The ongoing global epidemic of monkeypox differs in several ways from historical transmission patterns and typical symptoms previously seen in countries in Africa where the virus is endemic, according to the largest case series to date.
Almost all cases in this outbreak are among gay, bisexual, and other men who have sex with men, with most transmissions related to sexual activity. However, experts fear that if not promptly managed with testing, vaccination and treatment, the virus could spread beyond this group and become endemic in more countries.
“We have shown that current international case definitions need to be expanded to add symptoms that are not currently included, such as oral, anal mucosal sores and single ulcers,” said lead study author Professor Chloe Orkin of the University Queen Mary of London. “Expanding the case definition will help doctors more easily recognize the infection and thus prevent people from passing it on.”
Glossary of terms
lesions
Small abrasions, wounds or tears in the fabrics. Lesions in the vagina or rectum can be cellular entry points for HIV.
inflammation
The general term for the body’s response to injury, including injury from infection. The acute phase (with fever, swollen glands, sore throat, headache, etc.) is a sign that the immune system has been triggered by a signal reporting the infection. But chronic (or persistent) inflammation, even at low levels, is problematic because it is associated with many conditions in the long term, such as heart disease or cancer. The best treatment for HIV-inflammation is antiretroviral therapy.
mucosa
A moist layer of tissue covering body openings, including the genital/urinary and anal tracts, intestines, and respiratory tract.
polymerase chain reaction (PCR)
A method of amplifying fragments of genetic material so that they can be detected. Some viral load tests are based on this method.
rectum
The last part of the large intestine just above the anus.
As Aidsmap previously reported, the UK Health Safety Agency (UKHSA) reported the first case of monkeypox in the current outbreak on 7 May. As of 18 July, UKHSA has identified 2,137 confirmed cases in the UK. The European Centers for Disease Control and Prevention reported 10,604 cases across the European region as of July 19, while the US Centers for Disease Control and Prevention tallied a total of 15,848 cases worldwide, including 15,605 in countries not yet have reported monkeypox.
Orkin and a long list of colleagues formed an international collaborative group of clinicians (SHARE-net Clinical Group), which provided data on monkeypox cases in 10 European countries, the United States, Canada, Mexico, Australia, Argentina, and Israel.
In total, they collected information on 528 cases diagnosed with a positive PCR test for the monkeypox virus between April 27 and June 24. Most were diagnosed in HIV clinics, sexual health clinics, or emergency departments.
All but one of the people with monkeypox were male, and the remaining individual identified as trans or non-binary. There were no women in this case series, although several dozen women with monkeypox have been reported from individual countries. Almost all said they were gay (96%), 2% were bisexual, and 2% identified as heterosexual.
The average age is 39 years. Fifty-six people were over the age of 50, and 9% had previously received a smallpox vaccine, indicating that previous vaccination was not completely protective. The authors did not say whether it was under 18 years of age, but countries have reported several cases among children. Three-quarters are white, 12% are Hispanic, 5% are black, and 4% are mixed race.
Regarding HIV status, 41% were HIV positive. Of these, almost all (96%) were on antiretroviral therapy, most of them (61%) on an integrase inhibitor. Most had well-controlled HIV, with 95% having an undetectable viral load (less than 50); the median CD4 count was high, 680. Among the 59% of people who were HIV negative or had an unknown status, more than half were on pre-exposure prophylaxis (PrEP). Hepatitis B (1%) and active hepatitis C (2%) are uncommon.
“While people with HIV account for more than 40% of cases so far, it is reassuring that HIV status is not associated with the severity of monkeypox,” said Laura Waters, chair of the British HIV Association.
Transmission of monkeypox
According to the study authors, “transmission is suspected to have occurred through sexual activity” in 95% of people with monkeypox in this case series.
Monkeypox virus is transmitted through close physical contact, which may include skin-to-skin contact, exchange of body fluids, and close-range respiratory droplet transmission, although it does not spread through the air over greater distances. The virus can also potentially be spread through clothing, bedding or surfaces that have been in contact with fluid from lesions, although this appears to be much less common. It is not yet known whether the virus is transmitted through semen or vaginal fluid. Before the current outbreak, monkeypox was not thought to be easily transmitted from person to person, but sexual networks of men having sex with men have provided a favorable environment for rapid transmission.
NAM aidsmap’s Susan Cole talks to Haroon Tulunai, who shares his experience of being hospitalized with a severe form of monkeypox, and Dr Laura Waters, Chair of BHIVA, about the virus.
Indeed, this group has multiple sexual risk factors. Among those screened for sexually transmitted infections (STIs), 29% tested positive, with syphilis (9%), gonorrhea (8%) and chlamydia (5%) being the most common. Among those with a known sexual history, the median number of sexual partners was five in the previous three months. One in five reported “himsex” (use of recreational drugs during sex) and 32% reported visiting sex venues in the previous months. Just over a quarter reported traveling abroad in the month before diagnosis, mostly to European countries.
“Intimate sexual contact” was the most common suspected route of transmission (95%). About a quarter (26%) had contact with a person known to have monkeypox. Close non-sexual contact and domestic contact were suspected in 1% of cases, while 3% had an unknown route of transmission.
“It is important to emphasize that monkeypox is not a sexually transmitted infection in the traditional sense of the word; it can be acquired through any type of close physical contact,” said lead study author Dr John Thornhill of Barts NHS Health Trust and Queen Mary University of London. “However, our work suggests that most transmissions so far have been related to sexual activity – mainly, but not exclusively, among men who have sex with men. This research study increases our understanding of how it spreads and the groups in which it spreads, which will help to quickly identify new cases and allow us to offer prevention strategies, such as vaccines, to those with higher risk.
Symptoms and treatment
Only 23 people diagnosed with monkeypox had a clear enough history of exposure to determine the incubation time, which ranged from three to 20 days. Most (97%) had positive smears from the skin or anogenital lesions, and 26% had positive smears from the nose or throat. In addition, some had positive PCR tests on blood (7%), urine (3%) and semen (5%) samples.
However, “this could be a coincidence as we don’t know that [the virus] is present at high enough levels to facilitate sexual transmission,” Thornhill said. “More work is needed to understand this better.”
Almost all with monkeypox (95%) developed a rash or lesions, including 73% with anal or genital lesions, 55% with trunk or extremity lesions, 41% with mucosal lesions (predominantly anal, throat, or both), 25% with lesions on the face and 10% with lesions on the palms or soles. However, 28 people (5%) did not develop lesions. Seventy-five people (14%) reported proctitis or inflammation of the rectum. Other common symptoms included fever (62%), swollen lymph nodes (56%), fatigue (41%), muscle aches (31%), headache (27%) and sore throat (21%).
Some people included in the case series had symptoms not recognized in current medical definitions of monkeypox, including single genital lesions and sores on or inside the mouth or anus. In some cases, these symptoms resemble those of common STIs, which can lead to misdiagnosis, and some people have had monkeypox and an STI at the same time. The study authors emphasize the importance of educating healthcare providers on how to identify and manage these new clinical symptoms.
Seventy people (13%) were hospitalized, mostly for treatment of severe rectal pain (21 people), soft tissue infections (18 people), or a sore throat that led to difficulty swallowing (5 people); 13 were in hospital for quarantine. Two each had eye lesions, acute kidney injury and myocarditis (inflammation of the heart muscle). Several men who have shared their stories in the press or on social media have described severe pain in the anus or throat.
Only a small number of people (5%) received antiviral treatment, which is in short supply and difficult to obtain. Two each received tecoxiramit (Tpoxx) and cidofovir (Vistide), and one received immunoglobulin vaccine (antibody therapy).
No deaths were reported in this case series. There have been five deaths from monkeypox so far this year, all in African countries.
“Findings from this study, including the identification of those at greatest risk of infection, will help support the global response to the virus,” according to a news release about the report. “Public health interventions targeting this high-risk group could help detect and slow the spread of the virus.” Recognizing the disease, tracing contacts and advising people to self-isolate will be key components of the public health response.”
The study authors emphasize that public health measures need to be developed and…
Add Comment