Cambodia has reported an increase in the number of cases of chicken pox or varicella, according to a joint statement by the World Health Organization and the Cambodian Ministry of Health on Friday.

"Health centers, clinics and hospitals in Kandal province and other provinces have reported the increase in the cases," the statement said, urging parents and guardians to prevent their children from the disease through improving hygiene.

Chicken pox causes a blister-like rash, itching, tiredness and fever, the statement said, adding that the disease may last within 5 to 10 days.

It usually affects children and is in most cases benign. However, in some rare cases, particularly in newborn babies and in people with weakened immune systems, it may be complicated by pneumonia and encephalitis.

"The best effective prevention is hygiene, especially washing hands with soap, and for sick person staying at home to not further spread the disease," Cambodian Health Minister Mam Bunheng said.