Enzo Palombo, Swinburne University of Technology

Recent outbreaks of bird flu – in US dairy herds, poultry farms in Australia and elsewhere, and isolated cases in humans – have raised the issue of food safety.

So can the virus transfer from infected farm animals to contaminate milk, meat or eggs? How likely is this?

And what do we need to think about to minimise our risk when shopping for or preparing food?

How safe is milk?

Bird flu (or avian influenza) is a bird disease caused by specific types of influenza virus. But the virus can also infect cows. In the US, for instance, to date more than 80 dairy herds in at least nine states have been infected with the H5N1 version of the virus.

Investigations are under way to confirm how this happened. But we do know infected birds can shed the virus in their saliva, nasal secretions and faeces. So bird flu can potentially contaminate animal-derived food products during processing and manufacturing.

Indeed, fragments of bird flu genetic material (RNA) were found in cow’s milk from the dairy herds associated with infected US farmers.

However, the spread of bird flu among cattle, and possibly to humans, is likely to have been caused through contact with contaminated milking equipment, not the milk itself.

The test used to detect the virus in milk – which uses similar PCR technology to lab-based COVID tests – is also highly sensitive. This means it can detect very low levels of the bird flu RNA. But the test does not distinguish between live or inactivated virus, just that the RNA is present. So from this test alone, we cannot tell if the virus found in milk is infectious (and capable of infecting humans).

Does that mean milk is safe to drink and won’t transmit bird flu? Yes and no.

In Australia, where bird flu has not been reported in dairy cattle, the answer is yes. It is safe to drink milk and milk products made from Australian milk.

In the US, the answer depends on whether the milk is pasteurised. We know pasteurisation is a common and reliable method of destroying concerning microbes, including influenza virus. Like most viruses, influenza virus (including bird flu virus) is inactivated by heat.

Although there is little direct research on whether pasteurisation inactivates H5N1 in milk, we can extrapolate from what we know about heat inactivation of H5N1 in chicken and eggs.

So we can be confident there is no risk of bird flu transmission via pasteurised milk or milk products.

However, it’s another matter for unpasteurised or “raw” US milk or milk products. A recent study showed mice fed raw milk contaminated with bird flu developed signs of illness. So to be on the safe side, it would be advisable to avoid raw milk products.

How about chicken?

Bird flu has caused sporadic outbreaks in wild birds and domestic poultry worldwide, including in Australia. In recent weeks, there have been three reported outbreaks in Victorian poultry farms (two with H7N3 bird flu, one with H7N9). There has been one reported outbreak in Western Australia (H9N2).

The strains of bird flu identified in the Victorian and Western Australia outbreaks can cause human infection, although these are rare and typically result from close contact with infected live birds or contaminated environments.

Therefore, the chance of bird flu transmission in chicken meat is remote.

Nonetheless, it is timely to remind people to handle chicken meat with caution as many dangerous pathogens, such as Salmonella and Campylobacter, can be found on chicken carcasses.

Always handle chicken meat carefully when shopping, transporting it home and storing it in the kitchen. For instance, make sure no meat juices cross-contaminate other items, consider using a cool bag when transporting meat, and refrigerate or freeze the meat within two hours.

Avoid washing your chicken before cooking to prevent the spread of disease-causing microbes around the kitchen.

Finally, cook chicken thoroughly as viruses (including bird flu) cannot survive cooking temperatures.

Are eggs safe?

The recent Australian outbreaks have occurred in egg-laying or mixed poultry flocks, so concerns have been raised about bird flu transmission via contaminated chicken eggs.

Can flu viruses contaminate chicken eggs and potentially spread bird flu? It appears so. A report from 2007 said it was feasible for influenza viruses to enter through the eggshell. This is because influenza virus particles are smaller (100 nanometres) than the pores in eggshells (at least 200 nm).

So viruses could enter eggs and be protected from cleaning procedures designed to remove microbes from the egg surface.

Therefore, like the advice about milk and meat, cooking eggs is best.

The US Food and Drug Administration recommends cooking poultry, eggs and other animal products to the proper temperature and preventing cross-contamination between raw and cooked food.

In a nutshell

If you consume pasteurised milk products and thoroughly cook your chicken and eggs, there is nothing to worry about as bird flu is inactivated by heat.

The real fear is that the virus will evolve into highly pathogenic versions that can be transmitted from human to human.

That scenario is much more frightening than any potential spread though food.

Enzo Palombo, Professor of Microbiology, Swinburne University of Technology

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

As of January this year, Aotearoa New Zealand became just the second country (after Canada) to adopt a groundbreaking new procedure for patients experiencing cardiac arrest.

Known as “double sequential external defibrillation” (DSED), it will change initial emergency response strategies and potentially improve survival rates for some patients.

Surviving cardiac arrest hinges crucially on effective resuscitation. When the heart is working normally, electrical pulses travel through its muscular walls creating regular, co-ordinated contractions.

But if normal electrical rhythms are disrupted, heartbeats can become unco-ordinated and ineffective, or cease entirely, leading to cardiac arrest.

Defibrillation is a cornerstone resuscitation method. It gives the heart a powerful electric shock to terminate the abnormal electrical activity. This allows the heart to re-establish its regular rhythm.

Its success hinges on the underlying dysfunctional heart rhythm and the proper positioning of the defibrillation pads that deliver the shock. The new procedure will provide a second option when standard positioning is not effective.

Using two defibrillators

During standard defibrillation, one pad is placed on the right side of the chest just below the collarbone. A second pad is placed below the left armpit. Shocks are given every two minutes.

Early defibrillation can dramatically improve the likelihood of surviving a cardiac arrest. However, around 20% of patients whose cardiac arrest is caused by “ventricular fibrillation” or “pulseless ventricular tachycardia” do not respond to the standard defibrillation approach. Both conditions are characterised by abnormal activity in the heart ventricles.

DSED is a novel method that provides rapid sequential shocks to the heart using two defibrillators. The pads are attached in two different locations: one on the front and side of the chest, the other on the front and back.

A single operator activates the defibrillators in sequence, with one hand moving from the first to the second. According to a recent randomised trial in Canada, this approach could more than double the chances of survival for patients with ventricular fibrillation or pulseless ventricular tachycardia who are not responding to standard shocks.

The second shock is thought to improve the chances of eliminating persistent abnormal electrical activity. It delivers more total energy to the heart, travelling along a different pathway closer to the heart’s left ventricle.

Evidence of success

New Zealand ambulance data from 2020 to 2023 identified about 1,390 people who could potentially benefit from novel defibrillation methods. This group has a current survival rate of only 14%.

Recognising the potential for DSED to dramatically improve survival for these patients, the National Ambulance Sector Clinical Working Group updated the clinical procedures and guidelines for emergency medical services personnel.

The guidelines now specify that if ventricular fibrillation or pulseless ventricular tachycardia persist after two shocks with standard defibrillation, the DSED method should be administered. Two defibrillators need to be available, and staff must be trained in the new approach.

Though the existing evidence for DSED is compelling, until recently it was based on theory and a small number of potentially biased observational studies. The Canadian trial was the first to directly compare DSED to standard treatment.

From a total of 261 patients, 30.4% treated with this strategy survived, compared to 13.3% when standard resuscitation protocols were followed.

The design of the trial minimised the risk of other factors confounding results. It provides confidence that survival improvements were due to the defibrillation approach and not regional differences in resources and training.

The study also corroborates and builds on existing theoretical and clinical scientific evidence. As the trial was stopped early due to the COVID-19 pandemic, however, the researchers could recruit fewer than half of the numbers planned for the study.

Despite these and other limitations, the international group of experts that advises on best practice for resuscitation updated its recommendations in 2023 in response to the trial results. It suggested (with caution) that emergency medical services consider DSED for patients with ventricular fibrillation or pulseless ventricular tachycardia who are not responding to standard treatment.

Training and implementation

Although the evidence is still emerging, implementation of DSED by emergency services in New Zealand has implications beyond the care of patients nationally. It is also a key step in advancing knowledge about optimal resuscitation strategies globally.

There are always concerns when translating an intervention from a controlled research environment to the relative disorder of the real world. But the balance of evidence was carefully considered before making the decision to change procedures for a group of patients who have a low likelihood of survival with current treatment.

Before using DSED, emergency medical personnel undergo mandatory education, simulation and training. Implementation is closely monitored to determine its impact.

Hospitals and emergency departments have been informed of the protocol changes and been given opportunities to ask questions and give feedback. As part of the implementation, the St John ambulance service will perform case reviews in addition to wider monitoring to ensure patient safety is prioritised.

Ultimately, those involved are optimistic this change to cardiac arrest management in New Zealand will have a positive impact on survival for affected patients.

Vinuli Withanarachchie, PhD candidate, College of Health, Massey University; Bridget Dicker, Associate Professor of Paramedicine, Auckland University of Technology, and Sarah Maessen, Research Associate, Auckland University of Technology

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