Mpox

Increasing activity from the West African clade has been identified since early May in the UK, USA, Europe and Canada. This clade tends to cause milder disease.

Transmission:

Mpox does not spread easily between people. Person-to-person spread, may occur through skin-to-skin contact especially with lesions present, and can occur during sex, household contact, through contact with contaminated linens or clothing, or via respiratory droplets from prolonged face-to-face contact. Among the recent cases of mpox identified, a high proportion are people who self-identify as gay or bisexual, or men who have sex with men.

Clinical presentation:

The majority of recent cases have reported skin lesions in the mouth and on the genitals. Lesions can also involve the face, palms, soles of feet, and trunk. This can be preceded or accompanied by fever, night sweats, headaches, swollen lymph nodes, and joint or muscle pain. None of the cases have been seriously ill.

The incubation period (i.e. the time from exposure to when someone starts to develop symptoms) is usually brief (five to seven days) but can be up to 21 days from close, prolonged contact with a case. Cases are infectious from onset of symptoms and remain infectious until all skin lesions have healed and crusts have fallen off. In most cases, the illness resolves in two to four weeks. Serious complications (pneumonia, sepsis, keratitis, etc.) are rare. Children, pregnant women and some immunocompromised individuals may be at higher risk for severe disease.

Differential diagnosis:

Vesicular rashes can be caused by a number of viruses including Herpesviruses (herpes simplex or varicella), syphilis, chancroid, poxviruses (including molluscum contagiosum) and Lympogranuloma venereum.

Management of suspected cases:

Suspect cases are those with known contact with a case who have clinically compatible symptoms, or those who may fit the epidemiological profile (e.g., travel to an area with known cases) with clinically compatible symptoms where other diagnoses have been ruled out.

Diagnosis is confirmed by PCR testing of lesions. Before sampling, consult your local medical microbiologist (BCCDC Medical Microbiologist On-Call: 604-661-7033) or infectious disease physician. Samples from lesions (such as roofs, crusts, aspirate, or tissue), including dry swabs or swabs in Universal Transport Medium (UTM), should be shipped refrigerated to the BC Centre for Disease Control for mpox testing.

Droplet and contact precautions should be used in clinical settings, and airborne precautions in hospital settings, where feasible. Instruct suspected patients to isolate at home and limit close contact with others while pending results, as well as to cover lesions, wear a medical mask and regularly perform hand hygiene while around others.

Please report clinically compatible cases to public health by calling 604-587-3828 Monday - Friday during working hours and the Medical Health Officer on-call at 604-527-4806 after hours.

Treatment:

Most individuals have mild symptoms and do not require any specific interventions. Treatment is supportive and targeted for symptom control (fever, hydration). Antiviral treatment for individuals with severe disease (e.g., requiring hospitalization) may be considered under the guidance of infectious disease specialists.

Confirmed cases:

Public Health will conduct contact tracing of confirmed cases (i.e. those who test positive for mpox). Close contacts of cases may be eligible for mpox vaccine (Imvamune™) which is effective in reducing the risk of illness or its severity if given within 14 days of exposure. Decisions on eligibility for vaccine will be made by Public Health. Vaccine does not have any benefit in modifying illness in a case.

Advice for close contacts of a confirmed case:

• Sexual and household contacts are advised to monitor for symptoms for 21 days.
• Limit close contact, including sexual contact, during the monitoring period.
• If symptoms develop, visit a health care professional. Wear a mask and cover the lesions for your consult. Please inform the clinic ahead of your visit.