There are many types of parasites in cats. Every type of parasite is different, and will do different things to the overall health of your cat. Learn more about the different types of feline parasites.

Do Some Intestinal Parasites Have Medical Advantages?

What Causes Ringworms in Humans?

Toxoplasma, The Most Dangerous Cat Parasite

Live Whipworm Squirming Around Inside Intestines

Intestinal worms are more common in the average person and will cause a wide variety of negative symptoms, but parasites in your brain poses the most severe and immedieate health concern.

If you are experiencing any problems with your brain. It is imperative that you see a doctor or specialist immediately. Parasites in your brain are not very common, but if you do have them, you need to get rid of them as soon as possible. There are many other serious conditions that can affect your brain. Brain Anuerysms are very common and affect many Americans every year.

Do Some Intestinal Parasites Have Medical Advantages?

What Causes Ringworms in Humans?

Toxoplasma, The Most Dangerous Cat Parasite

Live Whipworm Squirming Around Inside Intestines

As mentioned in previous posts, hookworms in humans do not bear any prominent symptoms and due to this reason about 70% of people may suffer from the infection without having a single clue about it.

The infection of hookworms in humans occur in two ways; one through the skin and the other through dogs. The disease caused by hookworms in humans mostly occur in warm, humid climates – meaning, these intestinal parasites cannot survive in climates other than tropical or sub tropical. More on intestinal parasites in humans.

Hookworms are attributed as blood suckers as they suck blood from the host’s intestinal walls and damage the mucosa. It has been known that an adult hookworm sucks about 0.1mL of blood everyday. So you can estimate the amount of blood loss which can be caused by an infestation of 1500 hookworms – 150mL per day! The ill effect which follows is anemia, secondary to loss of iron (and protein) in the gut. Hookworm infection is more severe in children, as it might cause growth retardation. So as soon as a parasite infection is suspected the wisest thing would be to initiate the treatment immediately.

Symptoms of Hookworms in Humans

There are no specific signs of hookworms in humans, particularly at the start of the infection. However, people who suffer from long-term infection tend to be thin, tired and weak. Anemia may be associated with the symptom which occur due to heavy infestation of these intestinal parasites.

Probable symptoms of an infection might occur in an event where a person has been affected by a large number of larvae include itchy rash, cough, fever, abdominal discomfort and vague abdominal pain, increased gas production, bloody sputum, loss of appetite, nausea and vomiting. In some cases, coughing, wheezing, diarrhea, pallor, fatigue, black stools, malaise, eggs and blood in the stool might also show up as some of the symptoms of hookworms in humans.

Treatment for Hookworms in Humans

Local cryotherapy is usually administered when the parasite is till under the skin. Medicines such as medendazole or albendazole are recommended for the treatment as they help in killing the adult worms. Pyrantel pamoate is another medicine which can be used by both humans as well as dogs, however, the dosages vary.

It is advisable to get proper information about the adequate amount of dosages required for both adults and children from a chemist or most preferably from a doctor. However, studies have revealed that a moderately small number of hookworms in humans do not raise any concern, provided there is enough iron in the diet. Problems occur when these parasites in the human body grow rapidly and increase in numbers.

As hookworms affect people in tropical and subtropical regions, it is a good practice for the natives to wear shoes when they go out of their homes. This is because, majority of people are affected by the larva of these worms when an unsuspecting person or animal walks on them. These parasites then make their way from the foot to the intestines.

Because hookworms are a common parasite in dogs, it is also wise to do regular de-worming of your pet dogs (if you have any). Although, worms in dogs do not reach its maturity as in humans, but they cause nasty rash. So these are some of the prevention methods that should be followed in order to minimize the chances of infection by hookworms in humans. As mentioned, staying healthy and including sufficient iron content in your diet also keeps a check on the growth of the worms in humans and helps curb any infections.

article written by: Rajib Singha

Do Some Intestinal Parasites Have Medical Advantages?

What Causes Ringworms in Humans?

Toxoplasma, The Most Dangerous Cat Parasite

Live Whipworm Squirming Around Inside Intestines

As we’ve discussed in previous articles, intestinal parasites are something you don’t want to have. They can have a negative effect on your health and be the source for a wide variety of symptoms.

There are many ways to flush out parasites that may be affecting your health. Just be sure to do the proper research into cleansing methods. If you think you may have an intestinal parasite, be sure to check out this list of parasite symptoms.

In this video, the doc discusses two products that he would recommend for treating ringworms. These two products are Mycozil and Paratrex. Both products are made from organic ingredients, that are all designed to help kill off these types of parasites and fungus that may be inside your body.

Besides from the two products mentioned above, he also says that colloidal silver, oregano oil and probiotics may also help treat ringworms. These are all great options, especially the oregano oil. But be sure to do your research on the quality of some of these supplements. There is alot of cheaply made products floating around. It’s always best to get organically-grown herbs if you can.

Now, it would be asinine to believe that Mr. McKerrow is saying that intestinal parasites are good, but he does bring a great example to the table as to why some people would benefit from intestinal worms. For the vast majority of the population, you would obviously not want to get a human parasite, and do everything you can to remove the parasite off before it negatively affects your health.

Do Some Intestinal Parasites Have Medical Advantages?

What Causes Ringworms in Humans?

Toxoplasma, The Most Dangerous Cat Parasite

Live Whipworm Squirming Around Inside Intestines

The most common type of roundworm infection is the pinworm infection. Roundworms are basically intestinal parasites that use your body as a host to stay alive and reproduce. The microscopic eggs of the pinworm hatch inside your bodies and grow into adults that measure 13 millimeters or about half an inch. These worms mature inside the intestine and travel through the digestive system to lay their eggs in the anal area.

How Do Pinworms Spread?

An person that is infected with parasites, in most cases a child; transfers pinworms when he/she has scratched his/her bare anal area and the eggs get under his/her fingernails. Apart from this, pinworms are also spread in the following ways:

• Eggs may be passed on from an infected child who has not washed his/her hands after using the bathroom and then touched a playmate or play toy.
• Pinworm eggs can also be transferred from the fingers onto beddings and clothing and thus spread around the house.
• These eggs can also be inhaled from the air and deposited onto food and swallowed.
• The pinworm eggs are able to spread for a longer time as they are able to survive up to two weeks on clothes, bedding and other objects that are kept at room temperature.

Pinworm infections can be spread as long as either eggs or worms are present.

The Signs & Symptoms of Pinworm Infection?

If the infection is mild, then there may not be any pinworm symptoms. Most of the symptoms of parasites that are noticeable in humans, will only take place in case of moderate or heavier infections.

Some of the signs and symptoms in case of heavier pinworm infections are:

• Nervousness
• Irritability
• Loss of weight
• Difficulty sleeping
• A feeling of restlessness
• Itching that is concentrated around the anal area
• Gastrointestinal symptoms like intermittent abdominal pain and nausea
• Some girls may experience vaginal itching and irritation (vaginitus)

How is Pinworm Infection Diagnosed?

There are two methods used to diagnose pinworm infection. The first is the direct sighting of a Parasitic worm, where the adult worm is seen around the anus. The second method that is used is the tape test. This test involves the use of cellophane tape. In this procedure, a tape is pressed against the skin around the anus and then examined under a microscope. It is advisable to use this method of testing early in the morning before defecating or bathing, as the parasites typically lay eggs at night.

Pinworm Treatment Options

No treatment is usually required for mild pinworm infections. Of course, there are medicines that are almost always available for effectively eliminating the parasite. These medicines are usually prescribed for all the members of the family because children spread pinworms easily to other members. The doctor may also prescribe a soothing ointment or cream if the vaginal or anal itching is severe and interfering with your sleep.

The doctor might also remind you to keep your fingernails clean, avoid scratching the anal area and wash any potentially infected sheets and clothes.

Another common pinworm treatment method, is to do a parasite cleanse to help remove pinworm symptoms naturally.

What steps can I take to prevent pinworm infection?

To prevent pinworm infection you need to:

• Wash your hands and fingernails frequently.
• Encourage children to restrain from scratching their bare anal areas.
• Bathe daily.
• Change and wash clothes and bedding frequently.
• Since the pinworm eggs continue to be present in the faces of the infected person for up to a week after the treatment, precautions should be taken keeping this in mind.

Parasite worms can cause a significant amount of distress and even mortality throughout the world. They are especially prevalent in less developed nations where there are lowered standards of food preparation and personal hygiene. But these types of intestinal worms are not limited to these nations and are quite common in the United States.

There is a wide variety of parasites that are common in the United States, such as pinworms, roundworms, hookworms, and tapeworms. Here is what you need to know about each of these harmful invaders and how you can keep them out of your body.

• Pinworms — Enterobius vermicularis is the Latin name for pinworms, the most common parasite worm in the United States. Humans are the only known host of the pinworm, and it affects roughly 209 million people throughout the world. Humans can become infected with pinworms by ingesting contaminated food, water, or dust.

  Adult pinworms are small, reaching a length of two to ten millimeters. They live mainly in the large intestine. But when female pinworms reach maturity, they will travel to the area just outside the anus to lay their eggs. Up to fifteen thousand eggs may be laid in location! These eggs can then be easily spread to other hosts via contact with contaminated sheets, clothing, furniture, toilet seats, or hands.

  Anal itching is the number one complaint associated with pinworm parasite worms, followed by insomnia and sleep disturbances. In more serious cases of pinworm infection, symptoms such as weight loss, urinary tract infection, and appendicitis may be noted.




• Roundworms — The roundworm, Ascaris lumbricoides, are the largest intestinal parasite worms in the world. It affects roughly one billion people throughout the world, the majority of which are children. Roundworms are large parasites, resembling earthworms in their general appearance. They can infect their human host via direct contact with contaminated soil, food, or feces.

  These intestinal worms can travel throughout the body, causing destruction at several points along their journey. They may be responsible for severe tissue irritation and allergic reactions in the liver and the lungs. Adult roundworms may make their home in the liver, the lungs, or the heart. If you become infected with roundworms, there are many symptoms to be on the look out for.

  Symptoms of a roundworm infection include cramping, swelling, insomnia, allergic reactions, and weight loss. If left untreated, roundworms can multiply to such great numbers that they cause a blockage within the digestive system.



• Tapeworms — Tapeworms are very large intestinal parasite worms that can wreak havoc within the digestive system. There are several types of tapeworms, such as the beef tapeworm (Taenia saginata), the pork tapeworm (Taenia solium), the dog tapeworm (Dipylidium caninium), and the fish tapeworm (Diphyllobothrium latum).

  Tapeworms are whitish in color with a flat head and a long, ribbon-like body. In extreme circumstances, they can grow to several feet in length and live within their human host for up to twenty five years. In most cases, a tapeworm infection will elicit few noticeable symptoms and may go undetected throughout its entire lifespan.

  However, the most common symptoms of tapeworms would include diarrhea, abdominal cramping, irritability, nausea, vomiting, and loss of appetite. Symptoms will vary in people.

• Hookworms — Anclyostoma duodenal and Necator americanus are the two species of parasite worms that are found exclusively in humans. Anclyostoma duodenale, is found primarily in Europe, Africa, China, Japan, India, and the Pacific islands. Necator americanus, on the other hand, is found in North and South America and the Caribbean.

  Hookworms can penetrate the human skin. The main pathway of infection is through the soles of the feet. Individuals who walk barefoot in areas that are contaminated with hookworm larvae are likely to become infected by the parasite. The larvae then travel through the body until they reach their final destination, the small intestines. These parasite worms can range in length from approximately six to twelve millimeters.

  
  

  The greatest concern regarding hookworm infection is the loss of blood that occurs when this parasite attaches its teeth like hooks into the lining of the intestines. Symptoms of hookworm infection include itchy skin and blisters and the point of entry, followed by nausea, dizziness, weight loss, appetite changes, and anemia.

Keeping Parasite Worms Out!

Humans can contract parasite worms via a number of pathways — the foods we eat, the water we drink or bathe in, the animals we come in contact with, or even the (dirty) air we breathe. But this does not mean that we are destined to become infected with parasites. Here are some steps you can take to reduce your risk of a parasite infection.

• Wash hands frequently throughout the day, especially before eating and after using the toilet or handling animals. Use soap and hot water. Be sure to lather for at least thirty seconds.
• Only drink filtered or treated water. If you are not sure of the quality of your tap water, use a water filter to help purify the water.
• Wear shoes, especially on beaches and in playgrounds that may house animal feces. It is common for humans to become invested with worms while walking around barefoot in contaminated areas, such as locker rooms and dirty carpet.
• Do not swim in water that may be contaminated with parasites. This may include many public places, such as beachs, lakes and rivers. Do your research on the public waters located near your home, before your family takes a dip.
• Do not eat raw or undercooked meat. This is especially important for fish. While sushi is delicious for some, it is a common source of intestinal worms. Take caution before devouring.
• Wash and peel fruits/vegetables before eating them, especially if they are to be eaten raw. Use soap to sanitize the outside. Buy organic fruits and vegetables when possible.

by Dr. Edward F. Group III, DC, ND, DACBN, DABFM

Do Some Intestinal Parasites Have Medical Advantages?

What Causes Ringworms in Humans?

Toxoplasma, The Most Dangerous Cat Parasite

Live Whipworm Squirming Around Inside Intestines

In order to relieve the symptoms of a parasitic infection, it is essential to completely remove the parasites from the body. Any medication or nutritional supplement that aims to treat the parasitic infection without removing the parasites will be unsuccessful.

Rather, here are five comprehensive steps that will help you remove parasites from your body so you can get on with your life. These include cleansing the system, modifying the diet, administering supplements to kill the parasites in all of their life stages, reintroducing healthy bacteria to the digestive system with a high quality probiotic supplement, and making the necessary lifestyle changes to prevent re-infection from the same type of organisms.

Step 1) Cleansing the System to Help Remove Parasites

Most parasites entrench themselves within the various organs of the body, especially within the intestinal tract. Therefore, in order to get rid of these harmful organisms, it is essential to cleanse the system of mucus and waste that may be surrounding the parasites.

There are several herbal cleansers that can be used to detoxify your digestive system. Common ingredients in these herbal cleansing supplements include comfrey root, agar-agar, flax seeds, psyllium husks, alginate, beet root, citrus pectin, papaya extract, and bentonite clay. It is important to remember to drink lots of purified water while taking these types of cleansing products.

One of the most common side effects of these cleansing herbs include constipation and bowel impaction. This happens when you don’t drink enough water. Any sort of impaction inside your digestive system will only help these types of intestinal worms thrive.

There are also several ready made colon cleansing products on the market that may help. These products usually incorporate one of the herbal ingredients mentioned above in their formula. It is important to know the source and quality of the herbs used in any dietary supplement. Be sure to do the proper research, and follow the dosage and cleansing instructions carefully. Bottom-line, there are many different types of cleansing programs, so do your research on the best colon cleanse.

Home enemas and professional colonic irrigation are two more good methods for cleansing the system and parasite removal. A colonic irrigation is typically performed in a doctor’s office. It involves flushing the entire length of the large intestinal with a lukewarm water solution. This procedure may take up to 45 minutes to dislodge and remove toxins throughout the intestinal tract. Home enemas are the do-it-yourself version of the colonic irrigation. Ingredients such as garlic, vinegar, and blackstrap molasses can be added to the home enema to increase its effectiveness.

Step 2) Modifying The Diet

There are very few studies that explain the exact relationship between parasites and nutrition. However, it is pretty safe to assume that a healthy diet of fruits and vegetables will increase your immune system and your defenses against intestinal parasites, because of all the nutrients contained in the fruit.

In addition, since it is well documented that these types of organisms thrive on sugar and carbohydrates, it may be a good idea to limit your intake of simple-carbohydrates such as refined sugar, enriched white flour, and processed foods. It is especially important to avoid eating sushi and other undercooked fish (and pork). While sushi has deep roots in many cultures, it is also one of the most common sources of infection from the food we eat.

Step 3) Taking a Parasite Removal Supplement

There are several dietary and herbal remedies that can be utilized to help remove parasites in every stage of their life cycle. If you think you may be infected with some sort of intestinal or stomach parasite, it would be wise to take an herbal cleansing designed to flush out these types of organisms.

There are many ingredients included in these herbal cleansing supplements. Some of these incredients include black walnut hull, wormwood, clove, kamala, just to name a few. There are other herbs that can help flush out these organisms, so consult your local herbalist or specialist to help recommend a particular herb. At some stores, you can buy these herbs in bulk and add them to your smoothies for at-home cleansing methods. However, it is easier for most people to just do a parasite cleanse.

Step 4) Reintroduction of Healthy Bacteria

With all of the steps you have taken to cleanse the digestive system and remove parasites, it is now essential to reintroduce healthy bacteria to your intestinal tract. Healthy bacteria usually occurs naturally in the digestive system, but some cleansing herbs will remove the healthy bacteria, along with the harmful parasites.

Probiotics will help to detoxify your digestive system, maintain the proper chemical balance, and act as natural antibiotic against harmful bacteria and yeast organisms. The recolonization of the digestive tract with friendly flora will help protect the body against future parasitic infections, as well as the development of other yeast, bacterial, and fungal related disorders. There are many probiotic supplements that can be used to help maintain a healthy digestive system, as well as guard against further disorders.

Step 5) Lifestyle Changes to Prevent Reinfection

This is a proactive do-it-yourself step. Make it a point to learn everything you can about the risk factors for developing a parasitic infection. If possible, try to determine the cause of your infection, and then make the necessary changes to avoid further problems. If it is not possible or practical for you to determine the source of your parasitic infection, take the steps necessary to avoid re-infection. Properly cooking food, frequently washing hands, disinfecting water supplies, and limiting contact with pet feces are all good ways to reduce your exposure to parasites.

If you are planning a trip abroad, look into the food hygiene, sewage, and water treatment standards of the area you will be visiting. Contact the Center for Disease Control to learn about the regional disease that can be found at your destination. If there is a possibility of parasitic infection, be sure to stay away from unfiltered water, uncooked fruits and vegetables, and undercooked meats. Take the appropriate steps to protect yourself. Parasite removal should be practiced on a daily basis, and if you are infected, you should do a parasite cleanse at least 2x every year.

article written by: Dr. Edward F. Group III, DC, ND, DACBN, DABFM

Do Some Intestinal Parasites Have Medical Advantages?

What Causes Ringworms in Humans?

Toxoplasma, The Most Dangerous Cat Parasite

Live Whipworm Squirming Around Inside Intestines

There are many different types of parasites that can affect both animals and humans. Here is a list of the most common parasite infections:

Roundworm Parasite Infections

Necator americanus — This parasite can reach a length of just a little over one centimeter. It usually enters the system through the feet and attaches to the small intestine, causing anemia and abdominal disorders.

Ancylostoma duodenale — This parasite enters through the skin and makes its home in the small intestines. It can grow to a length of approximately 1.3 cm. Parasite infections with this roundworm cause anemia, and gastrointestinal distress.

Ancyclostoma braziliense — A. Braziliense parasite makes its way into the body through the skin and eventually makes its home there as well. The larva of this parasite can get to be three tenths of a millimeter. Infections cause skin lesions and itching.

Ascaris lumbricoides — This large roundworm can grow to a length of 35 centimeters. It enters the body through the mouth and matures in the small intestines. Infections cause vague symptoms of abdominal discomfort.

Toxocara canis — The toxocara worm parasite enters the body through the mouth and causes infections of the liver, lung, brain, and eyes. The larva are small at a length of about 0.3 millimeters. Symptoms of infection include pneumonitis.

Enterobius vermicularis — As known as the pinworm, this parasite enters the body through the mouth and makes its home in the appendix and the large intestine. It can reach a length of 1.3 centimeters. Infections of this organism is known to cause anal itching.

Trichuris trichuria — Trichuris is also referred to as whipworm or threadworm parasite. It makes its home in the large intestine or the ileum after entering the body through unwashed vegetables. These parasite infections cause abdominal discomfort, anemia, and bloody stool. Whipworm can grow to a length of 5 centimeters.

Trichinella spiralis — Trichinosis is the condition usually caused by this specific parasite. Trichinella infection occurs via infected pork. The parasite enters through the mouth and matures in the striated muscle. Once it reaches adulthood, it will enter and remains in the small intestine. It can grow up to 0.4 centimeters. Infections of trichonisis parasite may symptoms such as muscle pain and swelling.

Strongyloides stericoralis — Also known as Chinese diarrhea, this parasite enters the body through the skin and attaches to the wall of the small intestine. Infections cause abdominal discomfort and diarrhea. This parasite can get to be about 0.2 centimeters long.

Wuchereria bancrofti — This parasite is transmitted to humans through mosquito bites. It can grow to 10 centimeters long. Infections with this parasite cause swelling of the lymph nodes and fever.

Brugia malayi — Similar to W. bancrofti, this parasite is transmitted to humans through mosquitoes. Infections with this parasite cause swelling of the lymph nodes and fever. But B. malayi is a smaller parasite, with a maximum length of 6 centimeters.

Acanthocheilonema perstans — This parasite attaches to the body cavities after entering via a fly bite. Once there, it grows to a length of 8 centimeters and infections with this parasite cause abdominal pain and liver disorders.

Mansonella ozzardi — This parasite infects the body cavities via a fly bite. It reaches a maximum length of 8 centimeters, but it usually does not cause any noticeable symptoms.

Loa loa — Also known as eyeworm, L.loa infects humans through fly bites. Infections with this parasite cause localized inflammation and possibly the development of a transient tumor. Its maximum length is 7 centimeters.

Onchocerca volvulus — Infections with this parasite cause a condition called blinding filariasis in which the sufferer may experience either a temporary or a permanent loss of vision. It enters the body from a fly bite and grows to a length of 50 centimeters.

Dracunulus medinensis — Also known as fiery serpent or Guinea worm, this parasite can grow to a length of 120 centimeters. It enters the body via the mouth and makes its home in the skin. Infections with this parasite cause inflammation and ulceration of the legs and feet.

Tapeworm Parasite Infections

Taenia saginata — This parasite is also known as the beef tapeworm. It forms cysts in beef and infects humans through the ingestion of undercooked or raw beef. It enters the small intestines and can reach a length of 12 meters! However, it usually does not cause any noticeable symptoms.

Hymenolepis nana — The dwarf tapeworm enters the body through the ingestion of undercooked or poorly washed foods. It grows to 4 centimeters. Infections with this parasite can cause abdominal discomfort in the body.

Hymenolepis diminuta — The rat tapeworm grows to 60 centimeters long. It infects humans via insect cysts but usually does not cause any noticeable symptoms.

Taenia solium — The pork tapeworm infects humans via the infection of raw or undercooked infected pork. It can grow to 15 centimeters long, but it does not usually cause any noticeable symptoms.

Echinococcus granulosus — This tapeworm enters the body from the eggs of dog feces. Infections with this parasite affects the liver lungs, brain and bones causing pressure in the body and various symptoms of discomfort. Its maximum length is 15 centimeters.

Fluke Parasite Infections

Schistosoma mansoni — This fluke ranges in size from 1.4 to 2.6 centimeters. It enters the body via the skin and makes its home in the bladder or the intestines. Infections with this parasite include dysentery and other digestive disorders.

Fassiolopsis boski — This intestinal fluke enters the body via the ingestion of infected water nuts and vegetables. It ranges in size from 2 to 7 centimeters and it causes diarrhea, swelling, and abdominal pain.

Clonorchis sinensis — The human liver fluke infects humans through the ingestion of infected fresh water fish. It makes its home in the bile ducts, causing indigestion and diarrhea. It can reach a length of 2.5 centimeters.

Paragonimus westernani — The lung fluke grows to one centimeter in length. It infects the human body through the consumption of infected fresh water fish, namely crabs. This fluke makes its home in the lungs. Infections with this parasite can cause coughing, abdominal pain, and fever.

Protozoa Parasite Infections

Plasmodium species — There are several species of these parasite protozoa. They all enter the body through infectious mosquito bites, transfusions, or dirty syringes. Once in the body, infections with this parasite species of protozoa cause fever, chills, sweating, and enlarged spleen.

Leishmania species — This protozoa species enters the body via the skin and causes fever, leukopenia, and chronic ulceration.

Trypanosoma species — African sleeping sickness is among the diseases caused by this protozoa species. It enters the body through the bite from a tsetse fly causing fever, rash, headache, and enlarged spleen and liver.

Giardia lambia — This parasite causes giardiasis and condition characterized by gastrointestinal distress, diarrhea, and weight loss. It enters the body usually through contaminated food and water and makes its home in the small intestine.

Toxoplasma gondii — This protozoa enters the body through the consumption of infected meat, or contact with infected feline stools. Once inside, it causes a condition called toxoplasmosis. Infections with this parasite can lead to seizures, fatigue, and even death.

by Dr. Edward F. Group III, DC, ND, DACBN, DABFM

Do Some Intestinal Parasites Have Medical Advantages?

What Causes Ringworms in Humans?

Toxoplasma, The Most Dangerous Cat Parasite

Live Whipworm Squirming Around Inside Intestines