The recent spike in infection has lifted the total to seven cases at the primary school so far this year.

The directorate said on Thursday that the first four cases were of students from the Year 5/6 group.

There have been 83 cases of whooping cough, or pertussis, in the territory in 2015, a rise of six since ACT Health confirmed a total figure of 77 on Wednesday.

The news comes after the health directorate warned last week of a future outbreak of the disease in the ACT.

"Whooping cough outbreaks are known to occur every three to four years, the most recent in the ACT was in 2010-2011/12," ACT Health said.

ACT Deputy Chief Health Officer Andrew Pengilley said the rise in infection numbers was concerning, but nothing close to the high numbers seen during the most recent outbreak in 2010 and 2011.

"While it is concerning whenever people get sick, particularly children, this is just a cluster of cases in one place," he said.

The number of infections reported so far this year are in line with the past two years, but much less than the 367 cases reported in a similar period in 2011.

"Even though the cases are not at 2011 levels it is a timely reminder of the importance of vaccination," an ACT Health statement said.

"The ACT has excellent coverage with at least 93 per cent of children having had the vaccinations for pertussis."