Rapid urbanization has significant repercussions on migrants’ health. The increasing movement of people from rural to urban areas often alters the characteristic epidemiological disease profile of the country, and at the same time new diseases appear or old ones reemerge. Such is the case of HIV/AIDS, tuberculosis, and malaria. Urbanization is also associated with changes in diet and exercise that increase the prevalence of obesity with increased risks of type II diabetes and cardiovascular disease.
Additional mobility-related risks among migrants include poverty, vulnerability to sexual abuse and exploitation, dangerous working conditions and separation from social support networks. Many of these conditions affect the most vulnerable segments of the population: women, children and the elderly.
Although many migrants are young and healthy when they arrive in the cities, poor and overcrowding conditions increase the incidence of some diseases such as malaria, typhoid fever and respiratory diseases when compared to local residents. In recent years, for example, tuberculosis has shown higher rates of infection, a problem compounded by delayed diagnosis and inadequate care.
In addition, migrants show high rates of sexually transmitted diseases, including HIV/AIDS. Because of their high mobility, migrants tend to spread the virus when they return to the countryside, where health facilities are not as well equipped to deal with the infection as they are in the cities.
Many of migrants’ health problems are due to their lack of knowledge of how to use existing health services. In addition, because of the high cost of hospital attention, many migrants are reluctant to come to the hospitals to be taken care of.
On most indicators of maternal and infant health, migrants fare worse than the urban population. Many migrant women work in industries where they are in contact with environmental contaminants which are especially dangerous to the reproductive system of women when they are pregnant.
Each step in the reproductive process can be altered by toxic substances in the environment that increase the risk of abortion, birth defects, fetal growth and neonatal death. Many studies have shown that exposing pregnant women to carbon monoxide can damage the health of the fetus. In addition, the developing fetus is susceptible to environmental factors – for example through the mother’s exposure to toxic substances in the workplace.
Children are especially susceptible to disease when they are born and develop in an environment characterized by overcrowding, poor hygiene, excessive noise, and lack of space for recreation and study. They suffer not only from a hostile physical environment, but from stress and other factors such as violence that such environments create.
Many city dwellers take for granted access to basic public services, such as drinking water supply, housing, solid waste disposal, transportation and health care. For the poor, however, these services are either deficient or nonexistent. Instead, those living in marginal poor zones usually receive an extra dose of environmental pollution, since many industries tend to cluster in outlying areas where regulations are more lax. Unemployment, poverty and living in crowded conditions contribute to violence, substance abuse and mental illness.
Particularly in cities, motor vehicles are an important source of air pollution. In addition, they can be a significant cause of pedestrian injuries and fatalities. The pollutants that originate from motor vehicles, particularly nitrogen oxides, hydrocarbons, ozone, and particulate matter, account for a substantial proportion of air pollution in cities which can have a serious impact on health.
Crowded urban neighborhoods, combined with poor sanitary conditions and inadequate waste removal, create situations favorable to the spread of infectious diseases such as pneumonia, tuberculosis and diarrhea. Inadequate sanitation is an important risk factor for diarrheal and parasitic diseases.
Given the serious effects that urbanization can have on health, it is essential to include health considerations into policy making. Because many of the negative effects are suffered more acutely by the poor, migrants and minorities, it is important to adequately assess their needs.
Cities are magnets that attract migrants for the opportunities they offer but they must provide a safe and stable environment in order for people to prosper. As Herbert Girardet, an expert on urban sustainability has stated, “If we are to continue to live in cities, indeed if we are to continue to flourish on this planet, we will have to find a viable relationship between cities and the living world –a relationship not parasitic but symbiotic, or mutually supportive.”
Dr. Cesar Chelala, an international public health consultant, is the author of “Environmental impact on children’s health,” a publication of the Pan American Health Organization, the regional office of the World Health Organization.