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It is believed that all reptiles and amphibians living in the wild harbor parasites. The delicate balance

between parasite and host in the wild tends to vary dramatically from the relationship between parasite

and host in captivity. In the wild, where an animal is not confined within a small space, the

environmental concentration of parasites is not high. As a result, the parasite burden to any given host is

usually low.



However, in captivity, especially in poor sanitary conditions, the concentration of parasites

may be much higher, and therefore more dangerous. Couple this higher parasite concentration with the

stress from poor husbandry (i.e., Improper: temperature, nutrition, light exposure, overcrowding, etc.)

and these stressed captive animals with heavy parasite loads are more likely to succumb to the parasite

infestation.

Parasites affect their hosts in many different ways. The parasites can be external (e.g., ticks and

mites) or internal (e.g., gastro-intestinal worms). Parasites appear to have an effect on all aspects of

captive rearing. In general parasitized reptiles and amphibians have a shorter life span, tend to be more

susceptible to disease, and have a generally unthrifty appearance. Also, studies have demonstrated that

heavily parasitized reptiles have poor to no ability to reproduce. And, of those that do succeed in

producing offspring, the offspring may die at a young age, can be stunted, or have very slow growth

rates.





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So it is for these reasons that it is strongly recommended by this author to accurately diagnose and

treat for all observed parasites in captive reptiles and amphibians.

****



Concerning proper treatment of

reptiles and amphibians, each animal has to be treated on a case by case basis. In the literature and

formularies there are several different doses as well as different treatment schedules listed—it behooves

the veterinarian to evaluate each dose and regimen individually for each particular animal.

O

VERVIEW OF THE

I

SSUE

Enteric Parasites

Protozoa: The numbers and genera of protozoa present in an amphibian or reptile are very often

influenced by the individual animal differences in the physiological parameters that effect the intestinal

tract. Such differences, i.e., hydration status, pH, and the passage of digesta can have a profound effect on

the makeup of the enteric protozoal community. Other factors can include natural antagonism between

the different species of parasite and predation. Protozoa can also affect the bacterial flora due to substrate

competition and predation and thus can have secondary effects on the homeostasis of the intestinal tract.

Flagellates: Thus far at least 6 genera of flagellates have been identified, and these have probably

been transmitted by infective cysts or by copulation. The organism most likely to cause problems in

captivity is Hexamita, which has been known to affect the urinary bladder and kidneys of aquatic turtles

(renal hexamitosis) and is often a fatal infection. Chilomastixis frequently found in the intestine of

salamanders, frogs and toads. Tritrichomonas and Trichomonas, typically identifies by their well developed

undulating membrane, are widely distributed among amphibians and reptiles. Giardia are also frequently

seen in amphibians and reptiles. Retortamonad and diplomonad flagellates have also been reported in

poison dart frogs.

80th Western Veterinary Conference

Ciliates: Balantidium species are common in herbivorous turtles and lizards. It is thought that unless

this ciliate is present in large numbers, that it is unlikely to be causing any pathogenic effect. But again,

considering the other possible stresses placed on the animals in captivity—I usually recommend treating

for these parasites. Nyctotherus, another very large ciliate, can be found in turtles and the green iguana

(Iguana, iguana, iguana). The cyst of this “commensal” can easily be mistaken for a trematode egg.

Nyctotheroides has been observed in anurans.

Opalinids: These organisms resemble flagellates and ciliates. However, opalinids lack a cell mouth

and have only one type of nuclei. Zelleriella were observed in dendrobatid frogs.

Amoeba: In reptiles and amphibians, clinical signs of anorexia, weight loss, blood or mucus in the

feces, vomiting, green discoloration to the urates, or midbody to caudal swellings of the body may be

suggestive of infection with Entamoeba invadans. This is a highly pathogenic parasite in lizards and

snakes. The trophozoites may be observed in a direct smear of the fecal material. Amoeba may be

commensal symbionts in turtles and crocodilians, frequently making them responsible for infection of

exposed snakes and lizards. Several other species of pathogenic amoeba exist, of which Acanthamoeba has

been implicated in fatal infections. Star gazing is thought to be a sign of central nervous system

involvement with this organism.

Treatment for amoebae, flagellates and ciliates is typically with metronidazole (100 mg/kg PO

repeated in 2 weeks / or 50 mg/kg PO q 24h x 3–5 days /- repeat PRN) (As is the case with all

medications used in reptiles and amphibians, each animal has to be treated on a case by case basis—for

all medications, in the literature there are several different doses as well as treatment schedules listed—it

behooves the veterinarian to evaluate each dose and regimen individually for each particular animal.)

Coccidia: Isospora and Eimeria are the coccidia most recognized in the fecal specimens of infected

amphibians and reptiles. Listlessness, anorexia, regurgitation and intestinal hemorrhage and at times

intussusception are the typical signs of intestinal or gall bladder infection with coccidia. Isospora have two

sporozoites and have not been reported in turtles.



*******************

Eimeria have four sporozoites and it is considered the

primary coccidian of reptiles. Oocysts are ingested from contaminated soil or feces, and I am concerned

with the possible vector transmission of insects that have ingested contaminated matter. Sarcocystis and

Toxoplasma are occasionally found in reptiles. Typically it is believed that the affected reptiles if the

intermediate host, though reports exist for snakes and lizards serving as the definitive hosts.

Effective treatment for coccidia resulting in complete cure of the infestation can be difficult. I

typically use sulformethoxine and sulfamethazine at 75 mg/kg once daily for 7 days. Proper husbandry

and hydration of the patient as well as sanitation is very important to try and achieve best success with

treatment.





Cryptosporidium has frequently been seen in Boids. Typical presenting complaints by the owner is of

regurgitation, lethargy, depression and frequently a midbody swelling may be palpated in advanced

cases. The organism causes a proliferative gastritis for which there is presently no known cure or effective

treatment. The transmission is via the ingestion of sporulated oocysts, infected mice, snakes, lizards or

other prey items. A definitive diagnosis can be made on the basis of a direct smear or an acid fast stain

preparation of: the feces, the slime coat from a regurgitated meal, or an aspirate/stomach wash that

reveals multiple round organisms, 2 to 5 microns in diameter, staining bright red. Sometimes the

organisms will not retain the red dye but will leave a “ghost image” against the counter stain. Careful

identification must be made in male snakes as to not mistake tailless spermatozoa, which will also take

up the red stain, for coccidian oocysts.



******

Oocysts may be shed intermittently and therefore repeated fecal

evaluations of a biopsy may be required to arrive at the definitive diagnosis. Infected animals should be

completely isolated from the collection and due to the potential for zoonotic threat, and due to the fact

that effective treatment for cryptosporidia is typically unsuccessful at the present time, it is often

recommended that they be humanely euthanized and destroyed. An option to attempt treatment as

reported by Dr. Elliot Jacobson is SMZ–TMP at 30–60 mg/kg PO SID for 60 days, or Paromomycin (300–

800 mg/kg PO q 24–48h X 7–14 days/or/PRN).

Helminths

Nematodes: The presence of thin-walled embryonated eggs or rhabditiform larvae in a fecal sample are

indicative of Strongyloides or Rhabdias infestation. Rhabdias inhabits the hosts lungs and may cause

respiratory distress. Strongyloides can produce diarrhea and respiratory distress as infective larvae

migrate through the host’s lungs. Both parasites may cause anorexia, weight loss and debilitation. The life

cycle is direct and the parasite can be transmitted by ingestion of eggs, larvae, or possibly by direct skin

penetration. These parasites can exist as a free-living form, making proper and complete cage sanitation a

necessity. Oxyurid eggs are frequently encountered during fecal examinations of lizards and chelonians.

In snakes, care must be taken not to mistake rodent pinworm eggs for those parasitic for reptiles.

Pinworms are considered by many as non-pathogenic, though I typically treat to avoid any possible

problems associated with their presence. Oxyurids have a direct life cycle and can exist in significant

numbers within the colon, especially of tortoises, putting them at possible risk for impaction. Anorexia

may occur in animals coming out of hibernation and may be attributed to heavy oxyurid infestation. Two

genera of hookworms, Kalicephalus and Oswaldocruzia, occur in reptiles throughout the world, and usually

appear similar in appearance. Fecal examination will demonstrate the presence of typical “strongyle

type” eggs. Transmission is by ingestion of ova, infective larvae, or possibly by skin penetration. The

drinking of contaminated water is another means of oral transmission. Infestations may cause lethargy,

anorexia, general debilitation, anemia, ulceration, intestinal obstruction and peritonitis. Capillaria is the

only known trichurid genera affecting reptiles. These nematodes primarily infect the intestine but have

been found in other organs, such as the liver and gonads. They have a direct life cycle. Diagnosis is based

on the presence of eggs with opercula at either end. Ascarid eggs are recognized by their thick shells

Adult worms may be found embedded in the stomach, esophagus, or small intestine where their effect

may range from no apparent signs of illness too anorexia and regurgitation. Diarrhea and purulent

pneumonia may also be attributable to heavy worm infestations. The most likely source for transmission

is through the ingestion of intermediate hosts, such as amphibians and rodents. Spirurids are parasites of

the mouth and gastro-intestinal system. Reptiles may act as either intermediate or definitive hosts. For

terrestrial reptiles and amphibians, ants are a common source for infection. In aquatic animals, Copepods

are a common source for transmission. Diagnosis is by detection of the characteristic eggs. On

microscopic exam, the larva are curled within giving the egg the appearance of containing a paper clip.

Adult worms are easily removed from the mouth. Filariae can be found within lymph vessels, the eye,

subcutis or within the coelomic cavity. The microfilaria produced by the adults may circulate in the blood

or may be found in the skin, where they may cause dermal tumors. Pathology due to filariae is rare.

Treatment of nematode infestation can be accomplished using a variety of anthelmintics. For

example: thiabendazole (50–100 mg/kg PO), levamisole (5–10 mg/kg PO), fenbendazole (50–100 mg/kg

PO) Piperazine (40–60 mg/kg PO) ivermectin (o.2 mg/kg PO, IM or SC)(Do Not Use Ivermectin In

Chelonians, Indigo Snakes & Skinks) Milbemycin (o.5–1.o mg/kg PO) can also be used in reptiles and has

been injected in several species of turtles with no ill effects. All treatments are repeated in two weeks,

followed by a fecal examination 14 days after the second dose. If positive for parasites, a third dose is

given, and the cycle continued until the parasites are cleared from the animal.

Cestodes: The tapeworms that affect reptiles are hermaphroditic and non-host specific.

Transmission is by ingestion of an intermediate host. Diagnosis of an intestine dwelling cestode is by

detection of proglottids or eggs in the stool. Plerocercoids of Diphyllobothrium are frequently found in

tadpoles feeding on crustaceans. Niclosamide (150–300 mg/kg PO), bunamidine HCl (50 mg/kg PO), and

praziquantel (7–8 mg/kg IM,PO,SC), each repeated in two weeks are all reported to be effective in

treating adult tapeworms.

Trematodes: Operculated eggs in the fecal sample or oral mucosa are diagnostic for trematodes.

Some Monogenea are external or urinary bladder parasites of frogs, tadpoles and newts. Digenean

trematodes often form metacercariae in the skin, eye or various organs. The renifer group of digenetic

flukes are common in the mouth, pharynx, esophagus, trachea, and lung of indigo snakes. This fluke

requires an amphibian intermediate host therefore elimination of this food source or freezing/preparing

the prey item to kill potential parasites is required to prevent reinfestation. The infected animals are often

presented for anorexia or profuse salivation, due to the large number of organisms present in the oral

cavity. Praziquantel (7–8 mg/kg IM,PO,SC) or fenbendazole (100 mg/kg PO) repeated in two weeks will

control this and other metazoans.

Acanthocephalans: The thorny-headed worms or acanthocephalans are common in aquatic turtles,

frogs and toads. They may be found in the stomach or intestine. Clinical signs may include blood or

mucus in the stools, anemia, and weight loss. The eggs are typically dark, thick-shelled and tapered at the

ends, with fecal materials frequently adhering to the shell. Levamisole at 5–10 mg/kg PO, SC, ICe

repeated in two weeks has been used successfully for treatment.

Pentastomes: Pentastomids are considered to be a degenerative crustacean that parasitizes the lung

and airsac distal to the lung. Larvae and nymphs may be found in the stomach wall. Transmission occurs

by the ingestion of an intermediate mammalian host. Symptoms may include lethargy, anorexia,

dyspnea, and blood tinged saliva. Affected animals frequently harbor these parasites with no ill effects.

Diagnosis is based on observations of the characteristic eggs which contain a primary larva, which is oval,

tailed, and has four stumpy legs each bearing one or two retractable pincer claws. Humans can be an

accidental host, so care must be taken when handling infected animals and their feces. There is no known

completely effective treatment, though levamisole (5 mg/kg PO, SC, ICe) or one of the avermectins

(Ivermectin or Milbemycin) may be effective.

Hemoparasites

At this time, only the most common blood parasites will be discussed, as the number of described species

is extensive and the literature is often not helpful in determining the pathogenicity of certain species.

Hemoparasites are found within the cells or free in the plasma. Their development may involve other

organ systems. Often, with blood parasites, there is little or no clinical disease. Clinical signs that may

develop with hemoparasites include anemia, thrombocytopenia or purpura. There is little or no data on

the efficacy, but hemoprotozoa are often treated with tetracycline (10 mg/kg PO q24h) and/or

chloroquine phosphate-primaquine phosphate (125 mg/kg PO q 48h X 3 treatments) or Quinacrine (19–

100 mg/kg PO q48h X 2–3 wk).

Hemogregarines: A single schizont typically attacks a RBC, where replication occurs

intracytoplasmically. Hemogregarines are the dominant and characteristic hemoparasites of snakes but

affect all classes of reptiles including the Tuatara and sea snakes. Hemogregarina is found in aquatic

reptiles and relies on leeches for sexual reproduction. Hepatozoa is found in terrestrial arthropods or

leeches. Typically there is little pathology.

Hemoproteus: These are also found within the erythrocyte cytoplasm and vary from one to several

per cell. Turtles and lizards are the usual hosts. Typically there is little pathology.

Leishmania: With this hemoparasite, only the pro- and amastigote stages are observed.

Promastigotes are found in the blood, amastigotes are intracellular. Transmission is probably by the

sandfly. This is a benign infection, with lizards as the hosts.

Plasmodium: There are 68 species known that have been identified in turtles, lizards and snakes.

Depending on the species, different stages of the organism may be found within the cytoplasm of the

RBC’s, mononuclear leukocytes or endothelial cells of visceral organs. Some species may cause anemia or

thrombocytopenia. An insect vector is required for transmission.

Lankesterella: This protozoan hemoparasite may be transmitted by leeches. They penetrate and

destroy RBC’s potentially resulting in anemia.

Trypanosomes: These affect crocodilians, turtles, lizards, snakes, frogs and newts. Biting flies and

leeches are responsible for transmission. Effected animals may demonstrate listlessness, refuse food, and

potentially die due to heavy parasitism, however pathology is usually rare.

Microfilaria: The presence of microfilaria in the blood suggests the presence of a pair of adults in

the animal, i.e., the eye, subcutis or coelomic cavity. Typically pathology is rare with the exception being

the presence of adults in the eye.

Flukes: Spirorchis is found in the blood of semiaquatic turtles.

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