Lonomia obliqua

Lonomia obliqua
Lonomia sp. in Costa Rica (not L. obliqua, but similar)
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Lepidoptera
Family:	Saturniidae
Subfamily:	Hemileucinae
Genus:	Lonomia
Species:	L. obliqua
Binomial name
Lonomia obliqua Walker, 1855

Lonomia obliqua (or Giant Silkworm Moth, a name also used for a wide range of other Saturniid moths) is a species of Saturniid moths from South America. Its famous for its larvae form, rather than the adult moth, for several reasons. Recently announced in an episode of the Discovery Channel, known as the “assassin caterpillar,” this caterpillar has a spine covered back filled with venom, and has been responsible for several deaths, especially in southern Brazil. This caterpillar has also been in numerous medical studies.

Description

These caterpillars are about 4.5 -5.5 cm (about 2 in.) in length, 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.

Discovery

It has been known for a while that many caterpillars cause irritation by discharging body hairs, or can be poisonous if ever ingested. However, until Lonomia was discovered it was not known that caterpillars can produce enough toxins to kill a human being. 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. Lonomia obliqua is also found in Uruguay, Paraguay and Argentina. It first became internationally known when an epidemic occurred in an agrarian community in Rio Grande du Sol, Brazil. Doctors were mystified when scores of patients came in with the same symptoms. The symptoms shown were haematoma and gangrene-like symptoms, 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 Lonomia Caterpillar. With its hair growth covering its body, each clump of spines is able to easily puncture the skin and release toxins into the victim.

Toxicity

As an article by Antonio Pinto stated, the Lonomia obliqua has a very unique venom that causes disseminated intravascular coagulation and a consumptive coagulopathy, which can lead to a hemorrhagic syndrome. It was soon discovered that at the base of each spine was a sack where the toxins were stored. As the stems and needles were stuck into the victim, venom would flow through the hollow needles and into the puncture wound.

It was also discovered that the toxin in this creatures skin held one of the strongest anti-clotting agents ever found in nature. This anti-clotting agent would attach with another protein to 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 as a result of contact with Lonomia. Interestingly enough, the poison only takes effect in large amounts. In order to feel the extreme injuries caused by this creature, the victim would need at least 20 to 100 hundred stings.

The genus Lonomia includes 26 species found on the American Continent. However, only Lonomia obliqua and Lonomia achelous have caused severe accidents, 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%. 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.

Effects of venom

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 19671, 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 echimosis, hematuria, pulmonary and intracranial hemorrhages, and acute renal failure.”

Case studies

Although few cases are recorded, this is an example of a fatal encounter with this deadly caterpillar. “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.” In another case, the internal bleeding spread throughout their lower body. While they did not die, the still had to receive medical attention quickly. One victim shares, “My name is Marianne: I am still interested in publications about the Lonomia obliqua caterpillars that are found in Brazil and some other South American countries. Three years ago I was a victim of this caterpillar poisoning, ending up with haemolysis and acute kidney injury while in Brazil, after visiting Iguassu Falls. I accidentally touched a tree with my left hand and this resulted in a painful rash and swelling thereafter. I took a photograph for identification in case I had contracted something unfamiliar. It took another 3 days before I requested medical attention as the initial symptoms had cleared after a few hours. Luck was on my side as I attended a medical conference and my local medical colleagues saved my life as they were able to contact the local public health office who then arranged for the antivenin to be delivered to the hospital I was admitted to obtain urgent medical advice.”

Treatment

While there are many reported cases of serious injuries, if not fatal, there are not many records of proper treatment should an individual be stung. Before one is able to reach professional medical care there are certain steps that can help insure a healthy recovery. It is important to clean the wound with soap and water, as well as apply a sticky adhesive to help remove the small hairs. Duct tape works well in this situation. According to Dr. Robert Norris, stings and abrasions cause by Lonomia obliqua should be treated with antifibrinolytics. If blood products are required, they must be given cautiously to aviod feeding fuel to the constant consumptive coagulapathy. There is an anti-venom produced against this particular species in Brazil.

Medical applications

The threat and danger of Lonomia obliqua’s toxin is also intriguing. The qualities of this poison that allow it to prevent blood from clotting inside the body also have promising medical value. In several studies with rats and rabbits, the venom from these caterpillars has proven the anticoagulant qualities of the venom to be promising in medical circumstances, preventing unwanted blood clots and saving lives.