How urbanization affects the epidemiology of emerging infectious diseases

Neiderud, Carl-Johan

Residents who are subject to overcrowding and who lack access to safe drinking water or proper sanitation can be more susceptible to soil-transmitted helminths (21) . These infections are among the most important causes of physical and intellectual growth retardation in the world and have a major impact on public health (22) . Good hygiene practices and good sanitary conditions have lowered the prevalent levels of contamination. In the Brazilian city of Salvador, with a population of 2.5 million, an improvement of sewerage coverage from 26 to 80% of the households led to an estimated overall reduction of diarrhoeal diseases of 22% (23) . Neglected tropical diseases can cause substantial health problems in developing countries, and some of these diseases have a faecal-oral transmission pathway. Examples of such diseases could be schistosomiasis, trachoma, and soiltransmitted helminthiases. Improved sanitation could contribute to a significant improvement for the public health. In many countries, however, the focus is on treatment by medication and not improved sanitation. The reason could be that it would be much more expensive to carry out the necessary infrastructural improvements (24) . Safe drinking water and proper sanitary facilities must be taken into account in city planning. Factors like this can potentially have a profound positive effect in lowering infectious diseases with a faecalÁoral route. However, the real challenge lies in the uncontrolled growth of slum settlements.