This chapter contains information about twelve zoonoses we have selected, because: they may cause serious illness in people; they are very common; or there has been a lot of attention surrounding this disease recently or in the past. In the text, we have tried to provide information on the incidence of the specific zoonoses: in which regions they occur and how often. Because exact data on the occurrence of these diseases is difficult to provide for every region, we advise you to contact your local veterinary service.

Anthrax can affect all animals, domestic and wild. Animals become infected when they drink contaminated water or eat contaminated grass from a spot near where a carcass with anthrax lies exposed. In animals we can also see three forms:

1.) The peracute form progresses rapidly! The owner mostly only finds a dead animal and suspects that it died from poisoning or lightning. As the blood does not coagulate normally, it is possible that the blood in and around the nose, mouth, vulva and anus is black in colour. The carcass does not become rigid.

2.) The acute and sub-acute form exhibits the following symptoms: fever, nervousness, difficulties with breathing and walking, convulsions (fits) and death. The blood is not always observed to be black.

3.) The chronic form develops somewhat slower, with a swollen tongue and bloody foam from the mouth, but the animal soon dies because it cannot breathe.

Do not touch birds if there is a hint of suspicion of avian influenza, for example, when you find many dead birds together. By touching these animals, you could spread the disease to chickens. Note: avian influenza in poultry cannot be cured. If avian influenza is alerted in your region, keep your poultry inside and make sure that they cannot come into contact with wild birds and other poultry.

Vaccination against avian influenza in poultry is possible. Ask a veterinarian about this.

Why is there so much to-do about avian influenza in humans? At this moment, poultry owners should be aware of the fact that they can get seriously ill from chickens with avian flu. The main problem is the fear that this influenza virus may mutate (change) and then become extremely dangerous to people. Authorities are afraid that such a dangerous influenza could kill millions of people all over the world. On the other hand, there is no real evidence that this will ever happen. We just don?t know.

There are three types of tuberculosis in humans: human tuberculosis, bovine tuberculosis and avian/porcine tuberculosis. Most cases of tuberculosis in humans are human tuberculosis and this is not a zoonosis. The other two are zoonoses, of which bovine tuberculosis is the most significant.

Bovine tuberculosis most often affects weak or debilitated people. Thus, patients with immunodeficiency (for example patients with AIDS) run a greater risk of contracting the disease. The disease causes abscesses of different sizes that appear in the lungs, which in time can become hardened. Sometimes it can invade other organs of the body. It is a chronic disease. The patient coughs a lot, has pain in the chest, fatigue and sometimes dies. The treatment based on antibiotics is lengthy and expensive.

People get bovine tuberculosis through consumption of raw (uncooked) milk and other dairy products made from raw milk. It can sometimes be transmitted through the air (airborne), for example, when humans and cattle live together in the same tent or house.

Mycotuberculosis bovis is a cattle disease. It is a chronic disease of the lungs. Transmission between cows is airborne. Other species, like cats and dogs, can become infected by consuming raw milk, but they have natural resistance and do not transmit the disease to people.

Animals can become infected when they lick or eat the foetus, placenta or liquids from an animal that has aborted, and from eating the hay where a dead foetus had lain. A female animal can also get brucellosis when she mates with a male animal that is infected. Brucellosis can be even be transmitted via artificial insemination.

The main symptom in all animals is abortion, often combined with retention of the placenta, a lower milk production, mastitis and infertility:

Generally, there are no clinical symptoms in cattle or in pigs. Cows can get infected by eating grass that contains tapeworm eggs. This has to do with the people who defecate in open fields. Pigs get mostly infected when they directly eat human excreta. There are no medicines that can kill the cysts in the cow or pig. The cysts in pigs can sometimes be detected when they are alive, by inspection of the tongue. The cysts are white, round vesicles measuring between 0.5 to 1 centimetre in diameter.

The growth and reproduction cycle of tapeworms is as follows:

So, the tapeworms need the animals to hatch from the eggs and to grow. This cycle sometimes goes wrong in the case of pig tapeworms, when the larvae eaten by humans get confused and migrate through the human body to form cysts in different parts. It can happen that they form cysts in the human brain or liver.

The symptoms of tapeworms are less serious than the symptoms caused by the cysticercus; only sometimes causing stomach aches, diarrhoea, poor appetite and malaise.

The pig tapeworm is the tapeworm that causes cysticercosis in humans. Cysts can be present in all parts of the body. These cysts may become so large that in the end they will become life threatening, but mostly this will not happen. Cysticercus in muscles does not display many clinical symptoms, but when cysts grow in the brain you can get neurocysticercosis. Then the symptoms are severe headaches and epilepsy.

The main problem is cysticercosis, caused by the pig tapeworm. To prevent cysticercosis, it is important to interrupt the infectious cycle between humans and pigs.

These measures also prevent taeniasis from cattle: use latrines, keep animals in a stable or a field with a fence around it and observe strict meat control (of pork and beef) in slaughterhouses.

Do not buy meat if you are not sure whether is free from cysts!

Echinococcosis is caused by tapeworms from foxes, wolfs and dogs. It is also called hydatidosis. The disease is present globally and is especially a problem in rural communities.

These tapeworms live in the intestines of dog-like animals. They produce eggs that are excreted with the faeces. When a susceptible animal (cattle, sheep, pigs, mice, humans) accidentally ingests the eggs, the eggs will hatch in the intestines of the animal or person. After hatching, the larvae can move to different organs where they will start to grow as cysts (hydatids). When a carnivore eats the infected animal, the larvae develop into adult tapeworms in the intestines of the carnivore.

The adult parasites do not cause disease. The larva, however, can be dangerous. Symptoms depend on where the cyst is, often in the liver and/or lungs. Cysts grow slowly and may not show any signs for up to 20 years before becoming large enough to be visible as an abdominal swelling, or starting to cause problems by pushing on different organs. Death often occurs from this extreme compression of vital organs. Symptoms of liver cysts can include jaundice, abdominal pain and vomiting. Pulmonary cysts give rise to respiratory problems. Brain cysts may cause headaches and seizures (fits). The only curative treatment of cysts is surgical removal, but this is not always possible.

Eradication of this disease is very difficult and very costly. A rich country like Australia, for example, tried for ten years to get rid of echinococcosis but failed, because wildlife (dingoes, small rabbits and rodents) is a reservoir for echinococcosis. People have to prevent the disease from occurring by paying attention to the following:

There are no vaccines.

The symptoms vary much and can even be absent. In general two clinical types are distinguishable:

1.) Icteric leptospirosis, the more serious of the two: produces fevers, flu-like symptoms and yellowish skin. The kidneys can fail.

2.) Anicteric leptospirosis is less severe, though people can die of it! The symptoms are similar to influenza. The patient usually recovers in a month. This form is the commonest.

Rabies, or rage, is one of the most important and dangerous zoonoses! It is present in almost all countries over the world and as much in the cities as in rural areas.

Rabies is transmitted by the bite of a rabid animal, mostly a dog. Be especially aware of stray dogs! In rural parts of Latin America, vampire bats are dangerous as they are also able to transmit rabies. In some countries, especially in Africa, jackals, mongoose and other wild animals can transmit the disease; skunks and raccoons in the USA.

The symptoms are more or less the same in both humans and animals. They may occur after 10 days, but it can also take up to 10 months to appear, depending on the location of the bite. If the bite was near the head, this period will be closer to ten days, whereas if the bite was in a foot, for example, it could take longer.

The first symptoms are anxiety and pain around the bite wound. People also mention headache. Soon the person will not be able to tolerate light and sound and will start salivating profusely. The disease will cause spasms, paralysis and difficulties with swallowing, which is why the disease is also called "water fear" as the person - although very thirsty - is unable to drink.

In animals, the symptoms are more or less the same. Dogs and cats exhibit "furious rabies": the animals have the same symptoms as mentioned above, but also become nervous, excited and aggressive. Ruminants and horses exhibit a more quiet form, "dumb rabies": the animals become very timid and shy and not excitable at all. The dumb form can also affect dogs, which is then extra dangerous because people do not recognize it as rabies.

Once a person or animal has symptoms, there is no treatment and the only outcome is death!

Some countries have an eradication programme, meaning vaccination programmes for humans and animals, and birth control for stray dogs. In countries where vampire bats play a role, a monitoring system can be set up to control rabies in these bats.

Sleeping sickness or African trypanosomiasis is a disease that affects humans. Wild and domestic animals (particularly antelopes, buffalo and cattle) can also be infected with a subspecies, but they do not get symptoms. Sleeping sickness only occurs in sub-Saharan Africa. Another human form of trypanosomiasis occurs in the Americas and is known as Chagas' disease (see earlier chapter).

The disease is transmitted by the tsetse fly.

First there is redness, pain, and swelling at the site of the fly bite, but this is often ignored. The disease starts with fever, weakness, headaches, joint pain and itching. A characteristic symptom is a nut-sized bump in the neck, behind and below the ear (Winterbottom's sign). In a later phase, involvement of the brain produces the more characteristic signs of the disease: confusion and unpredictable mood changes. The person is unable to sleep at night and fall asleep during daytime, which gives the disease its name. Without treatment, the disease is fatal.

There are two forms of sleeping sickness:

1.) In central and western Africa (Gambian form), where the first phase can last for months or years without any manifestation of symptoms, suddenly starting in the second phase.

2.) In southern and eastern Africa (Rhodesian form), where the illness develops in a few weeks and the two phases are evident.

Avoid contact with the tsetse fly:

Toxoplasmosis is a very common parasitic disease both in the western world and in developing countries. A microbe, a protozoan that has a complex life cycle, causes it. Toxoplasmosis is especially dangerous to pregnant women and the foetus.

The cat plays a fundamental role in the infectious cycle. Cats become infected with the parasite when they eat wild mice or birds, after which the faeces of the cat will soon contain eggs that are infectious to other animals or humans. Flies, mice and cockroaches can transport the eggs to the kitchen and the rest of the house. Humans get infected most commonly by eating raw or inadequately cooked meat of pigs and sheep that have been in contact with cats.

Toxoplasmosis generally produces no symptoms. Infected humans sometimes have fever, pneumonia, heart problems and brain damage, especially those with a weak immune system. In pregnant women, the infection can affect the eyes and the brain of the foetus. The child can be born with hydrocephalus (commonly known as ?water on the brain? caused by excess fluid in the brain), epilepsy, deafness or can be retarded.

Infected cats, dogs, goats, pigs, horses, cattle, rabbits, guinea pigs and wild animals generally have no symptoms. The infection in sheep, on the other hand, can be the cause of abortion, nervous symptoms and eye problems.

Hemorrhagic fevers are rare but deadly diseases that are caused by a virus. Examples are Crimean-Congo hemorrhagic fever, Ebola hemorrhagic fever, Marburg hemorrhagic fever, Rift Valley fever, Nipah fever, Yellow fever and Lassa fever. Yellow fever is further explained in next the chapter Yellow Fever.

Mosquitoes or ticks transmit most hemorrhagic fevers. Nipah fever is transmitted by bats and pigs; Lassa fever by rodents. Ebola and Marburg can also spread from person to person (but are extremely rare diseases).

Fever and bleeding are the symptoms in humans and is the reason why they are called hemorrhagic fevers. Most patients die from shock, coma, seizures and sometimes kidney failure.

There is no cure for these diseases, so prevention is important. Vaccines exist only for yellow fever. For the other diseases, control of rodents, ticks and mosquitoes is vitally important. Clear away rodent nests and make sure that they cannot enter your house. Use insect repellents, mosquito nets, window screens and wear clothing that covers arms and legs

Yellow fever is a disease that affects monkeys and humans, called "black vomit" in some areas. The disease is found in tropical areas of South America and Africa. There is no explanation as to why the disease does not occur in tropical Asia, despite favourable conditions. Transmission of yellow fever occurs mainly during the rainy season, in moist savannah zones.

Yellow fever is transmitted to humans and monkeys by the bite of infected mosquitoes. These mosquitoes are different from those carrying malaria and, most important of all, they are daytime biters. So general precautions to avoid mosquito bites should be followed. These include wearing light-coloured clothing with full-length trousers and long sleeves, using insect repellent on exposed skin and mosquito nets.

Symptoms can appear 3-6 days after infection. They include fever, headache, muscle pain, loss of appetite, abdominal pain and jaundice. After 3-4 days, the general condition normally improves and most individuals will recover. But in some cases a high fever returns within 24 hours when the infection has taken a turn for the worse. If this happens, the sick person becomes very tired and bleeding from the mouth and nose can occur. It is difficult to distinguish from other diseases, especially in the early stages of the disease. The symptoms in monkeys are the same as in humans.

Vaccination is the single most important measure for preventing yellow fever. But there are also groups of people who cannot be vaccinated, because it would be too dangerous. They are: infants under 9 months of age, pregnant women, persons with AIDS and those hypersensitive to eggs (because the vaccine contains egg white).