Poverty is an important factor governing the risk of zoonotic diseases in rural and urban areas. Poverty can increase exposure to such infections and reduces the chances of getting rid of diseases. Poor communities are often trapped in a never-ending cycle known as "the devil's circle of poverty".

Poor people are more likely to suffer from zoonotic diseases for several reasons:

Many zoonoses cause disabling diseases in humans. A sick or disabled person cannot work as much or as well as a healthy person, hence will not earn enough money to buy proper food or healthy livestock. Unhealthy livestock produce less food. The result is less food to eat and less food to sell - less income again and not enough money to buy medicines or to pay for proper education or healthy livestock? The big challenge is to break out of this circle through simple and low-cost methods and means.

The main difference between rural livestock keeping and urban livestock keeping is experienced in accessibility to health services, affecting both humans and animals. The more remote the area the less access there is to public health care and veterinary care.

Close contact between domestic animals and humans is a characteristic of rural settings. Animals kept for food production in these areas have an economic value as well: animals can be sold and they can be a source of security. It is this close association that makes zoonotic diseases so vitally important in rural areas.

In general, three types of animal raising and keeping can be found in rural areas:
1) Pastoralists and herders
2) A more sedentary, small-scale system
3) Commercial, large-scale animal production.

Each system has its own advantages and disadvantages with regard to the risk of zoonotic diseases. An advantage of a large-scale system is that diseases are easier to keep out of the stable, whereas in smallscale systems there is more interaction between the animals and the outside world. The disadvantage is that when one animal is infected the disease can spread rapidly through a large-scale farm, because of the many animals living in close proximity under one roof. In this situation, small-scale systems have the advantage: fewer animals living close together so the chance that a sick animal infects another animal is relatively small. Detection is also easier.

Other factors that can enhance the occurrence of zoonotic diseases in rural areas include the following:

1) There is a far greater likelihood of contact between livestock and wildlife in rural areas. Some zoonoses can live in both livestock and wildlife, which makes it difficult to get rid of these diseases. An example of one such zoonosis is trypanosomiasis or sleeping sickness in cattle.

2) Civil unrest and insecurity can increase movement of people and their animals as they flee and return to their areas of habitation.

3) Certain development programmes promote inappropriate livestock production systems affecting pastoralists, for instance, who are often forced to settle instead of leading their usual nomadic life. They are not accustomed to the new situation and to the risks a sedentary life brings to their animals.

The importance of zoonotic diseases in rural areas extends beyond the realm of public health. Apart from causing human disease and mortality, they affect the agricultural production and social structures of a community. Zoonotic diseases decrease the availability of food creating local and international trade barriers.

Although zoonotic diseases are mentioned in the annual reports of ministries of health and livestock in many developing countries, they are rarely prioritized compared to other notable human and animal diseases like malaria and rinderpest.

The main public health hazards in urban areas relate to:

Megacities develop with large, often uncontrollable slums, where people and animals live close together allowing easy transmission of zoonoses from animals to humans. Animals in these slums are often seen feeding on waste dumps, which is not animal feed. These animals will produce less and are more likely to get ill. Worse still, these waste dumps may contain toxic substances, which can be detrimental to the health of those consuming the meat or milk from these animals. Competition for scarce water resources and animal waste contamination of these water resources also pose serious threats to public health.

Microbes can be transmitted directly from animals to humans through contact or secretions and faeces. Microbes can also be carried by insects (flies, tsetse flies and mosquitoes) or other vectors (bedbugs, ticks, etc). Unhygienic conditions, especially the absence of clean water or the lack of proper sewage systems can foster the presence of vermin (mice and rats) and therefore also the risk of disease.

Besides production animals, dogs and cats are kept in both developing and developed countries. Often these animals are kept unrestricted and unsupervised, without adequate care and vaccinations. Rabies is the most important zoonosis transmitted especially though dog bites. Streets and parks in many cities in developed countries are polluted with dog faeces, posing major problems for city councils. Apart from dogs and cats, inexperienced owners often also keep exotic animals. These animals need to be kept under stringent hygienic conditions to prevent transmission of zoonotic diseases to their handlers (such as salmonella and parasitic diseases in reptiles). Pets appear to be taking over an important emotional function in the ever-increasing individualizing societies.

As mentioned before, wildlife can be a source of disease. There is no problem as long as there is no contact with humans, or animals living together with humans. But there are many situations in which contact between wild animals and humans or domestic animals occurs.

Rats and mice are wild animals that live very close to people. These animals eat scraps of food left by humans or their animals. For example, they eat paper in a paper factory, grain left by horses and hay left by the cows. Pest animals are a kind of link between wild and domestic animals. They move into houses and stables and live in woods and bushes as well. The relationship between humans, domestic animals, wild animals and pest animals is illustrated in Figure 11.

Rats and mice can be controlled using pesticides and by simply keeping the house and environment clean and free from food and feed scraps. Wild animals cannot be controlled. It is impossible to know where they go and with which animals they come into contact. And it is not easy to know whether wild animals are carrying a certain disease or if the animal is ill. So the disease can spread among the group of wild animals and be transmitted to domestic animals without anyone noticing it. Wild animals, furthermore, do not get vaccinated.

The diseases that countries want to get rid of could still be prevalent among the wild animals of the countries. Wild animals can travel over borders as well. Migrating birds are a particular example, flying all over the world carrying their diseases with them.

To kill all the wildlife to get rid of diseases is no option. So, we have to find ways to prevent diseases from wild animals spreading to domestic animals or humans. Plague is a good example of a zoonosis that can be prevented successfully. But mostly, prevention is very difficult to accomplish, especially when the links between the animal disease and the disease in humans is not known or recognized. An example is described in Box 7.