Strategies for the control of pneumococcal diseases

Streptococcus pneumoniae (pneumococcus) is a Gram-positive, encapsulated ba cteria that is a major cause of human disease in people of all ages. It is the most important cause of bacterial pneumonia in infancy, childhood and a dult life, and the most important cause of meningitis in all age groups exc ept children of 3 months to 2 years in whom Haemophilus influenzae type b ( Hib) predominates (in the absence of Hib vaccination). Antibodies to the pn eumococcal polysaccharide capsule are protective, and at present 90 capsula r serotypes are recognized. The global burden of pneumococcal disease is poorly understood. II is belie ved to be responsible for 1-2 million deaths among children under 5 years o f age every year and probably a similar number among adults. Thus, the glob al burden of pneumonia in adults is probably significantly underestimated a t present. Strategies for the control of pneumococcal disease include contr ol of risk factors, treatment of established cases and vaccination. In chil dren, improved nutrition, better housing and reduced indoor air pollution a re difficult to address, but should eventually reduce pneumonia rates. In a dults, the risk factors are even more difficult to address, although contro l of alcohol and tobacco consumption and reduced transmission of HIV should all affect pneumococcal disease rates. Penicillin-resistant pneumococci ar e now widespread throughout the world. Where penicillin resistance occurs, penicillin should not be used to treat pneumococcal meningitis; however, pe nicillin, at higher doses if necessary, remains the drug of choice for the treatment of pneumococcal pneumonia, even where penicillin resistance is pr evalent. There are three approaches to pneumococcal vaccination: polysaccha ride vaccines (covering 23 serotypes), polysaccharide-protein conjugate vac cines (covering 9-11 serotypes) and common protein vaccines (which are not serotype-specific). Only polysaccharide vaccines are available now, but con jugate vaccines will be available soon. Polysaccharide vaccines probably ha ve a role in protecting the elderly from pneumococcal disease, especially t hose at high risk. The potential role of conjugate vaccines in infants is u nclear. (C) 1999 Elsevier Science Ltd. All rights reserved.