Human monkeypox was first identified in humans in 1970 in the Democratic Republic of the Congo in a 9-year-old boy in a region where smallpox had been eliminated in 1968.
Monkeypox is a disease of global public health importance as it not only affects countries in west and central Africa, but the rest of the world. In 2003, the first monkeypox outbreak outside of Africa was in the United States of America and was linked to contact with infected pet prairie dogs. These pets had been housed with Gambian pouched rats and dormice that had been imported into the country from Ghana. This outbreak led to over 70 cases of monkeypox in the U.S. Monkeypox has also been reported in travelers from Nigeria to Israel in September 2018, to the United Kingdom in September 2018, December 2019, May 2021 and May 2022, and to the United States of America in July and November 2021. In May 2022, multiple cases of monkeypox were identified in several non-endemic countries. Studies are currently underway to further understand the epidemiology, sources of infection, and transmission patterns.
Signs and Symptoms
In humans, the symptoms of monkeypox are similar to but milder than the symptoms of smallpox. Monkeypox begins with fever, headache, muscle aches, and exhaustion. The main difference between symptoms of smallpox and monkeypox is that monkeypox causes lymph nodes to swell (lymphadenopathy) while smallpox does not. The incubation period (time from infection to symptoms) for monkeypox is usually 7−14 days but can range from 5−21 days.
The illness begins with:
- Fever, Headache, Muscle aches, Backache, Swollen lymph nodes, Chills, Exhaustion
Within 1 to 3 days (sometimes longer) after the appearance of fever, the patient develops a rash, often beginning on the face then spreading to other parts of the body.
Lesions progress through the following stages before falling off:
- Macules, Papules, Vesicles, Pustules, Scabs
The illness typically lasts for 2−4 weeks. In Africa, monkeypox has been shown to cause death in as many as 1 in 10 persons who contract the disease.
Vaccination against smallpox was demonstrated through several observational studies to be about 85% effective in preventing monkeypox. Thus, prior smallpox vaccination may result in milder illness. At the present time, the original (first-generation) smallpox vaccines are no longer available to the general public.
JYNNEOSTM (also known as Imvamune or Imvanex) is an attenuated live virus vaccine which has been approved by the U.S. Food and Drug Administration for the prevention of monkeypox. The Advisory Committee on Immunization Practices (ACIP) is currently evaluating JYNNEOSTM for the protection of people at risk of occupational exposure to orthopoxviruses such as smallpox and monkeypox in a pre-event setting.
Description of the outbreak
As of 21 May, 13:00, 92 laboratory confirmed cases, and 28 suspected cases of monkeypox with investigations ongoing, have been reported to WHO from 12 Member States that are not endemic for monkeypox virus, across three WHO regions (Table 1). No associated deaths have been reported to date.
Table 1.Cases of monkeypox in non-endemic countries reported to WHO between 13 to 21 May 2022 as at 13:00.
|United States of America||1-5||–|
To date, all cases whose samples were confirmed by PCR have been identified as being infected with the West African clade. Genome sequence from a swab sample from a confirmed case in Portugal, indicated a close match of the monkeypox virus causing the current outbreak, to exported cases from Nigeria to the United Kingdom, Israel and Singapore in 2018 and 2019.
The identification of confirmed and suspected cases of monkeypox with no direct travel links to an endemic area represents a highly unusual event. Surveillance to date in non-endemic areas has been limited, but is now expanding. Available information suggests that human-to-human transmission is occurring among people in close physical contact with cases who are symptomatic.
There are number of measures that can be taken to prevent infection with monkeypox virus:
- Avoid contact with animals that could harbor the virus (including animals that are sick or that have been found dead in areas where monkeypox occurs).
- Avoid contact with any materials, such as bedding, that has been in contact with a sick animal.
- Isolate infected patients from others who could be at risk for infection.
- Practice good hand hygiene after contact with infected animals or humans. For example, washing your hands with soap and water or using an alcohol-based hand sanitizer.
- Use Personal Protective Equipment (PPE) when caring for patients.