As of 22 August, there are 3,207 confirmed and 133 highly probable monkeypox cases in the UK or 3,340 in total, according to the UK Health Security Agency (UKHSA). Of these, 3,191 are in England.
Many of the symptoms of the illness appear initially similar to chickenpox but there are several key differences between the two.
First, the diseases are caused by different viruses: monkeypox is an orthopoxvirus while chickenpox is caused by the varicella-zoster virus, which also causes shingles.
Both virus can spread through close contact through respiratory droplets and direct contact with skin lesions and recently contaminated objects.
While chickenpox is a common and highly contageous disease, monkeypox is rarer and spreads less easily.
Monkeypox is usually a mild illness with initial symptoms including fever, headache, muscle aches, backache, chills and exhaustion.
While many of these symptoms also appear in people infected with chickenpox, swollen lympnodes are a distinctive feature of monkeypox, which are not present in chickenpox.
The incubation period for monkeypox can be seven-to-14 days, while symptoms of chickenpox can take up to 16 days to appear, according to the US Centres for Disease Control and Prevention (CDC).
Following monkeypox infection, a rash, initially similar to a chickenpox, usually occurs within one to three days of a fever.
The rash goes through several difference stages first developing into papules and fluid filled pustules before forming a scab and falling off.
However, a chickenpox rash forms in a different way.
Spots do not develop uninformally in a chickpox rash, appearing at different times. Monkeypox lesions, however, appear and develop at the same time.
Monkeypox symptoms usually last between two to four weeks. Some strains can cause severe disease, with recent fatality recorded at 3 to 6 per cent, according to the World Health Organisation (WHO).
Chickenpox symptoms can last up two weeks but usually subside in seven days.
The UK government has released new guidance advising people with the virus, and those who have had direct exposure to a person infected with monkeypox, to isolate for three weeks.
People in this group are also being told not to travel and are advised to avoid contact with immunosuppressed people, pregnant women and children under 12.