Monkeypox outbreak takes a hold

Global cases are nudging 50,000, as cases continue to rise in Australia. How did we get here?

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It’s like the plot of a B-grade horror film. A Texas importer sends a shipment of more than 750 exotic rodents from Ghana, Africa, to pet stores in six US states. 

The animals include various species of squirrels, rats, porcupines and mice. A distributor in Illinois receives some of the rats and mice and houses them with some 200 prairie dogs. All the animals are destined for pet stores in Wisconsin, Illinois, Indiana, Missouri, Kansas, South Carolina and Michigan. 

A Wisconsin family buys one of the prairie dogs and takes it home. One day the dog bites their three-year-old child. Not long after, the child is taken to hospital with a high fever, swollen eyes and a red vesicular rash. The child’s parents also develop a rash but no other symptoms. 

As the symptoms are associated with an animal bite, local health authorities are notified and tests confirm the child and parents have monkeypox, directly linked to the prairie dog.  

The CDC gets involved but it’s too late – the virus is already spreading. Within six weeks, monkeypox has spread to Kansas, Missouri, Indiana, Illinois and Wisconsin, infecting more than 70 people aged from one to 51. Thanks to prompt medical care, isolation precautions and public health measures no one dies, although two children become seriously ill and many others are hospitalised. 

This is no Hollywood script however. It happened in 2003.  

INTERMISSION 

Fast forward to early May 2022. Cases of monkeypox were being reported in countries where the disease is not endemic, rather than confined to West and Central Africa where it is endemic. 

According to the World Health Organization, this is the first time that many monkeypox cases and clusters have been reported concurrently in non-endemic and endemic countries in widely disparate geographical areas. The WHO declared the current monkeypox epidemic a global health emergency on 21 July.  

WHO reporting accessed on August 31 put the number of cases globally at 48,895. By 28 August, case numbers were rising almost 10% higher than the week before. Most cases reported in the past four weeks were from the Americas (66.5%) and Europe (32.7%). 

There have so far been 15 deaths globally. 

The 10 most affected countries globally by the global monkeypox outbreak are the US (16,965 cases), Spain (6459), Brazil (4216), Germany (3422), France (3421), the UK (3340), Peru (1300), Canada (1228), the Netherlands (1136) and Portugal (846). Together, these countries account for 88.7% of the cases reported globally. 

Australia falls into the WHO’s Western Pacific Region and has by far the most reported monkeypox cases of any of our neighbours. Australia is in the only country in the region to have more than 100 cases. Singapore comes in second with 16 (as of 30 August), while Japan, New Zealand and the Philippines have four each. 

Australia’s first ever case of monkeypox was detected in May this year. The past couple of months have seen cases really start to climb. Latest official data from the National Notifiable Diseases Surveillance System (NNDSS) as of 30 August have the cases at 121, including 61 in Victoria, 48 in NSW, five in Western Australia, three in Queensland, two in the ACT, and two in South Australia. 

In July case numbers were still in the 30s. 

PUTTING IT IN PERSPECTIVE 

The average Aussie, still very much under the influence of the covid pandemic, might look at this number and be unimpressed. Australia has recorded more than 10 million cases of covid since the pandemic began, and more than 13,000 deaths. 

The number of monkeypox cases may still be relatively low when compared to other countries where the outbreaks are much more widespread, but they have been sufficient for Australia’s Chief Medical Officer, Professor Paul Kelly, to declare the situation a Communicable Disease Incident of National Significance on 26 July. 

On 1 June, monkeypox became a nationally notifiable disease, and this will stay in place for six months. During this time a decision will be made on whether to list the virus permanently. 

A lot rides on how the virus evolves in Australia. Up until recently, the bulk of cases have been acquired overseas, however local transmission is now known to be happening in NSW and Victoria, where the cases are highest. 

And part of that evolution depends on whether the virus finds an animal host in Australia, says Professor Raina MacIntyre, head of the biosecurity program at the Kirby Institute. She is also on the WHO’s Strategic Advisory Group of Experts on Immunisation Monkeypox and Smallpox and is an expert in influenza and emerging infectious diseases. 

And if it does find an animal host, the virus is likely here to stay, she warns. 

“We know that it infects rodents so rodents would be the most likely host, but we don’t know whether it can infect native Australian marsupials, for example,” she says. 

“It can certainly infect mammalian species, so we don’t know. We haven’t had it in the country before. In two and a half years’ time we may be thinking differently about monkeypox.” 

Professor MacIntyre believes Australia has a small window of opportunity to get a handle on the  monkeypox situation in Australia. 

“When you look at what’s happened globally, we went from double digits to over 12,000 cases in about two and a half months, so we don’t have a long time to sit and ponder things,” she says. 

“We don’t want it becoming established in animal hosts in Australia … it’s just another level of insecurity that we don’t need.” 

Australians may be more vulnerable to the virus because mass vaccination has never been needed here – only travellers to countries where it is endemic have been vaccinated. Professor MacIntyre estimates only about 10% of Australians have vaccine protection. 

VACCINE TO THE RESCUE 

That number will rise in the coming months, after the Federal Government secured 450,000 doses of the third generation monkeypox vaccine known as Jynneos, from international vaccine company Bavarian Nordic. 

The first 22,000 doses arrived in early August and were rolled out to the states and territories, largely through sexual health clinics. In this initial phase of the rollout, the vaccine will only be available at risk patients and healthcare workers, as recommended by ATAGI. 

While monkeypox is classified as a zoonotic disease, this epidemic has affected mostly men who have sex with men, a pattern Professor MacIntyre says has not been seen before. And while this is the group most affected, others including pregnant women and the immunocompromised are also at risk.  

Human-to-human transmission of monkeypox virus usually occurs through close contact with the lesions, body fluids and respiratory droplets of infected people or animals. The possibility of sexual transmission is now being researched around the world, as the current outbreak appears to be concentrated in men who have sex with men and has been associated with unexpected anal and genital lesions. 

Whether domesticated cats and dogs could be a vector for monkeypox virus is unknown. However a letter in The Lancet in early August detailed the case of two men who have sex with men, who presented to a hospital in France. The men are non-exclusive partners living in the same household.  

“The men had presented with anal ulceration six days after sex with other partners. In patient one, anal ulceration was followed by a vesiculopustular rash on the face, ears and legs; in patient two, on the legs and back. In both cases, rash was associated with asthenia, headaches and fever four days later,” the authors reported. 

Both tested positive to monkeypox, and 12 days after the onset of their symptoms, their male Italian greyhound, aged four years and with no previous medical disorders, presented with mucocutaneous lesions, including abdomen pustules and a thin anal ulceration. The dog also tested positive for monkeypox – providing evidence of human to dog transmission of the virus. 

“The men reported co-sleeping with their dog,” the authors reported. “They had been careful to prevent their dog from contact with other pets or humans from the onset of their own symptoms.” 

This could be a significant finding. The authors report that in endemic countries, only wild animals (rodents and primates) have been found to carry monkeypox virus. 

“However, transmission of monkeypox virus in prairie dogs has been described in the USA and in captive primates in Europe that were in contact with imported infected animals,” they wrote. 

“Infection among domesticated animals, such as dogs and cats, has never been reported. To the best of our knowledge, the kinetics of symptom onset in both patients and, subsequently, in their dog suggest human-to-dog transmission of monkeypox virus … Our findings should prompt debate on the need to isolate pets from monkeypox virus-positive individuals. We call for further investigation on secondary transmissions via pets.” 

CASUALTY OF WAR 

Research is severely lacking when it comes to monkeypox, largely because smallpox has been absent from Australia for decades, says Professor David Tscharke, head of the department of immunology and infectious diseases at the ANU’s John Curtin School of Medical Research. Poxviruses are one of his areas of expertise. 

He says the lack of comprehensive and recent literature on the virus severely inhibits control efforts. 

“Over the last decade or so, we’ve had these increasing numbers of incursions of human monkeypox infections in Europe and even the States, and everyone’s just assumed it has been imported from Africa,” he says. 

“The real concern is that with the majority of people infected now, there’s no link back to anywhere in Africa. So we don’t know. Now we have a situation where quite clearly this virus is propagating in the human population, and there doesn’t seem to be an end to that.” 

He warns that while the rate of spread may be relatively low, “it is, however, relentless.” 

“There’s no sense of this slowing down,” he says. 

He says one of the huge hurdles in studying this virus came from it being declared to be a pathogen of concern from a bio defence point of view back in the early 2000s. This followed anthrax attacks in the US in 2001 and led the WHO to warn governments around the world to prepare for a terrorist smallpox attack. Nothing eventuated, but it put the brakes on research, said Professor Tscharke. 

“That severely limited anyone’s ability to do research because basically it was treated as a as a massive biosecurity problem,” he says. 

“It meant that all of the paperwork to hold that virus or to work with that virus was almost overwhelming, so that greatly limited the number of labs that could actually work with that. 

“We have to reclassify this as an infectious disease. That that requires research, right? We have to stop thinking about this as a potential bioweapon and think about it like any other infectious disease that we need to understand.” 

Researchers have also faced the challenge of attracting funding to study a virus that was declared eradicated in the 1980s, says Professor Tscharke. 

“You get asked why you are studying this dead virus?” he says. 

“I’ve been saying in talks and in my applications for years saying that the re-emergence of pox virus disease is on the rise. It’s most likely that’s because residual immunity from the smallpox vaccination era is waning. And we can’t take our eye off these viruses.” 

He says urgent investment is needed to understand the current epidemic, especially the dominant trend of infection among men who have sex with men, and to help predict what might happen next. 

“We don’t know what we need to know,” he says. “The government needs to start investing in some fairly important and urgent research so that we do have the answers to these questions.” 

PRACTICAL PEARLS 

In the meantime, Australian clinicians, particularly GPs and dermatologists, who are likely to be the main ports of call for patients presenting with rashes, can only be vigilant and follow the public health advice, says University of Queensland’s Professor Paul Griffin, director of infectious diseases at Mater Health Services. 

He says one of the major difficulties with monkeypox is that most clinicians will have never seen it before. 

“It’s a very valid concern,” he says. 

He also cautions against only considering monkeypox as a potential diagnosis if the patient was a man who has sex with men. While the bulk of known cases in Australia to date have followed this trend, it’s important not to assume this would always be the case. 

“While we’ve certainly seen circulation of this virus occur at higher levels in those groups, it doesn’t mean it’s going to occur [there] exclusively.” Professor Griffin says. 

That kind of thinking will lead to missed cases. 

“If you had a teenager, let’s say, with a rash, and you diagnosed as shingles or chickenpox or whatever, when in actual fact, it was monkey pox – you’ve missed the boat there.” 

Against a backdrop of rising cases and vaccines currently reserved for at-risk patients, Professor Griffin says it’s important clinicians don’t shy away from testing for monkeypox if they have ruled out other causes of a non-specific rash. 

“If there’s any concern that it could be monkeypox, definitely pull the trigger on doing the right tests, but also have a low threshold to involve public health or critical microbiology or infectious diseases [experts] to seek the right kind of advice,” he said. 

“And if you’re not certain about the aetiology of a rash, then we have the tools to be able to make more specific diagnoses, including viral swabs for PCR, so we know exactly what is going on.”