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Understanding common worms and protozoa

Misty Corton, The Care Centre, Natal, South Africa

Parasites are a common cause of death in captive reptiles. Keepers are usually unaware of this due to the low number of autopsies done. In the wild, parasites do not often pose a significant risk as the animal is not confined to one area and seldom comes into direct contact with other species. In captive animals confined to a small area, infestation can reach disastrous levels in a very short time. Amongst other things, infection with parasites lowers the resistance of the host animal, and this in turn can cause susceptibility to disease.

The term 'parasite' usually causes any keeper to think of worms. There are any number of potentially harmful parasites - internal and external - that can cause disease. Ticks, mites, protozoa and worms can indirectly or directly result in the death of a tortoise.

Signs to watch for indicating that your tortoise could be infected:

Refusal to eat, weight loss, anemia, lethargy and depression, vomiting, diarrhoea, spluttering small amounts of liquid from the mouth, "gurgling" sounds when breathing and dehydration/malnutrition from a reluctance to feed or drink.

As this is a very comprehensive subject, we will deal now with internal parasites only. Protozoa are a complete one celled living organism that are only visible under a microscope, whereas worms are often visible to the naked eye. Internal parasites harm their hosts in many ways. There is active competition for any food/liquid ingested. Some suck blood and others destroy body cells. Excessive parasitic loads can lead to obstructions in the intestine, bile ducts and blood vessels. Some parasites can produce toxic substances and cause allergic reactions. Heavy parasitic loads can cause stress and suppress the immune system - opening the door to a wide variety of infectious bacteria. Heavy infections can also affect the fertility level of eggs and thus reproduction.

Some parasites - e.g. hookworm - have a direct life cycle. The worms reproduce in the host, and the eggs are excreted in the feces. The larva hatch, and can then re-infect the tortoise by being ingested via food/water or even by skin penetration.

Yet others - e.g. roundworms -have an indirect life cycle. Worm eggs are passed in the feces but do not re-infect the tortoise unless the larva are eaten by an intermediate host (e.g.snails)

General: There are over 500 identified reptile nematodes. Most occur in the intestine and stomach though some larva can migrate into the lungs and throat. Those most commonly found are 'roundworms' which have an indirect life cycle. These can rob the tortoise of up to 40% of available nutrients in food ingested.

Hookworms have a direct life cycle and huge loads can build up in the system in a very short time. Pinworms also have a direct life cycle and commonly cause an obstruction in the intestinal canal. Strongyloides have a direct life cycle, and these can cause severe diarrhoea, mucous in droppings, and sometimes respiratory distress owing to larva invading the lungs.

Establishing if your tortoise is infected:

Some owners are never aware that their tortoise has worms until they see them in droppings, and by then infestation can be severe. The responsible tortoise keeper should have droppings from animals in his care checked twice yearly. This test is simple and can be performed by any veterinarian or competent animal keeper with a microscope. Certainly, before any tortoise is added to your collection it should be tested for parasites repeatedly during the quarantine period.

You will need to supply: a fresh dropping sample. Some protozoa, worm larva and coccidia die if they dry out or are exposed to high temperatures. Place a sample dropping into an air/water tight container and get it to your vet as soon as possible. For those of you willing to purchase a microscope and the necessary chemicals, most vets would be only too happy to teach you to identify parasites yourself.

The most harmful parasites are those with a direct life cycle - e.g. hookworm.

As stated before, a tortoise in the wild may have worms without suffering any undue harm. Place this same tortoise in captivity and several things happen. He is confined to the same environment and is unable to escape constant exposure to parasite infection. He is stressed - from overcrowding, inadequate diet, inappropriate temperature differing from his natural habitat, lack of hideaways, handling, aggression from companions - and this lowers his immune system and increases susceptibility to heavy worm infestation.


Drugs commonly used:

Panacur (fenbendazole) 25-50mg/kg orally once every two weeks for two to three treatments. Infestation with hookworm may require weekly treatment until a fecal tests clear.

Oxfen (Systamex or oxfendazole) 65mg/kg orally as a single dose. This is roughly 3ml/kg of the 2.256% solution.

Tape worms: Droncit (praziquantal) 5mg/kg orally

Protozoa: Flagyl (metronadizole) is used for treating protozoa (Hexamita/trichomonas) and amoebic infections. Dosage 20-50mg/kg orally and repeat dose three days later. Some practitioners use a single dose of 250mg/kg, usually repeating this after two weeks. Sometimes a lower dose of 35mg/kg daily is used for ten days.

Hexamita: Is highly contagious and identified from a urine sample. Symptoms include Strong smelling urine, Dark green urine sometimes flecked with blood, excessive thirst, anorexia and fluid retention, weight loss.

Coccidiosis: this is common where rabbits, poultry and pigeons are kept and sometimes occurs in tortoises causing diarrhoea. Treatment is dosing with Sulfa drugs. This is best left to your vet. No drug for this disease should be administered in food as this can interfere with drug absorption and cause the drug to accumulate in the system.

Once your tortoise has been tested and treated, it is imperative to have a follow-up test done to ensure that no more worms/protozoa are present.

Drugs can be administered by stomach tube, though this is best left to qualified people. It can also be administered via food, and here you can divide the dose into three and give one third daily on a piece of favorite food for three days. For tiny baby hinged tortoises the dosage can be injected into a snail or worm and then fed to the tortoise. If you are fortunate enough to have Panacur paste available this is easily fed via a favorite tidbit of food.

Prevention: Isolation and testing of any 'new' animal added to your collection no matter what the source is.

Hygiene: removal of contaminated food and water. Disinfect ponds weekly (household bleach is commonly used here but rinse well afterwards). Prompt removal of tortoise droppings plus any surrounding soil that may be contaminated. Do not give any uneaten food to another enclosure/tortoise. Wash hands between handling tortoises. Remove other animal droppings (e.g. cat, dog) as soon as possible if the tortoise has access to them. Yes it is true that a tortoise will eat animal droppings in the wild, particularly hyena, but there is a vast difference between the diet of a hyena and the average household pet. A once or twice yearly routine testing. Discourage flies - fly "traps" work reasonably well.

After any treatment: Many drugs can and do upset intestinal flora, depleting them to a point where digestion is affected. It is very wise after any drug is used to feed the tortoise with either Benebac, live natural yoghurt or droppings from a healthy tortoise of the same species - these droppings should however be carefully screened by a fecal before using them. Droppings from hatchings of the same species are ideal for this purpose. The aim here is to boost the animal with benficial bacteria to offset any damage done by drug administration, and it is a wise precaution to take no matter what drug is used.

Prevention is always better than cure - always try to maintain your animals with the best possible husbandry and hygiene :).