For a virus we initially thought of as a respiratory bug, Sars-CoV-2 has produced a broad range of symptoms across many body systems. “Covid tongue” and “Covid toe” are just two of the unusual complaints experts now say may be part of the novel infection.
A recent tweet from a UK professor, saying he’s finding more Covid-19 patients reporting oral problems, such as tongue discolouration and enlargement, brought Covid tongue to public attention as a possible symptom of Sars-CoV-2 infection.
"Seeing increasing numbers of Covid tongues and strange mouth ulcers. If you have a strange symptom or even just headache and fatigue stay at home!" tweeted Tim Spector, professor of genetic epidemiology at King's College London.
My mail is full of tongues each morning from people who had tongue problems that coincided with Covid symptoms like fever and fatigue – but baffled doctors
“My mail is full of tongues each morning from people who had tongue problems that coincided with Covid symptoms like fever and fatigue – but baffled doctors. Happy to share so we all become experts...”
He added that 35 per cent of people exhibit non-classic symptoms of Covid in the first three days, such as skin rashes and Covid toes. Meanwhile a Spanish study of Covid patients suggests about 10 per cent experience tongue and mouth problems.
Neither the World Health Organisation or the US Centers for Disease Control lists Covid tongue as a recognised sign of coronavirus infection. While discolouration of the toes and fingers is listed as a rare symptom by the WHO, the term Covid toe has yet to receive scientific approval.
According to the Health Service Executive Library, Covid toe is a possible manifestation of Covid-19, a term it says was coined in the media as opposed to the scientific literature. "Several medical papers from Spain, Belgium and Italy described a surge in complaints about painful lesions on patients' toes, Achilles' heels and soles of the feet; whether the patients were infected was not always clear, because they were otherwise healthy and testing was limited," the literature search found.
Patients describe a chilblain-like inflammation of the feet, with their toes becoming red and swollen. The symptom has also emerged as a possible feature of so called “long Covid”, where the disease symptoms last for several months.
The UK National Institute for Health and Care Excellence (Nice) divides Covid-19 into three clinical definitions:
- Acute Covid-19 for signs and symptoms during the first 4 weeks after infection with Sars-CoV-2.
- New or ongoing symptoms 4 weeks or more after the start of acute Covid-19, which in turn is divided into: ongoing symptomatic Covid-19 for effects from 4 to 12 weeks after onset; and post-Covid-19 syndrome for effects that persist 12 or more weeks after onset.
While there have been varying estimates of the prevalence of post-Covid syndrome, it seems about 5 per cent of those who test positive for Sars-CoV-2 go on to develop prolonged symptoms
Nice describes the term long Covid, which it uses “in addition to the clinical case definitions”, as “commonly used to describe signs and symptoms that continue or develop after acute Covid-19. It includes both ongoing symptomatic Covid-19 (from 4 to 12 weeks) and post-Covid-19 syndrome (12 weeks or more).”
Nice defines post-Covid syndrome as “signs and symptoms that develop during or after an infection consistent with Covid-19, continue for more than 12 weeks and are not explained by an alternative diagnosis. It usually presents with clusters of symptoms, often overlapping, which can fluctuate and change over time and can affect any system in the body. Post-Covid-19 syndrome may be considered before 12 weeks while the possibility of an alternative underlying disease is also being assessed.”
While there have been varying estimates of the prevalence of post-Covid syndrome, it seems about 5 per cent of those who test positive for Sars-CoV-2 go on to develop prolonged symptoms. The likelihood of being affected is independent of whether someone had a mild infection or required lengthy treatment in hospital.
Clearly, there is much we have yet to learn about Covid-19.