Aristarhos M. Seimenis, DVM
The world is being urbanized at a furious pace. According to United Nations data, 28% of the world population during the '50s was concentrated in urban zones while in the '70s this percentage has increased to 38%. With the closure of the 20th century, the population of more than ten cities in developing countries ranged between 12 and 30 million inhabitants. Rapid urbanization is now mostly noted in developing countries with urban growth rates of 3% or more each year. These types of growth rates lead to the doubling of the cities' populations every twenty years, and thus the local authorities are unable to cope with the demands for basic services such as housing, water, and sanitation (Tabibzadeh & Liisberg, 1997).
Rapid urbanization in developing countries has caused a multitude of environmental and health problems. In many major cities, squatter settlements and shantytowns have grown rapidly, and green areas around cities have been encroached on or are getting destroyed. These cities suffer from congestion, air and industrial pollution, insufficient and unsafe water supply, poor sanitation, inadequate sewage, and solid waste management systems. In some cities, the cost of water and sanitation has escalated to be among the highest in the world. Most of them suffer from severe housing shortage, as urban land and housing prices have risen above affordable income range of the average person.
Communicable diseases flourish where resistance levels are low, immunization is inadequate, and environmental conditions support their spread. The situation becomes worse by overcrowding, by exposure of the urban migrants to diseases to which they have never been exposed to before, and by multiplication of animal and insect hosts.
In the Southern Mediterranean and the Middle East regions, as well as throughout the developing world, two types of urban areas are distinguishable (Seimenis, 2003):
1. Urban areas "sensu strictu", which are extended settlements with people living in areas where dogs, cats and other domestic animals are in close contact. These cities are not homogeneous, as they are composed of high-, middle-and low-income population groups. The health status of these groups varies according to their life-styles.
2. Semi-urban areas, which are agglomerations of habitats of different sizes and various concentrations of human and animal populations. The hygienic conditions may be one more variable. Movements of numerous free-roaming dogs and cats are very common. These animals are fed mainly with garbage, which is also attracting foxes and/or other wild animals. Agricultural animals are very close to the homes of their owners. Sometimes wild animals enter these settlements seeking food from garbage.
STRAY ANIMALS AND HUMAN HEALTH
In most urban environments, dogs and cats are normally well integrated into the community as pet animals. They represent a considerable economic and emotional investment to their owners and, usually, are under their control. However, in most towns dogs and cats breed outside human dwellings and the resultant feral animal populations represent a major problem from the Veterinary Public Health aspect (Abdou, 1999).
In developing countries, free roaming owned dogs have many opportunities to be infected among other pathogens, by echinococcosis' discarded materials of other animals raised in the same areas, either following slaughter or deaths. The parasite may be spread in urban districts through those animals, owned or stray, moving from the country or periurban sides. For example, dogs may feed on carcasses of infected sheep or goats preyed on by wolves and left on the ground (Mantovani, 2003).
Another important issue is urban rabies maintained and propagated primarily by dogs, and dog bites are the main cause of rabies among humans. Studies performed show that children account for the largest percentage of mortality. Worldwide 30.000 to 60.000 people are estimated to die from rabies. Despite considerable under-registration and underreporting, anti-rabies immunoprophylactic treatment rates are estimated to about 3.5 million per year (Wandeler and Bingham, 2002; Meslin et al., 2002).
Slaughterhouses may be insufficiently attended and/or accessible to dogs; they may, also, lack facilities for the destruction of infected material. Moreover, illegal and noninspected slaughtering represents an important source for dogs to be infected by discarded offal. Therefore, measures to be taken should aim, besides the control of free roaming dogs and cats, to impede their access to the sources of infections, particularly the slaughterhouses and butcheries (Mantovani, 2003).
Stray or even owned dogs are abundant where garbage is available and control measures are insufficient or absent. In addition, on some occasions, the presence of garbage may attract foxes and other wild animals.
Free roaming cats cause many of the same problems as dogs. Besides being a nuisance, they break into garbage, defecate and add to the cat overpopulation problem.
The situation in urban areas in most developing countries, as described above, shows that existing problems are referring not only to stray dogs and cats or even pigeons, as it occurs in some developed countries, but also to a series of complex and interrelated factors creating a "vicious circle".
ANIMALS AND THE CITY DWELLER
Man, as it is very well known, is not the only city dweller. He is in company with pet animals (dogs, cats, game birds, guinea-pigs, mice, rabbits etc.), with roaming and stray dogs, as well as with "synanthropic" animals, sharing with him the same urban environment, although they are not always well accepted. These are pigeons, swifts, bats, rats, mice etc. To the above animal population, in developing countries, food animals and in some occasions wild animals should also be added.
Under such situations, overpopulation conditions are created, generating many problems of different character and degree. These animal populations with their high-density presence in the urban environment, they increase the contact opportunities with man and consequently the zoonosis transmission risks, some of which, up to a few decades ago, were exclusively prevalent in rural areas. Moreover, because of the disorganized mode of urban expansion in developing countries, faeces are polluting water supply, the soil, vegetation etc. (Ballarini, 2003; Tarsitano, 2003).
ZOONOSES AND URBAN ENVIRONMENT
Zoonoses, which are infections naturally transmitted between animals and humans, frequently are environment--dependent. A classification of these diseases could be made according to their mode of transmission in urban settlements, such as (Ballarini, 2003):
1. Urban zoonoses closely linked to the city
2. Rural--dependent zoonoses introduced to a city from agricultural environment, frequently through food of animal origin
3. Rural zoonoses urban-dependent, outgoing from the city frequently through effluents
4. Exotic zoonoses, introduced to the city through uncontrolled importation of exotic animals (e.g., monkeys etc.)
The close link: human-animal-environment, where bad or mediocre hygiene conditions are almost the rule, creates appropriate presuppositions for town people to become infected with zoonoses in the course of their every day life. This is made either directly from contact with dung, urine and other excretions, or indirectly through infected food products obtained directly from diseased animals especially milk and its products, eggs, as well as inadequately prepared and preserved meat and meat products.
Food, companion and other domestic animals living under poor hygiene and alimentary conditions and in increased density in the urban areas of the developing countries, contribute to the maintenance and extension of various diseases. Among them, zoonoses like brucellosis, salmonellosis, tuberculosis, cystic echinococcosis, cysticercosis, etc. are frequently affecting also humans living in the same settlements.
The important role of domestic and synanthropic animals as well as wild life as reservoirs and transmitters of zoonotic and foodborne diseases has been recognized. This matter has been long neglected in developing countries, as manpower and other facilities needed for effective control programmes are still lacking.
IMPROVING URBAN HYGIENE CONDITIONS
Urban infrastructure, human and animal populations and their density, human literacy level, habits and traditions as well as general hygienic conditions are completely different between developed and developing countries. In the latter, interventions of urban veterinary hygiene in order to be effective should cover simultaneously all these factors, or at least, the most important among them, which create and maintain the existing urban epidemiology. This is more than a hard and difficult task.
For minimizing the health risks related to animals and improve the quality of life in the urban areas of developing countries, multidisciplinary and multi-sectoral efforts are required.
In order to go towards the appropriate approach aiming at the best possible management of the huge social problems in urban areas, all programmes and activities implemented should be based on the principles of the intersectoral co-operation. The lack of this kind of collaboration undermines any kind of effort aiming at improving the situation. Multi-disciplinary and multi-sectoral structures associated with an appropriate coordinating administrative mechanism are absolutely essential. When urban growth is not accompanied by adequate extensions of the infrastructure, when acts of legislation remain non-implemented, together with financial constraints, lack of will for co-operation, co-ordination and community involvement, important problems are created which are very difficult to solve. Regretfully, weak infrastructural co-operation and co-ordination is an additional characteristic in most of the developing countries, and this is one more occasion to emphasize the importance of a coordinated intersectoral involvement and the need for its continuous support and strengthening (Seimenis, 2003).
Another task to be undertaken at national level by state and municipal authorities as well as NGOs, is the health education of the public. Appropriate education campaigns should be integrated to the activities of public health and animal health services aiming at educating and informing the public on the ways to protect their own and society health. It should, also, be understood that indifference and unhygienic behaviors are rendering the environment they live, hazardous for themselves and their families.
Highly polluted urban environments in developing countries have a huge social and public health impact. Governmental and municipal services should approach the problems under a multi-sectoral and multidisciplinary concept. Such a structure can only contribute towards better coordination of the necessary activities as well as to an improved management of the, always insufficient, resources available. In this context, public health education on a permanent basis should be included as basic tool.
Decision makers should be more aware of environmental issues and of the interrelationships between development, health and the environment. There is a need for political commitment to the development of environmental health services and to ensuring that health and environmental health are incorporated in urban development plans.
The task towards a step-by-step, but consistent improvement on urban hygiene conditions is extremely complex and difficult but it deserves the challenge. This is the only way which might lead to establishing acceptable living conditions, alleviating human suffering as well as reducing social expenses and increasing productivity. In this context, it should be noted that investing in the health of people means investing in the future capital of the country, in its dynamics and finally in its progress.
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