Sixteen countries reported monkeypox virus infection in humans between April and June 2022

By Dr. Priyom Bose, Ph.D.Reviewed by Aimee MolineuxJul 27 2022

Monkeypox virus is a zoonotic DNA virus that was first discovered in 1970 in the Democratic Republic of Congo. This virus is related to smallpox and has caused sporadic outbreaks in Africa due to direct contact with infected animals, and in particular, rodents.

A limited secondary spread outside the country has indicated that human-to-human transmission is not a potent route of disease spread. Although for many years, the monkeypox virus has caused an endemic outbreak, it has been left mostly neglected by researchers.

Background

Since early May 2022, around 3000 monkeypox virus infections from 50 countries across five regions have been reported. As a result, on June 23, 2022, the World Health Organization (WHO) announced monkeypox virus infection as an evolving threat of moderate public health concern.

The monkeypox virus is transmitted through direct contact with skin lesions, large respiratory droplets, or contaminated fomites. Sexual transmission of the virus through vaginal or seminal fluids has not yet been confirmed. The first symptom related to monkeypox virus infection is fever, followed by the manifestation of vesiculopustular, multiple papular, and ulcerative lesions on the body and face.

Severely infected patients with the monkeypox virus may suffer encephalitis, pneumonitis, secondary bacterial infections, and keratitis. Previous studies have stated that immunocompromised persons, patients with human immunodeficiency virus (HIV), and younger children are at an increased risk of severe infection.

The recent global outbreak of monkeypox virus infection in humans indicates changes in the biological characteristics of the virus and/or changes in human behavior (e.g., waning of smallpox immunity). Importantly, scientists observed that gay or bisexual men are mostly affected by this virus through their sexual networks.

Researchers have conducted phylogenetic analyses and found that the monkeypox virus has been circulating undetected for some time, beyond the areas where it has previously caused an endemic. The current international guidelines do not appropriately define the changing spectrum of clinical presentation of the viral infection, early detection, or clarify transmission routes. 

A new study

Researchers have recently addressed the aforementioned research gap and analyzed the recent cases related to monkeypox virus infection. This study is available in the New England Journal of Medicine.

The current study used the U.K. Health Security Agency (UKHSA) definition for a confirmed monkeypox virus infection. According to this definition, a positive monkeypox virus infection is confirmed by polymerase-chain-reaction (PCR) assay, using a sample from any anatomical site. 

In this study, researchers formed an international collaborative group of clinicians who handled monkeypox virus infection. The London-based Sexual Health and HIV All East Research (SHARE) collaborative contacted fellow researchers in the affected countries and formed a global collaborative group, namely, SHARE-net. Members of this group have focused on quickly identifying the virus.

Findings

The current study reports a series of human monkeypox virus infections containing 528 cases from four WHO regions, i.e., America, Europe, Eastern Mediterranean and Western Pacific, and 16 countries. The data was collected from these locations between April 2022 and June 2022.

The authors reported that sexual activity, particularly among gay or bisexual men, is a common route of monkeypox virus transmission. This finding is supported by the occurrence of primary anal, genital or oral mucosal lesions, which may be the inoculation site. Scientists were able to detect the virus DNA in the seminal fluid of the infected candidates, which further supports the hypothesis. However, whether the viral DNA present in the semen was replication competent should be confirmed in the future. International travel, attendance at large gatherings, and sex-onsite activities may be the reason behind the global transmission of the virus.

Scientists stated that the presence of solitary lesions in the palms and soles, or genital skin lesions, may lead to misdiagnosis as syphilis or other sexually transmitted infections (STIs). These misdiagnoses may delay the proper treatment of monkeypox virus infection. However, the authors reported a high risk of monkeypox virus infection in patients with STIs.

In the study series, the diagnosis of monkeypox was mostly confirmed through swab samples obtained from skin or genital lesions, as well as the throat or nasopharyngeal tract. The authors recommended that anal or rectal swabs be considered for those presenting proctitis.

Scientists revealed that the clinical outcomes of the study cohort were reassuring, with no deaths. Thirteen percent of patients required hospital admission due to pain and bacterial superinfection, showing no serious complications. The authors reported that similar clinical symptoms and severe monkeypox infection occurred in patients with or without HIV infection.

Conclusion

The authors strongly recommended that healthcare professionals must be provided with proper guidance to manage monkeypox virus cases more efficiently. Although the UKHSA recommends the use of condoms for eight weeks after infection, the exact duration of infectious viral shedding through semen, after healing of lesions, is not yet clear. The effectiveness of vaccines in protecting individuals from monkeypox infection is yet to be determined. At present, the United Kingdom, New York City, and Canada are vaccinating individuals who are at a high risk of this infection.