The arrival of the first case of the more deadly ‘clade Ib’ strain of mpox in Europe signals the need for improved testing and treatment, says a leading testing expert.
Mpox: the PCR isn’t so ‘gold standard’ as we think
Currently, the ‘gold standard’ PCR test rely on swabs from rashes but by the time rashes develop it may be too late to prevent the spread of the virus. Likewise, there are still no specific drugs approved for mpox, with most treatment aimed at relieving symptoms and smallpox drugs standing in for targeted antivirals.
Dr Avinash Hari Narayanan (MBChB), Clinical Lead at London Medical Laboratory, says:
The first case of the deadlier clade Ib strain of mpox (formerly known as monkeypox) in Sweden shows that Europe is not entirely protected. According to the US Center for Disease Control (CDC), mpox clade I causes more severe illness and deaths. Some outbreaks have killed up to 10% of the people who got sick. The World Health Organisation (WHO) says “…clade I leads to more severe disease and death than clade II in the populations where it is endemic”.
Currently, European countries are used to dealing with clade II, the type that caused the global outbreak that began in 2022. Infections from clade II mpox are less severe and more than 99.9% of people survive.
PCR tests of rash fluids or crust, collected by “vigorous swabbing”, are the preferred laboratory test, says the UK’s Health Security Agency (UKHSA). However, by the time these rashes present it may be too late to prevent infection spread. It currently takes around five to 21 days after infection for the first symptoms to appear and a further five days after the first symptoms for the rash to appear. Clearly, that is a long period before the PCR “gold standard” test can be undertaken.
A viral throat swab can be administered to people who have developed systemic symptoms but do not have a rash or lesions, but results can take two or more days. Usually blood samples are a quicker, safer diagnostic.
Improved testing is needed
However, the WHO says testing blood is not recommended for identifying mpox antibodies. It states:
Antibody detection methods may not be useful as they do not distinguish between different orthopoxviruses.
Clearly, there is an urgent need for improved, focused blood tests to speed up detection of specific mpox antibodies in people who are not yet presenting symptoms.
Narayanan continued:
In Europe, treatment for most people with mpox has been aimed at relieving the symptoms of the less severe clade II cases. The concern is that there is no specific treatment approved for mpox and drugs developed for smallpox are often used in an emergency. In the absence of a specific mpox antiviral, the UK Government’s advice is that drugs such as tecovirimat (used to treat smallpox) or cidofovir (mainly used to treat a type of eye condition in AIDS patients) can be used to treat severe cases of mpox or those who are at high risk.
It is good to see that the UKHSA is stepping up its reaction. It announced last week that “planning is underway to prepare for any cases that we might see in the UK”. This includes ensuring that clinicians are aware and able to recognise cases promptly. Improved awareness is vital, as the symptoms of mpox can be easily confused with other conditions, including chickenpox, herpes simplex, measles, secondary syphilis, enterovirus and various bacterial skin infections.
What are mpox symptoms?
For anyone concerned, the first symptoms of mpox include:
- high temperature
- headache
- muscle aches
- backache
- swollen glands
- shivering (chills)
- exhaustion
- joint pain
A rash usually appears one to five days after the first symptoms. It often begins on the face, then spreads to other parts of the body. This can include the mouth, genitals and anus.
If people have come into contact with someone who has been in central Africa recently and they are experiencing any of these symptoms, they should contact their GP.
Get tested
Narayanan summed up:
Of course, in most cases, these symptoms are likely to have been caused by another condition. This includes people who have multiple sexual partners but have not come into contact with anyone who has been in central Africa recently. If they have any concerns, London Medical Laboratory’s sexual health tests can be taken in the privacy of their own home.
Most people who become very ill from mpox have other underlying health complications. A general “MOT” blood test can give a vast array of information about people’s health through a simple finger-prick test. London Medical Laboratory’s General Health Profile blood test monitors seven key areas of health. It can be taken at home through the post, or at one of the many drop-in clinics that offer these tests across London and nationwide in over 120 selected pharmacies and health stores.
For full details, see: https://www.
