulnerable population that did not have access to care,” Sorrel told Salon over the phone.
The rest of the world is anxiously observing as the U. S. . responds to bird flu, and the country has come under fire from some quarters for failing to eradicate the virus in cattle or birds before expanding its human infection. As of this writing, over 10,000 wild birds have been found to have bird flu, which is alarming because many of these species are still migrating to other regions of the world. Bird flu was reported in Hawaii last week and is still spreading throughout Europe, including the Netherlands.
Dr. Michael Osterholm, an epidemiologist and director of the Center for Infectious Disease Research and Policy at the University of Minnesota, expressed his deep concern that the USDA investigation and the measures implemented to curb transmission are currently obviously failing. This presents a significant obstacle. “.”.
If the cases in California and Canada were “one-offs,” as was the case in Missouri, only time will tell. However, that appears to be decreasing in likelihood with every new human case that is not connected to farm animals.
This virus is still spreading, popping up across the nation and across the Canadian border, and I believe this indicates that the United States will face a long-term threat. S. public health and agriculture,” Nuzzo stated. “The virus will continue to spread because we are not taking any action to stop it. “”.
