Mpox as a public health emergency of international concern

Abstract

Mpox is a disease caused by the monkeypox virus (MPXV), first documented in humans in 1970 in the Democratic Republic of Congo (DRC). Historically considered a zoonotic disease limited to certain regions of Africa (1), mpox has two clades, I and II, each with particular epidemiological and clinical characteristics.
The outbreak of mpox began in April 2022 and spread to several countries in Europe and the Americas, leading to the declaration of an international public health emergency by the WHO in July 2022 (2), valid until May 2023.
Clade IIb was identified as the cause of the outbreak, and a change in transmission patterns was observed. It has evolved from a primarily zoonotic disease to an infection with a higher efficiency of person-to-person transmission, occurring through close contact, including sexual contact.
The majority of cases occurred in cis men, and transmission in the setting of sexual practices was identified as the main route, especially among gay men and other men who have sex with men (MSM) (3). The high prevalence of co-infection with HIV, syphilis and gonorrhea confirmed these changes in transmission.
The epidemic curve had a rapid rise until August 2022, affecting more than 100 countries, with a subsequent decline, but maintaining the appearance of outbreaks or sporadic cases, mainly in the Americas. As of September 2024, 123 WHO member states have reported 109,699 cases and 263 deaths.
In the Americas, 65,884 cases and 150 deaths were recorded. Of the total, 95.8% were male, 84.8% were MSM, and 59.0% were people living with HIV.
The clinical presentation was characterized by progressive lesions, starting as macules, evolving to papules, vesicles, pustules and finally crusts. The novel feature was the location of the lesions in genital and perianal areas, and oropharyngeal mucosa, related to transmission routes. Intense pain in the affected areas was one of the main symptoms of consultation and hospitalization of these patients. Severe complications such as fever, superinfections, generalized lymphadenopathies and sepsis were observed in immunocompromised individuals and those with comorbidities.
Treatment focuses on alleviating symptoms and preventing complications, as antivirals such as tecovirimat are still in the research phase with no proven clinical effectiveness.
The identification of the new Ib clade in Africa, with an increase in cases in the Democratic Republic of Congo (DRC) and its spread to neighboring countries, has prompted the WHO Director-General to re-declare mpox as a public health emergency of international concern on August 14, 2024, under the IHR. This statement is prompted by the fact that the Ib clade maintains sustained human-to-human, close contact and sexual circulation in the DRC, Burundi, Kenya, Rwanda and Uganda in a previously unknown manner and with initial reports suggesting increased morbidity and mortality. As of October 18, 2024, three cases had been confirmed outside Africa, in Sweden, Thailand and Germany (4).
The outbreak of mpox that began in 2022, which continues to this day, albeit less frequently, together with the appearance of a new clade in Africa, requires maintaining and deepening epidemiological surveillance measures to detect new cases, control outbreaks and conduct studies to identify the circulating clade in each country. To this end, mandatory reporting of mpox should be included in surveillance systems.
It is crucial to integrate the response into HIV and STI prevention and control programs, including clinical suspicion and screening for signs and symptoms in key populations and people living with HIV.
Prevention should include dissemination of information on modes of transmission, risk communication and protective measures including vulnerable and key populations. practices of these populations.

The involvement of the affected communities was crucial in the control of the 2022/23 outbreak, including the dissemination of information for changes in the sexual practices of these populations (5). Risk communication should address stigma and discrimination, highlighting that while anyone can get mpox, there are key communities and populations that are more affected (6).
Smallpox vaccines have shown to be partially effective against mpox and WHO recommends their use in groups with higher exposure, especially in outbreak situations. Equitable access to vaccines remains a challenge due to limited supply and high cost. Each country should evaluate its immunization strategy based on epidemiology and resource availability.
In summary, the emergence of mpox as an infection associated with sexual practices, with greater impact on key populations and the appearance of a new clade with the potential for global dissemination, should alert us to deepen public health strategies that include surveillance, prevention and care of individuals. It is imperative to incorporate mpox surveillance, prevention and care into combination prevention and care strategies and services for HIV and STIs, which should include, among others, HIV/STI screening, PEP, PrEP, immunizations for hepatitis A and B, HPV and condom provision. 
The involvement of the affected communities was crucial in the control of the 2022/23 outbreak, including the dissemination of information for changes in the sexual