Monkeypox case numbers are rising in NSW, but the "cousin" of small pox is unlikely to become the next COVID-19, an infectious diseases expert says. There have been 42 cases of monkeypox identified in NSW residents with one case acquiring the infection in NSW, while two others were infected within Australia. This local transmission of the virus has prompted NSW Health authorities to urge the community - particularly men who have sex with men - to be vigilant for symptoms of fever, headache, body aches and a rash. Hunter Medical Research Institute researcher and infectious disease expert Professor Josh Davis said while there is a monkeypox "pandemic" by definition, it is "not in the same ballpark" as COVID-19. "It is far less transmissible," he said. "Nearly all of it is through direct skin-to-skin contact, and so far, nearly all of it has been in sexual contact in men who have sex with men. That's just the population it is circulating in at the moment." Professor Davis said women could catch it, and there had been cases of household transmission - but so far there have been far fewer cases in women. "But if we go back to say HIV, when it first started spreading, it was nearly all men who had sex with men," he said. "And yet we know that it can also affect women, and then it subsequently did. So I don't think there's anything special about the virus that's specific to men who have sex with men. That's just how it's spreading at the moment." He said the virus does not typically mutate at the same rate as COVID-19, and it is "almost certainly" not airborne. But in theory, it could be spread by respiratory droplets. "Most people don't need to change anything about their behaviour... We should be wearing masks indoors anyway because of COVID and flu," he said. "There isn't a reason to take any additional precautions than you normally take unless you are a man who has sex with men, in which case people should be more careful about casual partners. "I think the key thing is, this is not the same type of thing as COVID. Yes, we should be concerned, and yes, we need to keep looking closely at it, but we shouldn't panic." Professor Davis said there was a vaccine, although supply was scarce. Most people who have been vaccinated for small pox are in the older demographic. "I don't think this is going to spread into broad aspects of the general population," Professor Davis said. "But it's important for us to get hold of vaccines, vaccinate high risk people, and get the health messaging out there to anyone who thinks they might have symptoms to go and get a checkup at their GP or sexual health clinic, and to stay home and isolate for 21 days if they've got suspected or proven monkeypox." IN OTHER NEWS: Professor Davis said until this year, there had been almost no cases of monkeypox outside Africa. "So far here the mortality rates are well under one per cent, and we don't know if that's because it's mainly affecting healthy adults," he said. "Whereas the reports in the past from Africa have been affecting young kids, especially if they were already sick with other things." He said the typical symptoms people get is a flu like illness with fever, aches and pains, and then a rash. "And the rash is pretty similar to the smallpox rash... Basically small little lumps that turn into pustules. And if you don't do anything, they sort of crust over and heal up over a period of about three weeks. "The problem is, while someone has those lesions or while they're sick, they can potentially infect other people."