The CDC suggests that hospitals treating patients for flu symptoms perform clinical laboratory tests for avian influenza A within 24 hours. This additional testing will pinpoint the specific type of flu infecting an individual patient and help prevent further spread of the bird flu virus.
“It’s the subtyping that takes us from knowing that a virus is in the general bucket of ‘influenza A’ to knowing more specifically whether it’s a garden-variety seasonal version of influenza A or, more rarely, a novel version of influenza A like H5N1,” CDC Principal Deputy Director Nirav Shah, MD, JD, told CNN.
According to the CDC, a panzootic of pathogenic avian H5N1 flu virus is currently affecting wild birds, poultry, dairy cows, and other animals throughout the country. There have been 67 total cases of bird flu identified in humans in the US since 2022, with 66 of those cases occurring in 2024.
The risk of humans contracting bird flu are low but is elevated among those who work closely with wild birds, poultry, and dairy cattle. The incidences of the flu virus in animals continues to increase, so CDC says it is important to identify potential bird flu cases in humans in a timely manner.
This demonstrates recognition by the CDC and the clinical laboratory profession that advances in molecular diagnostics and genetic testing now make it feasible for many hospital labs to perform these tests in-house on relevant patients. Such molecular testing is less expensive and produces a faster answer today, compared to just a few years ago.
This call for more lab tests in hospitals is also recognition of the value near-patient testing has from a public health perspective. Historically, it was regional and local public health labs that were sent specimens for testing from patients identified as having an infection that were a public health concern.
The good news is that this expands the role of hospital laboratories for all the right reasons. The downside is that hospital labs will probably see many test claims for these assays not be paid promptly by payers—or paid after unnecessary delays.
“The system right now tells us what has already happened. What we need is to shift to a system that tells us what’s happening in the moment. That is what we are doing today,” Nirav Shah, MD, JD (above), CDC principal deputy told CNN. Hospital and clinical laboratories will likely see an increase in orders for molecular and genetic testing for influenza A. (Photo copyright: Centers for Disease Control and Prevention.)
CDC Recommendations to Clinical Laboratories
The CDC alert also acknowledges that most individuals infected with avian flu were exposed to the virus via the handling of infected dairy cows or poultry in unprotected workplaces. There are no known cases of human-to-human transmission of the disease.
Most cases of avian flu in humans have been clinically mild and the patients quickly recover. However, on January 6, the CDC announced that an elderly patient with underlying health conditions in Louisiana who was previously hospitalized with severe avian influenza A illness had passed away. This case was the first confirmed death in the US attributed to the illness.
The CDC’s Health Advisory makes the following recommendations to clinical laboratories:
Subtype respiratory specimens that are positive for influenza A, but negative for seasonal influenza A virus subtypes, and forward those specimens to a public health laboratory within 24 hours.
Refrain from batching specimens for consolidated or bulk shipment to public health laboratories if that process could result in shipping delays.
Notify public health officials if a hospital or clinical lab does not have access to influenza A virus subtyping and arrange for a public health or commercial lab with this testing capability to perform the analysis.
Clearly link specimens to clinical information from the patient to ensure the prioritization of severely ill and ICU patients.
Immediately contact local public health authority if a positive result for influenza A (H5) virus is obtained using a laboratory developed test (LDT) or another A (H5) subtyping test to initiate time-critical actions.
The CDC’s Health Advisory also states public health laboratories should complete influenza A subtyping assays within 24 hours of receipt and report those results to the CDC, as required.
“One of the motivators of accelerating testing [is] so that we are, again, able to faster see difference between signal and noise, given that the volume of hospitalizations is going up as expected in a rather routine flu season,” Demetre Daskalakis, MD, MPH, director of the CDC’s National Center for Immunization and Respiratory Diseases (NCIRD), told CNN.
Preparing for more Bird Flu in Humans
According to the CDC, approximately 100,000 Americans have been hospitalized with type-A flu this season. The agency expects another 100,000 hospitalizations due to the virus before the end of this year. CDC is tracking flu infections on a weekly basis. Data can be reviewed on its website.
Other government organizations also are developing methods intended to curb the spread of the influenza virus. The federal Department of Agriculture recently launched a national program to test for bird flu in untreated milk. And the US Department of Health and Human Services (HHS) allocated $211 million in new funding to address emerging infectious diseases.
On January 17, the HHS announced it would give $590 million to Moderna to “accelerate the development of mRNA-based pandemic influenza vaccines and enhance mRNA platform capabilities so that the US is better prepared to respond to other emerging infectious diseases.”
“The funding will allow us to bring the benefits of mRNA vaccine technology to bear against a wider array of emerging threats,” said HHS Assistant Secretary for Preparedness and Response Dawn O’Connell, JD, in the announcement. “mRNA technology can be faster to develop and easier to update than other vaccines making it a helpful tool to have against viruses that move fast and mutate quickly.
Hospital laboratories and public health labs should prepare for a spike in test orders for avian influenza A as this year’s flu season progresses. As bird flu increases in animals, it increases the possibility that the disease might infect humans.
Though PCR clinical laboratory testing is widely used, some scientists are concerned its specificity may limit the ability to identify all variants of bird flu in wastewater
Wastewater testing of infectious agents appears to be here to stay. At the same time, there are differences of opinion about which methodologies and clinical laboratory tests are best suited to screen for specific contagions in wastewater. One such contagion is avian influenza, the virus that causes bird flu.
Wastewater testing by public health officials became a valuable tool during the COVID-19 pandemic and has now become a common method for detecting other diseases as well. For example, earlier this year, scientists used wastewater testing to learn how the H5N1 variant of the bird flu virus was advancing among dairy herds across the country.
In late March, the bird flu was first detected in dairy cattle in Texas, prompting scientists to begin examining wastewater samples to track the virus. Some researchers, however, expressed concerns about the ability of sewage test assays to detect all variants of certain diseases.
“Right now we are using these sort of broad tests to test for influenza A viruses,” Denis Nash, PhD, Distinguished Professor of Epidemiology at City University of New York (CUNY) and Executive Director of CUNY’s Institute for Implementation Science in Population Health (SPH), told the Los Angeles Times. “It’s possible there are some locations around the country where the primers being used in these tests might not work for H5N1.” Clinical laboratory PCR genetic testing is most commonly used to screen for viruses in wastewater. (Photo copyright: CUNY SPH.)
Effectiveness of PCR Wastewater Testing
Polymerase chain reaction (PCR) tests are most commonly used to distinguish genetic material related to a specific illness such as the flu virus. For PCR tests to correctly identify a virus, the tests must be designed to look for a specific subtype. The two most prevalent human influenza A viruses are known as H1N1 (swine flu) and H3N2, which was responsible for the 1968 pandemic that killed a million people worldwide. The “H” stands for hemagglutinin and the “N” for neuraminidase.
Hemagglutinin is a glycoprotein that assists the virus to attach to and infect host cells. Neuraminidase is an enzyme found in many pathogenic or symbiotic microorganisms that separates the links between neuraminic acids in various molecules.
Avian flu is also an influenza A virus, but it has the subtype H5N1. Although human and bird flu viruses both contain the N1 signal, they do not share an H. Some scientists fear that—in cases where a PCR test only looks for H1 and H3 in wastewater—that test could miss the bird flu altogether.
“We don’t have any evidence of that. It does seem like we’re at a broad enough level that we don’t have any evidence that we would not pick up H5,” Jonathan Yoder, Deputy Director, Infectious Disease Readiness and Innovation at the US Centers for Disease Control and Prevention (CDC) told the Los Angeles Times.
The CDC asserts current genetic testing methods are standardized and will detect the bird flu. Yoder also affirmed the tests being used at all the testing sites are the same assay, based on information the CDC has published regarding testing for influenza A viruses.
Genetic Sequencing Finds H5N1 in Texas Wastewater
In an article published on the preprint server medRxiv titled, “Virome Sequencing Identifies H5N1 Avian Influenza in Wastewater from Nine Cities,” the authors wrote, “using an agnostic, hybrid-capture sequencing approach, we report the detection of H5N1 in wastewater in nine Texas cities, with a total catchment area population in the millions, over a two-month period from March 4th to April 25th, 2024.”
The authors added, “Although human to human transmission is rare, infection has been fatal in nearly half of patients who have contracted the virus in past outbreaks. The increasing presence of the virus in domesticated animals raises substantial concerns that viral adaptation to immunologically naïve humans may result in the next flu pandemic.”
“So, it’s not just targeting one virus—or one of several viruses—as one does with PCR testing,” Eric Boerwinkle, PhD, Dean of the UTHealth Houston School of Public Health told the LA Times. “We’re actually in a very complex mixture, which is wastewater, pulling down viruses and sequencing them. What’s critical here is it’s very specific to H5N1.”
Epidemiologist Blake Hanson, PhD, Assistant Professor, Department of Epidemiology, Human Genetics, and Environmental Sciences at the UT Health Houston Graduate School of Biomedical Science, agreed with Boerwinkle that though the PCR-based methodology is highly effective at detecting avian flu in wastewater samples, the testing can do more.
“We have the ability to look at the representation of the entire genome, not just a marker component of it. And so that has allowed us to look at H5N1, differentiate it from some of our seasonal fluids like H1N1 and H3N2,” Hanson told the LA Times. “It’s what gave us high confidence that it is entirely H5N1, whereas the other papers are using a part of the H5 gene as a marker for H5.”
Human or Animal Sources
Both Boerwinkle and Hanson are epidemiologists in the team studying wastewater samples for H5N1 in Texas. They are not sure where the virus originated but are fairly certain it did not come from humans.
“Texas is really a confluence of a couple of different flyways for migratory birds, and Texas is also an agricultural state, despite having quite large cities,” Boerwinkle noted. “It’s probably correct that if you had to put your dime and gamble what was happening, it’s probably coming from not just one source but from multiple sources. We have no reason to think that one source is more likely any one of those things.”
“Because we are looking at the entirety of the genome, when we look at the single human H5N1 case, the genomic sequence has a hallmark amino acid change, compared to all of the cattle from that same time point,” Hanson said. “We do not see that hallmark amino acid present in any of our sequencing data. And we’ve looked very carefully for that, which gives us some confidence that we’re not seeing human-human transmission.”
CDC Updates on Bird Flu
In its weekly updates on the bird flu situation, the CDC reported that 48 states have outbreaks in poultry and 14 states have avian flu outbreaks in dairy cows. More than 238 dairy herds have been affected and, as of September 20, over 100 million poultry have been affected by the disease.
In addition, the CDC monitored more than 4,900 people who came into contact with an infected animal. Though about 230 of those individuals have been tested for the disease, there have only been a total of 14 reported human cases in the US.
The CDC posts information specifically for laboratory workers, healthcare providers, and veterinarians on its website.
The CDC also states that the threat from avian flu to the general public is low. Individuals at an increased risk for infection include people who work around infected animals and those who consume products containing raw, unpasteurized cow’s milk.
Symptoms of H5N1 in humans may include fever or chills, cough, headaches, muscle or body aches, runny or stuffy nose, tiredness and shortness of breath. Symptoms typically surface two to eight days after exposure.
Scientists and researchers have been seeking a reliable clinical laboratory test for disease organisms in a fast, accurate, and cost-effective manner. Wastewater testing of infectious agents could fulfill those goals and appears to be a technology that will continue to be used for tracking disease.
Researchers used CRISPR-based assays to develop new clinical laboratory point-of-care blood test which boasts accuracy, affordability, and accessibility
According to UPI, the test can “distinguish between influenza A and influenza B—the two main types of seasonal flu—as well as identifying more virulent strains like H1N1 and H3N2.”
Many research teams are working to develop paper-based diagnostic screening tests because of their lower cost to produce and usefulness in remote locations. Should this near-patient point-of-care test become clinically viable, it could mean shorter times to answer, enabling speedier diagnoses and earlier start of treatment.
It also means patient specimens do not have to be transported to a clinical laboratory for testing. And reduced cost per test makes it possible to test more people. This serves the public health aspect of monitoring outbreaks of influenza and other diseases and gives hope for improved treatment outcomes.
“Being able to tease apart what strain or subtype of influenza is infecting a patient has repercussions both for treating them and public health interventions, said Jon Arizti Sanz, PhD, co-lead study author and postdoctoral researcher at the Broad Institute of Harvard and MIT, in a Broad Institute news release.
“Ultimately, we hope these tests will be as simple as rapid antigen tests, and they’ll still have the specificity and performance of a nucleic acid test that would normally be done in a laboratory setting,” Cameron A. Myhrvold, PhD (above), Assistant Professor of Molecular Biology at Princeton University in New Jersey, told CIDRAP. Influenza tests that can be performed at the point of care and in remote locations may reduce the number of screening tests performed by clinical laboratories. (Photo copyright: Michael James Butts/Hertz Foundation.)
Her team developed their tests using Streamlined Highlighting of Infections to Navigate Epidemics (SHINE), “a clustered regularly interspaced short palindromic repeats (CRISPR)-based RNA detection platform,” the researchers wrote in their Journal of Molecular Diagnostics paper.
“SHINE has a runtime of 90 minutes, can be used at room temperature and only requires an inexpensive heat block to heat the reaction. The SHINE technology has previously been used to identify SARS-CoV-2 and later to distinguish between the Delta and Omicron variants,” Bioanalysis Zone reported.
“The test uses genetically engineered enzymes to identify specific sequences of viral RNA in samples,” the researchers told UPI. Originally designed to detect COVID-19, the team adapted the technology to detect influenza in 2022 “with the aim of creating a screening tool that could be used in the field or in clinics rather than hospitals or high-tech diagnostic labs,” they said.
Influenza A and B as well as H1N1 and H3N2 subtypes were the targets of the four SHINE assays. “When tested on clinical samples, these optimized assays achieved 100% concordance with quantitative RT-PCR. Duplex Cas12a/Cas13a SHINE assays were also developed to detect two targets simultaneously,” the researchers wrote in their paper.
The team used “20 nasal swabs from people with flu-like symptoms during the 2020-2021 flu season, nasal fluid from healthy people as the control, and 2016-2021 influenza sequences downloaded from the National Center for Biotechnology Information Influenza (NICB) database. They compared the results with those from quantitative reverse transcription-polymerase chain reaction (RT-PCR) tests,” CIDRAP reported.
The original 2020 test (shown above) takes 90 minutes to develop at room temperature. The test developers aim to drop this down to 15 minutes. In comparison, typical polymerase chain reaction (PCR) testing requires medical laboratories to have specialized equipment, trained staff, and prolonged processing times, the Broad Institute news release notes. (Photo copyright: Broad Institute.)
Implications of the New Tests
The ease of the new tests is an important development since approximately only 1% of individuals who come down with the flu see doctors for testing, according to the news release. And researchers had this in mind, looking at speed, accuracy, and affordability as a means to “improve outbreak response and infection care around the world,” UPI reported.
There are great benefits to strain differentiation that be achieved with the new test. Doctors are hopeful the test will help dial in the best treatment plans for patients since some strains are resistant to the antiviral medication oseltamivir (Tamiflu), UPI noted. This is significant since Tamiflu “is a common antiviral,” said Sanz in the Broad Institute news release.
“These assays have the potential to expand influenza detection outside of clinical laboratories for enhanced influenza diagnosis and surveillance,” the Journal of Molecular Diagnostics paper noted. This allows for more strategic treatment planning.
“Using a paper strip readout instead of expensive fluorescence machinery is a big advancement, not only in terms of clinical care but also for epidemiological surveillance purposes,” said Ben Zhang, an MD candidate in the Health Sciences and Technology at Harvard and co-first author of the study, in the Broad Institute news release.
Future Plans for Tests
“With further development, the test strip could be reprogrammed to distinguish between SARS-CoV-2 and flu and recognize swine flu and avian flu, including the H5N1 subtype currently causing an outbreak in US dairy cattle,” the study authors told CIDRAP.
The team is also looking at ways to help prevent H5N1 from crossing into human contamination, Sanz told UPI.
The new Princeton/MIT/Harvard tests echo the trend to bring in affordability and ease-of-use with accurate results as an end goal. Faster results mean the best treatments for each person can start sooner and may render the transport of specimens to a clinical laboratory as a second step unnecessary.
As research teams work to develop paper-based viral tests for their plethora of benefits, clinical laboratories will want to pay close attention to this development as it can have a big implication on assisting with future outbreaks.
Additional research is needed before these tests are going to be commonplace in homes worldwide, but this first step brings inspiration and hope of what’s to come.
Asian locales reacted swiftly to the threat of COVID-19 by leveraging lessons learned from previous pandemics and making use of serology testing in aggressive contact tracing
America’s healthcare leaders in government, hospitals, clinical pathology, and medical laboratories can learn important lessons from the swift responses to the early outbreaks of COVID-19 in countries like Taiwan and South Korea and in cities like Singapore and Hong Kong.
Strategies such as early intervention, commitment to tracing contacts of infected people within two hours, quarantines, and social distancing all contributed to significantly curtailing the spread of the latest coronavirus pandemic within their borders, The New York Times (NYT) reported.
Another response common to the efforts of these countries and cities was the speedy introduction of clinical laboratory tests for SARS-CoV-2, the novel coronavirus that causes coronavirus disease 2019 (COVID-19), supported by the testing of tens of thousands of people in the earliest stages of the outbreaks in their communities. And that preparation and experience is paying off as those countries and cities continue to address the spread of COVID-19.
‘We Look at SARS as the Dress Rehearsal’
“Maybe it’s because of our Asian context, but our community
is sort of primed for this. We will keep fighting, because isolation and
quarantine work,” Lalitha
Kurupatham, Deputy Director of the Communicable Diseases Division in
Singapore, told the NYT. “During peacetime, we plan for epidemics like
this.”
Clinical laboratory leaders and pathologists may recall that Hong Kong was the site of the 2003 severe acute respiratory syndrome (SARS) epidemic. About 8,096 people worldwide were infected, and 774 died from SARS, according to the World Health Organization (WHO). In Hong Kong, 299 died out of 1,755 cases. However, Singapore had just 238 cases and 33 deaths.
To what does Singapore attribute the country’s lower
COVID-19 infection/death rate today?
“We can look at SARS as the dress rehearsal. The experience was raw, and very, very visceral. And on the back of it, better systems were put in place,” Jeremy Lim, MD, Co-Director of the Leadership Institute for Global Health Transformation at the National University of Singapore, told TIME.
“It’s a mix of carrots and sticks that have so far helped us. The US should learn from Singapore’s response and then adapt what is useful,” Lim added.
Singapore Debuts Serology Testing for COVID-19 Tracking
As microbiologists and infectious diseases doctors know, serology tests work by identifying antibodies that are the sources of infection. In the case of COVID-19, these tests may have aided in the surveillance of people infected with the coronavirus.
This is one lesson the US is learning.
“CDC (Centers for Disease Control and Prevention) has developed two serological tests that we’re evaluating right now, so we can get an idea through surveillance what’s the extent of this outbreak and how many people really are infected,” Robert Redfield, MD, CDC Director, told STAT.
The graphic above, which is based on data from the federal Centers for Disease Control and Prevention, illustrates how contact tracing is accomplished. “We believe this is the first time in the world where these particular tests have been used in this context of contact tracing,” Danielle Anderson, PhD, Scientific Director, Duke-NUS Medical School ABSL3 Laboratory, told Science. (Graphic copyright: CDC/Carl Fredrik Sjöland.)
‘Leaving No Stone Unturned’
As of March 27, Singapore (located about 2,374 miles from
mainland China with a population of 5.7 million) had reported 732 COVID-19
cases and two deaths, while Hong Kong had reported 518 cases and four deaths.
According to Time, in its effort to battle and treat
COVID-19, Singapore took the following steps:
Clinical laboratory testing for COVID-19 of all
people presenting with “influenza-like” and pneumonia symptoms;
Contact tracing of each infected person,
including interviews, review of flight manifests, and police involvement;
Using locally developed test to find antibodies
after COVID-19 clears;
Ran ads on page one of newspapers urging people
with mild symptoms to see a doctor; and
Government paid $100 Singapore dollars per day to
quarantined self-employed people.
The Singapore government’s WhatsApp account shares updates on the coronavirus, and Singapore citizens acquire wearable stickers after having their temperature checked at building entrances, Wired reported. The article also noted teams of healthcare workers are kept separate in hospitals—just in case some workers have to be quarantined.
FREE Webinar | What Hospital and Health System Labs Need to Know About Operational Support and Logistics During the COVID-19 Outbreak Wednesday, April 1, 2020 @ 1PM EDT — Register Now
Meanwhile, in Hong Kong, citizens donned face masks and
pressured the government to respond to the COVID-19 outbreak. Officials subsequently
tightened borders with mainland China and took other action, the NYT reported.
Once the COVID-19 genetic sequence became available, national medical laboratory networks in Singapore, Hong Kong, and Japan developed their own diagnostic tests, reported The Lancet, which noted that the countries also expanded capacity for testing and changed financing systems, so people would not have to pay for the tests. In Singapore, the government pays for hospitalization as well, noted The Lancet.
Lessons Learned
The US has far less experience with pandemics, as compared to the Asian locales that were affected by the H1N1 influenza (Spanish Flu) of 1918-1920 and the H5N1 influenza (Avian Flu) of 1957-1958.
And, controversially, National Security Council (NSC) officials in 2018 discontinued the federal US Pandemic Response Unit, moving the NSC employees into other government departments, Associated Press reported.
According to the March 26 US Coronavirus Task Force’s televised
news conference, 550,000 COVID-19 tests have been completed nationwide and
results suggest 86% of those tested are negative for the disease.
The fast-moving virus and rapidly developing story are placing
medical laboratory testing in the global spotlight. Pathologists and clinical laboratory
leaders have a unique opportunity to advance the profession, as well as improving
the diagnosis of COVID-19 and the health of patients.
