THEIR LIFE CYCLE,
CONTROL, TREATMENT AND
The snake mite Ophionyssus natricis is a tenacious and debilitating macronyssid ectoparasite that thrives in captive environments. The snake mite is abundant in many collections across the world. A common ecto – parasite of many reptile species, it has managed to survive in many conditions and collections over many years. Attempts to eradicate this species have met with inevitable failure. Reintroduction occurs regularly and a regime of prevention and observation is essential in its prevention.
The ability of reptiles to regulate their mite burden, the serious effect of mites on sub adult and juvenile reptiles is also important. The warning signs are clearly here, the continual spread in Victoria is assisted by reptile keepers, wildlife shelters, research groups, wildlife controllers and staff from Conservation Departments releasing reptiles into new locations with out adherence to strict release protocols. The release of reptiles housed in captivity under shelter permits and for research purposes must have a detailed release protocol established. Wildlife controllers should also be encouraged to have clean snake tools and equipment. Mite prevention techniques should also be documented and implemented in the control of reptiles across Australia. Not only are mites a threat but now with cryptospiridium, a protozoal infection that is near impossible to treat and additionally two new virus’s may also be spread from captivity to wild snakes. Snake controllers should maintain two separate groups of equipment for controlling reptiles and the other for captivity. Alternatively run their equipment through strict and constant cleaning and disinfection routines.
In captivity it has been collected from numerous species of snakes and lizards, commonly animals with large overlapping scales. Snakes that are particularly prone to serious outcomes are Death Adders, Tiger Snakes, Red Bellied Black Snakes, Copperheads, small elapids can be susceptible to mites often fatally. Small eyed Snakes, Little Whip Snakes have been fatally infested, as have the juveniles of most elapids, boids and some Colorbrids. The effect of large amounts of blood withdrawal from these animals would be a factor in the high mortality.
Snake mite infestations of snakes and lizards may cause mild, moderate or severe anaemia, skin irritation, skin or corneal ulceration, while large infestations often cause dysecdysis. Sometimes large infestations will lead to mortality of snakes and lizards in poor condition, animals that are juveniles and sub adults presumably through excessive blood loss. Snake mite infestations may also cause stress, reduce food intake, loss or waste of energy/activity, this may lead to secondary infections and slow recovery from other illness or conditions.
Poor husbandry practices are often conducive to mite infestations of captive stock. Enclosures with damp (spilled water) warm conditions typically see a sharp rise in mite numbers. Enclosures with crevices, logs, grains, rough edges are more prone to recurrent mite infestations. However clean enclosures and well maintained set ups still receive infestations.
Some reports suspect snake mites are implicated in the transfer of Inclusion Body Disease, an introduced retrovirus most common in pythons and boas (Bush, 2000). The lifestyle of feeding mites as a protonymph and then several times as an adult, potentially means it can transmit infectious disease to other snakes through other enclosures. Some reports have linked the transmission via snake mites of several blood-borne viral, bacterial Aeromonas hydrophila and filariid (round worms) pathogens of snakes and lizards.
The complete life cycle of O. natricis at 25oC takes between 13 – 19 days, with occasional specimens living for up to 40 days.
Five stages exist;
Egg, (Eggs hatch in 28 – 98 hours). Newly laid eggs can be found in groups in an enclosure..
Larva (Lasts 18 – 47 hours). Larvae only have six legs
Protonymph (3 – 14 days). they have developed a fourth set of legs and the other legs can be seen to be longer, especially the first pair. Unfed protonymphs are pale ivory or yellowish in colour, they are almost invisible to the naked eye, but when engorged after a blood meal, protonymphs are dark red in colour
Deutonymph (13-26 hours) The deutonymphs are larger in size than the protonymphs – the body is around twice the size although the legs are similar in length – and are dark in colour (dark red to black) and soft-bodied
Adults: Larger than other stages. Both sexes are tan in colour. bBut when dark red mites are engorged females. Females engorge on blood, fall off and lay up to 20 eggs in dark cracks or crevices with rocks logs, enclosure walls. Blood meals are necessary at each nymph stage (Camin, 1953; Reiss, 1995).
CLINCAL SIGNS OF SNAKE MITE INFESTATION
The snake mites are quite small (use a hand magnifying lens or an eye piece), typically their presence can be visibly seen by sight of red, black or brown even yellowish specks with legs or commonly whitish specks around the reptiles scales, especially around the eyes, jaw or cloaca.
Several methods to check for mites can be employed. To get a good look at mites suspected on a reptile a large sheet of white paper should be placed down on a table. Using a small brush, flick around the scales near the head neck, cloaca, mouth and watch for any movement from particles on the paper. Often small bits of dirt, skin are present but the mites will be shown up quickly, especially when they start moving.
Animals can also be placed in a sealed white box, plastic or otherwise spray the inside of the box with Top of Descent spray. Give up to 5 – 15 minutes after the animal has been placed in the box. Take it out and look at the contents of the box. Mites will be seen inside. Sometimes mites will be observed in large numbers that may have been difficult visually to see.
Other signs that a reptile may have mites are excessive rubbing around the enclosure, rolling, twitching, constantly closing eyes, abnormal basking or not basking, typically many snakes submerge in water bowls and spend large amounts of time in the water bowl. The mites can be collected from the water bowl and confirmed. Drowning the mites does provide only temporary relief as the eggs are still hatching in the enclosure and ironically the water spillage dampens the enclosure creating excessive humidity this combined with warm temperature provide optimal breeding condition for mites. Interestingly reptiles that are predominantly aquatic, semi aquatic rarely are mite infested.
CONTROL AND TREATMENT
Once the diagnosis of mites has been made. What can you do, what mite control do you choose / now that you have found the mites it is important to act quickly. Suspend any trading of animals both in and out of the collection. Check the entire collection and treat all reptiles even if their enclosures do not appear to have the infestations. The incidental group of adults may hide in cracks and crevices in their enclosure. Remove all items, water bowls, anything like branches, logs and rocks should all be discarded, burnt and tossed into the bin. If you persist or really need to keep shelter sites they will need to be kept out of the enclosure treated and kept outside for three weeks retreated then reintroduced back into the collection. The enclosures should now be reduced to cardboard boxes, paper and reptiles.
For those who have sensitive animals such as geckoes etc it important to have them high off the ground or in another room, likewise crickets, cockroaches and meal worms need to be removed from the room. Do not feed the insects for a week after to ensure none are carrying sprays, which may inadvertently affect the animals they are fed to. Frogs and other spiders, scorpions etc should be placed out of the range of sprays. Depending on what treatment you choose. Treated.
MITE CONTROL AGENTS
It is now difficult to get Shelltox or Vapona Pest Strips in most commercial shops, Pest Strips are part of an older mite control that resulted in many deaths and sick reptiles. It usage was mostly unmeasured and roughly estimated which allowed toxicity in animals, also some animals came into contact with the strips. The dosage and exposure times reported were widely variable and subject to many other internal and external conditions.
A frequently recommended dose rate is Shelltox 0.6cm of strip per 0.28cubic metre of enclosure. Remove all food and water bowls etc from cage prior and immediately after treatment. Pest strips should be placed in a perforated box, a box with holes to allow the fumes out while reducing the chance of direct contact with the strip itself. One of the headaches with strips is the ability to have various cage sizes and dimensions and the strip needs more time to kill mites in larger cages and a shorter time in smaller cages. Hence experience and a keen observation will go a long way in strip usage.
Snakes especially sick or juveniles can be susceptible to the fumes. Many smaller lizards were accidentally killed via exposure to strips. In this article my view especially given the range of alternatives is a pest strip is really the last resort and choice if legally available in your state or country.
The main ingredient in these pest strips is Dichlorvos, and is released as a vapour, this produces a thin layer on surfaces. Pest strips do not work well against mites in open spaces e.g. animals in pits or other outside enclosures will need a different treatment regime. Pest strips can be extremely effective in controlling mites in smaller cages but generally are more effective when used in conjunction with other mite control methods. Further the vapour does not affect the eggs from mites.
Numerous reports have outlined sudden or prolong fatalities from pest strips, mostly from direct contact with a strip or prolonged exposure to fumes. Snakes and lizards especially juveniles, animals about to slough, geckoes, small lizards and some elapids (venomous snakes) seem more at risk. Therefore avoid pest strips in these areas if not experienced or confident in skill. Carefully monitor the reptiles that are exposed to pest strips, look for any sluggishness or motor-control problems. If any problems are detected, or even suspected, remove the pest strip from the cage.
A wonderful addition to the control of mites, it is used widely and has a safety margin that can be effective in mite control on many sensitive elapids. The dilution is safe even in strong mixes intially ten years agog I was in a private zoo, when I first started the biggest challenge was the mites in every cage. Some reptiles were severely affected. I used orange medic 50% solution and sprayed the entire animal house. I did not see a mite for several months. I sprayed baby copperheads, Tigers, Browns and small lizards no discernible effects. Orange medic is also safe to use routinely spray enclosures once a month as a preventative measure. Orange Medic has a nice citrus smell that does give the reptile room a rather sweet aroma.
There have been some reports of toxicity effects in snakes undergoing shedding(sloughing).be careful around the eys use a cottonbud.
Ivermec® is formulated for horses, and is only available through prescribed veterinary practises. It has the advantage of topically controlling mites and ticks. Orally / injectable Ivermectin controls intestinal worms (not tapeworm/flukes) and microfilariae (blood borne parasite). It was noted that when Ivermectin was injected that burdens of mites and ticks were controlled and reinfection was limited for up to a week. Warning Freshwater Turtles cannot be treated with Ivermectin at any time as they can be fatally treated.
Ivermec should be diluted in water to make a 2% solution (2 ml of Ivermec to 98 ml of water). 2% Ivermec solution is used as a spray. The spray kills mites on contact while not affecting the snake or lizard. The spray can be applied directly on snakes and lizards, cages, and the immediate areas outside the cages to prevent further spread and reinfection.
Take care over any ‘possible ‘ overdoses that may occur, side effects may be: dilated pupils and a uncoordinated movements which can progress to respiratory paralysis and death.
TOP OF DESCENT/REPTILE INSECTCIDE
An aerosol that has recently become available and is now widely used in Australia. This spray is a derivative of the commercial spray used to control insects on international and domestic aviation circles. Reptile Insecticide – “Top of Descent” Aerosol Insecticide with low toxicity, its shown to be safe and needs no mixing and has no noxious odours. Top of Descent contains d-phenothrin which is rapidly biodegradable and is not stored in the body tissues of those exposed to it. Thus the reptile can be left in the cage at time of spraying. Any food, water, or empty water bowls should be removed from the area being sprayed.
Neguvon has been reported successfully in treating snakes both topically and as a preventative spray. The 1.5% (mix 1.5 ml of Neguvon with 98.5 ml) solution applied with a mister /sprayer. In other words, mix 1.5 ml of Neguvon with 98.5 ml of water to make 100 ml of 1.5% Neguvon. Please do not use a concentrated Neguvon spray use only around 1.5%. The active ingredient Trichlorufon is apparently biodegradable. Be careful around the yes alternatively apply eye ointment to protect them from the spray. Leave water and food out of enclosure for up to two days following treatment and obviously during treatment.
However this is very difficult to handle and extreme care is needed when mixing the solution gloves and a mask are essential. I believe that this is only for the experienced and not the average younger keepers especially in family homes. Also once neguvon is mixed with water, the solution remains a potent mite and tick killer for only one week. Neguvon has a noticeable chemical odour, this should be aired out of enclosures correctly.
Neguvon is serious stuff, especially in its concentrated form. Don’t get it on your skin. Wear your latex gloves, handle it carefully and follow the handling instructions on the label.
Long been used (Worrell, 1958) oils such as Olive, Canola, were used to prevent mites from attaching to snakes. The oil lightly applied drowned attached mites and prevents mites from attaching in the near immediate future. Oils I believe are suitable to use on reptiles in mite infested pits, this is the hardest environment to control mites. The oils longer extended protection as opposed to sprays means added resistance to reinfestation.
These oils are sometimes used to remove small areas of retained sloughs (Dysecydis) from reptiles. I find that their use after a spray on heavily infested reptiles is quite good. There is something rather masculine with gleaming reptiles in the enclosures a rather “Bondi beach look”
MALABAN / FIDO DOG WASH
Largely debatable on the safety margin allowed, it is nevertheless an option for many keepers.
This solution is widely used especially as an emergency solution to sudden outbreaks or over the phone consults for large outbreaks. The soapy water prevents mites from remaining on submerged reptiles. It is only a preventive for reptiles in the short term.
There are some aspects of mite prevention that can be applied. Quarantine is essential, when reptiles first enter the premises, they must be placed in a quarantine enclosure in a separate room. It remains the biggest threat to collections that people still rush in without any good quarantine procedures the new snake or lizard. Many pet shops still consistently place new stock straight in the show room, reptiles often display little signs of mites but when conditions are right the inevitably explosion begins. QUARANTINE is a must. Ignore it at your own peril. Not to mention the numerous other reptile diseases that can be spread throughout your enclosures. All animals should be isolated in a separate room and have faeces analysed, behaviour recorded and fed.
Some other measures may help, spray with top of descent any animals that come in, I should mention one example that a lost reptile Water python arrived in my care. A Top of Descent spray while it was still in its bag over two days, was followed by a spray one week later in its enclosure this snake still managed to have adult mites 16 days later. Which resulted in another quarantine protocol followed by intensive spraying and being kept on paper and with a card board box for two months before been allowed back out.
Double-sided tape has made some impression on me, I have several enclosures with contact sheets some of these sheets probably from the humidity peeled back exposing the sticky adhesives surface. I noticed that during mite invasions that the animals (Elapids, large skinks and Boids) in these enclosures rarely showed any signs of infestations. I checked the sticky surface and yep mites were fixed to them. So I now run double sided tape across many surfaces especially the outside of the cages. The tape needs to be rubbed to remove the sticky substance and ensure snakes or lizards cannot be fixed to them accidentally, you do not need large amounts of adhesive to stick mites to them. It’s likely that running tape around the enclosures may help prevent mites from easily accessing the other enclosures.
In some instances Mite control spray Orange medic/Top of Descent, Ivermectin or Neguvon spray /powder can be placed around the enclosure perimeter to prevent mites from their spread across numerous enclosures. Mites travel quite quickly and through other enclosures rapidly. So mite control sprays should be done in adjoining cages and the floor, top of the units and around windows walls etc. If you can spray all these areas before you treat the enclosures that way any of the mites that fall out of cleaning process land on the recently sprayed floor.
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Cogger, H.G. 2000. Reptiles and Amphibians of Australia. 6th Edn. Reed Books, Sydney.
McCracken, H.E. 1988. Husbandry and diseases of captive reptiles. pp. 1-50 in, Australian Wildlife. Proceedings of the John Keep Refresher Course for Veterinarians. Postgraduate Committee in Veterinary Science, University of Sydney.
Reiss, A. 1995. Veterinary Care and Management of Non-Domestic Animals. M.V.Sc. thesis, University of Melbourne.
Viggers, K.L, Lindenmayer, D.B. & Spratt, D.M. 1993. The importance of disease in re-introduction programs. Wildlife Research 20: 687-698.
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Watharow, S. 1997. Ecology of Eastern Tiger Snake (Notechis scutatus) and Lowland Copperhead (Austrelaps superbus) within metropolitan Melbourne. Monitor, Journal of the Victorian Herpetological Society 8(3): 145-151.