Parasitic Diseases. There are three main classes of parasites that cause disease in humans: Protozoa. Helminths. Ectoparasites.

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1 Parasitic Diseases Introduction Parasites are living things that use other living things, like your body, for food and a place to live. You can get them from contaminated food or water, a bug bite or sexual contact. Diseases caused by parasites are known as parasitic diseases. Parasitic diseases can be mild or life threatening. Prevention is especially important. There are no vaccines for parasitic diseases. Some medicines are available to treat parasitic infections. This reference summary will help you better understand parasitic diseases. It talks about how parasites cause disease, symptoms of parasitic diseases and common parasitic diseases. Parasites & Disease A parasite lives on or in a host organism. A host organism can be any animal or human. Billions of people are affected by parasites each year. Parasites can cause infection and disease in the host organism. Some parasitic diseases are easily treated. Others can be life threatening. There are three main classes of parasites that cause disease in humans: Protozoa. Helminths. Ectoparasites. 1

2 Protozoa and helminthes are often called endoparasites. Endo means inside. These parasites live inside the body of the host. Ectoparasites are parasites that live on the surface of the host. Ecto means outside. Ectoparasites may live on the skin and feed on the blood of humans or other animals. The next three sections talk about the main classes of parasites. Each section also provides examples of common types of parasitic diseases. Protozoa Protozoa are tiny parasites. They are often made of a single cell. A microscope is needed to see them. Protozoa are able to divide and multiply in humans. This means that even a single organism can cause a serious infection. Protozoa parasites can live in the intestines, blood or tissue of a human. If protozoa are in the intestines, they can spread to other people through an infected person s feces, or poop. Food or water can be contaminated with infected feces. If a person drinks or eats the contaminated food, they can get the parasite. If protozoa are in the blood or tissue, they can also spread to other humans. This can happen if a mosquito or other insect bites an infected person. The next person the insect bites can become infected. Protozoa can cause many different parasitic diseases. Some examples are: Malaria. Giardia Infections. Toxoplasmosis. Malaria is a major cause of death worldwide. About 250 million new cases of malaria arise in the world each year. Infected mosquitoes spread the disease. Malaria symptoms include: Chills. Fever. Flu-like symptoms. Jaundice, which is yellowing of the skin or whites of the eyes. Sweating. Vomiting or diarrhea. 2

3 Malaria can be life threatening. It causes more than 1 million deaths worldwide each year. But medicines are available to treat the disease. Giardia infections cause diarrhea, stomach cramps and nausea. You can get the illness if you swallow the parasite that causes it. The parasite lives in soil, food and water around the world. Symptoms of a Giardia infection may be mild or severe. It can lead to weight loss and a dangerous loss of body fluids called dehydration. Giardia infections often last two to six weeks. Several drugs may be used to treat it. Toxoplasmosis is a foodborne illness. It is commonly spread through contaminated food or water. You can also get it from the waste of an infected cat. The parasite may be swallowed if you touch your mouth after: Cleaning a cat litter box. Gardening. Touching something that has come into contact with infected cat feces. Toxoplasmosis does not cause symptoms in most people. But people with weak immune systems can have severe symptoms, such as: Blurred vision. Confusion. Lung problems. Seizures. Pregnant women who get infected early in pregnancy may experience a stillbirth or miscarriage. Infections that happen later in pregnancy can cause serious problems in the baby. Helminths Helminths are large, worm-like parasites. They can usually be seen by the naked eye when they are adults. As adults, helminths are not able to multiply in humans. Most helminths can live in the gastrointestinal tract of humans. But some can also be found in the blood, lymphatic system or under the skin. The lymphatic system is made up of tissues and organs that make, store and carry white blood cells that fight infections and other diseases. 3

4 A person can get these worm-like parasites by swallowing their eggs. This may happen after a person touches contaminated soil. The eggs can be swallowed when they are transferred from the person s hands to the mouth. Some helminths can also enter the body by entering through the skin. A person may walk barefoot through soil contaminated with parasite larvae. Larvae are immature worms. These worms are not full-grown adult worms. The larvae can enter the skin, travel through the bloodstream and end up in different parts of the body. Sometimes parasitic worms can enter the body when a person swallows contaminated food or water. Food or water may be contaminated by coming into contact with urine or feces. Raw or undercooked meat can also contain parasitic worms. In some cases, helminths can also spread if a mosquito or other insect bites an infected person. The next person the insect bites can become infected. Helminths can cause many different parasitic diseases. Some examples are: Pinworms. Hookworms. Strongyloidiasis. Pinworms are parasites about the length of a staple. They live in the colon and rectum. They are one of the most common worm infections in the world. Pinworms are even present in areas that have good sanitation practices. Many people with a pinworm infection have no symptoms at all. But pinworms can cause intense itching. At night, while you sleep, the female pinworms leave the intestines through the anus and deposit eggs on nearby skin. This can cause itching around the anus or vagina. Hookworms are also very common. They live in the intestines and sometimes even the lungs. Hookworms are more common in warmer climates. They affect about 740 million people worldwide. Hookworms often cause diarrhea. They may also cause nausea, abdominal pain or cramps. Some people may only have mild symptoms. Others may develop anemia caused by blood loss, poor nutrition or other complications. Anemia is a low red blood cell count. 4

5 Strongyloidiasis is an infection caused by a type of roundworm. The roundworm is mostly found in warm, moist areas. These parasites also live in the intestines. But, unlike other parasites, they can re-enter the body through the skin around the anus after they have been passed through stool. Strongyloidiasis often does not cause any symptoms. But it may cause: Burning upper abdominal pain. Cough. Diarrhea or constipation. Nausea or vomiting. Rash. Red, irritated skin near the anus. Weight loss. Ectoparasites Ectoparasites attach or burrow into the skin. They can stay on or in the skin for weeks or months. Examples of ectoparasites are: Fleas. Lice. Mites. Ticks. These types of parasites spread very easily. Ectoparasites spread in many different ways. These include: Close contact with pets. Close contact with someone who has parasites. Participating in outdoor activities, like walking near wooded areas. Sexual contact with someone who has parasites. Sharing personal belongings, such as hats, hairbrushes or towels. Ectoparasites can cause many different parasitic diseases. Some examples are: Scabies. Head or pubic lice. Tick bites. 5

6 Scabies is an itchy skin condition caused by a type of mite. It is common all over the world and affects people of all races and social classes. It can spread very easily in crowded areas. The mite that causes scabies burrows into the upper layer of skin. This causes the symptoms of scabies, including: Pimple-like irritations or a rash. Intense itching, especially at night. Sores caused by scratching. Symptoms may affect the whole body or may be limited to certain parts of the body. Head lice are tiny insects that live on the scalp and feed on blood. They are very common in children ages 3 to 11 and their families. Symptoms of lice are: Frequent itching. Irritability. Inability to sleep. Sensation of something moving in the hair. Skin sores from scratching. Tick bites happen when a tick attaches to the skin. Ticks live in wooded areas and brushy fields. Once attached to the skin, ticks survive by eating blood. It is important to remove a tick quickly since ticks can spread many diseases, including Lyme disease. Lyme disease is a bacterial infection you get from the bite of an infected tick. It can cause joint and muscle aches or nervous system problems. See your health care provider right away if you have symptoms of a tick-borne illness after being bitten by a tick. Symptoms of a tick-borne disease are: Aches and pains. Fever or chills. Rash, some of which may look like a bull s eye. 6

7 Diagnosis Your health care provider will ask you about your symptoms and personal health history. He or she will also perform a physical exam. A parasitic infection may be suspected if you have recently traveled or lived in an area with poor sanitation or where such infections are common. Special tests may be needed to diagnose a parasitic disease. For example, antigen testing may be done. This test looks for substances released by a parasite. Lab tests may also be done on a sample of blood, stool, urine or phlegm. These tests examine body fluids for the presence of parasites. For example, a stool sample may show the eggs of a parasite. You should not use antibiotics, laxative or antacids until after a stool sample has been collected. These medicines can reduce the number of parasites and affect the test results. In some cases, your health care provider may take a sample of tissue that may contain a parasite. Tissue may be taken from your lungs, intestines or skin. This is known as a biopsy. Sometimes it takes more than one sample to find the parasite. Other tests may also be done to look at a specific area of the body. These may include: An endoscopy, to look at the esophagus, stomach and upper part of the small intestine. A colonoscopy, to look at the colon and rectum. Imaging tests, to see if a parasitic disease has caused lesions in any organs. Treatment Treatment depends on which parasitic disease you have. In some cases, treatment may not be needed. Some mild parasitic diseases get better without treatment. If you have diarrhea or vomiting, it is important to stay hydrated. Drink lots of fluids. You can also ask your health care provider about oral rehydration solutions. Some medicines are available to treat parasitic diseases. Depending on the type of disease, medicines may be taken orally or may be given another way. For example, scabies is often treated with medical lotions. 7

8 Prevention It may be possible to prevent some parasitic diseases. This section provides tips on preventing the spread of parasites. Always wash your hands with soap and water before eating or handling food. Also wash your hands after using the toilet. If soap and water are not available, you can use an alcoholbased hand sanitizer. In areas of the world where food, drink and water may be contaminated with parasites, avoid drinking tap water. You should also cook or boil foods and peel fruits and vegetables. Because some parasites survive freezing, ice cubes can sometimes contain parasites. Always use ice cubes made from purified water when traveling. To avoid certain types of worm-like parasites, you should not: Touch sand or soil with your bare hands. Walk barefoot in the sand or soil. These precautions are only necessary if you are in an area where the soil or sand may be contaminated. Always cook meat thoroughly. Never eat raw or undercooked meat. To prevent ectoparasites, never: Lie on or near a bed, couch, pillow, carpet or stuffed animal that has had contact with an infected person. Share personal items, like combs, towels or hair accessories. You should also use hot water to wash clothing, bed linens and other items recently used by an infected person. Vacuum the floor and furniture to help get rid of any parasites. Do not have sex or close contact with someone who has a parasitic infection that can spread easily. Mosquitoes can spread some types of parasites. To prevent these parasitic diseases: Keep arms and legs covered. Sleep under mosquito netting if you are traveling to an area known to have malaria or other parasitic diseases spread by mosquitoes. Use mosquito repellent. Stay indoors beginning at dusk and through the night. 8

9 To prevent tick bites that can cause many different diseases, you should: Avoid wooded and bushy areas. Walk in the center of trails. Use tick repellent. Find and remove ticks from your body after coming indoors. Check your pets for ticks daily, especially if they spend time outdoors. Summary Parasites are living things that use other living things, like your body, for food and a place to live. You can get them from contaminated food or water, a bug bite or sexual contact. Diseases caused by parasites are known as parasitic diseases. There are three main classes of parasites that cause disease in humans: Protozoa. Helminths. Ectoparasites. Each of these classes can cause many different parasitic diseases. Parasitic diseases can be mild or life threatening. Prevention is especially important. There are no vaccines for parasitic diseases. Some medicines are available to treat parasitic infections. 9