Nine new diphtheria cases were reported in Negeri Sembilan, Penang and Kedah, bringing the total cases to 24 including five deaths as of yesterday.

Health director-general Datuk Dr Noor Hisham Abdullah said six cases were in Negeri Sembilan, two were in Penang and one in Kedah involving those from eight to 50 years old, whereby six had had diphtheria immunisation.

"Four of the six cases in Negeri Sembilan were the children of the woman in the case from Rembau and two more are personnel of the Rembau Health Clinic who were the contacts of the first case," he said in a statement today.

He said the diphtheria cases in Kedah and Penang were isolated cases and had no connection with any case previously.

"All the cases are reported to be in stable conditions, and have been isolated and given antibiotic treatments," he said.

In another development, Noor Hisham said the status of the laboratory test on diphtheria which was reported at the Universiti Sains Malaysia Hospital on July 17 was negative.

Meanwhile, the rise in diphtheria cases among adults was caused by the bacteria Corynebacterium diphtheriae.

"Cases among adults with complete diphtheria immunisation histories do not experience serious symptoms and do not require antibiotics treatment.

"Meanwhile, the risks of complications from diphtheria infection among children specially those without or with incomplete immunisations are high," said Noor Hisham.