There has been so much in the news about monkeypox – perhaps because we’ve seemingly had nothing but COVID-19 information for the past two-plus years - so Travelvax has put together a few salient points about the illness and its prevention and transmission.
In the past few years, rare cases of monkeypox have been diagnosed in people returning from countries which are known to be endemic for this zoonotic infection. A zoonosis is an infection that passes from animals to humans – think rabies, leptospirosis, Q fever, plague, etc etc. Even COVID-19 has been classified as a zoonosis although as yet no animal reservoir has been confirmed.
UK public health experts were on the case quickly earlier this month after two monkeypox infections were detected in non-travellers, then four more soon after (five in total in London and the other, a linked case in England’s NE), and it was ascertained that none of those infected or their contacts had travelled to countries known to be endemic for the virus. This indicated local transmission of the virus in the community.
Just two weeks after the UK government health agency issued an alert to the public, reports of outbreaks of suspected or confirmed monkeypox infections had emerged from a dozen countries – including two cases in Australia. Of note: at this stage, reporting of case numbers is likely to be higher due to greater awareness among both health professionals and the general public.
A few points to make:
- Monkeypox, a zoonotic disease found in Central and Western Africa, is caused by a virus closely related to the variola, or smallpox virus.
- It is an orthopoxvirus and is not related to chickenpox (a herpesvirus).
- Endemic countries are: Benin, Cameroon, the Central African Republic, Congo, Côte d’Ivoire, the D R of Congo, Gabon, Ghana, Liberia, Nigeria, Sierra Leone and South Sudan.
- First named in 1958 when laboratory monkeys in Denmark were found to be infected with an unknown virus causing a “pox-like” disease, hence the term “Monkey Pox”.
- First human case: a baby living in the D R of Congo in 1970.
- Its animal reservoirs are unknown, but for humans, rodents are the most common source of transmission
- Several animal species are susceptible to infection (including non-human primates).
- There are two clades, or strains, of the virus: the Congo Basin clade produces a more serious illness with reported fatality rates in Central Africa of 10 percent, while the West African clade generally causes a self-limiting infection, which can, however, be severe, particularly in children, pregnant women or people with immune suppression. So far no deaths have been reported in the non-endemic countries reporting cases in the current outbreak - it appears this outbreak involves the West African clade.
- Person-to-person transmission is primarily through large respiratory droplets, but also via direct contact with skin lesions or body fluids (i.e. close or intimate contact) and indirect contact by way of contaminated bedding, clothes etc.
- Incubation period ranges from five to 21 days, generally six to 13 days.
- Symptoms include fever, headache, chills, muscle aches and back pain, together with swollen lymph nodes in the neck, groin or axilla. A day or so later, an acute rash appears over the body (including palms and soles) with lesions that gradually change from being flat, to having raised areas, then containing clear fluid, and lastly to being pus-filled. The lesions eventually form a scab and fall off, at which point the person is no longer infectious.
- From the limited information available to date in the recent outbreaks, most cases (but certainly not all) have been in ‘men who have sex with men (MSM) seeking care in primary care and sexual health clinics’.
- The smallpox vaccine, which has been found to be around 85% effective against the monkeypox virus, was used widely in many countries (not in Australia however) until 1984 and vaccination ceased to be a requirement for international travellers around that time. The WHO declared the eradication of smallpox in 1980. (As an aside: The first vaccine ever created was a smallpox vaccine, developed by Edward Jenner in the 18th century)
Prevention of infection is primarily through public awareness of risk factors and the measures that can be taken to reduce exposure to the virus. This is particularly important in the current situation for anyone engaging in casual sex or who has multiple sexual partners.
For people concerned about possible exposure to the monkeypox virus, the advice is to isolate immediately and contact (phone) your doctor, local hospital or sexual health clinic. Also ensure strict hygiene is used for managing the infected person and their clothing/bedding to protect other members of the household (people and pets) – hand washing, use PPE including masks, adequate ventilation. Avoid skin to skin or face to face contact with an infected person. It would also be beneficial to compile a list of close contacts.
Diagnosis of the infection can be confirmed through testing of fluids from the rash.
Treatment of a confirmed case is generally supportive using analgesia and fluids, but also aims to prevent secondary bacterial infections - most people can be treated at home. Antiviral medication and immunoglobulin may be used for severe cases or outbreak control, but are most effective when given soon after infection onset. The smallpox vaccine may be given to at-risk contacts who are vulnerable to severe disease. A stockpile of smallpox vaccines is kept by the Australian government but is not available for general supply.
- WHO Monkeypox factsheet: https://www.who.int/news-room/fact-sheets/detail/monkeypox
- NSW Health Monkeypox factsheet: https://www.health.nsw.gov.au/Infectious/factsheets/Pages/monkeypox.aspx
- The changing epidemiology of human monkeypox—A potential threat? A systematic review: PLOS https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0010141#sec001
- Monkeypox: CDC Clinical Recognition: https://www.cdc.gov/poxvirus/monkeypox/clinicians/clinical-recognition.html
- PAHO Epidemiological Alert Monkeypox in non-endemic countries: https://www.paho.org/en/documents/epidemiological-alert-monkeypox-non-endemic-countries-20-may-2022
- ECDC Risk assessment: Monkeypox multi-country outbreak https://www.ecdc.europa.eu/en/publications-data/risk-assessment-monkeypox-multi-country-outbreak
- Global Health Monkeypox tracker: https://monkeypox.healthmap.org/
- Johns Hopkins Center for Health Security: https://www.centerforhealthsecurity.org/resources/monkeypox/index.html