Cases of scarlet fever shot up in Malta last year as international public health experts warn the disease that killed thousands in the 19th century could be making a comeback.

According to figures from the Disease Surveillance Unit, the islands registered 49 cases of scarlet fever last year, more than five times the number reported between 1997 and 2007.

Britain too saw an increase last year, although the jump was nowhere near that of Malta. Nearly 3,000 cases were recorded in England and Wales while the number of cases in the past decade had hovered between 1,600 and 2,500 per year.

The increase in cases could be due to a slightly different strain of the bacteria to which the Maltese do not have any immunity. "This does not mean the strain causes more severe disease; only that more children might get a rash together with their sore throat," the unit said on its website.

Health Promotion and Disease Prevention director Charmaine Gauci said the increase in cases could be explained by the fact that it could spread easily, especially among children, through close contact and saliva. In fact, the vast majority of patients were children, although there were also some adults.

She said there was also more awareness about the condition last year, which meant patients were taking their children to the doctor more and doctors were reporting cases.

"We cannot say what will happen this year because the upsurge was only seen last year but we are stressing control measures so we can limit the spread," she said.

British public health experts are worried that the disease may be becoming more infectious. In fact, the Health Protection Agency started enhanced surveillance to study the number of cases and look for unusual signs.

At the end of January 2008, five children attending the same class in a primary school in Gozo fell ill. Early in March, another small outbreak in another school in Gozo was reported, followed by another outbreak in the same school a week later. Another outbreak was reported in Gozo at the end of March. In May, three children contracted the disease in Malta.

Following last year's first outbreak, Dr Gauci had said that this was not common in Malta although sporadic cases had occurred over the years.

Dr Gauci said that when a number of linked cases were reported, the department gave the necessary treatment and asked patients to stay at home until they were no longer infectious. This had been done to limit the spread of disease. Eleven of the cases were linked in five clusters.

Scarlet fever, which is transmitted through close prolonged contact, is caused as a complication of the streptococcus bacteria, which normally causes the common sore throat known as "strep throat" and the disease usually occurs after a throat or skin infection. Symptoms of scarlet fever, known in Maltese as Skarlatina, include a rash that shows up as tiny red bumps, sore throat, fever and swollen glands.

The disease was responsible for a number of epidemics in the 19th and early 20th century and, before antibiotics were available, about three per cent of untreated cases resulted in potentially-deadly complications. Although nowadays most cases are easily treated with antibiotics, in rare circumstances the bacteria can cause septicaemia (blood poisoning) and even necrotising fasciitis, known as the flesh-eating bug.

Dr Gauci encouraged parents to look out for symptoms because early treatment could prevent complications and early isolation could stem spread.