Monkeypox Q&A
What is monkeypox?
Monkeypox is caused by the monkeypox virus, which belongs to the Orthopoxvirus genus in the family Poxviridae. Though monkeypox is rare, it is endemic in Central and West African countries. There are two distinctive clades of the virus: the West African and the Congo Basin (or Central African). The Congo Basin clade (a group of similar viruses based on genetic sequences) is thought to cause more severe disease and be more lethal than the West African clade. The current virus seen in cases in the U.S. is the less severe West African clade. Despite the name, the reservoir species for monkeypox is unknown, though non-human primates remain susceptible to the disease, along with many other mammals including rodents. The most recent prior U.S. outbreak in 2003 was traced to infected prairie dogs, and there are concerns that if this outbreak is able to infect rodents, a persistent reservoir could develop leading to ongoing sporadic outbreaks in the future. Monkeypox can be transmitted from animal to human (zoonotic) or human to human. Transmission can occur through large respiratory droplets (theoretical risk of airborne transmission but not as contagious as SARS-CoV-2), body fluids, skin lesions (contact), and contaminated items. Contact during sex can spread monkeypox, but it is not classically a sexually transmitted disease — it is simply that during sex, there is skin to skin contact and shared air.
What are the symptoms of monkeypox?
Within 1-3 days after fever appears, patients develop a rash. This rash generally starts on the face and extremities (including palms and soles of the feet), and spreads to other parts of the body. The rash evolves from macules, to papules, to vesicles, to pustules before scabbing and eventually crusting over. Lesions are often noted in the oral mucous membranes and can cause difficulties with drinking and eating. These can also develop in the conjunctivae and cornea, as well as groin and genitals. It has been reported that patients in the current monkeypox outbreak have presented differently, with minimal symptoms prior to rash development, and rash originating in the groin area. Confirmed cases of monkeypox should be isolated until lesions have crusted over and a fresh layer of skin has formed underneath. Pitted scars, hyperpigmentation and/or hypopigmentation skin may remain after the crusts have fallen off. Once all crusts have fallen off, a person is no longer contagious. Generally, the duration of diseases is between 2-4 weeks.
Are there vaccines for monkeypox?
The virus that causes smallpox (variola virus) also belongs to the family Poxviridae. Like monkeypox virus, variola virus belongs to the genus Orthopoxvirus. Individuals who are vaccinated for smallpox may be at reduced risk for monkeypox. Routine vaccination for smallpox was halted in the U.S. in 1972, and most individuals under the age of 50 are unvaccinated. The smallpox vaccination has been shown to be approximately 85% effective in preventing monkeypox, however the number of people who have received this has declined since the eradication of smallpox. There is currently one FDA approved vaccine for the prevention of monkeypox (JYNNEOS), which is currently under evaluation for the protection of individuals at increased risk of exposure to orthopoxviruses.
Is there any treatment for monkeypox?
There is no specific treatment FDA-approved for monkeypox at this time. Symptoms usually resolve on their own, though patients should take care of their rash by allowing it to dry or applying a moist dressing. There are currently several experimental antiviral treatments for monkeypox, though there is limited data as to who may benefit from these treatments.
How does the West African clade variant of monkeypox death rate compare to smallpox?
Historically, the case-fatality rate of smallpox was estimated to be as high as 30%. In comparison, the case-fatality rate of the West African clade of monkeypox is estimated to be 3.6%, but there have been no reported deaths in recent U.S. outbreaks, possibly due to the level of supportive care available.
How long after vaccination is the smallpox vaccine effective against monkeypox? Is the protection lifelong?
In individuals historically vaccinated for smallpox with the Dryvax vaccine, immunity may be maintained for up to 75 years against smallpox. Research has shown that the duration of monkeypox immunity from the smallpox vaccination varies, but some level of protection may be offered long after an individual has been vaccinated.
At what point does an individual with monkeypox become infectious to others — incubation, systemic symptoms such as fever, or only once the rash develops?
According to the CDC, individuals are not contagious during the incubation period. Individuals may be contagious during initial symptom onset and are contagious from the rash phase of the disease until the lesions are completely crusted over.
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