Authored by: Venkat Rao
In a just published disease surveillance report, a high prevalence of HIV, the virus that causes AIDS, among people diagnosed with Monkeypox. According to the US Centers for Disease Control and Prevention (CDC) analysis of 1,969 monkeypox cases in the US diagnosed between May to July 2022, 38% were infected with HIV and another 41% were treated for other sexually transmitted diseases (STI), and 61% had either HIV or a STI. Persons with both monkeypox and HIV reported more severe rectal bleeding and cramping rectal pain (tenesmus), and inflammation of the lining of rectum (proctitis).
Among persons with monkeypox and diagnosed with HIV infection, 94% had received HIV care in the preceding year and 82% had an HIV viral load indicative of viral suppression. Also, compared to only 3% of monkeypox patients without HIV infection requiring hospitalization, 8% of persons with HIV infections and having monkeypox required hospitalization. CDC reported a disproportionately higher percentage of monkeypox patients also infected with HIV or other STI.
An international collaborative group of clinicians reported in the New England Journal of Medicine of 528 infections diagnosed between April and June 2022 at 43 clinical locations in 16 countries. Overall, 98% of the clinical cases of monkeypox infection were MSM or bisexual men, 75% were White, and 41% had HIV infection, with a median age of 38 years. Transmission in 95% of the cases reported were linked to sexual activity. Earlier this week, researchers from Europe reported presence of viable monkeypox virus in anal and urethral samples from monkeypox patients, further substantiating the likely transmission route of the virus.
With more reports on monkeypox virus and transmission route for infection, it is becoming increasingly clear that human-to-human transmission occurs through contact with infectious materials, skin lesion and exposure to respiratory droplets, or prolonged face-to-face contact as it would happen during intimate and sexual interactions between individuals.
A complicating factor is that the current outbreak is not confined to sexual mode of transmission. The virus is detected from many other sources as well including feces, semen, urine as well as nasopharyngeal and rectal swabs. The primary route of transmission for the current version of monkeypox outbreak seems to be skin-to-skin contact and exposure to respiratory droplets from infected persons. These modes of exposure are not typical of a STI and the mode of transmission of this virus resembles more like herpes.
Note that both CDC and Eurosurveillance reports were based on a small patient sample diagnosed and reported monkeypox cases and cannot be used to generalize the current outbreak as a STI. Reports of monkeypox virus in children and other population groups make it hard to narrow the scope and range of monkeypox to a select population group and sexual behaviors.
Is monkeypox a solely sexually transmitted disease?
Given the divergent conclusions from published studies, answer to this question is rather murky. Whereas more than 95% of the monkeypox cases reported in the United States were associated with some form of sexual contact among men who have sex with men (MSM).
CDC recommends STI screening for all persons diagnosed with monkeypox with an implicit acknowledgement of its overlap characterization. Monkeypox spreads through other routes as well, although most involve skin-to-skin contact, not necessarily sexual in nature. Exposure to respiratory secretions from monkeypox patients to those caring the patient, and healthcare personnel, is also a cause of spread. In the US alone, confirmed monkeypox cases were reported in at least 22 adolescents and children aged 15 or younger and 314 cases in young people aged 16 to 20. Nevertheless, the risk of monkeypox to children and adolescents in the United States is deemed very low. Also, there have been no reports of spread through unwashed surfaces such as bed linens and towels. Casual encounters with someone with monkeypox while walking, casual conversation, or touching doorknobs are not generally considered a route for spread of monkeypox.
Monkeypox virus in the current outbreak appear different
Note that monkeypox is not a new virus. It was first discovered by researchers in colonies of monkeys kept in the 1950s, hence, the name, monkeypox. The virus was first discovered in humans in the 1970s. In the past 50 years there have been sporadic outbreaks of monkeypox all over the world, including the 2003 outbreak in the US that was linked to imported Gambian giant rats by an exotic pet dealer.
Researchers and public health officials are concerned about the 2022 outbreak. According to the WHO epidemiologist Rosamund Lewis, previous monkeypox outbreaks were mild, “causes skin lesions resembling smallpox and is not easily transmitted and spread typically limited to isolating cases”. More importantly, currently available vaccines and several drugs developed to combat smallpox are effective countermeasures against the monkeypox virus as well.
It is interesting to note that, in 2017, Nigerian researchers indicated sexual transmission of the virus might have occurred in several patients with genital ulcers. In the current outbreak, first detected in Spain among MSM or transgender people who had attended a sauna in Madrid or a gay pride festival in the Canary Islands. In Belgium, several cases were linked to a gay festival in Antwerp.
The ongoing global monkeypox outbreak which, in July 2022, was declared by the WHO as a global health emergency appears different compared to previous outbreaks by way of the severity of the disease, mode of transmission and environmental stability of the virus. We are beginning to learn more about the virus through data from disease surveillance in the US and Europe on the nature and mode of spread of monkeypox. Targeted research is underway to find if the virus has mutated that makes it more pathogenic and transmissible. This could be a monumental job, as Monkeypox virus genes are seven times larger than SARS-CoV-2 (COVID-19 virus) and twenty times larger than HIV (AIDS virus). The genomic analysis reveal monkeypox virus in the ongoing outbreak closely resembles the virus from the 2017 monkeypox outbreak in Nigeria with almost similar pathogenicity and person-to-person transmission efficiency.
Based on the data from the current outbreak, monkeypox is not solely a sexually transmitted infection, and is not limited to MSM. Other modes of transmission through person-to-person contact not necessarily sexual in nature makes the current outbreak unique. We need additional studies to characterize the virus and continue close monitoring of a broader category of at-risk population.