Whanganui District Health Board is advising the community to be vigilant around the spread of Respiratory syncytial virus (RSV).
The contagious illness, which especially affects young children, is infecting people all over New Zealand, however simple hygiene such as keeping children at home and washing hands can help stop the virus from spreading.
Whanganui DHB's chief medical officer, Dr Ian Murphy, said adults with RSV had symptoms similar to the common cold and would mostly be able to recover at home, but babies and very young children can become very unwell quickly.
Older adults or people with compromised immune systems, or those with heart or lung conditions may also be more at risk from RSV.
Murphy said RSV was not a new virus and is common during the winter.