Six New Cases of a Caterpillar-Induced Bleeding Syndrome

Deadly and venomous Lonomia caterpillars are more than the two usual suspects

Caterpillars of the Neotropical genus Lonomia (Lepidoptera: Saturniidae) are responsible for some fatal envenomation of humans in South America inducing hemostatic disturbances in patients upon skin contact with the caterpillars' spines. Currently, only two species have been reported to cause hemorrhagic syndromes in humans: Lonomia achelous and Lonomia obliqua. However, species identifications have remained largely unchallenged despite improved knowledge of venom diversity and growing evidence that the taxonomy used over past decades misrepresents and underestimates species diversity. Here, we revisit the taxonomic diversity and distribution of Lonomia species using the most extensive dataset assembled to date, combining DNA barcodes, morphological comparisons, and geographical information. Considering new evidence for seven undescribed species as well as three newly proposed nomenclatural changes, our integrative approach leads to the recognition of 60 species, of which seven are known or strongly suspected to cause severe envenomation in humans. From a newly compiled synthesis of epidemiological data, we also examine the consequences of our results for understanding Lonomia envenomation risks and call for further investigations of other species' venom activities. This is required and necessary to improve alertness in areas at risk, and to define adequate treatment strategies for envenomed patients, including performing species identification and assessing the efficacy of anti-Lonomia serums against a broader diversity of species.

Epidemiological characterization of lonomism in South America

Lonomism is the envenomation caused by accidental contact with Lonomia caterpillars, and this is a public health priority in South America since it is relatively common but remains underestimated. This study presents an updated and integrative analysis of reliable global data from 1960 to 2020 on the epidemiology of this envenomation in the whole continent. A total of 13,186 notifications were recorded for South America: 13,056 (99.01%) in Brazil, 49 (0.37%) in Argentina, 43 (0.33%) in Colombia, 29 (0.22%) in Venezuela, 6 (0.05%) in Peru and 3 (0.02%) in French Guiana. The number of new locations reporting accidents has increased since the first formally notifications at the middle of the last century. Most of these locations are situated in Brazil, the pioneer in deeply researching the Lonomia genus and its impacts in public health. Most victims were males, in the economically productive age group, and accidental contact occurred more frequently in the upper limbs while doing activities outdoors in urban/rural areas. Regarding the determinants of clinical outcome, countries where patients received delayed medical care were associated with a higher number of moderate and/or severe cases, as well as a higher chance of progressing to death. Additionally, the longer the delay for accessing medical care, the higher the risk of developing systemic complications, thereby increasing the need for specific treatment. Our study also shows that accidents globally occurred more frequently in the summer months and in the beginning of autumn. Although having identified several shortcomings in the documents selected and verified that notifications are strongly biased by public policies adopted by each South American country, this study provides the first comprehensive assessment of lonomism in South America, demonstrating the increase in the number of accidents, and their expansion to other areas of the continent over time. Our findings will undoubtedly help guide the appropriate allocation of resources and implementation of prevention strategies and define priority criteria for epidemiological surveillance of this neglected tropical disease.

Lonomia obliqua Envenoming and Innovative Research

As a tribute to Butantan Institute in its 120th anniversary, this review describes some of the scientific research efforts carried out in the study of Lonomia envenoming in Brazil, a country where accidents with caterpillars reach over 42,000 individuals per year (especially in South and Southeast Brazil). Thus, the promising data regarding the studies with Lonomia’s toxins contributed to the creation of new research centers specialized in toxinology based at Butantan Institute, as well as to the production of the antilonomic serum (ALS), actions which are in line with the Butantan Institute mission “to research, develop, manufacture, and provide products and services for the health of the population”. In addition, the study of the components of the Lonomia obliqua bristle extract led to the discovery of new molecules with peculiar properties, opening a field of knowledge that could lead to the development and innovation of new drugs aimed at cell regeneration and inflammatory diseases.

Lonomia obliqua Venom Induces NF-κB Activation and a Pro-Inflammatory Profile in THP-1-Derived Macrophage

Envenomation caused by contact with Lonomia obliqua bristles is characterized by pain, an intense systemic proinflammatory reaction and disturbances in the coagulation cascade that can cause severe clinical manifestations and death. However, the role of immune system components in these effects is still poorly understood. In this study, we evaluated the cytotoxic effect of L. obliqua venom on THP-1-derived macrophages and its ability to modulate inflammatory markers, as well as the cytokine and chemokine release profile. Our results show that L. obliqua venom is able to directly exert a potent pro-inflammatory reaction in macrophages, characterized by the activation of the NF-κB transcription factor pathway, the expression of CD80 and CD83, and the release of pro-inflammatory mediators such as TNF-α, IL-1β, IL-6, IL-8 and CXCL10. These results suggest that macrophages can play an important role during the orchestration of the inflammatory response present in envenomation caused by Lonomia obliqua caterpillars.

Venomous caterpillars: From inoculation apparatus to venom composition and envenomation

Envenomation by the larval or pupal stages of moths occurs when the victim presses their hairs. They penetrate the subcutaneous tissue, releasing toxins such as proteolytic enzymes, histamine and other pro-inflammatory substances. Cutaneous reactions, including severe pain, oedema and erythema are frequent local manifestations of caterpillar envenomation, but, in some cases, the reactions can evolve into vesicles, bullae, erosions, petechiae, superficial skin necrosis and ulcerations. Alternatively, some individual can develop allergic reactions, renal failure, osteochondritis, deformity and immobilization of the affected joints and intracerebral bleeding. Caterpillars produce venom to protect themselves from predators; contact with humans is accidental and deserves close attention. Their venoms have not been well studied, except for toxins from some few species. The present review brings together data on venomous caterpillars of moths, primarily addressing the available literature on diversity among the different families that cause accident in humans, the structures used in their defense, venom composition and clinical aspects of the envenomations. Understanding the molecular mechanisms of action of caterpillars' toxins may lead to the development of more adequate treatments.

Lonomia caterpillar envenoming in French Guiana reversed by the Brazilian antivenom: A successful case of international cooperation for a rare but deadly tropical hazard

In the American continent, larval forms (caterpillars) of the Lonomia genus can cause systemic reactions in human beings. In this Paper, we report the third case of Lonomia envenoming recorded in French Guiana in 25 years, and the first in which specific antivenom was administered. Severe symptoms of the envenoming were observed in our patient including pain; coagulopathy and systemic hemorrhage. They are caused by skin contact with caterpillars. Recovery, however, was quite satisfactory thanks to the international cooperation of the health authorities in both France and Brazil.

Hemostatic disorders induced by skin contact with Lonomia obliqua (Lepidoptera, Saturniidae) caterpillars

Patients envenomed by Lonomia sp caterpillars initially experience a mild burning pain, headache, nausea, vomiting, and skin and mucosal hemorrhages. Some patients can rapidly progress to a severe coagulopathy that presents as visceral or intracerebral hemorrhaging. We studied the hemostatic alterations that occurred in 14 patients who were envenomed by Lonomia obliqua in Southern Brazil and presented at the Hospital São Vicente de Paulo (Passo Fundo, RS), Brazil during the summers of 1993 and 1994 when Lonomia antivenom was not yet available for treatment. The patients were classified into to 4 clinical groups: 0 (two patients), I (eight patients), II (two patients), and III (two patients). The patients were admitted to the hospital between 4 hours and five days after contact with the caterpillars. In this study, the coagulation parameters of the patients were followed up for up to 172 hours after the accidents. The patients received no treatment with the exceptions of two patients who received blood transfusions and antifibrinolytic treatment. The observed abnormalities related to blood coagulation and fibrinolytic factors were similar regardless of the severity of the bleeding symptoms. These findings suggest that alterations in hemostatic parameters without thrombocytopenia are not predictors of the seriousness of such accidents. Thus, consumptive disorder and reactive fibrinolysis are not proportional to mild coagulopathy. Furthermore, these patients recovered. The hemostatic parameters of most of the patients normalized between 96 and 120 h after the accident.

Lonomia obliqua Walker (Lepidoptera: Saturniidae): hemostasis implications

Summary In southern Brazil, since 1989, several cases of accidents produced by unwilling contact with the body of poisonous caterpillars of the moth species Lonomia obliqua Walker, 1855 (Lepidoptera: Saturniidae), were described. L. obliqua caterpillars have gregarious behavior and feed on leaves of host trees during the night, staying grouped in the trunk during the day, which favors the occurrence of accidents with the species. This caterpillar has the body covered with bristles that on contact with the skin of individuals, breaks and release their contents, inoculating the venom into the victim. The basic constitution of the venom is protein and its components produce physiological changes in the victim, which include disturbances in hemostasis. Hemorrhagic syndrome associated with consumption coagulopathy, intravascular hemolysis and acute renal failure are some of the possible clinical manifestations related to poisoning by L. obliqua. Specific laboratory tests for diagnosis of poisoning have not been described previously. The diagnosis of poisoning is made based on the patient's medical history, clinical manifestations, erythrocyte levels, and, primarily, parameters that evaluate blood coagulation. Treatment is performed with the use of supportive care and the administration of specific hyperimmune antivenom. Poisoning can be serious and even fatal.

A mouse model to study the alterations in haemostatic and inflammatory parameters induced by Lonomia achelous caterpillar haemolymph

A mouse model was established to reproduce the haemorrhagic syndrome which occurs in humans after accidental contact with the hairs of the caterpillar Lonomia achelous (LA) and measures the haemostatic and inflammatory alterations that occur as a result of this contact. Mice were injected intradermally with different doses (0.4, 0.8 and 1.6 mg/animal) of L. achelous haemolymph (LAH). Haematological (haemoglobin, haematocrit, platelet count, differential leukocyte count), haemostatic (fibrinogen, plasminogen, factor XIII [FXIII], fibrinolytic activity) and inflammatory parameters (tumour necrosis factor alpha [TNF-α], nitric oxide [NO]) were measured at different times up to 48 h. C57BL/6 mice responded to LAH injection, in terms of these parameters, in a manner similar to that seen in humans, whereas the BALB/c mice were unresponsive. In C57BL/6 mice injected with LAH, time course measurements showed: a) a reduction in the haemoglobin, haematocrit, fibrinogen, FXIII and plasminogen levels, b) no effect on the platelet count and c) immediate leukocytosis and an increase in the fibrinolytic activity in plasma. An inflammatory response (TNF-α) was observed within 1 h post-injection, followed by a more persistent increase in serum NO. These findings suggest that C57BL/6 mice represent a useful model of the haemorrhagic syndrome observed in humans who have suffered contact with the caterpillar, permitting a deeper understanding of the role of the inflammatory response in the haematological and haemostatic manifestations of this syndrome.

Lonomia obliqua venom: In vivo effects and molecular aspects associated with the hemorrhagic syndrome

Caterpillar envenomation has been an emergent health issue. Lonomia obliqua is a medically important animal that causes a hemorrhagic syndrome that can progress to acute renal failure, intracranial hemorrhage and death. In the past few years the molecular characterization of L. obliqua venom in addition to experimental models has provided fundamental information to the understanding of the envenomation syndrome. Herein studies from several authors which characterized the complex toxic-pharmacological actions of whole venom are reviewed.

The action of Lonomin V (Lonomia achelous) on fibronectin functional properties

Lonomia achelous caterpillar, Lepidoptera distributed along some South American countries, induces a hemorrhagic syndrome in people who come into contact with its bristles. A clinical characteristic in these patients is that fresh healed wounds are re-opened and bleed. In order to explain this symptomatology, we evaluated the effect of Lonomin V (a protein isolated from L. achelous hemolymph), on some functional properties of fibronectin, which in turn plays an important role in the hemostasis. The effect of Lonomin V on fibronectin was studied by SDS-PAGE in reduced condition, binding to gelatin and heparin, crosslinking to fibrin and platelet adhesion. Formation of degradation products of 120, 66, 50, 40 and 29 kDa, some of which retain affinity to heparin and gelatin were observed; however, the fibronectin degradation fragments presented a significant decrease of crosslinking capacity to fibrin and platelet adhesion, suggesting that the proteolysis of fibronectin by Lonomin V induces changes in its crosslinking sites and on platelet receptors. These findings might partially explain the wound dehiscence observed in the patients. Due to its effect on adhesive proteins with concomitant impairment of some functional properties, Lonomin V might be useful for cellular adhesion studies involved in hemostasis such as platelet adhesion.

Efficacy of serum therapy on the treatment of rats experimentally envenomed by bristle extract of the caterpillar Lonomia obliqua: Comparison with epsilon-aminocaproic acid therapy

Large number of accidents caused by contact with Lonomia obliqua caterpillars, with hemorrhagic complications, have occurred in southern Brazil. Based on Venezuelan expertise to treat Lonomia achelous envenomation, the use of the antifibrinolytic drug epsilon-aminocaproic acid (EACA) has been indicated to treat L. obliqua envenomation, although no evidence has been presented to justify its use. Specific antivenom (antilonomic serum (ALS)) that neutralizes toxins that cause envenomation was developed. To compare the effectiveness of such treatments, rats were injected i.d. with the bristle extract of L. obliqua caterpillars and treated 15 min, 1 and 6 h after with saline, ALS, EACA, or with both ALS and EACA. ALS elicited fibrinogen recovery and normalization of thrombin time (TT), prothrombin time (PT) and activated partial thromboplastin time (APTT), independent of when it was administered; however, hematocrit was decreased in the group treated later. Saline or EACA-treated groups presented neither fibrinogen recovery nor normalization of hemostatic parameters. A high death rate was observed in the group treated with EACA 15 min after the envenomation. Prolongation of TT and APTT observed in the group treated with EACA and ALS indicated that this association gave no benefit in relation to the group treated solely with ALS. The results presented herein suggest that ALS is the only effective treatment for envenomation caused by contact with Lonomia obliqua caterpillars and indicate that EACA should not be administered in the initial phase of envenomation.

The venom of the Lonomia caterpillar: an overview

Contact with the Lonomia caterpillar causes numerous accidents, especially in Venezuela and the southern region of Brazil, where it is considered a public health problem. The Lonomia obliqua venom causes disseminated intravascular coagulation and a consumptive coagulopathy, which can lead to a hemorrhagic syndrome. The venom of Lonomia achelous also causes hemorrhage, but through increased fibrinolysis. In vivo and in vitro studies have shown that the venom of the Lonomia caterpillar contains several toxins with procoagulant, anticoagulant and antithrombotic activities. These toxins also affect the endothelium. The recent construction of cDNA libraries of the transcripts from L. obliqua bristles enables the use of biotechnological approaches to study the venom. This paper presents an overview of the biochemical and biological properties of Lonomia caterpillar venom, discussing aspects of human accidents, experimental envenomation, toxins and targets and future perspectives.

Degradation of extracellular matrix proteins (fibronectin, vitronectin and laminin) by serine-proteinases isolated from Lonomia achelous caterpillar hemolymph

Lonomia achelous is a caterpillar distributed in southern Venezuela and in northern Brazil that causes an acute hemorrhagic syndrome in people who have contact with its bristles. The effect of the crude hemolymph and its chromatographic fractions (FDII, Lonomin V and Lonomin V-2) on extracellular matrix proteins was studied. The chromatographic fractions show activities similar to plasmin and urokinase. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, both lonomins appear as a protein band of 25 kDa under reduced conditions. By exclusion chromatography, the molecular weights of Lonomin V and Lonomin V-2 were 26.5 and 24.5 kDa, respectively. Fibronectin, laminin and vitronectin were degraded by all venom components. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, under reduced conditions, shows that lonomins degrade fibronectin in four main fragments of 116, 60, 50 and 30 kDa. Molecular exclusion chromatography in native conditions shows that the molecular masses of these fragments are > or = 300, 62 and 27 kDa. The proteolytic effect of lonomins was abolished by benzamidine/HCl, iodoacetic acid and aprotinin. The extracellular matrix protein degradation together with the fibrino(geno)lytic activity of hemolymph and its fractions could explain, in part, the hemorrhagic syndrome, and the wound dehiscence in persons who have had contact with the L. achelous caterpillar.

Proteases from Lonomia obliqua venomous secretions: comparison of procoagulant, fibrin(ogen)olytic and amidolytic activities

The hemorrhagic syndrome caused by Lonomia obliqua caterpillars is an increasing problem in Southern Brazil. The clinical profile is characterized by both hemorrhagic and pro-coagulant symptoms, constituting a paradoxical action of the venom. The effects upon blood coagulation and fibrin(ogen)olysis have been shown to result from the combined action of several active principles found mostly in the bristle extract. The present study reports quali-quantitative differences among L. obliqua secretions: Cryosecretion, hemolymph, bristle extract and tegument extract. Cryosecretion and hemolymph displayed strong amidolytic activity upon several substrates, presented moderated procoagulant activity and high fibrinogen degrading ability. Bristle and tegument extracts presented low amidolytic activity, but bristle extract showed the most potent procoagulant activity and both extracts presented low fibrinogen degrading ability. The differential involvement of these secretions during the accidents with L. obliqua can elucidate the different symptoms presented after envenomation.

Acute renal failure provoked by toxin from caterpillars of the species Lonomia obliqua

Acute renal failure (ARF) is a complication of envenoming by contact with caterpillars of the species Lonomia obliqua. A cohort study was conducted to evaluate development of acute and chronic renal failure (CRF) in patients who been in contact with L. obliqua during the period from 1989 to 2003 in the State of Santa Catarina, southern Brazil. Patients were evaluated in two distinct groups: those prior to 1995, who did not receive specific treatment of any type, and those after this date who were treated with antilonomic serum (SALon). The presence of creatinine > or = 1.5 mg/dl in patients who had no history of previous renal illness was considered to be indicative of acute kidney failure. Of the 2067 patients evaluated, 39 (1.9%) developed ARF. Eleven (32%) of these patients were treated with dialysis and four (10.3%) developed CRF. The seven deaths (4%) occurred in the period before treatment with SALon. Blood coagulation measures (TC, TP, and TTPA), were significantly longer in the group with ARF. All patients with ARF and 67% of the control group presented hematuria. The majority of the patients recovered prior renal function, however, four (10.3%) needed chronic dialysis. Envenoming by L. obliqua can be considered an important risk factor for the development of potentially fatal ARF, as well as for developing CRF.

Identification and partial characterisation of hyaluronidases in Lonomia obliqua venom

By studying Lonomia obliqua (caterpillar) venom we were able to detect a lytic activity on purified hyaluronic acid. The venom hydrolyses purified chondroitin sulphate, but was unable to degrade either heparan sulphate or dermatan sulphate. Moreover, through purified hyaluronic acid-degrading kinetic assays, we observed that this lytic activity was caused by a hydrolase rather than lyase enzyme. In addition, by using the Reissig colorimetric reaction, we detected this hyaluronic acid hydrolase action as a beta-endohexosaminidase enzyme originating terminal N-acetylglucosamine residues rather than beta-endoglucuronidase, which may originate glucuronic acid residues. Zymogram analysis of the venom detected 49 and 53 kDa molecules with hyaluronic acid lytic activity. An examination of these hyaluronic acid degrading activities as a function of pH showed that these hydrolases had no apparent activities at a pH below 5.0 and higher than 8.0 and displayed their optimal activities at pH ranging from 6.0 to 7.0. Finally, through a fluorescence reaction to hyaluronic acid and confocal microscopy, we confirmed this cleaving action upon hyaluronic acid organised on the extracellular matrix of the dermis of rabbit. The data provide experimental evidence of the presence of hyaluronidases in the L. obliqua venom, probably involved in the harmful effects of the venom.

Purification and initial characterization of a novel protein with factor Xa activity from Lonomia obliqua caterpillar spicules

A novel protein with factor Xa-like activity was isolated from Lonomia obliqua caterpillar spicules by gel filtration chromatography and reversed-phase high-performance liquid chromatography. The protein had a mass of 20745.7 Da, as determined by mass spectrometry, and contained four Cys residues. Enzymatic hydrolysis followed by de novo sequencing by tandem mass spectrometry was used to determine the primary structure of the protein and the cysteine residues linked by disulfide bridges. The positions of 24 sequenced tryptic peptides, including the N-terminal, were deduced by comparison with a homologous protein from the superfamily Bombycoidea. Approximately 90% of the primary structure of the active protein was determined.

Lonofibrase, a novel alpha-fibrinogenase from Lonomia obliqua caterpillars

Envenomation caused by Lonomia obliqua caterpillars is an increasing problem in Southern Brazil. The clinical profile is characterized by a profound hemorrhagic disorder. In the present study, we describe the characterization of a fibrin(ogen)olytic factor (lonofibrase) isolated from a venomous secretion of the caterpillars. The crude extract showed a dose-dependent inhibitory effect in the rate of thrombin-induced fibrinogen clotting and produced fragmentation of fibrinogen. Isolation of the fibrin(ogen)olytic enzyme was achieved by combining ion exchange chromatography followed by gel filtration in a fast protein liquid chromatography (FPLC) system. A single 35-kDa band was identified and the isolated enzyme named lonofibrase. Lonofibrase rapidly degrades Aalpha and Bbeta chains of fibrinogen, also being able to cleave fibrin in a distinct way from that observed with plasmin. The presence of lonofibrase with both fibrinogenolytic and fibrinolytic activities in L. obliqua secretion is coherent with the severe hemorrhagic clinical profile resulting from envenomation caused by these insects.

Lonomia obliqua caterpillar venom increases permeability of the blood-brain barrier in rats

Human envenoming by caterpillars of the saturniid moth Lonomia obliqua in southern Brazil produces a mild local response (erythema, some edema, and pain) and systemic effects that include incoagulable blood, renal failure and in severe accidents intracerebral hemorrhage. In this work, we used light and electron microscopy to investigate the morphological alterations in the brain and blood-brain barrier of rats injected intravenously with venom from L. obliqua spicules (200 microg/kg). Five semi-purified fractions of venom (200 microg/kg each) were also assayed. Quantitative morphological and ultrastructural analyses were done 6, 18, 24 and 72 h after the i.v. injection of venom and its fractions. Light microscopy showed that 6h after envenoming there was cerebellar edema, which decreased by 72 h. Intracerebral hemorrhage occurred in only one rat 24h after the injection of venom. Blood-brain barrier (BBB) breakdown, assessed by transmission electron microscopy based on the passage of an extracellular tracer (lanthanum nitrate) between brain capillary endothelial cells, was observed in the cerebellum and hippocampus 18 h after venom injection. At this time, the cerebellum was more sensitive to the venom than the hippocampus, as shown by the greater number of leaky vessels. The number of capillaries showing breakdown was lower after 72 h than after 18 h. None of the semi-purified fractions significantly increased the number of leaky vessels. These results indicate that L. obliqua caterpillar venom has a deleterious action on the rat BBB. The lack of effect of the venom fractions when administered alone suggested that a synergistic action of venom components may be responsible for the damage seen in the central nervous system, but this was not confirmed when three combinations of the fractions were tested.

Intravascular hemolysis induced by Lonomia obliqua caterpillar bristle extract: an experimental model of envenomation in rats

Hemostatic disturbances are frequent findings in human accidents caused by Lonomia obliqua caterpillars in the southern region of Brazil. In severe envenomation, patients may present life-threatening bleedings. Such disturbances may be mimicked in rats, which also develop intravascular hemolysis. The scope of this study was to investigate the time-course and intensity of intravascular hemolysis induced by i.d. injection of 750 microg/kg crude L. obliqua bristle extract in rats. Total blood cell count, reticulocyte count, plasma hemoglobin and haptoglobin assays were performed in control and envenomed rats at 1, 6, 24 and 48 h after envenomation. Rats presented a drastic drop of haptoglobin levels at 1 and 6h with increased plasma hemoglobin levels, a decrease in packed cell volume values at 6, 24 and 48 h, and increased reticulocyte counts throughout after envenomation. Such observations indicated that intravascular hemolysis occurred as early as 1h following envenomation, and lasted for more than 6h. Intravascular hemolysis is probably induced by phospholipase A(2) and other proteins with direct hemolytic activity present in crude caterpillar bristle extract.

Effects of Lonomia obliqua (lepidoptera, saturniidae) toxin on clotting, inflammatory and antibody responsiveness in genetically selected lines of mice

Lines of mice genetically selected for high (H) or low (L) antibody response and for maximal (AIRMAX) or minimal (AIRMIN) acute inflammatory reaction, in which the opposite extreme potentialities have been clearly defined, offer an appropriate model for investigating the environmental and genetic factors acting on innate and adaptative immunobiological functions. This model has been successfully employed to study the resistance or susceptibility against pathogens and/or toxins. It had been demonstrated that the skin contact with Lonomia obliqua caterpillar bristles induces local inflammation and may elicit severe hemorrhagic disorders. In the present study, blood coagulation time, and the acute inflammatory reaction were scored 24 h after injection of the Lonomia bristles crude extract in a subcutaneous dorsal air pouch. The acute inflammation was determined by the leukocyte concentration in the local exudates. The highest interline differences were observed between the AIRMAX (10(6) cells/ml) and AIRMIN (2 x 10(5) cells/ml) and this distinct expression involves the number of monocytes, eosinophils and mainly neutrophils. Regarding coagulation, the highest interline difference was observed between the HIII and LIII mice, and the F1)[LIII x HIII] hybrids showed the overdominance of the fast clotting character. The adaptative immune response was evaluated by comparing the anti-Lonomia bristle extract IgG titer among the lines: the antibody titers were higher in the H lines than in the L ones and equivalent in the AIRMAX and AIRMIN mice, in accordance to the phenotype profiles generated by the distinct selective processes. The genetically selected mice lines-AIRMAX, AIRMIN, HI, HIII, HG, LIII and LG-showed an almost continuous distributions for inflammation, coagulation time and IgG antibody titers, being the interline variances always higher than the intraline ones for the individually measured phenotypes. Altogether, these results suggest the independent polygenic regulation of these traits, being indicative of the genetic control to Lonomia toxin innate and adaptative sensitivity in humans.

Clinical effects of exposure to the White-stemmed gum moth (Chelepteryx collesi)

BACKGROUND

The White-stemmed gum moth (Chelepteryx collesi) can be found in eastern Australia. The clinical effects of injuries caused by its many spine-like hairs are poorly defined and concern about the numerous hairs that remain embedded following contact with the cocoon have led to heroic means of removal.

OBJECTIVE

To examine the clinical effects of injuries by the caterpillar or cocoon of the White-stemmed gum moth.

METHODS

Prospective observational study of caterpillar injuries from calls to the New South Wales Poisons Information Centre. Cases resulting from C. collesi exposure were included for analysis. Caterpillars and cocoons were expertly identified where available and a follow-up consultation of all patients was conducted. Information was collected on the circumstances of exposure, local and systemic effects and treatment.

RESULTS

From the 26 included cases, seven had confirmed caterpillar contact (all children aged 1-11), six had confirmed cocoon contact and 13 had exposures consistent with C. collesi, but no caterpillar was caught. All cases occurred in summer. Of 13 confirmed exposures there was no difference between caterpillars and cocoons, and these were considered together. Affected areas were hands, feet, or both, following C. collesi being handled or trodden on. Pain was reported in all 13 cases, one with severe pain. In 10 cases pain duration was < 60 min. Six subjects had more than 100 hairs embedded (small black dots). In three cases, the hairs were surrounded by swelling and yellow discolouration. Despite the attempted removal of multiple hairs, they remained embedded for prolonged periods but caused no sequelae.

CONCLUSION

The clinical effects of the White-stemmed gum moth were minor with local pain. Although hairs remained in all cases, they caused no problems. Complete removal of hairs is neither possible nor necessary, and painful and invasive methods should be avoided.

Prospective study of definite caterpillar exposures

Exposure to caterpillars results in a variety of clinical effects depending on the species involved. The aim of this study was to describe the clinical effects from caterpillar exposures within Australia. Cases were recruited prospectively from calls to a poison information centre. Subjects were included if they had a definite exposure and they had collected the caterpillar or cocoon. The caterpillars were identified to genus and species level where possible. There were 36 included cases: two were contact exposures to caterpillar contents, one was an ingestion of a caterpillar and the remaining 33 patients had definite reactions from caterpillar or cocoon exposure. There were five families of caterpillars identified in the study: Arctiidae, Limacodidae, Anthelidae, Lymantriidae and Sphingidae, many of which occur worldwide. Clinical effects ranged from severe pain to an urticarial response depending on the species involved. There were no adverse effects following ingestion in this study. Treatment consisted primarily of removal of the caterpillar or cocoon. Other treatment measures consisted of symptomatic treatment such as ice packs and antihistamines. This is the first prospective study of caterpillar exposures within Australia and demonstrates that exposures can result in a variety of reactions depending on the family and species involved.

Antivenom treatment in arachnidism

Envenomation by arachnids causes significant medical illness worldwide. Scorpion sting is the most important arachnid envenomation causing adult morbidity and pediatric mortality. Important groups of spiders include the widow spiders (Latrodectus spp.), the recluse spiders (Loxosceles spp.), and two spiders confined to single countries: the Australian funnel web spider (Atrax and Hadronyche spp.) and the armed spider (Phoneutria spp.) from Brazil. There are four widow spider antivenoms available, including the Australian redback spider antivenom and the American black widow antivenom. Despite good in vitro animal work demonstrating effective neutralization with these antivenoms, and cross-reactivity between many species, there continues to be a reluctance to use them in some countries. They are both associated with a relatively low rate of allergic reactions. Redback antivenom is routinely used by the intramuscular route, which may not be as effective as intravenous use based on clinical experience and animal studies. Antivenoms are available for Loxosceles spp., but there is little evidence to support their effectiveness, particularly against local effects. The Australian funnel web spider causes severe neurotoxic envenomation, and antivenom appears to be effective in reported cases. An antivenom exists for the Brazilian armed spider, but is used in only a minority of cases. Many scorpion antivenoms exist worldwide, but there remains significant controversy regarding their efficacy. Animal and human venom level studies demonstrate neutralization of circulating venom in systemic envenomation. Clinical experience in countries where antivenom has been introduced suggests it has reduced pediatric mortality. However, three controlled trials demonstrated that antivenom was not effective, but these included few severe cases. Until controlled trials of antivenom in systemically envenomated patients are undertaken, antivenom use appears justified in severe envenomation. Although envenomation from arthropods is common, no antivenoms exist for these, excepting Lonomia caterpillars in South America, and Ixodes paralysis ticks in Australia.

Clinical toxinology--where are we now?

Clinical toxinology encompasses a broad range of medical conditions resulting from envenomation by venomous terrestrial and marine organisms, and also poisoning from ingestion of animal and plant toxins. Toxin-related disease is an important cause of morbidity and mortality worldwide, particularly in the tropical and subtropical continents. Snake bite is the single most important toxin-related disease, causing substantial mortality in many parts of Africa, Asia, and the Americas. The most important snake families are Viperidae and Elapidae, causing a range of clinical effects including local necrosis, neurotoxicity, coagulopathy and hemorrhage, myotoxicity and renal toxicity. These effects vary according to geography and group of snake. Arachnid envenomation results mainly in morbidity, particularly scorpion stings which can cause severe systemic envenomation. Spider bite is far less of a problem, and the majority of medically important cases can be attributed to widow spiders (Latrodectus spp.) and recluse spiders (Loxosceles spp.). Marine-related envenomations are common, but severe effects are less so. Plant and mushroom poisoning occur in most parts of the world, but the types and methods of poisoning vary considerably between continents. Management of toxin-related disease is often difficult, and in many cases meticulous supportive care is all that is available. The mainstay of treatment is the use of antivenoms for many envenomations and poisoning, although these do not exist for all dangerous organisms. Unfortunately antivenoms are not an economically viable product, so development and manufacture of these agents have been limited. This is now further worsened by a current shortage of antivenom. There is a need for improvement in the preventionand management of toxin-related disease. This will require well-designed studies to define the extent of the problem, initiatives to improve the prevention and management of these conditions, and development of new, and continuation of current, antivenom supplies.

In vitro hemolytic activity of Lonomia obliqua caterpillar bristle extract on human and Wistar rat erythrocytes

Human accidental envenomation caused by skin contact with the bristles of Lonomia obliqua caterpillar causes coagulation and fibrinolysis disorders. Alterations of hematologic parameters are observed only in severe cases of envenomation, but with no clinical evidence of intravascular hemolysis. However, since we have observed intravascular hemolysis in preliminary studies using Wistar rats as an experimental model for investigating L. obliqua envenomation, the objective of the present study was to investigate the in vitro hemolytic activity of the bristle extract of L. obliqua caterpillars on human and rat erythrocytes. Our results showed that the bristle extract has indirect and direct hemolytic activity on human and rat erythrocytes, although direct hemolytic activity was only observed at higher bristle extract concentrations. We also observed that the bristle extract has a proteolytic activity on band 3 of human and rat erythrocyte membranes. Thus, crude L. obliqua bristle extract was found to contain at least two components with hemolytic activity on erythrocytes, a phospholipase enzyme and another protein with a direct activity on the erythrocyte membrane.

Antithrombotic effect of Lonomia obliqua caterpillar bristle extract on experimental venous thrombosis

The venom of Lonomia obliqua caterpillar may induce a hemorrhagic syndrome in humans, and blood incoagulability by afibrinogenemia when intravenously injected in laboratory animals. The possible antithrombotic and thrombolytic activities of L. obliqua caterpillar bristle extract (LOCBE) were evaluated in this study. The minimal intravenous dose of the extract necessary to induce afibrinogenemia and anticoagulation was 3.0 and 10.0 microg protein/kg body weight for rabbits and rats, respectively. In rabbits, this dose induced total blood incoagulability for at least 10 h and did not reduce the weight of preformed venous thrombi, in contrast to streptokinase (30,000 IU/kg). In rats, pretreatment with 5.0 and 10.0 microg/kg LOCBE prevented the formation of thrombi induced by venous stasis or by injury to the venous endothelium. The dose of 5.0 microg/kg LOCBE did not modify blood coagulation assay parameters but increased bleeding time and decreased plasma factor XIII concentration. When the extract was administered to rats at the dose of 10.0 microg/kg, the blood was totally incoagulable for 6 h. These data show that LOCBE was effective in preventing experimental venous thrombosis in rats, justifying further studies using purified fractions of the extract to clarify the mechanisms of this effect.

Lonomia genus caterpillar toxins: biochemical aspects

In 1967 we reported for the first time five cases of an acquired bleeding disorder in humans which developed after contact with saturnidae caterpillars. Since that time, other cases have been reported in Brazil, French Guyana, Peru, Paraguay and Argentina. The caterpillars have been identified as Lonomia achelous (LA) in Venezuela and northern Brazil and as Lonomia obliqua (LO) in southern Brazil. All patients present pain and a burning sensation at the site of contact. Within a few hours hematomas and hematuria are seen in combination with intracerebral and intraperitoneal hemorrhage (in some cases also renal failure). Hematological tests show: mild anemia with leucocytosis; prolonged PT, PTT and ThT; decreased fibrinogen, factor V, factor XIII, plasminogen and alpha2-antiplasmin levels; increased factor VIII:c, von Willebrand factor, and FDPs/D-dimers levels with normal ATIII and platelets. Factor VII, factor II and PC levels varied. Several activities similar to or directed against blood clotting factors have been identified in LA: fibrinolytic enzymes, which degrade fibrinogen producing abnormal FDPs; prothrombin activators: one direct and one factor Xa-like; a thermostable factor V activator; a thermolabile factor V inhibitor; a factor XIII proteolytic/urokinase-like activity; and a kallikrein-like activitiy. In LO three activities have been described: a prothrombin activator called 'Lonomia obliqua prothrombin activator protease' (LOPAP); a factor X activator; and a phospholipase A(2)-like activity called Lonomiatoxin. No fibrinolytic activity has been described in LO. Subcutaneous injection of crude hemolymph and some chromatographic fractions of LA induce a decrease in fibrinogen, plasminogen and factor XIII. Intravenous injection of factor XIII proteolytic/urokinase-like activity induce a dose-dependent thrombolysis with a decrease in plasmatic factor XIII without hemorrhagic manifestations. Intradermal injection of LO bristle extracts in rats and rabbits produce incoagulability whereas intravenous injection of LOPAP induced DIC in mice.

The action of Lonomia achelous caterpillars venom on human factor V

The bleeding syndrome produced by contact with the Lonomia achelous caterpillars is characterized by a decrease of fibrinogen, factor XIII, plasminogen, and factor V with normal platelets. In this study, we report the effect of crude hemolymph and some semipurified chromatographic fractions on human factor V. Incubation of factor V with crude hemolymph resulted in an increase in procoagulant activity, followed by a subsequent decline in factor V activity. Identical results were obtained with fraction I, whereas with fraction II there was only a decrease in activity reaching its minimum at 30 minutes. fraction III did not modify the activity of factor V. All concentrations of fraction I tested produced an initial rise and subsequent fall in activity. However, at lower relative concentrations of fraction I, more sustained increases in activity were observed. The activator and inactivator activities present in fraction I show differences in temperature and pH stability, susceptibility to different inhibitors, and in SDS/PAGE pattern. The factor V activator is a thermostable protein, with maximum activity at acid pH and is inhibited by o-phenantroline, EDTA, and EGTA, while the factor V inactivator is thermolabile, presents maximum activity at basic pH, precipitates at pH 5.0, and is completely inhibited by iodoacetic acid and TLCK. It is partially blocked by diisopropyl fluorophosphate, phenylmethylsulfonyl fluoride, and p-chloromercuribenzoic acid. These results suggest that the activator should be a metallo-proteinase, while the inactivator is a serine or cysteine proteinase with a serine, histidine, or cysteine residue in the active site.

The action of Lonomia achelous caterpillar venom on some blood coagulation and fibrinolysis parameters of the rabbit

The bodily secretions of the Lonomia achelous caterpillar cause a severe and often fatal acquired bleeding diathesis in humans. The rabbit was selected as model animal in an attempt to understand the mode of action of the venom. The animals were injected subcutaneously with either hemolymph or chromatographically purified fractions. Injections of hemolymph produced a drop in fibrinogen and factor XIII levels and an increase in fibrinogen degradation products (FDP). In addition one batch of hemolymph decreased plasminogen levels. The chromatographically semipurified fraction II decreased both fibrinogen and plasminogen. The effect was dose dependent but, unlike in humans, there was a fairly rapid return to baseline values. In conclusion, the response to Lonomia achelous venom in the rabbit is similar to the response seen in humans, but with a more rapid recovery.

Effect on platelet FXIII and partial characterization of Lonomin V, a proteolytic enzyme from Lonomia achelous caterpillars

Contact with Lonomia achelous caterpillars venom induces a severe bleeding syndrome in humans. A constant finding in all reported cases is a marked decrease of blood coagulation factor XIII (FXIII), which has been attributed to the presence of a proteolytic enzyme, isolated and named Lonomin V, in the hemolymph and hair secretion. In this study, the effect of Lonomin V on transglutaminase activity from human plasma, rabbit plasma, and platelet FXIII was analyzed. The decrease of activity was more pronounced in platelet (A2) when compared with rabbit plasma (AB) and human plasma FXIII (A2B2). This finding might be explained by the differences in FXIII molecular structure. In addition, platelet FXIII molecule was degraded by Lonomin to several fragments of low molecular mass. Lonomin V was stable over a wide range of pH (6-8.5) and temperatures of -70 degrees C, -20 degrees C and between 4 to 24 degrees C, with a progressive decrease at 37 degrees C and total inactivation at 60 degrees C after 2 hours incubation. Diisopropyl fluoro-phosphate, phenylmethylsulfonyl fluoride, tosyl-l-lysine chloromethyl ketone, and iodoacetamide abolished the effect of Lonomin V on FXIII; in contrast dithiothreitol and EDTA-Na enhance the activity. We concluded that Lonomin V is a serine proteinase with a free Cys essential for the enzymatic activity. Due to its proteolytic activity on FXIII, with concomitant impairment of fibrin cross-linking, Lonomin V might be useful in association with thrombolytic drugs for preventing rethrombosis.

Fibrinolytic action on fresh human clots of whole body extracts and two semipurified fractions from Lonomia achelous caterpillar

The severe bleeding diathesis produced by intoxication with the venom of Lonomia achelous caterpillars is characterized by prolonged bleeding from superficial skin wounds as well as massive hemorrhage into body cavities. The aim of the present study was to evaluate the effect of the crude venom and its fibrinolytic fractions on in vitro lysis of whole blood clots. Venom fractions with fibrinolytic activity were obtained by gel filtration chromatography on Sephadex G75 using imidazole buffer, pH 7.4, at a flow rate of 24 ml/h. Four peaks with fibrinolytic activity were obtained by this method. The highest activity was found in the first two peaks (both peaks were used for the experiments). The results show that the caterpillar venom degraded the preformed clots at a slower rate than plasmin. In addition, plasma protease inhibitors of the fibrinolytic system (alpha 2-antiplasmin, alpha 2-macroglobulin, PAI, etc.) only weakly inhibited the lytic effect of the caterpillar venom. These characteristics, as well as the pattern of fibrinogen degradation products, the delay period on fibrin plate lysis and amidolytic activity on chromogenic substrate, reported previously, indicate that the caterpillar enzymes are different from plasmin and trypsin.

Degradation of human factor XIII by lonomin V, a purified fraction of Lonomia achelous caterpillar venom

Lonomia achelous caterpillar venom (LACV) causes a severe bleeding diathesis in humans. A constant finding in these cases is a profound depression of blood clotting Factor XIII (FXIII) activity. The molecular mechanisms by which LONOMIN V (a chromatographically purified fraction from LACV) alters the FXIII complex is the subject of the present study. Incubation of human purified FXIII with Lonomin V shows that both the zymogen and the activated forms of FXIII were proteolytically degraded, with the generation of peptidic fragments of low molecular weight. Both the A and B subunits of FXIII were degraded in a progressive, dose dependent manner. The B subunit was more resistant to the action of Lonomin V, requiring higher concentrations in order to achieve complete degradation. On the basis of these findings we postulate that the proteolysis of FXIII in vivo is one of the pathophysiological factors behind this bleeding syndrome.

Lonomia achelous caterpillar venom (LACV) selectively inactivates blood clotting factor XIII

Lonomia Achelous Caterpillar Venom (LACV) causes a severe acquired bleeding diathesis in exposed persons. The condition is characterized by prolonged bleeding from superficial wounds and mucous membranes. Intracranial or intra-abdominal hemorrhage is a common and often fatal complication. A constant finding in these cases is a profound decrease of clotting Factor XIII (FXIII) activity. In the present study, the effects of LACV on plasmatic and purified human FXIII has been evaluated. The results show that native LACV and one of its chromatographically purified fractions (termed FIID) produce a dose dependent decrease of FXIII activity accompanied with an impairment of fibrin(ogen) crosslinking. We conclude that the inactivation of FXIII by fraction FIID (which will be named Lonomin V), is one of the principal patho-physiological mechanisms behind the acquired bleeding diathesis seen in these cases.

Development of an antivenom against toxins of Lonomia obliqua caterpillars

Skin contact with caterpillars of Lonomia moths causes haemostatic disorders that may evolve into a haemorrhagic syndrome. Replacement therapy has been shown to exacerbate the clinical symptoms of this envenoming. In this study it is shown that horses immunized with a bristle extract of L. obliqua caterpillars produced IgG antibodies that completely neutralized, in vitro, the toxin(s) responsible for the blood incoagulability observed in rats. This antivenom offers the possibility of specific treatment for envenoming caused by contact with caterpillars of Lonomia moths.