Cat flea (Ctenocephalides felis)

Cat flea (Ctenocephalides felis). Similar to a dog flea, it usually lives on cats and dogs. The most convinient developing conditions for this kind of parasite are in humid and moderate temperatures. It often sucks blood. Females lay eggs on the host’s fur where they develop. The bites of this parasite are painful. The bite spots are blushing swellings and red. The skin lesions are difficult to cure. Animals with cat flea presence might suffer from anaemia and weight loss. Because the infected animals live close to people they may spread infection and diseases.

Canine tapeworm (Dipylidium caninum)

Canine tapeworm (Dipylidium caninum). The most common tapeworm among dogs, cats, foxes and other carnivorous animals. The development of a canine tapeworm is complicated. Indirect hosts are fleas and lice, which assimilate tapeworm eggs from the environment. In the body of the host, a subsequent transformation of tapeworm eggs takes place. As the host grows, the eggs convert into an invasive form and can infect the final host: dog, cat or an accidental man that ensures its further transformation. The human canine tapeworm infection occurs very rarely, but people shouldn’t undestimate this disease. Sometimes, an adult person can be infected with this parasite, although a majority of infection cases regard children who do not wash their hands after a direct contact with animals, kissing them, taking their fingers into their mouth, licking things picked up from the floor or dirty toys and food.

Canine tapeworm presence symptoms in animals

  • vomiting
  • diarrhoea
  • enlarged stomach
  • loss of weight and growth impede are caused by bowel mucosa damage which adversely affects digestion and assimilation by depriving the host of a plenty of essential substances necessary for a normal growth
  • nervous symptoms, metabolites (neurotoxins) excreted by parasites affect the nervous system
  • fur getting dull


The disease process

Dogs, cats, foxes and others carnivorous animals are the final hosts of a canine tapeworm. A mature tapeworm locates itself in the small bowel of the final host, and when it gains its sexual maturity, it starts to reproduce. Uterine segments filled with eggs separate from the tapeworm and are excreted from the body of the host or they crawl out from the anus and embed on the fur around the anus.

Tapeworm segments are white and their shape is similar to cucumber or pumpkin seeds and have a capability of shrinking and moving for a short period of time. The excreted segments of the tapeworm get dry and come apart releasing groups of eggs gathered in bags, which have to be picked up by indirect hosts to allow further growth.


Infection sources

The fact that the infection is very common among carnivorous animals is caused by a wide proliferation of fleas and lice. Carnivores scratch, lick and bite the itchy fur with their teeth and they simply swallow a flea or louse which contain an invasive form of the canine tapeworm in its body. Young tapeworms that get into the digestive system of the final host together with a flea or louse, transform into mature tapeworms. After 2-3 weeks from the infection, the first uterus segments filled with eggs are excreted by the animal.


Who is the most likely to get infected

The infection rarely affects a human. It can occur when a flea or louse containing an invasive canine tapeworm gets into the human digestive system where in the small bowel, it grows up. Most infection cases concern children who do not wash their hands after a direct contact with animals, kissing them, taking their fingers into their mouth, licking things picked up from the floor or dirty toys and food. Infected adults usually show no symptoms.


Children infection symptoms

  • alimentary system disorders like: indigestion, loss of appetite, stomachache resulting from bowel mucosa damage.
  • nervous disorders caused by metabolites (neurotoxins) excreted by parasites


Beef tapeworm (Taenia saginata)

A beef tapeworm (Taenia saginata) is very long and flat like a ribbon. It has a small head containing adhesive organs, a short neck and numerous segments. They are able to absorb food through the whole surface of their body, by osmosis effect. The beef tapeworm has a well-developed excretory system and a perfectly expanded reproductive system where in every segment there are male and female organs (bisexualism). Mature segments filled with large amounts of eggs, separate from the tapeworm and exit the body with faeces. Its further growth takes place in an indirect host, mainly in muscles, but also in the liver or brain and other organs until it takes an invasive form of a blackhead. The blackhead has the shape of a blister and contains a head and some fluid. The disease caused by blackhead is called cysticercosis. Taeniasis has a wide geographical range.

Infection sources

Beef tapeworms live mostly in humans whereas its larvas develop in cattle. People can be infected by eating raw or undercooked meat. The tapeworm lives in the small bowel of a human body, it is 4-10m long and contains 2000 segments. The ending uterus segments, exit the body through the anus. Every segment contains 100000 eggs which easily spread out in the environment. They are able to survive in contaminated soil for over a year. Their further development takes place in cattle where during 10-12 weeks they grow up to become blackheads. A blackhead is a blister, 7×4 mm, filled with fluid and containing invasive heads. After 3 months from infection, the tapeworm is fully grown and starts to release uterus segments. Beef tapeworms can stay in a human organism for more than dozen years, self-treatment happens rarely.

Balantidiasis (Balantidium coli)

Balantidiasis (Balantidium coli) lives in the form of a trophozoite and a cyst. Both forms have the biggest size of all protozoons able to lead a parasite lifestyle in a human organism. Balantidiasis traphozoites reach 20-200 µm and cysts 45-90µm. Because of their size the detection does not cause any problems for an analyst. It has a pear-like asymmetric shape with a thick equal cover of short piluses. On the front pole of the traphozoite, the cytostome is located by which the protozoon collects food while on the rear pole there is a cavity (cytophyge), which is used for excreting undigested food remnants. In the traphozoite cytoplasm there is a characteristic for balantidiasis nucleus organ containing a kidney-shaped core (macronucleus) and the second core (micronucleus) lying on the concave side of the big core.

On the cytoplasm there are also two pulsing vacuoles and numerous smaller ones. Balantidiosis is an infectious disease developing as a result of balantidium coli protozoons infection.


Balantidiosis symptoms
-diarrhoea with ample amount of blood and mucus
-nausea and vomiting
-loss of appetite
-loss of weight
-blood morphology anaemia

Balantidiosis development cycle
The protozoon is widespread and a pig is a typical host of the parasite. Men can be infected by the oral tract, swallowing food or water contaminated with pig faeces containing cysts. There have also been infection cases caused by direct contact with an infected person. The swallowed cysts release trophozoites which reproduce in the large bowel causing inflammatory infiltration with necrosis and ulceration. Most people do not have any visible symptoms but some are affected by diarrhoea – the main symptom of this disease. The course of the disease is often connected with bleeding from the alimentary system which can imitate dysentery. In case of balantidiosis, there is no infection of other organs by the blood duct (as it takes place in ambeoic dysyntery).

Armed tapeworm (Taenia solium)

Armed tapeworm (Taenia solium)

An armed tapeworm has its head equipped with 4 suckers and a double crown of hooks with the length of 4-6m. Hypermature segments are excreted with faeces, a man can be infected by eating raw or undercooked pork meat. People can also be infected orally. Developing eggs might embed in tissues. The hypodermic tissue cysticerscosis shows no symptoms while the brain and the eye-balls suffer from serious consequences. The armed tapeworm defers from a beef tapeworm by its skolex, which is armed with a double crown of hooks, strobila is shorter (2-4m, 800-900 segments), uterus segments are separated in groups and passively excreted with faeces. Eggs excreted with faeces might infect man, although the natural indirect hosts are pigs. It takes approximately two months for an armed tapeworm to grow up and it lives in the small bowel sometimes even longer than ten years.


Anisakiasis (anisakis simplex)

Anisakiasis (anisakis simplex). Anisakiasis is an infestation of Anisakidae nematodes. The nematodes develop in sea shellfish, fish and mammals and are quite common in many regions of the world. Humans are infected accidentally by eating raw infected sea fish like: green herrings or sushi. Two-centimetre-long larvas penetrate the stomach mucosa causing painful stomach cramps and vomiting after several hours since the consumption. About a week after the infection parasites get into the small bowel causing rough stomach reactions sometimes leading to laparoscopy or laparotomy. Anisakiasis usually leads to such complications as: intestinal perforation  and peritoneal anisakiasis. As there are no effective anthelmintics against anisakiasis the treatment consists in removing the parasite by an endoscopic or surgical method. The infection might be detected by a serologic examination. In order to prevent anisakiasis sea fish are frozen (-20C kill these parasites after 60 hours) or it is better to  remove the  entrails of the infected fish directly after catching.