Hugh Pennington Monkeypox LRB June 9, 2022

JheLast name is misleading. The most common natural hosts of monkeypox are small rodents that live in the rainforests of West and Central Africa. But it can infect a very wide range of animal species, including humans. Unlike bat coronaviruses, it does not need to mutate to jump from one species to another. When smallpox was common, cases of monkeypox were not recognized, because the two diseases are so similar that they could not be distinguished in the field. Without a definitive laboratory test, it was not possible to answer the two fundamental questions facing the smallpox eradicators at the end of their project: had smallpox really disappeared (were the remaining cases actually monkeypox) and did it have an animal reservoir? (like monkeypox did)?

The World Health Organization created committees and distributed grants. Various laboratories got to work. One of them was in Birmingham. In 1977, I visited him to assess his progress in developing a new test to distinguish smallpox from monkeypox using viral proteins labeled with radioactive amino acids. It produced excellent results. But on August 11, 1978, Janet Parker, a photographer who worked upstairs in the smallpox lab, developed a flu-like illness and then a blistering rash. On August 24, electron microscopy of the vesicle contents showed brick-shaped virus particles. She had smallpox. Vaccination of contacts has started. On August 31, the media telephoned the department head’s home forty times. The next morning, he slits his throat (he dies six days later). Janet Parker died on 9/11, the last person in the world to be killed by smallpox – a lab escape and an escape in which monkeypox played a part.

The WHO finally declared the successful eradication of smallpox in 1980. Today, monkeypox is the most common in the Democratic Republic of the Congo. Epidemics there are associated with the hunting, butchering and eating of infected rodents; some children have died. Human-to-human spread has occurred, but chains of transmission are not long due to the low likelihood of catching infection through casual contact. A genetically distinct and less virulent monkeypox variant is present in West African rodents. It causes a non-fatal disease in humans. After a day or two of fever, prostration, and development of swollen lymph nodes, a rash begins to appear, usually on peripheral parts of the body, sometimes on the genitals and tongue. The spots dry after a few weeks.

On April 9, 2003, a wholesale pet store in the US Midwest imported six species of rodents from Ghana. They were housed with two hundred prairie dogs, which were then sold as pets. Prairie dog keepers began falling ill with monkeypox in May; 72 people have been infected, all have recovered and none have transmitted the infection to their human contacts. In Europe, there have only been a few cases of monkeypox in recent years, all involving a history of travel to Africa. So the big outbreak that began in mid-May – affecting individuals in North America, Australia and many European countries, but apparently not involving travel to Africa – took everyone by surprise. Was this a worrying new variant?

Almost certainly not. Poxviruses are DNA viruses. They evolve much more slowly than RNA viruses such as influenza and Sars-CoV-2. The explanation for this monkeypox outbreak likely lies in human behavior and its effect on the transmission of infection. Cases in the outbreak are predominantly among men who have sex with men (MSM). Monkeypox has joined microbes like hepatitis A and Shigella flexneri by showing a capacity for sexual transmission. In the old days shigella was not an STD. My grandfather became an asylum clerk (nurse in a psychiatric hospital) in 1893. Two years later shigella hit in a big way, killing many patients. For the next thirty years, it was more common in mental hospitals than in the community, causing “asylum dysentery”. Closing asylums solved the problem (although many people with dementia are now in nursing homes, where they have instead suffered high death rates from Sars-CoV-2). Today the most reliable way to catch shigella is to go on vacation in the tropics; there are occasional outbreaks on cruise liners.

shigella is transmitted by the fecal-oral route, and its transmission between MSM by direct or indirect oral-anal contact explains its sexual transmission. Hepatitis A epidemics and shigella among MSM in recent years have been among men with multiple sex partners. Hepatitis A infections in the UK have been caused by viruses related to strains found in South America, and elsewhere in Europe by viruses related to strains in Japan and Taiwan. Contact tracers will no doubt investigate the extent to which similar risk factors apply to the current outbreak, and whether monkeypox has become an STD due to direct sexual transmission from vesicles on the tongue or genitals, or through intimate person-to-person contact facilitating direct transmission. inoculating the skin from the virus-laden rash or inhaling dried scabs from a healing rash.

The good news is that genome sequencing has shown that the current monkeypox virus belongs to the least virulent West African strain; that the smallpox vaccine gives good protection, even when given after exposure; and that STD clinic staff have more experience as contact tracers than any other public health worker. More importantly, monkeypox is about as different from HIV and Sars-CoV-2 as it gets: it doesn’t create life-threatening chronic long-term infections, it doesn’t mutate quickly, and the worst residue of the disease Acute it causes – which resolves spontaneously – is the facial scarring caused by its pustules, of the kind that affected Lady Mary Wortley Montagu after her recovery from smallpox in 1715.

The likelihood of finding out how the virus got out of Africa is low, and it is too early to tell whether the current outbreak will die down or linger in the MSM network. It is a manifestation of the way we live now. “Infectious diseases are one of the few true adventures left in the world,” wrote microbiologist Hans Zinsser in his classic Rats, lice and history (1935):

The dragons are all dead and the spear is rusting in the corner of the fireplace… The only real sporting proposition… is war against those ferocious little creatures, who lurk in dark corners and stalk us in the bodies of rats, mice and of all kinds of pets… and lead us astray in our food and drink and even in our love.

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