Public Health England figures show there were four cases of TB on average annually in the area between 2017 and 2019.
Although this was a fall on the five diagnosed each year between 2016 and 2018, TB Alert said any increase in the disease – which primarily affects the lungs – is a concern because it may put sufferers at increased risk from coronavirus.
In Northumberland, the rate of TB was 1.2 cases for every 100,000 people.
This compares to a figure of 8.4 nationally – up from 8.2 and ending seven successive years of falling rates.
The disease is curable but can be fatal in itself if left untreated.
Mike Mandelbaum, chief executive of TB Alert , said: "It is worrying that the number of people with tuberculosis rose in 2019. We should take this as an early warning sign so that we don’t return to a pattern of rising rates like we saw in the 1990s and 2000s."
Like Covid-19, tuberculosis is an airborne disease that can be passed on by inhaling tiny droplets from an infected person's coughs and sneezes.
A PHE spokesman said England has surpassed the World Health Organization's targets to reduce TB rates to 10 per 100,000.
He added: “Despite a small rise in case numbers, the TB rate in England remains below the definition of a low-incidence country, for a third consecutive year."