Box Jellyfish, a jellyfish found in Northern Australia waters, has tentacles that each contain up to 750,000 nematocysts. The tentacles are raised and lowered allowing 'fishing' at various depths.
The tropical reef environment is a harsh but beautiful world.
In areas powerful waves break upon its inhabitants and strong surges scour the reef.
Bio-available nutrients are lacking, with many creatures competing with others for these scarce morsels.
The reef's greatest asset is the intense sun providing energy, both directly and indirectly, for algae and animals low on the food chain to synthesize carbohydrates, lipids, and proteins.
Again, organisms must compete with others, for access to the sun's rays.
Additionally every organism must protect itself from higher animals seeking to make a meal of them.
Moreover, these higher animals must also guard against attack from other predators, and so on and so forth.
Over the millennia all of these creatures have evolved specialised appendages and mechanisms to defend themselves and secure an advantageous position within the reef.
Often it is these appendages and mechanisms that attract aquarists to marine aquaria and reef keeping.
The unique and brilliant shapes, colors, and patterns of marine life can rapidly turn an average room into a surreal realm of beauty and intrigue.
Yet, many of these highly evolved designs are not as benign as the aquarist might wish.
Instead, many camouflage jaws, spines, nematocysts, and potent toxins.
This article will address these dangers that may confront the hobbyist.
In addition, steps that can be taken to protect against injury, methods to treat minor trauma, and when professional treatment at the local emergency room should be sought will be discussed.
It is by no means all-inclusive, and although the author strives for perfection, errors may escape his notice.
Therefore, please feel free to forward any and all questions or comments.
Injury Prevention
Before acquiring a specimen, the hobbyist should always seek information concerning its care and requirements.
At this time, inquires into any potential threat that this organism poses to the aquarist should be undertaken as well.
Pictures and scientific names are very important in the correct identification of a specimen.
Often a store will sell one specimen under a different common name to another of the same species, either because of ignorance, mislabeling, or differences in regional "reef vernacular".
This error can become important since similar species can vary greatly.
For example, some sea urchin and octopus species produce venom, while others do not.
If the prospective buyer has seen a similar specimen with a different name before in a store or book, such discrepancies should be discussed with the store person.
Some important questions to ask include:
Is this creature dangerous?
Can it sting, stab, or bite?
Does it produce a toxin?
What precautions must be taken when handling it or placing my arm in the tank?
Am I qualified to have this specimen in my tank?
The answers to these questions can be found in numerous aquarium books, by talking to other hobbyists, and by asking questions to knowledgeable store employees.
Recently the author had a conversation with a store manager who has raised and collected fish for many years.
He had been stung and bitten on about a dozen different occasions by a number of fish and invertebrate species.
Talking to someone who has seen the dangerous side of a species can provide great insight!
If it is decided to purchase an organism that is potentially dangerous, do not ignore the information learned prior to acquisition.
If the creature is a sessile invertebrate carefully consider the placement issues:
What is the best spot for the animal so that it will not have to be approached during routine tank maintenance?
How stable will the animal be in this spot, and what is the potential that it will fall on an arm if the rockwork is disrupted while something is being done in the aquarium?
If the organism is motile, is the aquarium set up such that hiding places and shelter are provided so that it can retreat when an arm is introduced into the aquarium?
Most fish will only become aggressive if they feel threatened.
Many, but not all reef inhabitants that possess injurious defense mechanisms are actually rather benign provided the aquarist takes the necessary precautions when introducing a hand or arm into the tank.
One must always know where the animal is relative to the arm.
By following these simple rules and some common sense, the majority of deleterious encounters will easily be avoided:
If the distance is too small, consider withdrawing the arm or using a net to help widen the buffer zone.
Use a "spotter" to help keep track of the animal.
When handling dangerous corals and anemones, disposable latex gloves will often provide a suitable barrier.
Arm-length gloves can also protect the arm from less visible sources of injury such as nematocyst-laden mucus.
Always move slowly; quick movements will scare the tank's inhabitants and precipitate erratic and aggressive responses.
Injury Types
Obviously, the vast majority of tank related injuries will involve the fingers, hands, and arms since these areas are most often exposed to danger.
After confronting a tank inhabitant and losing, a rigid protocol should be followed.
It is always best to alert others of the predicament and ask for help sooner rather than later.
Standard first aid should be practiced.
If you are not certified in CPR and first aid, seriously consider taking the time to do so.
It is much better to have some idea of what is to be done in an emergency, whether it involves a fish tank, the dinner table, or a traffic accident.
Nobody likes to teach or learn CPR over the phone....
Acutely, most aquarium accidents will not cause airway, breathing, or circulation problems.
Yet, this type of situation could present itself with extremely dangerous organisms like the Blue-ring octopus (Octopus maculosa or lunulatus).
Moreover, shock in response to trauma from an organism that is generally considered relatively harmless, is always a possibility.
Thus, it is a good idea to be always be prepared for the worst.
Hemorrhage
A more realistic acute consequence to aquarium related injury would be hemorrhage.
Animals such as moray eels and reef sharks can produce very deep lacerations, or even tissue loss.
Consequently the immediate need is to control bleeding.
This can almost always be accomplished by sustained direct pressure on the site of injury.
In very severe cases, pressure on the local artery will help.
Tourniquets are dangerous and should not normally be used since they can increase the tissue damage.
Anyone seriously injured in this way should obviously visit the emergency room.
More commonly, the trauma will be small in size with bleeding minimal.
The possibilities are almost endless, but live rock and hard corals are two easy ways to produce minor scrapes.
In this type of controlled situation bleeding should probably be encouraged, thus helping to clean and sterilizes the wound.
To clarify, it is not suggested that a butcher knife is used to expand the wound.
Instead, treat it like any other small cut or scrape. Wash the area thoroughly with soap and freshwater.
Antibiotic ointments such as neosporin will help to prevent infection.
Scrapes from hard corals usually heal slowly, with it being hypothesised that some corals produce compounds that specifically impede healing.
Tetanus immunization should be up-to-date. By far the biggest complication from marine injury is infection, but this will be discussed later in more detail.
Envenomation
Numerous animals including sea urchins, the Crown-of-thorns starfish, stingrays, tangs, rabbitfish, dragonettes, catfish, and scorpion fish posses spines on their bodies.
Many of these animals also posses venom that enters the wound.
Depending on the species, this venom can produce local vasoconstriction of the vessels.
This limits its spread, but also can create ischemic areas susceptible to tissue death and infection.
Interestingly, each individual will have a different qualitative description of the pain associated with venom or a trauma.
Therefore it is hard to say which organism produces the most "painful" injury.
Often, dangerous stinging apparatus are retroserrate and will cause more damage if they are pulled out of the wound.
In addition, they usually are fragile and readily break off within the wound.
Hence, anymore than superficial injury will require medical care to detect and remove possible remaining foreign material.
Small wounds should be encouraged to bleed, although this will be difficult with most puncture wounds.
All should be thoroughly washed and treated with topical antibiotics.
Most envenomating marine animals produce a protein based toxin that is exquisitely heat sensitive.
Immersion of the area in hot water (45-50�C) for 30 to 90 minutes will help to denature the toxin and greatly reduce the symptoms.
Always immerse an unaffected area as well to guard against scalding because of numbness around the wound.
Do not be afraid to seek medical attention if needed!
These wounds can easily become infected with bacteria, producing new symptoms several days later.
Again, tetanus immunizations should be up-to-date.
Echinoderms
Certain echinoderms are covered in spines.
These include sea urchins and the Crown-of-thorns-starfish (Acanthaster planci).
Some species of sea urchins also contain pedicellariae.
Pedicellariae are small jaw-like appendages that protrude from an underlying venom gland.
They contract following sufficient stimulation of the sensory hairs present within the organ.
Envenomation continues until the pedicellariae are removed, which Halstead suggests should be done using shaving cream and a razor blade.
Pedicellariae venom can produce severe systemic reactions.
Dangerous urchins (including the members of the families Diadematidae, Arbaciidae, Echinothuridae and Toxopneustidae) can usually be recognized by their long thin spines (often filled with venom) or short spines and pedicellariae.
Solid and blunted spines pose little threat to the aquarist.
The needle spines easily penetrate clothing, gloves, and the skin.
These spines are very fragile and readily break and fragment in the wound.
The puncture wound can be quite painful, with the possibility of the wound becoming black and it may appear to hold a broken spine when none is present.
Sting Rays
Of the numerous species of stingrays, very few are actually kept by aquarists.
Yet, this animal can be extremely dangerous and requires some attention.
The stinger is located in the tail, although the exact site varies according to four general patterns.
The stinger is composed of a bone-like core with retroserrate processes along the sides.
Tissue and venom glands cover the stinger and the entire apparatus is covered by an epidermal layer.
Following the penetrating thrust of the stinger, the epithelial layer is ruptured and the venom flows into the wound, following grooves in the spine.
The stinger can break off within the wound, which will usually require medical attention.
The pain is sharp, shooting, and throbbing in nature.
The pain increases over the first two hours and resolves over several days, with the majority easing within 12 hours.
The wound bleeds profusely, and rapidly becomes swollen and red, with a central cyanotic zone.
The venom can also produce physiological reactions, including vomiting, radiating pain to the central lymph nodes, diarrhea, and changes in the heart rate and blood pressure.
Removal of imbedded stingers can require surgical attention because of the retroserrate spines.
Surgeonfish
Surgeonfish (genera Acanthurus and Naso) possess a sharp spine at the base of their tail.
This spine is moveable and is extended away from the body and locked when the fish becomes excited.
A quick thrash of the tail will produce a painful wound that will swell and become discolored.
Some species appear to have venom glands, while others do not.
The pain lasts for several hours and then reduces to a dull ache.
As with stingray envenomations, the pain can radiate to more central lymph nodes (i.e. the axilla).
Rabbitfish
Rabbitfish (genus Siganus) fins contain multiple spiny processes, all associated with venom glands.
To be exact, there are 13 dorsal, 4 pelvic, and 7 anal spines.
The spines have two deep grooves that contain venom glands along the distal third of the spine.
The spine is covered with an epidermal layer that is ruptured by trauma, releasing the venom in much the same way as with stingrays.
The pain is sudden and severe lasting for hours to several days and producing considerable distress.
Like surgeonfish, the wound swells, becomes numb and pain radiates to the regional lymph nodes.
The immediate area can become cyanotic with a surrounding red area.
Dragonettes
Dragonettes (family Callionymidae) have preocular spines that can inflict puncture wounds, though it is not clear that they produce any venom.
Again, this is an example of a colorful, small, peaceful fish that can inflict harm if mishandled.
Marine Catfish
Marine catfish (including the family Plotosidae) are among the most dangerous venomous fish.
They contain a single spine immediately anterior to the soft rays of the dorsal and pectoral fins.
These spines can be locked in an extended configuration when the fish is agitated.
The spines consist of a central bony area with retroserrate processes.
Venom glands are located in tissue around the spine, and according to Halstead, continue into the epidermal region.
The wound is immediately painful, and the pain has been described as intensely throbbing or stabbing.
The wound swells, is initially pale and the pain may radiate to regional lymph nodes.
It becomes cyanotic and then red.
The Oriental catfish (Plotosus lineatus) has an especially potent venom that produces violent pain lasting up to two days.
Catfish spines can produce considerable damage to tissue because of the retroserrate pattern.
Wounds often become infected and take weeks to heal.
Scorpionfish
Scorpionfish (family Scorpaenidae) can be divided into three main groups based upon their venom gland anatomy: the zebra, lion, and/or turkeyfish (including genera Pterois and Brachirus), the scorpionfish (including genera Apistus, Centropogon, Notesthes, Scorpaena, Scorpaenopsis, and lnimicus), and the stonefish (including genera Choridactylus, Minous, and Synanceja).
Zebrafish have 13 venomous dorsal spines, 3 anal spines, and 2 pelvic spines.
The spines are long, thin, and well hidden among the ornate finnage.
Like the rabbitfish, zebrafish spines are grooved and have small venom glands located within.
The entire spine is covered with a thin epidermal layer.
Scorpionfish frequently have 12 dorsal spines, 3 anal spines, and 2 pelvic spines.
These spines are shorter and thicker than those of zebrafish.
Additionally, the grooves and venom glands only fill the distal two-thirds of the process.
Moreover, the epidermal layer is thicker than over the zebrafish spine.
Stonefish usually possess 13 dorsal, 3 anal, and 2 pelvic spines.
These spines are shorter and heavier than the other two variations.
Furthermore, they contain greatly enlarged venom glands and a very thick sheath.
Because of the amount of toxin, these fish produce the most serious stings of the three.
All three types produce essentially the same type of pain, which only varies in intensity from species to species.
The pain is immediate and intense, but resolves in hours.
It can be sharp, radiating, or throbbing.
The wound is numb, swollen, and pale or cyanotic.
Ischemia can complicate the picture, leading to ulceration and necrosis.
Rapid immersion in hot water can bring great relief of the symptoms.
Finally, stonefish (Synanceja) antivenin has been developed by the Commonwealth Serum Laboratories, Melbourne, Australia, and can be used to inactivate the poison of certain species.
Cnidarians
Envenomation can occur by other mechanisms besides venom-laden spines.
Other organisms, including bristleworms (such as the families Amphinomidae and Glyceridae), cone shell snails, the Blue-ring octopus, jellyfish, certain sea anemones (such as Actinodendron plumosum, Stoichactis kenti, Triactis producta, and Anthothoe species), and some corals and hydroids (such as Millipora, Aglaophenia, Lytocarpus, Catalaphyllia, Plerogyra, and Euphyllia species) produce toxins that at minimum are irritating to the skin and at maximum, deadly.
Nematocyst-induced envenomations should be handled differently than bite or puncture wounds.
Firstly, do not apply freshwater to stings from jellyfish, sea anemones, or corals.
Since the triggers are modulated by osmolarity changes, freshwater will cause any remaining nematocysts within the mucus coating to fire.
The same is true with physical stimulation.
Therefore, do not rub or scratch the area.
Additionally, exercise care to prevent transferring any active nematocysts to other areas, including the eyes, lips, and mouth.
Because the epithelial layer covering these surfaces is more delicate than that of the fingers, hands, and arm, it is possible to produce stings in these areas with nematocysts from corals that are not capable of stinging through the thicker skin of other areas. Instead, gently rinse off the surface using water from the aquarium.
The skin should then be washed with vinegar (5% acetic acid) to inactivate any remaining nematocysts.
Papain, or meat tenderizer, has also been reported to inactivate the toxin.
For jellyfish stings, the attached nematocysts can then be shaved off using a razor and shaving cream.
Certain jellyfish are quite dangerous and will require urgent medical care.
Tetanus immunization should be current following any sting.
Coral and anemone stings will generally range from prickly to intensely painful initially.
Immersion of the area in hot water (45-50�C) for 30 to 90 minutes will help to denature the toxin and greatly reduce the symptoms.
The "prickling" or burning from most marine envenomations will usually resolve over about 90 minutes, but it can potentially last for a number of hours.
Usually it is followed by itching, a rash, and possible blisters which can last for several weeks.
It may respond to mild topical anesthetics and steroids.
Systemic antibiotics are usually not necessary for these superficial envenomations.
Yet, severe reactions, which can develop ulcerations and necrosis, require immediate medical attention.
Cone Snails
The author does not know of anyone who has cone shell snails (genus Conus) in their aquariums so they will only be touched on.
Cone shell snails are extremely beautiful predatory univalve mollusks that contain a highly developed and potent venom apparatus.
The apparatus consists of a poison producing bulb and duct within the shell.
The duct connects to a hollow rolled sheath and harpoon like tooth.
Prior to stinging, the radicular tooth is released into the proboscis where it can be used to thrust into the prey.
Contraction of the bulb forces venom through the duct, the hollow tooth, and then into the prey.
A cone shell snail sting will produce variable symptoms depending on the species.
Most will result in numbness and tingling that rapidly spreads throughout the body, especially to the mouth and lips.
This is followed by muscle paralysis and possible respiratory or cardiac failure.
It can occur rapidly and requires urgent medical attention.
Halstead recommends using a lymphatic-venous occlusive bandage to secure a 6-8 cm x 6-8 cm x 2-3 cm gauze pad firmly over the wound, being careful not to occlude arterial circulation, until proper medical attention can be provided.
Octopuses
Octopuses should quickly be commented upon.
These intelligent creatures can bite with their parrot-like jaws causing a wound that may burn or tingle, and will usually bleed profusely.
Besides some swelling and redness, most octopus bites will heal uneventfully and can be treated like any other bite or wound.
In contrast, the Blue-ringed octopus, Hapalochlaena maculosus and a closely related species, Hapalochlaena lunulatus, produces an extremely toxic venom that is often fatal.
Though these organisms are quite beautiful, they are very dangerous and should not be sold by collectors or kept by aquarists.
The Blue-ringed octopus has anterior and posterior venom-producing salivary glands.
They connect via a duct to the tip of the subradular organ on the front of the tongue (posterior duct) and the pharynx (anterior ducts).
The jaws attach to a powerful muscular buccal mass.
Blue-ring octopus venom, maculotoxin, is one of the most powerful neurotoxins known.
Initially the wound is painless, a stinging sensation and then numbness will develop.
The individual will then experience a tingling sensation around the mouth, neck and head.
Nausea, vomiting, visual disturbances, generalized weakness, and often fatal respiratory distress will develop.
In those lucky enough to survive, the muscle paralysis lasts 4-12 hours, though some symptoms can last for weeks.
Anaphylaxis
Anaphylaxis, an allergic reaction to the animal's venom, is a medical emergency.
Anaphylaxis is a systemic immune response to a compound.
It is independent of the compound's innate toxicity.
Because it is dependent upon the immune system, an anaphylactic response requires prior exposure to the compound.
Following this initial exposure, there will be no physically evident symptoms.
One could consider this exposure as "priming" the immune system.
Later contact, either the next time or several times down the road, will produce a systemic, life-threatening response in susceptible individuals within seconds to minutes of re-exposure.
Again, this response is variable from person to person, and generally independent of the level of exposure.
This reaction is characterized by vascular collapse and shock, with or without respiratory distress.
Possible symptoms include:
Upper airway swelling -- hoarseness and a "lump in the throat" feeling.
Lower airway obstruction -- chest tightness.
Wheezing, and shortness of breath.
Cutaneus involvement -- intensely itchy, red, raised hives with pale centers and wandering borders, that can be local or spread over the entire body.
Gastrointestinal symptoms -- nausea, vomiting, diarrhea, and cramping stomach pains.
Anaphylaxis requires prompt medical treatment with epinephrine and other support measures.
Anyone who has experienced a severe allergic reaction should avoid exposure to the precipitating compound.
If this compound is a toxin produced by a reef inhabitant, the animal should be removed from the aquarium.
At a minimum, epinephrine should be readily available for immediate use in case the individual is exposed to the compound again.
Because anaphylaxis is immune regulated, each response will likely be more severe than any previous exposure.
Local Allergies
In addition to the severe anaphylactic reaction, minor local allergic responses can also be initiated.
This contact dermatitis can be very similar to the hypersensitivity reaction of poison ivy.
Often, it will be difficult to differentiate an allergic response from the response of a toxin or foreign body.
Sponges of the genus Tedania (fire sponges) can produce this type of allergic reaction.
Moreover, spicules from the sponge are irritating, though they can be removed by gently applying adhesive tape to the dried area and peeling the imbedded spicules off attached to the tape.
Inorganic compounds such as the salt used in tank water can be irritating and produce a type of dermatitis.
The rash, or chronic eczema, is often located near the antecubital fossa (the part that is hidden when the elbow bends).
This patch is usually dry, red, and itches.
The lesion is often produced by rubbing the arm against dried salt deposits along the top of the tank during routine maintenance.
The dried deposits disturb the epithelial integrity and produce a local irritation.
This type of hobby-related injury will heal in several days once exposure is stopped.
Hydrocortisone creams may alleviate some of the symptoms.
This type of irritation can be prevented by wiping salt deposits off the top of the tank before introducing the extremity into water and exposure can be limited by wearing arm-length gloves.
Moreover, carefully washing the arm with freshwater afterwards will remove any salts before they can dry or sufficiently irritate the skin.
Infection
Finally, the most important non-acute complication of marine trauma is infection.
Tank inflicted or otherwise unrelated injuries or wounds can become infected with halophilic (salt-loving) bacteria from the aquarium, or with other bacteria from the environment.
In a study in which animal wounds were inoculated with Hong Kong beach water, 318 bacterial strains were isolated.
The predominant marine/estuarine species were of the genera Vibrio, Pseudomonas, and Aeromonas.
The infection rate was highly correlated with fecal coliform counts, implying that aquarium water, which is relatively pure when compared to seawater from many recreational beaches, does not harbor virulent bacteria in the same densities.
In another experiment, oral cultures from two captive moray eels at the Chicago Shedd Aquarium were taken.
Isolated bacteria "included Vibrio fluviolis, V. damsela, V. vulnificus, Micrococcus species, and coagulase-negative Staphylococcus."
In addition, Pseudomonas puterfaciens was also isolated from cultures of the tank water.
Other species of Vibrio have been isolated from oral cultures of Leopard, Maco, and Great White sharks.
Therefore animal bites can directly inoculate numerous virulent bacterial species into the wound.
In addition, many of the bacterial species found free in tank water and in the slime coating of fish cause infections in both aquatic creatures and humans.
This includes Erysipelothrix rhusiopathiae and related species which can produce a red patch with vesicles and smaller papules.
The borders are well demarcated and slightly raised.
The bacteria enter through minor skin trauma and initially produce an itchy and painful purplish area following an incubation period of less than four days.
The infection expands slowly, mostly towards the body proper.
Untreated, the infection will resolve within several weeks.
Rare cases of disseminated disease and endocarditis, an infection of the heart, have been reported.
Though this disease has yet to be described as an aquarium-associated problem, it is relatively common in the fishing industry and is most likely transferred through dead fish.
Moreover, human wounds are exposed to Staphylococcus and Streptococcus species that are ubiquitous on the skin.
Finally, it has been reported that fish handlers and aquarists are at a higher risk for common warts caused by various types of human papilloma virus, though this has yet to be substantiated.
In short, the likelihood for some type of infection at some point is high among hobbyists.
Vibrio sp.
Species from the Vibrio genus are the most common marine bacteria, accounting for over 31% of all colonies culturable from water samples.
V. vulnificus is probably the most common Vibrio species isolated from human wounds.
It is gram negative, highly motile, strongly oxidase-positive, and ferments glucose (other species of Vibrio ferment lactose).
Virulence is associated with the presence of an acidic polysaccharide capsule that protects the bacteria from host defenses.
Virulent strains also produce destructive enzymes including proteases, lipases, DNAses, chondroitin sulfatase, mucinase, and hyaluronidase; with all of these enzymes being capable of dissolving different tissue components.
This bacterium rarely causes infections in healthy humans, yet it can cause devastating infections in individuals with certain illnesses or those who are immunologically compromised.
V. vulnificus is found at peak levels in water temperatures of 21-23oC, the temperature that some reef aquariums may be maintained at.
Furthermore, the presence of V. vulnificus is unrelated to fecal coliform counts in two studies, and it grows best in clean water.
Filter feeding organisms such as oysters can concentrate this bacteria in very high amounts.
Hence, eating contaminated raw oysters can produce severe sepsis, a systemic infection of the blood, with a high mortality rate.
But, most aquarists do not eat the fruits of their labor, so a more likely form of disease is via wound infection.
This can rapidly progress to secondary sepsis and is associated with a 7-24% mortality rate, even with medical treatment.
V. vulnificus cutaneus infections are restrained to the extremities, even if they are secondary to a primary sepsis from ingestion of the bacteria.
This is most likely a result of its preference for a temperature lower than that of central core areas of the body.
The initial infection presents early with redness, swelling, and intense pain.
It quickly overwhelms the local immune response, as evidenced by the plethora of bacteria on biopsy at the dermal/epidermal junction, but the general lack of inflammatory cells.
The redness changes to a bronze discoloration and bacteria move into the lymphatics and surrounding tissue.
The bacteria spreads rapidly, destroying tissue with their toxins and producing large areas of necrosis.
The process can mimic gas gangrene, with vesicles and bullae (blisters) often present.
The bacteria destroy skin, blood vessels, connective tissue, and muscle. Invasion of blood vessels can lead to secondary sepsis.
This infection requires aggressive treatment with antibiotics and surgical debridement.
Even with this therapy, it is often rapidly fatal.
Several factors place certain populations at a heightened risk for V. vulnificus infections.
First, its virulence is associated with host iron availability.
The bacteria produce proteins that can complex free iron and allow for growth.
Normally in the body, a protein called transferrin binds iron tightly and greatly limits the availability of the free form.
Chronic diseases that increase blood iron levels produce a more favorable environment in which the bacteria can grow.
Some of these diseases include: hemolytic anemia, where red blood cells are lysed and iron from the hemoglobin is released; hemochromatosis, a genetic disease in which excess iron is stored in the body; and liver diseases such as hepatitis and alcohol-related liver damage, which destroy the liver and decrease the amount of transferrin synthesised.
Other proteins, such as complement (the body's immediate defense against invasion), are not produced in adequate amounts in severe liver disease.
Furthermore, ethanol increases stomach acid secretion, which increases iron absorption from the small intestine. This leads to a net increase in the amount of total iron present in the body.
Second, disorders that compromise the immune system will give V. vulnificus an advantage and allow for infection.
These diseases include HIV, cancer, diabetes (also a problem because peripheral nerve damage can allow a wound or infection to go unnoticed for days), and genetic immune disorders.
Mycobacterium sp.
A second "hobby-associated infection" is caused by the bacterium Mycobacterium marinum.
Unlike Vibrio species, M. marinum infections are very insidious.
For example, in a Thailand study of 44 reported cases over 20 years, the average known disease duration prior to presentation was 2.5 years (range 1 month to 10 years).
In another study of 31 patients presenting at 33 Kaiser Permanente medical centers in Northern California over 7 years, the average known disease duration prior to presentation was 2 months (range 2 days to 3.5 years).
In the Thailand study, 12 patients (66.7%) had hobbies or occupations associated with fish and water exposure.
The second study reported 16 patients (52%) who had potential exposure through fish tanks.
Hence, this disease is intimately connected to water contact and the aquarium hobby.
This has lead to several names, including "swimming pool granuloma" and "fish tank granuloma."
M. marinum is a slow growing acid-fast bacterium that is closely related to M. tuberculosis, the causative agent of tuberculosis.
Thus, a percentage of M. marinum infected individuals will also have a cross-reacting positive tuberculin skin test.
Unlike most other mycobacteria, M. marinum grows best at 32oC.
Hence, even in extremely rare disseminated infections, lesions are predominantly on the cooler extremities.
Normally, the bacteria enter through sites of minor trauma, with the site of infection often on the fingers, hands, or arms.
Since the onset is insidious, the incubation period is not known and has been estimated to be 2-4 weeks.
Most cases evolve into a single granuloma.
Granulomas are lesions composed of special immune cells that form a wall around infected tissue.
This is done because the immune system has trouble killing the bacteria.
It tries to surround and contain the bacteria, so that they cannot spread beyond the immediate area.
Also, the immune cells in a granuloma are activated and produce strong bactericidal agents, facilitating the containment and eradication process.
Most frequently, the infected site is red with some swelling.
Granulomas will appear as elevated papules or lumps.
Sometimes the granulomas crust or ulcerate.
Bacteria can spread along the lymphatic drainage system, producing multiple granulomas and lesions.
This most often occurs 4-8 weeks following the formation of the primary lesion (range 5 days to 1.5 years).
Unlike Vibrio and other more aggressive infections, M. marinum infections are painless.
Superficial infections respond to antibiotic therapy, and involution of the lesions usually begins within 2 weeks of the initiation of therapy.
Treatment is often several months long, and the infected area will heal with a scar.
Multiple drug therapy is recommended since the bacteria can develop resistance during the long treatment period.
Deep infections can occur following more severe trauma, including bite wounds.
This type of infection often requires a combination of surgery and antibiotics.
Disseminated M. marinum infections have been reported rarely in immuno-compromised individuals.
This infection will present with numerous small papules covering the head and extremities but sparing the trunk.
Except for the distribution, this disease will resemble chicken pox.
Bone and joint involvement will also occur in these extremely rare disseminated cases.
Infection Prevention
Several steps can be taken to limit or prevent infection and disease caused by bacteria from an aquarium.
First, try to avoid allowing traumatized areas from coming in contact with aquarium water.
If possible, use the other arm or wear a long latex glove.
All cuts and scrapes should be immediately washed with soap following contact with aquarium water.
Use topical antibiotics such as neosporin.
Do not let bowls or containers that come in contact with aquarium water/inhabitants be used for eating or drinking purposes.
Vibrio septicemia is caused when the bacteria enter the circulation from the gastrointestinal system.
Theoretically, contamination of food could cause infection.
Do not dump aquarium water in sinks or bathtubs.
A case of disseminated M. marinum has been reported in an infant that occurred from bathing in the same bathtub used for tank water disposal.
Additionally, use antibiotics in your aquariums with caution.
Exposure to antibiotics will lead to selection of resistant strains of bacteria, especially when these medications are not used properly (which is usually the case).
For example, most aquarium freshwater bacteria are resistant to tetracycline because of its misuse by aquarists.
Because these bacteria can cause infection and severe illness in humans, it is dangerous to expose them to substandard antibiotic therapy and risk selecting resistant strains.
Finally, look for warning signs -- pain, redness, tenderness, a wound that is getting worse instead of healing, and red streaks spreading centrally from the wound towards the body.
These are indications of infection, with the last two indicating the definite need for medical intervention.
In short, simple steps can largely prevent aquarium-related infections and diseases.
Conclusion
In conclusion, over the ages reef inhabitants have evolved exquisite devices to aid in hunting, protection, and to allow them to gain an advantage in their fierce and competitive world.
To the human eye, these same designs are beautiful works of nature's art.
Unfortunately, these same adaptations can cause the aquarist much aggravation if proper precautions are not taken to guard from accidental injury.
But then, everything has a price, right?
This article has attempted to provide the reader with a solid introduction into the "dark side" of tropical reefs, and it must be remember that it is by no means complete.
Other, probably more immediate threats include many of the chemicals that are added to tanks, and the electricity that powers the artificial reef.
When in doubt the aquarist should always search out more detailed information; it is the unknown threat that is always most dangerous.
Yet, probably the single most important thing aquarists can do to avoid injury is to use common sense.
With a solid background, proper planning, common sense, and a little luck, one can experience many years of trouble-free fish keeping.
This is the case for most aquarists.
Special thanks to Tom Heo for taking the time to edit this article.
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