No evidence links ‘black fungus’ to repeated use of unwashed masks

A message circulating on Facebook and WhatsApp claims that black fungus, also known as mucormycosis, is “on the rise in post covid patients”. It links this to repeatedly wearing the same face mask without washing it. 

“Once we wear it, due to the humidity in our breathing, it gets wet which we don’t feel,” the message reads. It is credited to a Dr Samir Shah, “HOD Surgery” and a Dr Tejas Doshi.

“Then the mask is being used for 3-5 days, a perfect atmosphere for growth of fungus, which we then breathe and goes straight into our respiratory system.”

A similar message posted on Facebook warns that “reusing unhygienic masks may cause black fungus infection”. Another post, from the All India Institute of Medical Sciences, claims that “using masks for 2-3 weeks without washing” causes black fungus. 

Are these warnings correct? We checked. 

Weakened immune system main cause of black fungus

Mucormycosis is a rare infection caused by fungi found in soil and decaying organic matter. 

Most people encounter these fungi daily. They are usually not harmful. But people with weak immune systems are at risk of developing an infection in their lungs or sinuses if they inhale the fungi. 

There have been reports from India of Covid-19 patients developing black fungus. On 14 May 2021, the country’s Press Information Bureau reported that “more than 2,000 people had already been affected by this fungal infection” in Maharashtra state, and 10 had died. 

Diabetes, steroids and long ICU stays

Several news sources have quoted medical professionals linking unhygienic masks to black fungus. But other medical professionals have argued that there is no evidence to support this. 

The Indian Council of Medical Research released an advisory on mucormycosis where they listed uncontrolled diabetes, steroids and a prolonged stay in a hospital intensive care unit, or ICU, as factors that could predispose a person to black fungus. They advised that the link between black fungus and Covid-19 could be due to lowered immune systems and immuno-suppressant treatments such as dexamethasone. 

Oxygen treatment in ICU exposes patients to moisture due to the use of humidifiers, also increasing the risk of black fungus. 

Personal hygiene advised by experts

Wearing a mask repeatedly is not listed as a cause of black fungus on any reliable platform. Experts say there is no clinical evidence to support this claim. But maintaining personal hygiene is advised. 

It is important to wear a clean mask. The World Health Organization says effective storage, cleaning and disposal of masks is “essential to make them as effective as possible”. They recommend that material masks be washed every day and disposable masks be thrown away every day.