Parasitic Worms - Ringworm, Roundworms and Tapeworms



Question: Website data re tapeworms seem pretty adamant that tapeworms only come from fleas... How about fecal matter from other animals containing tapeworm segments...? Neighborhood cats visit out yard at nite --- dog takes offense & cleans up next day. Tape worms usually once a year --- no sign of fleas. Is the cat poop a likely source --- or is the only possible source definitely fleas --- meaning we need to forget the cat poop and do a better job of flea control...or...? thanks, Joyce

Answer: Joyce- There are several types of tapeworms that can affect dogs and cats. The method of transmission varies some between the species. The most common tapeworm is Dipylidium caninum. This tapeworm's life cycle starts as an egg passed in the dog or cat's feces. The egg is eaten by a flea or louse and develops into an intermediate stage called a cysticercoid. This is the infective stage. The dog or cat eats the flea which now contains the cysticercoid and becomes infected. The cysticeroid develops into the adult tapeworms and the cycle starts again. There are two other fairly common tapeworms, Taenia pisiformis, which infects dogs and Taenia taenaeformis, which infects cats. Taenia species of tapeworms have a life cycle that involves an intermediate host but it tends to be a small rodent (T. taenaeformis) or lagomorph (rabbit, T. pisiformis). As far as I know, it is necessary to eat the intermediate host to get these tapeworms, as well. Taenia taenaeformis seems to have the name Hydatigera taeniaforms now. There are some Taenia species that can be acquired by eating undercooked meat of goats, sheep and cattle but I don't know how commonly these infect dogs. A much less common tapeworm in domestic dogs is Echinococcus multilocularis. This tapeworm is normally found in wild canine species and is transmitted through an intermediate host, usually a rodent. It is of special concern because if a human ingests the egg of this tapeworm the intermediate host can develop in the human and cause serious disease. This tapeworms isn't a common problem in dogs but it is a serious infection from the standpoint of risk to people. What this means is that the dog is either eating rabbits or eating fleas to get the tapeworms, in all liklihood. Fleas are more likely in most dogs but some dogs are good at hunting rabbits or at finding dead ones to eat. Mike Richards, DVM 7/22/2004

Deworming treatment for pregnant cat

Question: hi.... my niece has a cat and she is pregnent. but they noticed that she has worms she is due any time. and she asked me if i though she should worm her. i said no not now. to weight . i think there tape worms she said they look like little megits grose i know.... lol but i told her to weight . untill after the babys are borne, but!!!! then she will be feeding them . is it safe to worm her when she is milking?????? we dont want to hurt the babys can you please let me know what we can do to help her . thanks always diane

ps thank you for having this sight on the net... may god bless you pss my niece has 4 little children . i told her to keep the kids away from the cat . is that a good idea?? could the kid,s get worms? my niece has little money and cant afford a vet so once again i think you for your help

Answer: Diane- It is usually best to wait to deworm a cat until after it has had its kittens. It is a good idea to deworm the cat with a medicine that kills roundworms after the kittens are born and then every 2 to 3 weeks until the kittens are weaned. Pyrantel pomoate (or tartrate) is a good dewormer for roundworms that is also very safe. It can also be given to the kittens once they are 4 to 6 weeks of age. Roundworms can cause damage in people and so it is best to avoid contact with cat feces and to routinely deworm cats who are in contact with children. The worms that you are seeing are probably tapeworms, as these tend to be about 1/2 inch long or shorter and to move some at first. These are actually worm egg sacs rather than worms but they are an indication that tapeworms are present in the cat's intestines. Your niece will probably have to buy dewormer from this worm from a veterinarian to find an effective product. Praziquantal (Droncit Rx) or epsiprantal (Cestex Rx) are the best deworming ingredients for tapeworms. There are some combination products that kill tapeworms and other worms and contain this ingredient along with others. I think that there may be an over-the-counter product now containing praziquantal but I am not sure of that. Tapeworms are not especially harmful but it would be best to get rid of them. Tapeworms are carried by fleas so good flea control will help prevent them from coming back. Tapeworms can infect people but the are transferred to people the same way they are to cats -- by ingesting fleas. Most people don't ingest fleas but sometimes toddlers will. Mike Richards, DVM 2/18/2004


There are four species of hookworms that infect dogs and cats in the United States. They are Ancylostoma braziliense, Ancylostoma caninum, Ancylostoma tubaeforme and Uncinaria stenocephala. In dogs, A. caninum is the most common hookworm and causes the worst disease. In cats, A. tubaeforme is more common but is less likely to cause severe disease than A. caninum. Dogs in the Northern states and in Canada are more likely to be infected with U. stenocephala as it prefers cold climates and A. caninum prefers warm climates.

A. caninum hookworm infestation in dogs can lead to severe anemia, especially in puppies. These hookworms have big appetites and attach to the intestine and feed on the dog's blood. The other three types of hookworms are less likely to cause severe anemia but it is a potential problem with them. Signs of hookworm infection include weight loss, pale color, black or tarry looking stools, weakness, anemia and death. In areas in which hookworms are prevalent there can be skin disease in pets associated with exposure to the larval worms as well.

Hookworms can be acquired from the mother's milk, from penetration of the skin by hookworm larvae in the environment and from eating hookworm larvae. Some vets think that it may also be transmitted during pregnancy from mothers to puppies but this is controversial and I believe that it has been ruled out in cats.

One of the problems with hookworms is that they can accidentally infect humans. This creates a problem called cutaneous larva migrans, which loosely translates to worms migrating through the skin. Humans pick up the hookworm larvae from areas contaminated by dog feces and they penetrate the human's skin just like they would the dog's. Since they don't belong in the human they don't develop into adults but just migrate around in the skin, causing sores and inflammation, until they die. This is a good reason to keep dogs and cats from defecating in playground areas, beaches and other places where people's skin is likely to come in contact with the ground.

Fortunately, the monthly heartworm preventatives are also effective at controlling hookworms and can provide a measure of protection against the possibility of the cutaneous larva migrans syndrome occurring in the humans that own dogs and cats on heartworm preventative medications. In areas in which heartworms are not a problem but hookworms are, it is a good idea to consider having a pet's stool examined for the presence of worm eggs once a year and when clinical signs that may indicate infestation occur.

Michael Richards, DVM

Roundworms - persistent infestation

Question: Dear Dr. Richards,

My mother recently adopted two feral cats. They were hanging around her house and she started feeding them, and now (would you believe this) they live completely indoors, have been fixed and gotten all shots, and are really happy. I always believed it was near-impossible to get wild cats to live happily indoors. SO my question is, last week the cats were boarded at the vet's, and the vet said he found a roundworm in the boy cat. Since these kitties were indoors and healthy for a year, I don't understand how one (or both) of them could have roundworms? Can you advise me?

Thanks, Beverly

Answer: Beverly-

Roundworms have an interesting way of infecting dogs and cats that can lead to persistent infections in some pets.

Roundworms eggs are expelled in the stool when infected pets have a bowel movement. The eggs develop into an infective larval stage that sticks to the skin as a new host walks around an infected area. The larvae then bore through the skin and migrate right through body tissues until they find their way to the intestines where they develop into adult worms. During the migration period the animal has a good chance of developing an immune response capable of killing the worms and when they are in the intestines adult worms can be killed with several deworming agents. The immune system is capable of developing a protective cyst around the migrating worms but not quite able to kill them. These worms are also difficult to kill with dewormers. So they live in a sort of "jail" built by the immune system. In times of stress, especially pregnancy, the immune system weakens and encysted worms begin to migrate again and develop into adult worms.

In your mom's cat's case, the most likely scenario is that the stress of boarding allowed development of a previously arrested case of roundworms, although there are some cats that just never develop the immune response necessary to control the worms and have to be dewormed frequently throughout their lifetime. The only way to check on this, that I know of, is to do repeat fecal examinations. If they keep coming up positive for roundworms then it is necessary to develop a routine deworming program for the affected cat or dog. More often, deworming once or twice will stop the new infection and things will be OK until the next big stressful event occurs.

Mike Richards, DVM 5/12/2001

Tapeworms in Cats

Question: Is there any health reason to treat a cat for tapeworm? I always thought tapeworms were not impacting the cat's health; that it was treated because humans found it disgusting. Thanks.

Answer: Karen-

Tapeworms are among the best adapted of parasites, meaning that they harm their host the least. A few patients develop diarrhea, weight loss, vomiting or just an unthrifty appearance when infested with enough tapeworms. Most cats do not have clinical signs associated with tapeworm infestation, though.

I think it is worth treating for these worms when it obvious that a cat has them due to the presence of tapeworm segments around the rectum or in the stool since I don't know which patients will have problems. I would have a hard time arguing that it was absolutely necessary, though.

I have always assumed that tapeworm medicine costs more than other worm medications because people find them to be so disgusting -- so we have similar theories!

Mike Richards, DVM 9/7/2000

Worm eggs

Q: Dear Mike,

I am confused about the tapeworm and roundworm eggs being discussed on your website. I have noticed that my cat seems to be shedding something that looks much like a small sesame seed. However, I am not seeing these in her stools, but around the house in places that she likes to sleep. Are these the tapeworm eggs? They did not look much like the picture you have shown. Also, could they be roundworm eggs, or are those too small to see with the naked eye. Either way, could you please show a picture of roundworm eggs?

Thank you for the wonderfully informative website. Keep up the good work.

R. S

A: R-

Roundworm eggs are microscopic in size. I don't think that anyone could see one with the naked eye.

Tapeworm eggs are also microscopic in size but they are released in an egg case that is muscular and has a pore that expels the eggs as it moves and uses up energy. When a tapeworm segment (egg case) is expelled it is about 1/2 to 3/4th of an inch long (around 10 to 20mm) and is usually moving. These can be seen on the stool or in the hair around the rectum. After the segments dry up most people think they look like a rice granule but a sesame seed might be an OK description, too. These can be found on the hair around the rectum or around the house where the cat has been. Seeing these segments is sufficient evidence to deworm a cat or dog to kill tapeworms.

Mike Richards, DVM


Ringworm (a fungal infection) is the big worry when it comes to cat skin diseases that are contagious to people. Ringworm is tough to rule out when there is patchy hairloss in cats without doing a culture for it. This is not usually too expensive to do. Ringworm can mimic a lot of other skin problems but most of the time when we see it there is some scaling or scabbiness, too.


Q: Hello, My daughter recently got ringworm on her arm. I have a cat and I don't see any type of skin problem with the cat. Can you tell me what to look for? I have had the cat for 3 weeks now and nothing like this has ever happened before. Please Help.

A: M- Some cats can carry the ringworm fungus without any apparent sign of illness at all. The best way to find out if your cat is infected is to ask your vet to do a "toothbrush" culture. In this test a sterile toothbrush is used to brush the cat's hair over a wide area and then the bristles are pressed on the surface of a special culture medium for dermatopyhtes (the ringworm organism).

Dermatophyte infection can be picked up from the environment as well as from cats but it does seem suspicious that you just got the cat and your daughter has a new ringworm infection. It would be best to have your cat checked for this.

Mike Richards, DVM


Toxocara infestation (roundworm infection) is another worm that is contagious to people. The best way to avoid this is to have your vet check your cat's stool for roundworms and treat if they are present. In some cases it is just easier to go ahead and treat for these worms -- such as very young cats.


Q: Hi I have just found out one of my cats has round worms. How do I protect myself and my daughter from getting them? How are they transmitted to humans from cats? How do we know if we have them and what is the treatment? Thank you so much for your time in answering my questions. Thanks again!!! Bye Tammy

A: Tammy- The roundworms most commonly associated with pets are the Toxocara and Toxascaris species of roundworm (there are many, many species of roundworms). These two species of worms are transmitted to humans through the ingestion of roundworm eggs which contain infective larvae. Typically it takes between one and three weeks for these eggs to develop from the time they are "laid" to the time they contain an infective larvae. Therefore, in an indoor cat, the best protections against infection are proper deworming of the cat and regular cleaning of the litterpan so that stools are disposed of before any roundworm eggs that might be present become infective. For outdoor cats it may be worthwhile to consider routine deworming or regular checks of the cat's stools for infection.

Dogs can acquire roundworm infections from their mothers while in the uterus. Therefore, it is important to begin to deworm dogs at 2 weeks of age. To the best of my knowledge cats are not able to transfer roundworm infections to kittens in the uterus and therefore it is usually recommended that deworming begin at about 6 weeks of age in kittens as it takes about that long for the infection to reach the stage where deworming medications are effective. Dogs should be dewormed every 2 weeks until they are about 3 months old and kittens every 2 weeks for the same period or perhaps just a bit longer (suggestions vary).

There is some fear that roundworms may be passed by a kitten or puppy licking the owner. While the transmission rate through this avenue of infection is probably very very low it is still a good idea to observe good hygiene and wash hands and faces after playing with the kitten or puppy.

Once the initial infection is treated properly it is a good idea to occasionally check a stool sample for the presence of worms or to consider prophylactically administering deworming medications if the situation seems to warrant it (outdoor cats, for instance).

Occasionally a physician will advise one of my clients to put their cat outside to reduce the risk of infection with Toxocara or toxoplasmosis. I truly believe that this advise is wrong. An indoor cat is unlikely to pick up an infection with roundworms or toxoplasmosis as there is no ready source of the worm eggs indoors. The litterpan is easily cleaned and most people don't dig around in the pan much. On the other hand, an outdoor cat is easily reinfected with roundworms from the soil and is very likely to defecate in places like gardens where people do tend to dig around a lot. If you have cats, or even if you don't, it is a good idea to wear gloves while gardening. Clean vegetables grown in the garden before eating them. For most people, these preventative measures are just normal procedures but it is good to know there is a reason for all this caution!

Roundworm infection in people can cause "flu like" syndromes, with fever, liver enlargement, changes in the white blood cell count and differential and in some cases eye damage. I do not know for certain how the diagnosis of roundworm infection in a human is made. Your physician will probably know, though. It is unlikely that you have been exposed to infective eggs but if you or a family member experience an illness it would be worthwhile to inform your physician of this possibility.

Mike Richards, DVM


Q: I just noticed that my cats are starting to have a milky looking discharge from their anus. At first I thought it was a little diarrhea. This morning I watched a drop of the discharge for a moment and to my surprise it was moving. It looks like a very tiny worm. These worm like things dry up very quickly and have the appearance of a seed. I'm assuming that these seed looking things are eggs that will soon start reproducing in the near future. Have you any idea of what this could be and is there any suggested treatment.

A: Your cats almost certainly have tapeworms. What you see is one segment of the tapeworm, which is a specialized muscular egg sac. As it wiggles around it spreads tapeworm eggs. These are eaten by fleas. The cat eats the flea and starts the cycle all over again. The only really effective, safe tapeworm medications are prescription dewormers available from your veterinarian. Praziquantal (Droncit Rx, others) and epsiprantal (Cestex Rx) are the active ingredients that are both safe and effective.

Michal response: Push here and it will take you to a tapeworm picture.creepies and crawlies


Q: Hi Dr. Mike, Thanks to your excellent site I have realized that my cat has tapeworms. Can a cat's tapeworms infect humans? I didn't find it mentioned in your Q&A section on zoonotic diseases. By the way, I'm taking her to a vet tomorrow to have her treated. Thanks in advance, Todd

A: Todd- The most common tapeworm in cats is transmitted by ingestion of fleas. Humans are susceptible to this tapeworm in the same manner -- by the ingestion of an infected flea. This usually isn't a problem in adults but may be a problem with young children who may swallow a flea when nuzzling a pet.

Mike Richards, DVM

Tapeworm Eggs

Q: After studying your homepage I'm quite sure that my cats have tapeworms, and I'm going to the vet as soon as possible to get some medication. But I'm a bit worried about the possibility that my entire house could be full of eggs from the tapeworms, is there anything I can do to reduce the risk of the cats getting a new tapeworm from the eggs around the house ?? Does ordinary flea poison kill the eggs, and how long can the eggs stay alive ??? Finally, is it possible for humans to get these tapeworms, or is it some other species that attack humans ??? Keep up the good work !!!!!! Lars in Denmark

A: Lars- The most common form of tapeworm is transmitted when a flea eats the egg of the tapeworm, allowing it to "hatch" and then the flea is eaten by the dog or cat. Humans occasionally get these tapeworms by ingesting a flea, too. If we didn't have hands we'd probably have a lot more tapeworm problems but since we pick fleas off rather than lick them off we are spared this parasite in most cases. The eggs are not directly infective. They do last a while in the environment (possibly as long as 15 months) so vacuuming well and throwing out the vacuum cleaner bag each time for a couple of times might be a good idea. Controlling the fleas in the house and on the pets will eliminate the spread of tapeworms.

Mike Richards, DVM


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...