Whooping Cough

Whooping Cough a respiratory illness also known as Pertussis caused by the Gram-negative bacteria Bordetella pertussis. It is a very common childhood illness in Bangladesh as it is in many other countries of the world. The causative organism does not survive for long outside the human host so that the spread of the germ primarily occurs through person to person contact. The route of infection is the nose. An infected individual expels the germ through sneezing and coughing. The airborne bacteria are readily inhaled by healthy individuals in crowded conditions with poor ventilation. The organism, after establishing the infection in trachea and bronchi, continues to multiply rapidly at the site of infection while a fraction dies. The latter disintegrates and releases a toxin from inside the cell which causes severe irritation of the epithelial cells of the trachea and bronchi causing characteristic violent deep coughing that ends in a high-pitched whooping sound, hence the name whooping cough. In severe cases of infection of the respiratory system, the patient may suffer from poor oxygenation of the blood that may lead to convulsion. Because of person to person transmission, sanitation conditions are not thought to significantly contribute to spread of the disease. Its incidence is generally related to crowding and inadequate ventilation. The disease is a public health problem of both the developing and industrialised countries.

Whooping cough is a highly endemic disease in Bangladesh affecting millions of children every year. Explosive epidemics occur particularly in the dry season, that is, during the spring and summer months. Infected persons are to be treated with antibiotics soon after diagnosis. The disease, fortunately, is vaccine-preventable. The vaccine currently in use consists of killed cells of the bacteria which is given as a course of three injections at certain intervals. In Bangladesh, the extended programme on immunisation (EPI) includes this vaccine in the formulation commonly known as DPT- that is, vaccines against diphtheria, pertussis and tetanus, given together in one injection. After the initiation of EPI in 1986, pertussis vaccine coverage reached in 1996 to nearly 80% of all children in the immunisation age from a figure of merely 2% at the initiation of the EPI programme. The decade of successful childhood immunisation, 1986-1996, is globally acknowledged as a noteworthy achievement of Bangladesh, and is an example which other developing countries of the world are trying to duplicate.

Unlike the smallpox vaccine which was made in Bangladesh by the Institute of Public Health (IPH) at insignificant cost and which led to eradication of smallpox from Bangladesh, the six EPI vaccines that are being used in the EPI programme are purchased from abroad. At present the cost of fully immunising a child in Bangladesh with the six EPI vaccines has been variously estimated. A reasonable estimate is $11.76 per child, which has been made recently by the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) based on total spending of $18.3 million to immunise 1.56 million infants under the age of one year during a one year period, 1997-98. Since the EPI programme is a highly sustainable activity, empowerment of the national biomedical facilities to acquire vaccine production capability is being addressed by the government in order that the future demand for the EPI vaccines can be fully met by productions made in the country. [Zia Uddin Ahmed]