Throat culture swabs of brother, his friends negative

Health officials investigating the case of a six-year-old fully immunised child contracting diphtheria at Vellanad in the district have not been able to pinpoint the source or the cause of the infection.

A team of health officials, including a team of doctors from the Department of Community Medicine, Government Medical College Hospital, had visited Vellanad to screen all classmates of the child, Aparna, her brother, and his close friends, all of whom were likely to have come into contact with the child, as diphtheria is an air-borne infection.

All 27 throat culture swabs thus collected tested negative for diphtheria, indicating that the disease-causing bacteria (Corynebacterium diphtheriae) was not circulating in the community.

The child had been clinically diagnosed as having diphtheria as she had developed typical symptoms of the infection, such as a false membrane on the mucous lining of the throat and palatal palsy or soft palate paralysis. Her throat culture had, however, been negative for diphtheria, possibly because the culture was taken after she had been started on antibiotics.

“The child is fully immunised and hence at present, we can only surmise that it could be a rare case of secondary vaccine failure or decreased efficacy of the vaccine owing to improper storage. No vaccine is 100 per cent efficient. The diphtheria component in the DPT vaccine has the highest efficacy at 95 per cent and there is only a 5 per cent chance that a child may not be sensitive to the vaccine,” a senior health official said.

The DPT vaccine has to be stored between 2-8 degrees Celsius, and the vaccine loses its potency if stored in the freezer, as per the guidelines on vaccine storage issued by the Union Health Ministry. The child had been given the first DPT doses at a private hospital and the subsequent booster doses at a government hospital.

Incidentally, health officials who visited the private hospital where the child is believed to have been given the vaccine had found that the DPT vaccines were stored in the freezer

But DPT is administered at 6, 10, and 14 weeks and the booster doses at 16-24 months and 5-6 years. Hence, there is no way of ascertaining if the vaccine given to the child had been stored properly at the time.

Diphtheria can be dangerous as it can lead to severe complications, including myocarditis.

The child had been treated in a private hospital and later referred to SAT hospital. She is currently doing well.