The World Health Organization (WHO) warned on Friday that the number of tuberculosis deaths in Europe is on the rise again after declining for almost 20 years.

In 2021, tuberculosis resulted in 27,300 European deaths compared to 27,000 deaths in 2020, according to data.

WHO attributed the rise to the Covid-19 pandemic, citing lockdowns, diverted medical resources, and delayed diagnoses, as well as the spread of a drug-resistant form of tuberculosis.

WHO Europe said this was the first time the downward trend was broken in two decades.

Read more: WHO: Tuberculosis cases rise for 1st time in years

The two most affected countries were Russia and Ukraine with around 4,900 and 3,600 deaths respectively. 

Almost 230,000 people contracted tuberculosis across the 53 countries which make up the WHO's European region, which includes countries in Central Asia. The number continued to decline from previous years.

Tuberculosis is mainly caused by a bacteria which attacks the lungs. It is air-transmittable by infected people through coughing, for instance. The illness is preventable and curable. 

"The increase in TB deaths that we are seeing in 2021 is most likely a consequence of delay in, or lack of, TB diagnosis due to disruption to TB services during the Covid-19 pandemic, leading to increased severity of disease and an associated increase in deaths," the WHO Europe said.

In 2021, the prevalence of drug-resistant TB also rose; one of the three cases of the illness was resistant to rifampicin, which is the main drug used to treat the illness.

The WHO expressed concern in October regarding the rise of new cases worldwide in 2021. Almost 10.6 million people developed tuberculosis in 2021, as data show.

Read next: 'Sacrifice Zones', where pollution causes more deaths than COVID-19