Iguanid Herpesvirus IgHV-1
©2000 Melissa Kaplan
Herpesviruses are found throughout the vertebrate animal kingdom, including many strains associated with reptiles, including IgHV-1 - iguanid herpesvirus, 1 (meaning that, so far, there is only one known strain, or species, of iguanid herpesvirus; to put this into perspective, only within the last few years have new human herpesviruses been found and identified - HHV6-9).
To be able to determine whether an animal has an HV infection, electron microscopy must be done on tissue samples taken from skin or organs. Histology and electron microscopy evaluations can also be done on negatively stained bodily fluids, such as saliva, urine and vesicular fluid.
Typically, as with the human herpesvirus H. simplex (HSVI; infection remains dormant in body; when activated, causes cold and canker sores in mouth and elsewhere on face, and in some cases elsewhere on the body; is different than HSVII, the HHV that causes genital herpes), the virus is dormant for long periods of time during which the host is active and healthy. Acute environmental and/or psychosocial (including work-related) stress can compromise the body's immune system function and result in the herpesvirus becoming active again.
Acyclovir (brand name Zovirax) is available as a topical ointment, in pill and in parenteral (injectible) form; of the first two forms, it is most effective and more quickly effective in pill form. This antiviral is specifically for HV (HSVI and HSVII, and H. zoster [shingles]) infections, as well as Epstein-Barr virus (EBV) and cytomegaly virus (CMV). It works not by killing the virus but by disrupting the virus's DNA, preventing it from replicating. The flare subsides as the immune system is supported in other ways, and the lesions heal and disappear, the virus dormant again until the next flare.
A review of what little literature there is finds nothing to indicate that IgHV-1 is any more serious than H. simplex in humans, meaning that while an otherwise healthy body may occasionally go through a reactivation of the usually dormant virus, immune support and the use of acyclovir (which does not have harmful or serious side effects) to stop the reactivated virus from replicating. In humans 70% of the drug is eliminated in the urine (making it a damned expensive one, if you think about how much gets flushed down the sewer system!); this means that, like all drugs, it is being processed through the liver and kidneys, so, as with antibiotics, you need to make sure a reptile on acyclovir is getting extra fluids while actively taking the drug and for a week or so after the prescribed dose has been completed. Other side effects are rare.
If your iguanid lizard has IgHV-1, you might want to talk to your vet about the use of oral or injectible acyclovir. You may want to encourage your vet to contact one of the consulting vets on the Consulting Veterinarians list to discuss IgHV-1 and the use of acyclovir for reactivations.
It is unknown just how viruses are transmitted between reptiles. To reduce the risk of infecting other reptiles including other iguanid lizards, an iguana who tests positive for IgHV-1 can go to a home where he or she will be, for the rest of his or her life, the only reptile.
I have seen no data on iguanid infection rate, but estimates are that H. simplex, for example, is already found in at least 50% of the human population in most areas; it is higher in less-developed countries. The majority of humans who have the dormant HSVI have it by age 5 years. For all we know, infection rates in iguanids and other reptiles may be comparable, and perhaps higher in imported species or wild domestic iguanid species. If this is the case, the only risk factor would be to either keep an IgHV-1 positive iguana away from other iguanas during a reactivation that results in skin lesions, or keep any such lesions coated with topical acyclovir while the lizard is being treated systemically (either by pill or injection).
For those of you who don't already know or haven't figured it out yet, the word herpes and herps (the collective noun for reptiles and amphibians) both come from the same root word, the Greek herpeton, meaning things that creep and crawl. In the case of herpes, the virus crawls along nerves; in the case of herps, well, whoever named herps herps has obviously never seen an iguana leap from his basking shelf to the floor rather than scurry down his climber!
Electron microscopy observations on a new herpes-type virus isolated from Iguana iguana and propagated in reptilian cells in vitro. Infect Immun 1972 Apr;5(4):570-82
Iguana virus, a herpes-like virus isolated from cultured cells of a lizard, Iguana iguana. Infect Immun 1972 Apr;5(4):559-69
Viruses of lower vertebrates. J Vet Med B Infect Dis Vet Public Health 2001 Aug;48(6):403-75
Rapid acquisition of entire DNA polymerase gene of a novel herpesvirus from green turtle fibropapilloma by a genomic walking technique. J Virol Methods 2001 Feb;91(2):183-95
Viruses of Chelonia. Zentralbl Veterinarmed [B] 1993 Feb;40(1):35-45
Species selective interaction of Alphaherpesvirinae with the "unspecific" immune system of the host. Arch Virol 1993;130(3-4):353-64
[Cutaneous lesions with papillomatous structure associated with viruses in the green lizard (Lacerta viridis Laur.)]. C R Acad Sci Hebd Seances Acad Sci D 1976 Oct 4;283(7):845-7
[Herpesvirus epidemic in Greek (Testudo hermanni) and Moorish land tortoises (Testudo graeca) in Switzerland]. Schweiz Arch Tierheilkd 1990;132(4):199-203
Herpesvirus in red-headed (common) agamas (Agama agama). J Vet Diagn Invest 1993 Jul;5(3):444-5 [No abstract available]
Herpes-like virus particles in necrotic stomatitis of tortoises. Vet Rec 1988 Nov 19;123(21):544 [No abstract available]
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