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Stephen Divers BSc(Hons), GIBiol, BVetMed, MRCVS

Introduction

Hookworms are commonly diagnosed as causing widespread disease and mortality if untreated. These parasites have a direct life-cycle and can cross species boundaries - they require no intermediate host and can spread from one animal to another in the same vivarium, or between vivaria if adequate hygiene is not practised. The author discusses with us the signs to look out for in an animal with a suspected parasitic load and it's diagnosis and treatment, as well as preventive methods to keep your reptile handy. The article has several photo's to accompany it.

SUMMARY


The increasingly rapid advancements in reptile husbandry and herpetological medicine have led to a reduction in the morbidity and mortality rates of captive reptiles. These improvements are undoubtedly due to;

  • The relative increase in captive bred vs wild caught stock.
  • The development of new herpetological equipment (heating, lighting etc.).
  • A better understanding of reptile nutrition (vitamin/mineral preparations, probiotics).
  • A better understanding of captive environments (substrates, humidity, broad spectrum lighting) and vivarium hygiene (disinfectants).
  • Improvements in reptilian medicine.

Nevertheless, the most common causes of death among captive reptiles are;


  • Malnutrition.
  • Maladaptation.
  • Parasitism.
  • Bacterial/viral/fungal infections


PARASITISM


The natural world is built upon the inter-relationships between different animals and plants. A parasite is an organism that lives in or on another animal (host), in this case a reptile or amphibian. The parasite has a life-cycle (for example egg-larva-adult) which can be direct or indirect. A parasite with an indirect life cycle requires two or more hosts (often prey and predator) to complete its life-cycle. The final or definitive host is the stage of adult sexual reproduction, while the other intermediate hosts are stages of development, maturation and asexual reproduction. An example of an in direct life-cycle parasite is the lizard stomach worm, Physaloptera sp, which uses ants as intermediate hosts. A parasite with a direct life-cycle requires only one host to complete its life-cycle. The parasite may spend its entire existence on the host or live in the environment and visit the host to feed. An example of a direct life-cycle parasite is the snake hookworm, Kalicephalus sp.

In the wild, most parasites live in a steady state with their hosts; after all if parasites ultimately killed their hosts, they would ultimately die out themselves. Not all reptilian parasites are deleterious to their hosts, in fact some are essential for the herptile’s continued health. For example, the green iguana (Iguana iguana) maintains a large population of protozoa within its caecum (large intestine). The iguana (host) provides the protozoa with a suitable environment in which to flourish and in return the protozoa (parasite) digest plant matter and liberate nutrients which the iguana absorbs into its blood stream. This mutually beneficial relationship, termed symbiosis, is essential for the continued health of both protozoa and iguana alike.

Overt clinical disease due to parasites is almost invariably associated with captivity. Captivity concentrates reptiles and their parasites, induces stress, makes parasite-transmission more likely, and creates unnatural host-parasite relationships that simply do not exist in the wild. It is the responsibility of every owner to provide the best possible captive conditions, if not for welfare reasons, then for the personal and economic benefits of maintaining and propagating healthy reptiles.

Reptiles and amphibians that are suffering from parasitism may not demonstrate obvious clinical signs, however the added complication of parasite diversity (nematode worms, tapeworms, flukes, mites, ticks, protozoa etc.) means that parasitic disease to another. The variety of clinical signs is due to the variety of ways in which parasites “feed” on their hosts. For example, hookworms ingest blood, which results in anaemia, lethargy and debilitation, whereas intestinal worms compete for the herptile’s food, causing emaciation and cachexia.

Parasitic disease is often chronic and insidious in nature and death can result despite late therapeutic intervention. Some herpetologists may well insist that they have never had a death due to parasites however such statements are too commonly made without the benefit of a post-mortem. It is therefore vital that owners understand and appreciate herpetological parasitism so that early veterinary advice and treatment, and corrective husbandry can be instigated where necessary.

 

Adult Hookworm recovered from the mouth of a Royal Python (Python regius )

High Stocking densities predispose to parasitic disease

The kalicephalus sp. Hookworm can penetrate intact reptile skin. Note the reddening (haemorrhage) under several of the ventral scales.

The hookworm larvae can penetrate the lining of the mouth.

Acute gastritis (Kalicephalus sp.) Royal python

Indicators of Parasitism


There are general signs of poor health that are attributable to many sub clinical diseases including parasitism;


  • Anorexia (refusal to feed).
  • Cachexia (poor body condition).
  • Emaciation (weight loss).
  • Stereotypic behaviour (lethargy, depression, agitation, altered basking behaviour).
  • Reproductive failure (infertility, egg-binding).

In addition there are several more specific signs that are directly attributable to parasites;


    • Regurgitation
    • Diarrhoea (altered stool colour, consistency and smell).
    • Parasite presence (mites on the skin causing irritation, tapeworm segments in the stools).

DIAGNOSIS AND TREATMENT

The diagnosis and treatment of parasitic disease can only be accurately ascertained by a veterinary surgeon, however, the owner still has an important role to play. Principally, it is up to the owner to decide on routine worming and to bring the herptile to the veterinary clinic. In cases of disease, the owner will be the first to realise that something is “not quite right”, perhaps growth is not as great as expected or weight loss and regurgitation have become a problem.


In this respect the keeping of records is vital;


    • Record weight on a weekly basis for juveniles and monthly for adults
    • Record feedings (type of food and frequency of feeding, timing of regurgitation, nature of regurgitated material)
    • Record defecation (frequency, colour, consistency) and urination (urate vs urine components)
    • Record drinking (frequency increased or decreased, frequency of water changes)
    • Record environmental temperatures (day and night, air vs basking)
    • Record all additions to the collection
    • Record any history of previous diseases and treatments.

When a problem is apparent, a consultation with a veterinary surgeon should be sought, and remember to take your own records and a fresh sample of the herptile’s faeces with you. Other material of diagnostic interest, for example, regurgitated food or material from glottis should also be taken.

Diagnosis requires specialised techniques and equipment, including a good quality microscope. Direct wet preparations, faecal flotation, and sedimentation using fresh faeces, gastric, cloacal or lung washes will produce results upon which the correct treatment can be instigated.

Regular annual worming is advisable for large colonies of chelonia and other herbivorous species, but a pooled faecal sample can be examined to validate the necessity for treatment every year. Single treatment of all wild-caught specimens is usually sufficient, but again faecal analysis before and after treatment is recommended. Captive-bred herptiles are often free from worms unless they have been in close contact with infected specimens or offered contaminated food or water. Some parasites can cause disease in humans and therefore treatment is strongly encouraged on public health grounds as well as animal health and welfare grounds.

The visit to the local vet to get your herptile wormed should never be considered a waste of time or money. Your pet will receive a thorough health check prior to treatment. It is also a convenient time for you to ask questions concerning optimum captive husbandry and nutrition and to be instructed on how to stomach-tube your herpitile safely and effectively, a technique that is invaluable.

NEMATODES

Nematode parasites are worms that infect every order of reptiles and amphibians. These worms can infect the mouth, the oesophagus, stomach, small and large intestine, trachea, lungs, liver and blood stream.

Hookworms

Hookworms are commonly diagnosed as causing widespread disease and mortality if untreated. These parasites have a direct life-cycle and can cross species boundaries - they require no intermediate host and can spread from one animal to another in the same vivarium, or between vivaria if adequate hygiene is not practised.

The snake hookworm (Kalicephalus sp.) is particularly pathogenic and requires prompt veterinary treatment. The adults are stated to live in the oesophagus, stomach and anterior small intestine, however the author has also recovered adults, larvae and eggs from the buccal cavity of infected snakes. The larvated eggs, passed in the faeces, quickly hatch to form motile larvae. These larvae swim through moist substrates to infect other snakes, either by penetrating the skin or the lining of the mouth. The larvae then migrate through body tissues until they reach the gastrointestinal tract, where they mature into adults and reproduce. Within the oesophagus, stomach and intestine these parasites feed on blood, cause inflammation of the oesophagus, stomach and intestine, produce ulcers and can lead to severe bacterial infections including peritonitis. Treatment using ivermectin, fenbendazole or preferably oxfendazole is effective if given in time, but therapy may have to be repeated before a complete cure is achieved.



COMMON NEMATODE PARASITES OF REPTILES
PARASITE SNAKE LIZARD CHELONIA
Hookworms Kalicephalus sp. Oswalsocruzia sp. Carnallanus sp.
Spineoxys contortus
Pinworms   Oxyuris sp Tachygonetria sp.
Atrractis sp.
Roundworms Ophiascaris sp. Polydelphis sp. Suicascaris sp.
Angusticaecum sp.
Lung Worms Rhabdias sp. Entomelas sp.  
Stomach Worms Physaloptera sp. Physaloptera sp. Physaloptera sp.
Strongyloides Strongyloides sp. Strongyloides sp. Strongyloides sp.
Hepatic worms Capillaria sp. Capillaria sp.  
Filarial nematodes Oswaldofilaria sp.
Foleyella sp.
Macdonaldius sp.
Oswaldofilaria sp.
Foleyella sp.
Macdonaldius sp.
Oswaldofilaria sp.
Foleyella sp.
Macdonaldius sp.

Editor Note: Reproduced with kind permission from the Reptillian Magazine
This site has information on the following genera of Ratsnakes ... Spilotes, Spalerosophis, Ptyas, Zamenis, Elaphe, Rhinechis, Senticolis, Pseudelaphe, Pantherophis, Bogertophis, Orthriophis, Gonyosoma, Oreocryptophis, Oocatochus, Euprepiophis, Coelognathus, Archelaphe