Lonomia obliqua | |
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Lonomia obliqua larva | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Lepidoptera |
Family: | Saturniidae |
Genus: | Lonomia |
Species: | L. obliqua |
Binomial name | |
Lonomia obliqua Walker, 1855 | |
Lonomia obliqua is a species of saturniid moth ("giant silk moth") from South America. [1] It is famous for its larval form, rather than the adult moth, primarily because of the caterpillar's defense mechanism, urticating bristles that inject a potentially deadly venom. The caterpillar has been responsible for many human deaths, especially in southern Brazil. Its venom has been the subject of numerous medical studies. [2] The species was first described by Francis Walker in 1855. Guinness World Records classified Lonomia obliqua as the most venomous caterpillar in the world. [3]
These caterpillars are about 4.5 to 5.5 centimeters (about 2 in) long, with background colors ranging from green to brown. Well camouflaged, they have rows of tubercles crowned with whorls of easily detachable spines of different sizes. [4]
Caterpillars of many species can cause irritation by their hollow body hairs that envenom or detach easily, or can be poisonous if ingested; [5] . Prior to investigations into Lonomia caterpillars, it was not known that caterpillars could produce toxins in sufficient quantities to kill a human. Lonomia obliqua is found in the south of Brazil in the states of Rio Grande do Sul, Santa Catarina, and Paraná. The species appears to be spreading to the southeast of Brazil, and recent accidents with the species were reported in the states of São Paulo, Rio de Janeiro, and Minas Gerais. L. obliqua is also found in Uruguay, Paraguay, and Argentina.
The species became internationally known when an epidemic occurred in an agrarian community in Rio Grande do Sul. Hematoma and gangrene-like symptoms manifested, spreading throughout the body, eventually causing massive blood leakage into the brain and, in several cases, death. At first the cause could not be determined, although each victim stated they had "just handled a bunch of leafy branches to break the trail or gather vegetation." Exploring the area, the only creature commonly found within all the incidents was the L. obliqua caterpillar. Its hair growth covers its body, and each clump of spines is able to easily puncture the skin and release toxins into the victim. [6]
Lonomia obliqua has a toxic venom which causes disseminated intravascular coagulation and a consumptive coagulopathy, which can lead to a hemorrhagic syndrome. The toxins are stored in sacs at the base of each spine. As the spines penetrate the victim, venom flows through the hollow bristles and into the puncture wound. [7]
It was discovered that the toxin in the caterpillar's skin held potent anti-clotting agents. This anti-clotting agent would attach to another protein of the body's cells and cause them to leak as blood is unable to clot. This internal bleeding would fill the surrounding tissue with "bruised blood". This internal bleeding spreads through the internal organs and eventually leads to compression and brain death. This accounts for the minimum of 500 deaths resulting from contact with L. obliqua caterpillars.
Of the 26 species of the genus Lonomia found on the American continent, only Lonomia obliqua and Lonomia achelous have caused severe reactions, leading to hemorrhagic syndrome. Since 1989 the number of human accidents caused by these caterpillars has been increasing in the southern region of Brazil. Most victims were male (63%), many were between 0 and 19 years old (45%), and lesions are especially common on the hands (38%). The reported death rate is 2.5%. [7]
During the venom extraction, after removal of all spicules, each caterpillar produces approximately 2.4 mg of venom, the total amount of venom injected in an individual weighing 70kg can reach up to 1.4 - 1.7 mg/kg. [8]
Disseminated intravascular coagulation occurs as the toxin interacts with the victim's body. One serious effect on envenomed victims is hemorrhage syndrome. "First described by Arocha-Pinango and Layrisse in Venezuela in 1967, the hemorrhagic diathesis caused in humans by touching the Lonomia species begins with inflammatory changes at the site of envenoming, followed by systemic symptoms such as headache, fever, vomiting, and malaise. After 24 hours, a severe bleeding disorder ensues, leading to ecchymosis, hematuria, pulmonary, and intracranial hemorrhages, and acute kidney injury." [9]
Although few cases are recorded, a case study of a fatal encounter was published in Arquivos de Neuro-Psiquiatria: "A 70-year-old, previously healthy woman developed a sudden coma. Four days before, she had started to present hematuria. Shortly after admission, her coma was rated as Glasgow 3. Physical examination revealed several skin hemorrhages, and gross hematuria was present. Based on information in a note left by the patient, two small hyperemic lesions were identified on the tip of her left toe. Along with the note was the green caterpillar which was hidden inside of her slipper. CT-scan imaging revealed multiple intracerebral hemorrhages. She died seven days after being envenomed." [9]
In another case, internal bleeding spread throughout the lower body. While this victim did not die, prompt medical attention was necessary.[ citation needed ]
While there are many reported cases of serious injuries and fatalities, there are not many records of proper treatment should an individual be stung. According to Dr. Robert Norris, stings and abrasions caused by Lonomia obliqua should be treated with antifibrinolytics. If blood products are required, they must be given cautiously to avoid fueling the constant consumptive coagulopathy. An antiserum is produced by the Butantan Institute in São Paulo, Brazil. It effectively reverses the coagulation disorders induced by Lonomia obliqua venom, and patients treated with this antiserum recover rapidly. [7] [10]
L. obliqua caterpillar toxin has been the subject of numerous studies to determine its medical value. In particular the component called "Lopap" (L. obliqua prothrombin activator protease) has exhibited anticoagulant and anti-apoptotic qualities. [11] [12]
Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved venom apparatus, such as fangs or a stinger, in a process called envenomation. Venom is often distinguished from poison, which is a toxin that is passively delivered by being ingested, inhaled, or absorbed through the skin, and toxungen, which is actively transferred to the external surface of another animal via a physical delivery mechanism.
Caterpillars are the larval stage of members of the order Lepidoptera.
Bleeding, hemorrhage, haemorrhage or blood loss is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vagina or anus, or through a puncture in the skin. Hypovolemia is a massive decrease in blood volume, and death by excessive loss of blood is referred to as exsanguination. Typically, a healthy person can endure a loss of 10–15% of the total blood volume without serious medical difficulties. The stopping or controlling of bleeding is called hemostasis and is an important part of both first aid and surgery.
Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The process of coagulation involves activation, adhesion and aggregation of platelets, as well as deposition and maturation of fibrin.
Disseminated intravascular coagulation (DIC) is a condition in which blood clots form throughout the body, blocking small blood vessels. Symptoms may include chest pain, shortness of breath, leg pain, problems speaking, or problems moving parts of the body. As clotting factors and platelets are used up, bleeding may occur. This may include blood in the urine, blood in the stool, or bleeding into the skin. Complications may include organ failure.
A snakebite is an injury caused by the bite of a snake, especially a venomous snake. A common sign of a bite from a venomous snake is the presence of two puncture wounds from the animal's fangs. Sometimes venom injection from the bite may occur. This may result in redness, swelling, and severe pain at the area, which may take up to an hour to appear. Vomiting, blurred vision, tingling of the limbs, and sweating may result. Most bites are on the hands, arms, or legs. Fear following a bite is common with symptoms of a racing heart and feeling faint. The venom may cause bleeding, kidney failure, a severe allergic reaction, tissue death around the bite, or breathing problems. Bites may result in the loss of a limb or other chronic problems or even death.
In medicine (hematology), bleeding diathesis is an unusual susceptibility to bleed (hemorrhage) mostly due to hypocoagulability, in turn caused by a coagulopathy. Therefore, this may result in the reduction of platelets being produced and leads to excessive bleeding. Several types of coagulopathy are distinguished, ranging from mild to lethal. Coagulopathy can be caused by thinning of the skin, such that the skin is weakened and is bruised easily and frequently without any trauma or injury to the body. Also, coagulopathy can be contributed by impaired wound healing or impaired clot formation.
Urticating hairs or urticating bristles are one of the primary defense mechanisms used by numerous plants, almost all New World tarantulas, and various lepidopteran caterpillars. Urtica is Latin for "nettle", and bristles that urticate are characteristic of this type of plant, and many other plants in several families. This term also refers to certain types of barbed bristles that cover the dorsal and posterior surface of a tarantula's or caterpillar's abdomen. Many tarantula species eject bristles from their abdomens, directing them toward potential attackers. These bristles can embed themselves in the other animal's skin or eyes, causing physical irritation, usually to great discomfort. The term "hairs" is technically a misnomer, as only mammals possess true hairs. The scientific term for plant hairs is trichomes.
Snake venom is a highly toxic saliva containing zootoxins that facilitates in the immobilization and digestion of prey. This also provides defense against threats. Snake venom is usually injected by unique fangs during a bite, though some species are also able to spit venom.
Convulxin is a snake venom toxin found in a tropical rattlesnake known as Crotalus durissus terrificus. It belongs to the family of hemotoxins, which destroy red blood cells or, as is the case with convulxin, induce blood coagulation.
The genus Lonomia is a moderate-sized group of fairly cryptic saturniid moths from South America, famous not for the adults, but for their highly venomous caterpillars, which are responsible for a few deaths each year, especially in southern Brazil, and the subject of hundreds of published medical studies. They are commonly known as giant silkworm moth, a name also used for a wide range of other saturniid moths.
Loxoscelism is a condition occasionally produced by the bite of the recluse spiders. The area becomes dusky and a shallow open sore forms as the skin around the bite dies (necrosis). It is the only proven type of necrotic arachnidism in humans. While there is no known therapy effective for loxoscelism, there has been research on antibiotics, surgical timing, hyperbaric oxygen, potential antivenoms and vaccines. Because of the number of diseases that may mimic loxoscelism, it is frequently misdiagnosed by physicians.
Venom-induced consumption coagulopathy (VICC) is a medical condition caused by the effects of some snake and caterpillar venoms on the blood. Important coagulation factors are activated by the specific serine proteases in the venom and as they become exhausted, coagulopathy develops. Symptoms are consistent with uncontrolled bleeding. Diagnosis is made using blood tests that assess clotting ability along with recent history of envenomation. Treatment generally involves pressure dressing, confirmatory blood testing, and antivenom administration.
The pathophysiology of a spider bite is due to the effect of its venom. A spider envenomation occurs whenever a spider injects venom into the skin. Not all spider bites inject venom – a dry bite, and the amount of venom injected can vary based on the type of spider and the circumstances of the encounter. The mechanical injury from a spider bite is not a serious concern for humans. Some spider bites do leave a large enough wound that infection may be a concern. However, it is generally the toxicity of spider venom that poses the most risk to human beings; several spiders are known to have venom that can cause injury to humans in the amounts that a spider will typically inject when biting.
The whole blood clotting test is a blood test used to check the coagulation mechanism in the blood following a snake bite. If the test is positive after a bite in South East Asia it indicates the snake was a viper rather than an elapid. It can also be used to assess the effectiveness of antivenin therapy.
Snakebite envenomation is considered a public health problem in Latin America, with an estimated 70,000 cases annually, but due to underreporting, these numbers may be even higher.
Lonomia achelous, the Brazilian caterpillar or giant silkworm moth caterpillar, is a venomous caterpillar endemic to South America. The species was first described by Pieter Cramer in 1777.
List of reported attacks and species involved in Latin America.
Phalotris lemniscatus is a species of venomous snake found in South America. It's usually known as Pampeana black headed snake or Duméril's diadem snake.