The United States’ Centers for Disease Control and Prevention (CDC) has issued a health alert after the first case of H5N1 avian influenza, or bird flu, seemingly spread from a cow to a human.

A farm worker in Texas contracted the virus amid an outbreak in dairy cattle. This is the second human case in the US; a poultry worker tested positive in Colorado in 2022.

The virus strain identified in the Texan farm worker is not readily transmissible between humans and therefore not a pandemic threat. But it’s a significant development nonetheless.

Some background on bird flu

There are two types of avian influenza: highly pathogenic or low pathogenic, based on the level of disease the strain causes in birds. H5N1 is a highly pathogenic avian influenza.

H5N1 first emerged in 1997 in Hong Kong and then China in 2003, spreading through wild bird migration and poultry trading. It has caused periodic epidemics in poultry farms, with occasional human cases.

Influenza A viruses such as H5N1 are further divided into variants, called clades. The unique variant causing the current epidemic is H5N1 clade 2.3.4.4b, which emerged in late 2020 and is now widespread globally, especially in the Americas.

In the past, outbreaks could be controlled by culling of infected birds, and H5N1 would die down for a while. But this has become increasingly difficult due to escalating outbreaks since 2021.

Wild animals are now in the mix

Waterfowl (ducks, swans and geese) are the main global spreaders of avian flu, as they migrate across the world via specific routes that bypass Australia. The main hub for waterfowl to migrate around the world is Quinghai lake in China.

But there’s been an increasing number of infected non-waterfowl birds, such as true thrushes and raptors, which use different flyways. Worryingly, the infection has spread to Antarctica too, which means Australia is now at risk from different bird species which fly here.

H5N1 has escalated in an unprecedented fashion since 2021, and an increasing number of mammals including sea lions, goats, red foxes, coyotes, even domestic dogs and cats have become infected around the world.

Wild animals like red foxes which live in peri-urban areas are a possible new route of spread to farms, domestic pets and humans.

Dairy cows and goats have now become infected with H5N1 in at least 17 farms across seven US states.

What are the symptoms?

Globally, there have been 14 cases of H5N1 clade 2.3.4.4b virus in humans, and 889 H5N1 human cases overall since 2003.

Previous human cases have presented with a severe respiratory illness, but H5N1 2.3.4.4b is causing illness affecting other organs too, like the brain, eyes and liver.

For example, more recent cases have developed neurological complications including seizures, organ failure and stroke. It’s been estimated that around half of people infected with H5N1 will die.

The case in the Texan farm worker appears to be mild. This person presented with conjunctivitis, which is unusual.

Food safety

Contact with sick poultry is a key risk factor for human infection. Likewise, the farm worker in Texas was likely in close contact with the infected cattle.

The CDC advises pasteurised milk and well cooked eggs are safe. However, handling of infected meat or eggs in the process of cooking, or drinking unpasteurised milk, may pose a risk.

Although there’s no H5N1 in Australian poultry or cattle, hygienic food practices are always a good idea, as raw milk or poorly cooked meat, eggs or poultry can be contaminated with microbes such as salmonella and E Coli.

If it’s not a pandemic, why are we worried?

Scientists have feared avian influenza may cause a pandemic since about 2005. Avian flu viruses don’t easily spread in humans. But if an avian virus mutates to spread in humans, it can cause a pandemic.

One concern is if birds were to infect an animal like a pig, this acts as a genetic mixing vessel. In areas where humans and livestock exist in close proximity, for example farms, markets or even in homes with backyard poultry, the probability of bird and human flu strains mixing and mutating to cause a new pandemic strain is higher.

The cows infected in Texas were tested because farmers noticed they were producing less milk. If beef cattle are similarly affected, it may not be as easily identified, and the economic loss to farmers may be a disincentive to test or report infections.

How can we prevent a pandemic?

For now there is no spread of H5N1 between humans, so there’s no immediate risk of a pandemic.

However, we now have unprecedented and persistent infection with H5N1 clade 2.3.4.4b in farms, wild animals and a wider range of wild birds than ever before, creating more chances for H5N1 to mutate and cause a pandemic.

Unlike the previous epidemiology of avian flu, where hot spots were in Asia, the new hot spots (and likely sites of emergence of a pandemic) are in the Americas, Europe or in Africa.

Pandemics grow exponentially, so early warnings for animal and human outbreaks are crucial. We can monitor infections using surveillance tools such as our EPIWATCH platform.

The earlier epidemics can be detected, the better the chance of stamping them out and rapidly developing vaccines.

Although there is a vaccine for birds, it has been largely avoided until recently because it’s only partially effective and can mask outbreaks. But it’s no longer feasible to control an outbreak by culling infected birds, so some countries like France began vaccinating poultry in 2023.

For humans, seasonal flu vaccines may provide a small amount of cross-protection, but for the best protection, vaccines need to be matched exactly to the pandemic strain, and this takes time. The 2009 flu pandemic started in May in Australia, but the vaccines were available in September, after the pandemic peak.

To reduce the risk of a pandemic, we must identify how H5N1 is spreading to so many mammalian species, what new wild bird pathways pose a risk, and monitor for early signs of outbreaks and illness in animals, birds and humans. Economic compensation for farmers is also crucial to ensure we detect all outbreaks and avoid compromising the food supply.

C Raina MacIntyre, Professor of Global Biosecurity, NHMRC L3 Research Fellow, Head, Biosecurity Program, Kirby Institute, UNSW Sydney; Ashley Quigley, Senior Research Associate, Global Biosecurity, UNSW Sydney; Haley Stone, PhD Candidate, Biosecurity Program, Kirby Institute, UNSW Sydney; Matthew Scotch, Associate Dean of Research and Professor of Biomedical Informatics, College of Health Solutions, Arizona State University, and Rebecca Dawson, Research Associate, The Kirby Institute, UNSW Sydney

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

People often believe they are allergic to house dust. But of the 20% of Australians suffereing with allergies, a number are are actually allergic to microscopic house dust mites.

House dust mites belong to the same family as spiders and ticks. They measure just 0.2-0.3 mm, with 50 fitting on a single pinhead. They live for 65–100 days, and females lay 60–100 eggs in their life.

House dust mites love temperate climates and humidity. They feed off the skin cells we and animals shed, as well as mould, which they digest using special enzymes. These enzymes are excreted in their poo about 20 times a day. They also shed fragments of their exoskeletons.

All these fragments trigger allergies in people with this type of allergic rhinitis (which is also known as hay fever)

What are the symptoms?

When people with house dust mite allergy inhale the allergens, they penetrate the mucous membranes of the airways and eyes. Their body recognises the allergens as a threat, releasing chemicals including one called histamine.

This causes symptoms including a runny nose, an itchy nose, eyes and throat, sneezing, coughing and a feeling of mucus at the back of your throat (known as a post-nasal drip).

People with this type of allergy usually mouth breath, snore, rub their nose constantly (creating a nasal crease called the “dust mite salute”) and have dark shadows under their eyes.

House dust mite allergy can also cause poor sleep, constant tiredness, reduced concentration at work or school and lower quality of life.

For people with eczema, their damaged skin barrier can allow house dust mite proteins in. This prompts immune cells in the skin to release chemicals which make already flared skin become redder, sorer and itchier, especially in children.

Symptoms of house dust mite allergy occur year round, and are often worse after going to bed and when waking in the morning. But people with house dust mite allergy and pollen allergies find their year-round symptoms worsen in spring.

How is it diagnosed?

House dust mite allergy symptoms often build up over months, or even years before people seek help. But an accurate diagnosis means you can not only access the right treatment – it’s also vital for minimising exposure.

Doctor and nurse practitioners can order a blood test to check for house dust mite allergy.

Alternatively, health care providers with specialised allergy training can perform skin prick tests. This involves placing drops of the allergens on the arm, along with a positive and negative “control”. After 15 minutes, those who test positive will have developed a mosquito bite-like mark.

How is it treated?

Medication options include one or a combination of:

• daily non-sedating antihistamines
• a steroid nasal spray
• allergy eye drops.

Your health care professional will work with you to develop a rhinitis (hay fever) medical management plan to reduce your symptoms. If you’re using a nasal spray, your health provider will show you how to use it, as people often use it incorrectly.

If you also have asthma or eczema which is worsened by dust mites, your health provider will adapt your asthma action plan or eczema care plan accordingly.

If you experience severe symptoms, a longer-term option is immunotherapy. This aims to gradually turn off your immune system’s ability to recognise house dust mites as a harmful allergen.

Immunotherapy involves taking either a daily sublingual tablet, under the tongue, or a series of injections. Injections require monthly attendances over three years, after the initial weekly build-up phase.

These are effective, but are costly (as well as time-consuming). So it’s important to weigh up the potential benefits and downsides with your health-care provider.

How can you minimise house dust mites?

There are also important allergy minimisation measures you can take to reduce allergens in your home.

Each week, wash your bedding and pyjamas in hot water (over 60°C). This removes house dust mite eggs and debris.

Opt for doonas, covers or quilts that can be washed in hot water above 60°C. Alternatively, low-cost waterproof or leak proof covers can keep house dust mites out.

If you can, favour blinds and wood floors over curtains and carpet. Dust blinds and surfaces with a damp cloth each week and vacuum while wearing a mask, or have someone else do it, as house dust mites can become airborne during cleaning.

But beware of costly products with big marketing budgets and little evidence to support their use. A new mattress, for example, will always be house dust mite-free. But once slept on, the house dust mite life cycle can start.

Mattress protectors and toppers commonly claim to be “hypoallergenic”, “anti-allergy” or “allergy free”. But their pore sizes are not small enough to keep house dust mites and their poo out, or shed skin going through.

Sprays claiming to kill mites require so much spray to penetrate the product that it’s likely to become wet, may smell like the spray and, unless dried properly, may grow mould.

Finally, claims that expensive vacuum cleaners can extract all the house dust mites are unsubstantiated.

For more information, visit healthdirect.gov.au or the Australian Society of Clinical Immunology and Allergy.

Deryn Lee Thompson, Eczema and Allergy Nurse; Lecturer, University of South Australia

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