The new patient, a 29-year-old woman, had got in close contact with an infected patient, said CDC Bac Giang.

She first tested negatives for the disease, but the second test proved she had contracted with diphtheria.

The patient was immediately transferred to Hanoi-based Central Hospital for Tropical Diseases for isolation and treatment on July 10.

According to local authorities, there were seven people in close contact with the fresh infection and they were all on the list of 15 people identified as F1 of the first patient who has been put in quarantine for medical surveillance and treatment since July 7.

The first case of diphtheria was documented on July 6 after she got in close contact with an 18-year-old girl in central Nghe An province, who had died of the disease.

She was said to pose a high risk of spreading the disease to the community when she returned to Bac Giang.

More than 100 people who had come into contact with the infections have been isolated for medical surveillance and given prophylactic treatment with antibiotics.

According to the World health Organisation, diphtheria is a disease caused by a bacterium that affects the upper respiratory tract and less often the skin. It also produces a toxin that damages the heart and the nerves. Diphtheria is a vaccine preventable disease, but multiple doses and booster doses are needed to produce and sustain immunity.

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