Inclusion body disease

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Inclusion body disease (IBD) is an infectious and invariably fatal viral disease affecting captive specimens of the boid family of snakes, particularly Boa constrictor . It has been recognized since the mid-1970s. It is so named because of the characteristic intracytoplasmic inclusion bodies that are observed in clinical examinations in epidermal cells, oral mucosal epithelial cells, visceral epithelial cells, and neurons. In the 1970s and 1980s, the disease was most commonly observed in Burmese pythons (Python bivittatus).[ citation needed ] From the 1980s on, it has been most commonly observed in boa constrictors.[ citation needed ] To date, no treatment for IBD is known, and snakes that are diagnosed with IBD should generally be euthanized to prevent suffering in the snake and to reduce the risk of further infections.

Contents

All boid snakes should be considered susceptible to the disease. Many zoos quarantine boas specifically as a result of the risk of IBD before introducing them into their permanent collections and breeding programs. While the disease has not been identified in non-boid snakes, non-boid snakes can harbour the virus. Mites are thought to be the primary vector of the virus, or at least to be a contributory factor.

Its distribution is worldwide, specifically in captive boid snakes. Its occurrence in the wild is unknown. The disease has only been identified in adult and subadult specimens, not neonates. Even so, all age groups are considered susceptible, and anecdotal reports of the infection in neonates have been made. A retro-like virus infection was suspected as the causative agent of IBD, but identification of highly divergent arenavirus sequences from boa constrictors with IBD [1] [2] suggested arenaviruses to be the etiological agent of IBD. Cell culture isolation of several arenaviruses from boid snakes with IBD further solidified, but did not yet confirm, the etiological relationship between IBD and arenaviruses. [3]

In python species, the disease presents as a profound, highly severe neurological illness that is swiftly fatal. In adult boa constrictors, the disease assumes a milder, more chronic or, sometimes, even asymptomatic form with a wide array of extremely variable manifestations that may or may not gradually progress to death.

Clinical signs

Clinical signs may vary, with regurgitation and neurological symptoms being the most prominent in the early and later stages of its progression, respectively. In boa constrictors, the first signs may include off-and-on regurgitation followed by inappetence, and some develop head tremors. Abnormal shedding may occur. Some develop chronic regurgitation and anorexia (lack of appetite or refusal to feed). However, not all infected snakes may regurgitate. Boas lose weight and may develop clogged nares (nostrils), stomatitis, or secondary pneumonia. The disease can rapidly progress to produce nervous-system disorders, such as disorientation, corkscrewing of the head and neck, holding the head in abnormal and unnatural positions, rolling onto the back, or stargazing. Stomatitis, pneumonia, undifferentiated cutaneous sarcomas, lymphoproliferative disorders, and leukemia have all been observed in affected specimens. Burmese pythons generally show signs of central nervous system disease without manifestation of other clinical signs and regurgitation is seen only in boas. These are symptoms similar to those seen in specimens infected by Chlamydia–specifically Chlamydophila psittaci , the so-called parrot's disease.[ citation needed ]

Several snakes have been seen with proliferative pneumonia, while inclusions are commonly seen in the liver, kidney, and pancreas. Cases have also been observed with only very few inclusions. In a few snakes with signs of central nervous system disease, and with a severe encephalitis, no inclusions have been seen in any cells. While the presence of characteristic inclusions is diagnostic for the disease, the absence of such inclusions does not necessarily indicate that the snake is not diseased or is free from the IBD virus. While cells having inclusions may show mild degenerative changes, inflammation is rarely seen in visceral tissues. In the brain, mild to severe encephalitis occurs, with lymphocytic perivascular cuffing. Several snakes with lymphoproliferative disorders have been identified with lymphoid infiltrates in multiple organs.[ citation needed ]

Laboratory diagnosis

The disease can be diagnosed in live snakes through blood tests. [4]

Primary route of transmission

The primary route of transmission has not yet been identified, but direct contact may result in its transmission to developing embryos in viviparous species and eggs in oviparous species. Venereal transmission is also indicated as a possibility. The snake mite, Ophionyssus natricis , has been implicated as a possible vector for the virus, since mite infestations are commonly seen in epizootics of IBD and in captive specimens of these snakes. Mites are sometimes very difficult to eradicate due to their resistance to certain toxins used to eliminate them.[ citation needed ]

Permethrin is effective against mite infestations, but must be used with great caution and only in small quantities due to its toxicity to snakes. [5] Alternative approaches include biological agents that are sprayed onto infested animals that desiccate the mites, rendering them unable to lay their eggs or consume blood beneath the scales of their host.[ citation needed ] The incubation period for mite eggs is thought to be about 10–14 days, so the treatment should be repeated after 10 days to ensure that any eggs that hatch or larvae that develop into nymphs are eliminated from the host before reaching sexual maturity and becoming able to repeat their reproduction cycle.[ citation needed ]

Prognosis and treatment

To date, no treatment for IBD is known. Snakes diagnosed with or suspected of having IBD should be euthanized because progression and transmission of the virus is both very rapid and destructive. Newly acquired snakes should be quarantined for at least 3 and preferably 6 months before being introduced into established collections. The recommended period of quarantine for any wild-caught boa or python is at least 4–6 months.

Related Research Articles

<span class="mw-page-title-main">Pythonidae</span> Family of snakes

The Pythonidae, commonly known as pythons, are a family of nonvenomous snakes found in Africa, Asia, and Australia. Among its members are some of the largest snakes in the world. Ten genera and 39 species are currently recognized. Being naturally non-venomous, pythons must constrict their prey to induce a cardiac arrest prior to consumption. Pythons will typically strike at and bite their prey of choice to gain hold of it; they then must use physical strength to constrict their prey, by coiling their muscular bodies around the animal, effectively suffocating it before swallowing whole. This is in stark contrast to venomous snakes such as the rattlesnake, for example, which delivers a swift, venomous bite but releases, waiting as the prey succumbs to envenomation before being consumed. Collectively, the pythons are well-documented and -studied as constrictors, much like other non-venomous snakes, including the boas and even kingsnakes of the New World.

<span class="mw-page-title-main">Boidae</span> Family of snakes

The Boidae, commonly known as boas or boids, are a family of nonvenomous snakes primarily found in the Americas, as well as Africa, Europe, Asia, and some Pacific islands. Boas include some of the world's largest snakes, with the green anaconda of South America being the heaviest and second-longest snake known; in general, adults are medium to large in size, with females usually larger than the males. Six subfamilies comprising 15 genera and 54 species are currently recognized.

<i>Boa</i> (genus) Genus of snakes

Boa is a genus of boas found in Mexico, the Caribbean, and Central and South America. Five extant species, and one extinct, are currently recognized.

IBD may refer to:

<i>Loxocemus</i> Genus of snakes

Loxocemus bicolor, the sole member of the monotypic family Loxocemidae and commonly known as the Mexican python, Mexican burrowing python and Mexican burrowing snake, is a species of python-like snake found in Mexico and Central America. No subspecies are currently recognized. Analyses of DNA show that Loxocemus is most closely related to the true pythons and the sunbeam snakes.

<span class="mw-page-title-main">Green tree python</span> Species of snake

The green tree python, is a species of snake in the family Pythonidae. The species is native to New Guinea, some islands in Indonesia, and the Cape York Peninsula in Australia. First described by Hermann Schlegel in 1872, it was known for many years as Chondropython viridis. As its common name suggests, it is a bright green snake that can reach a total length of 2 m (6.6 ft) and a weight of 1.6 kg (3.5 lb), with females slightly larger and heavier than males. Living generally in trees, the green tree python mainly hunts and eats small reptiles and mammals. It is a popular pet, and numbers in the wild have suffered with large-scale smuggling of wild-caught green tree pythons in Indonesia. Despite this, the green tree python is rated as least concern on the IUCN Red List of endangered species.

<span class="mw-page-title-main">Arenavirus</span> Family of RNA viruses

An arenavirus is a bi- or trisegmented ambisense RNA virus that is a member of the family Arenaviridae. These viruses infect rodents and occasionally humans. A class of novel, highly divergent arenaviruses, properly known as reptarenaviruses, have also been discovered which infect snakes to produce inclusion body disease, mostly in boa constrictors. At least eight arenaviruses are known to cause human disease. The diseases derived from arenaviruses range in severity. Aseptic meningitis, a severe human disease that causes inflammation covering the brain and spinal cord, can arise from the lymphocytic choriomeningitis virus. Hemorrhagic fever syndromes, including Lassa fever, are derived from infections such as Guanarito virus, Junin virus, Lassa virus, Lujo virus, Machupo virus, Sabia virus, or Whitewater Arroyo virus. Because of the epidemiological association with rodents, some arenaviruses and bunyaviruses are designated as roboviruses.

<span class="mw-page-title-main">Green anaconda</span> Species of snake

The green anaconda, also known as the giant anaconda, emerald anaconda, common anaconda, common water boa, or southern green anaconda, is a semi-aquatic boa species found in South America and the Caribbean island of Trinidad. It is the largest, heaviest, and second longest snake in the world, after the reticulated python. No subspecies are currently recognized. Like all boas, it is a non-venomous constrictor. The term "anaconda" often refers to this species, though the term could also apply to other members of the genus Eunectes. Fossils of the snake date back to the Late Pleistocene in the Gruta do Urso locality.

<span class="mw-page-title-main">Calabar python</span> Species of snake

The Calabar python is a species of non-venomous snake in the family Boidae. The species is endemic to West and Central Africa. It is the only species in its genus.

<i>Sanzinia madagascariensis</i> Species of snake

Sanzinia madagascariensis, also known as the Madagascar tree boa or Malagasy tree boa, is a boa species endemic to the island of Madagascar. It was once considered conspecific with the Nosy Komba ground boa. Like all other boas, it is non-venomous.

<span class="mw-page-title-main">Pelvic spur</span> Modified reptilian appendages

Pelvic spurs are external protrusions found around the cloaca in certain superfamilies of snakes belonging to the greater infraorder Alethinophidia. These spurs are made up of the remnants of the femur bone, which is then covered by a corneal spur, or claw-like structure. This femur derives from ancestral hind limbs found in the most recent common ancestor of modern snakes and the other reptiles of the clade Toxicofera, many of which have fully functional front and hind limbs. Due to the fact that the spurs derive from the ancestral state of functional legs, but are no longer functional for locomotion specifically, these structures meet the criteria for being considered vestigial. Nonetheless, uses for the structures have been thoroughly documented. Species that have external spurs have corresponding muscles, neurological structures, and vascularization to allow for independent movement. The spurs are more pronounced and visible in male specimens and have been observed in use during courtship behavior. The spurs are specifically used in the clasping and stimulation of females by males during courtship and mating. In certain species, males will also use their spurs to engage in combat with one another.

<i>Boa imperator</i> Species of snake

Boa imperator is a large and heavy-bodied arboreal species of nonvenomous, constrictor-type snake in the family Boidae. One of the most popular pet snakes in the world, B. imperator's native range is from Mexico through Central and South America, with local populations on several small Caribbean islands. It is commonly called the Central American boa, northern boa, Colombian boa, common boa and common northern boa.

<i>Titanoboa</i> Extinct genus of snakes

Titanoboa is an extinct genus of giant boid snake that lived during the middle and late Paleocene. Titanoboa was first discovered in the early 2000s by the Smithsonian Tropical Research Institute who, along with students from the University of Florida, recovered 186 fossils of Titanoboa from La Guajira in northeastern Colombia. It was named and described in 2009 as Titanoboa cerrejonensis, the largest snake ever found at that time. It was originally known only from thoracic vertebrae and ribs, but later expeditions collected parts of the skull and teeth. Titanoboa is in the subfamily Boinae, being most closely related to other extant boines from Madagascar and the Pacific.

Lujo is a bisegmented RNA virus—a member of the family Arenaviridae—and a known cause of viral hemorrhagic fever (VHF) in humans. Its name was suggested by the Special Pathogens Unit of the National Institute for Communicable Diseases of the National Health Laboratory Service (NICD-NHLS) by using the first two letters of the names of the cities involved in the 2008 outbreak of the disease, Lusaka (Zambia) and Johannesburg. It is the second pathogenic Arenavirus to be described from the African continent—the first being Lassa virus—and since 2012 has been classed as a "Select Agent" under U.S. law.

<i>Ophionyssus natricis</i> Species of mite

Ophionyssus natricis, the reptile mite, is a parasitic mite most commonly found on snakes, but also occurring on captive lizards, turtles, crocodiles, and other reptiles. The parasites feed on snakes, which cause the bodies of the mites to be engorged with blood and fluids from the snake. Once the mites feed by puncturing through the snake skin, the snake usually shows symptoms of irritation and discomfort. The involvement of snake mites in transmission of infectious illnesses like inclusion body disease and ophidian paramyxovirus remains controversial. Human infestation has been reported.

<span class="mw-page-title-main">Boa constrictor</span> Species of snake

The boa constrictor, also known as the common boa, is a species of large, non-venomous, heavy-bodied snake that is frequently kept and bred in captivity. The boa constrictor is a member of the family Boidae. The species is native to tropical South America. A staple of private collections and public displays, its color pattern is highly variable yet distinctive. Four subspecies are recognized.

<i>Boa constrictor occidentalis</i> Subspecies of snake

Boa constrictor occidentalis, also commonly known as the Argentine boa, is a subspecies of large, heavy-bodied, nonvenomous, constricting snake. Boa constrictor occidentalis is a member of the family Boidae, found mostly in tropical and subtropical areas in northern Argentina and Paraguay, although some members have been reported to exist in Bolivia as well.

Boa blanchardensis, also known as the Marie-Galante boa, is an extinct species of Boa from the island of Marie Galante in the Lesser Antilles. It lived on the island during the Late Pleistocene until approximately 15.000 years ago when it became extinct for unknown reasons. With an estimated length of up to 1.39 m, it was the largest terrestrial vertebrate on the island. Discoveries of fossil bones in caves suggest that it may have at least occasionally hunted bats.

Serpentovirinae, commonly known as serptentoviruses, is a virus subfamily within the family Tobaniviridae which is within the order Nidovirales. The virions of Serpentovirinae have a viral envelope and a positive-sense single-strand RNA genome. They infect vertebrates, mostly Ophidians, but sequencing has identified serpentovirinae infections in other reptiles including turtles, chameleons, and lizards. Although clinical significance varies across the clade, several pathogenic infections by this subfamily have been observed and studied, primarily in snakes with some observations in other groups. This subfamily comprises seven genera and 12 subgenera.

References

  1. ↑ Stenglein, M.D., Sanders, C., Kistler, A. L., Ruby, J. G., Franco, J. Y., Reavil, D. R., Dunker, F and DeRisi. J.L. (2012): Identification, characterization, and in vitro culture of highly divergent arenavirus from boa constrictors and annulated tree boas: Candidate etiological agents for snake inclusion body disease. mBio 3(4):e00180–12. doi:10.1128/mBio.00180-12.
  2. ↑ Bodewes, R., Kik, M., Stalin, R. V., Schapendonk, C., Haagmans, B., Smits, S.L., and Osterhaus, A (2013): Detection of novel divergent arenavirus in boid snakes with inclusion body disease in the Netherlands. J. Gen. Virol; 0.051995–0.
  3. ↑ Hetzel U, Sironen T, Laurinmäki P, Liljeroos L, Patjas A, Henttonen H, Vaheri A, Artelt A, Kipar A, Butcher SJ, Vapalahti O, Hepojoki J. Isolation, identification and characterization of novel Arenaviruses, the etiological agent of Boid Inclusion Body Disease. J Virol. 2013 Aug 7. PMID   23926354
  4. ↑ [Schumacher, J., Jacobson, E.R.; Homer, B.L.; Gaskin, J.M. 1994. Inclusion body disease in boid snakes. J. of Zoo and Wildlife Med. 25(4):511–524.
  5. ↑ Klingenberg, Roger J. (2016). External Parasites Treatment for Reptiles: Pyrethrins and Permethrins (book excerpt). ISBN   978-1620082720 . Retrieved July 24, 2018– via Reptiles Magazine.{{cite book}}: |work= ignored (help)

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