Table.
Comparison of the clinical presentation in the 2022 outbreak with previous outbreaks
| 2022 outbreak | Previous outbreaks | |
|---|---|---|
| Population features | ||
| Mean age | 37–41 years | 26–32 years |
| Smallpox vaccination in childhood | 11–18% | 20% |
| Incubation period | 6–7 days | 12 days |
| Sex | ||
| Male | 97–100% | 53–78% |
| Female | 0–3% | 22–47% |
| Systemic features | ||
| Systemic symptoms | Fever (54–72%), fatigue or myalgia (24–81%), and headache (25–53%) | Fever (45–90%), fatigue or myalgia (73–85%), and headache (48–79%) |
| Lymphadenopathy | 55–87%, localised in the lymph catchment area of lesions | 57–87%, localised or generalised |
| Systemic symptoms start after rash | 38–52% | 15–66% |
| Clinical features of the rash | ||
| More than 10 lesions | 22–36% | 100% |
| More than 20 lesions | 12% | 46% |
| More than 100 lesions | 0–4% | 20–42% |
| Progression | Lesions present at different stages simultaneously; not all lesions progressed from one phase to another in order | Progression from one phase to another occurs in order |
| Distribution | Commonly localised to 1–3 body regions | Commonly disseminated to >3 body regions |
| Localisation | Genitalia (55–61%), perianal (34–44%), oropharyngeal (14–43%), trunk (25–57%), arms and legs (50–60%), face (20–39%), and palms or soles (0–10%) | Genitalia (67–68%), perianal (not reported), oropharyngeal (38%), trunk (80–93%), arms and legs (81–91%), face (96–98%), palms (28–55%), and soles (10–64%) |
| Outcome | ||
| Complications | Rectal pain (14–36%), sore throat (17–36%), difficulty swallowing related to tonsillar or pharyngeal ulcer (5–14%), penile oedema (8–16%), proctitis (11–25%), secondary bacterial infection (3–4%), and conjunctivitis (1%) | Secondary bacterial infection of skin lesions (19%), bronchopneumonia (12%), sepsis (1%), encephalitis (0·4%), keratitis (0·4%), and retropharyngeal abscess (0·4%) |
| Hospital admission | 1–13% | 26% |
| Risk factors for severe disease | Unknown | Age (younger ages are more at risk), living with HIV and not being on antiretroviral therapy |
| Fatality rate | <0·1% | Clade 1 had 1–12%, clade 2 had <0·1% |
| Sexual health | ||
| Living with HIV | 36–67% | ND |
| Concomitant STI | 16–76% | ND |
| History of STI in past 12 months | 54–55% | ND |