mpox

Cúm là gì?

Mpox (previously known as monkeypox) is a viral zoonosis (an infection spread from animals to humans). It is caused by a virus that belongs to the orthopoxvirus genus (which also causes the variola virus responsible for smallpox disease). Since the eradication of smallpox in 1980, mpox has become the most important orthopoxvirus affecting humans.

Cần để ý những gì

The incubation period of mpox is usually 7-14 days, but can be as short as 5 days or as long as 21 days. The initial symptoms include fever, headache, muscle aches, fatigue and lymphadenopathy. Lymphadenopathy in this early phase is a key feature of mpox.

1-3 days following the beginning of fever, a rash may develop, often beginning on the mouth and face, and then spreading to other areas of the body. The face is involved in 95% infections, followed by the palms of the hands and soles of the feet (75%). Oral mucous membranes are involved in 70% of cases, and involvement of the genitalia is also common (30%).

The rash is initially characterised as being erythematous (reddened) and macular (flat), which then develops papular features (raised areas) and turns into well-demarcated pustules and vesicles (blisters). These then dry into crusts and fall off. The number of lesions is highly variable, ranging from a couple to over a thousand.

The infection is usually self-limiting with symptoms lasting from 2-4 weeks. Complications can include secondary infection such as cellulitis, sepsis, infection of the cornea (which can threaten vision), bronchopneumonia and encephalitis. The case fatality ratio is between 3-6%. More severe illness can occur in immunocompromised people.

Bệnh lây truyền qua đường nào

Mpox lây lan qua đường lây truyền từ động vật sang người (zoonotic) hoặc lây truyền từ người sang người.

Zoonotic transmission involves direct contact with the bodily fluids, blood, or lesions (cutaneous or mucosal) of infected animals (often through bites or scratches). This is most common for people living near or within forest areas with exposure to infected animals.

Human-to-human transmission involves close contact with respiratory secretions (through activities such as kissing), the skin lesions of an infected person (by touching or sexual contact), or through contact with contaminated objects such as linen or clothing. Droplet particle transmission requires prolonged face-to-face exposure, placing household contacts at highest risk. This can be minimised by isolating away from other members of the household. Infections during pregnancy can be transmitted to the baby.

Nhân viên y tế chăm sóc cho những người mắc bệnh mpox phải thực hiện các biện pháp phòng ngừa kiểm soát nhiễm trùng và việc xử lý các mẫu xét nghiệm phải do nhân viên được đào tạo phù hợp thực hiện.

Dịch tễ học

Mpox rất phổ biến ở Tây và Trung Phi, thường ở những khu vực có rừng mưa nhiệt đới. Tuy nhiên, hiện đang có những đợt bùng phát ở nhiều quốc gia khác trên toàn cầu bao gồm Úc và một số khu vực của Châu Âu và Vương quốc Anh.

Vắc-xin

There are two types of vaccines available for use in Australia for the prevention of mpox:

• ACAM2000 – 2nd generation, live-attenuated vaccine
• JYNNEOS (MVA-BN) – 3rd generation, non-replicating vaccine.

Both vaccines are formulated using the vaccinia virus, a poxvirus related to smallpox and mpox.

JYNNEOS (MVA-BN) can be administered either subcutaneously (preferred) or intradermally. ACAM2000 must be administered via a percutaneous route which can only be performed by a provider who is trained in this complex technique. ATAGI preferentially recommends JYNNEOS (MVA-BN) vaccine due to the ease of administration and decreased likelihood of side effects.

khuyến nghị

Vaccines can be administered as either primary preventative vaccination (PPV) or post-exposure preventative vaccination (PEPV). For PEPV, vaccination within 4 days is recommended to provide optimal protection against the development of mpox infection. Vaccination between 4-14 days following exposure may lessen the severity of disease.

Tiêm chủng hiện được khuyến nghị cho các nhóm sau:

• sexually active gay, bisexual or other men who have sex with men (GBMSM), including transgender and gender diverse people
• sex workers
• people living with HIV or other immune suppressive conditions if at risk of mpox exposure
• laboratory personnel working with orthopoxviruses
• high-risk contacts of a confirmed case of mpox.

Vaccination may also be considered for:

• healthcare workers at risk of exposure to patients with mpox
• regular sexual partners of GBMSM, sex workers and people living with HIV.

Chống chỉ định

Bất cứ ai có tiền sử sốc phản vệ to a previous dose of the vaccine to be administered or anaphylaxis to a component of the vaccine to be administered should not be vaccinated.  Due to the risk of vaccine associated disease, ACAM2000 is contraindicated for those with suy giảm miễn dịch hoặc những người có thai.

Individuals with active eczema, atopic dermatitis or other exfoliative skin conditions should not receive ACAM2000 due to the risk of developing eczema vaccinatum (a reaction to smallpox vaccination experienced by people with eczema/atopic dermatitis resulting in a severe rash and systemic illness).

Các biện pháp phòng ngừa

Subcutaneous vaccination is preferred over intradermal in individuals with a history of keloid scarring.

Individuals receiving ACAM2000 as PPV should consider an interval of 4 weeks between vaccination and administration of COVID-19 vaccines due to the rare risk of viêm cơ tim/viêm màng ngoài tim.

Table 1: Vaccine brands, dose and route 

* subcutaneous and intradermal routes are considered interchangeable to complete a primary course; when vaccinating post-exposure (PEPV) using a subcutaneous route is preferred for the first dose
^ only immunisation providers with appropriate training and experience should administer vaccines via an intradermal route
# percutaneous administration involves using a bifurcated needle and scarification technique which requires specialised training and accreditation
Ω for full aftercare instructions, refer the Thông tin sản phẩm

Tài liệu

Thông tin chương trình Victoria

• Bộ Y tế Victoria: Mpox [bao gồm thông tin về nơi tiếp cận vắc xin]

Các nguồn lực khác

• Bộ Y tế và Chăm sóc Người cao tuổi của Chính phủ Úc: Tài nguyên Mpox
• Nhiễm vi-rút Mpox: Hướng dẫn Quốc gia CDNA cho các Đơn vị Y tế Công cộng
• Kênh sức khỏe tốt hơn: Mpox