Hand, foot and mouth disease is spreading at childcare centres in the Northern Territory, with dozens of children having fallen ill.

About 70 cases of the viral infection that causes fluid-filled blisters have been reported in the Top End region in recent weeks, NT Health says.

"Hand, foot and mouth disease is a common viral illness causing small, blister-like lesions on the inside of the mouth, sides of the tongue, hands and feet," infectious diseases expert Kate Proudmore said.

Other symptoms include fatigue, loss of energy, poor appetite, mild fever and a sore throat and mouth.

The disease is spread by direct contact with an infected person's blisters, saliva, mucus or faeces.

It can also be spread through sneezing or coughing and is most common in children under 10.

"There is no vaccine for hand, foot and mouth disease but the body will develop an immunity to the virus after you have been exposed," Dr Proudmore said.

"Unfortunately, many viruses can cause hand, foot and mouth so you may get it again."

Symptoms generally develop three to five days after exposure and blisters remain infectious only as long as they contain fluid.

Faeces can remain infectious for several weeks.

The illness is mild for most people and the blisters usually disappear within a week.

"In very rare cases, complications of hand, foot and mouth disease can occur, including meningitis, encephalitis or paralysis," she said.

The infection is rarely fatal.

There is no specific treatment and for most people paracetamol relieves the discomfort and fever.

"Protect yourself and your loved ones by promoting good hygiene, which is the best way to stop the spread of the virus," Dr Proudmore said.