The skin is a critically important part of the immune system and provides excellent defense against infections. In addition to being a structural barrier, the skin contains specialized cells which respond quickly to contain invading pathogens and start the healing process after injury. Any break in the skin—including sores caused by monkeypox—can cause scarring if the healing process is disrupted. To understand how scars form during healing, it is useful to first consider how the immune system detects an invading pathogen and resolves the infection by generating new skin.
Monkeypox is transmitted by close skin-to-skin contact
Monkeypox can be transmitted in a variety of ways, including intimate contact, such as during sexual activity, or other close skin-to-skin contact. The virus can also be acquired by handling animals, such as by being scratched or bitten. In a 2003 US outbreak, monkeypox was passed from infected rats to prairie dogs while they were caged in proximity to each other during importation to the US. The virus was then passed to 47 people in 6 states by handling the infected prairie dogs or their bedding.
Scientists are currently gathering more precise information about the mode of monkeypox transmission in the current outbreak. For example, data is being gathered on whether monkeypox can be transmitted by someone who does not have symptoms, and how often it is spread through respiratory secretions or seminal fluid, urine or feces.
Immune defense lies just beneath the skin
When a virus like monkeypox comes in contact with the skin, it is detected by dendritic cells. These special parts of the adaptive immune system are so named because of their probing nature, squeezing between cells while they are on the hunt for viruses and bacteria. Invading microbes are picked up by immature dendritic cells, which carve their proteins up into smaller pieces (peptides) and present the peptides as antigens to the T cells, inducing a cascade of activities resulting in antibody production. One of the reasons why the new intradermal monkeypox vaccine option can work with just 1/5th the dose of a subcutaneous injection is due to the rapid uptake of these dendritic cells just beneath the surface of the skin.
This vast oversimplification does not do justice to the complexity of the immune response, but it should provide some reassurance about our underlying defenses against viruses like monkeypox. In addition to the adaptive immune system and the antibodies produced specifically against monkeypox, we also have innate immune cells which tell infected cells to self-destruct. Staying hydrated is one simple step we can take to boost immunity. Good hydration allows all these roving first-responders to squeeze between cells quickly while patrolling the body.
Can monkeypox live on household surfaces?
Curbing the spread of monkeypox will require humans to make behavioral changes, such as taking note of new lesions (e.g., bumps, pimples, insect bites) and systemic symptoms (e.g., fever, headache, swollen lymph nodes in the neck, under the arms or the groin area) and staying home when ill. As with any illness, avoid prolonged close contact with others, especially face-to-face and skin-to-skin contact, and contact your local health department about getting tested.
Covering the lesions will reduce the chance of contaminating clothes, linens and the environment with material from the sores. A 2021 study collected monkeypox virus samples from a residence to evaluate the potential for household transmission. The authors found that monkeypox is detectable on surfaces for at least 15 days, but the virus was much more likely to be viable—capable of causing infection—on porous surfaces like bedding or clothing than non-porous surfaces such as plastic or metal. Still, it is uncertain what amount of virus is necessary to cause infection in another person. We do know that household transmission can occur, and that people have contracted monkeypox without engaging in any sexual activity.
Keep lesions covered to promote healing, reduce scarring
The lesions caused by the monkeypox virus will slowly scab and flake off as new skin forms. A person is considered infectious until new skin grows over the lesion. The inflammatory process involved in healing goes through phases as fascinating as the immune response to infection, and can take three to six weeks or longer. The first phase is inflammation, during which the immune system responds to antigens presented by the dendritic cells while other immune agents clean up the debris formed by dead cells. This debris is carried away by the lymphatic system and is what causes swollen lymph nodes.
The second phase—called proliferative—is when collagen is deposited to stabilize the damaged area and provide a scaffold for new cells to grow. The third and longest stage of healing is the remodeling phase which starts around week three. During this time, the collagen used to close the wound is removed because it is no longer needed. If this process is disrupted, the skin does not close over fully and the collagen remains, appearing as a flatter or pale section of skin.
The process of wound remodeling can take from a few weeks up to twelve months, so any scarring is not necessarily permanent. Many products such as vitamin E or silicone gels are promoted to reduce scarring, however, the scientific evidence in support of their effectiveness is somewhat limited.
Immunity is more than skin deep
Any break in the skin—including sores caused by monkeypox—can cause scarring if the healing process is disrupted. The best prevention against scarring is to avoid scratching the cuts or monkeypox lesions as they heal. Keeping monkeypox sores covered prevents the shedding of infectious virus particles around the house, on clothes, towels and bedding. It is also less likely that itchy bumps will be scratched, causing secondary infections with bacteria which can slow down the healing process and potentially increase the likelihood of scarring. Although the outbreak of monkeypox is worrisome, remember how well the immune system is prepared to defend against the everyday assaults of viruses and bacteria.