Validation of a documentary on Chagas disease by a population living in an endemic area / Validação de um documentário sobre a doença de Chagas por uma população de área endêmica

Abstract Educational interventions may trigger actions that contribute to prevent parasitic diseases, such as Chagas disease (CD). This study aimed at investigating the impact of an instructional video named "Documentary on Chagas Disease" on knowledge about CD and its vectors displayed by a population that lives in an endemic area in Brazil, so as to validate it as an educational tool. The video was shown to 226 subjects, divided into two groups. Group 1 was composed of users of Basic Health Units (BHU) in Pelotas and Pinheiro Machado, cities located in Rio Grande do Sul (RS) state, Brazil, where CD is endemic. Group 2 consisted of students who attend three public schools located in the rural area in Pinheiro Machado, RS. Two questionnaires with questions about their knowledge about triatomines and CD were applied, before and after the documentary was shown. After the video was shown, there was significant increase in individuals' knowledge (in both groups) about "kissing bugs", their notification, the disease and its prevention. Besides, watchers considered that the quality of the material was satisfactory. Since the "Documentary on CD" can be easily accessed on the internet and was effective in teaching the population that lives in endemic areas, its use should be encouraged in places and meetings connected to health that aim at fighting against triatominae and at exposing an updated view of CD.

Resumo Intervenções educacionais podem desencadear ações que contribuam para a prevenção de doenças parasitárias, como a doença de Chagas (DC). Este estudo teve como objetivo investigar o impacto de um vídeo instrucional denominado "Documentário Doença de Chagas" no conhecimento sobre DC e seus vetores exibidos a uma população que vive em área endêmica no Brasil, para validá-lo como uma ferramenta educacional. O vídeo foi exibido para 226 indivíduos, divididos em dois grupos. O grupo 1 foi composto por usuários das Unidades Básicas de Saúde (UBS) de Pelotas e Pinheiro Machado, cidades do estado do Rio Grande do Sul (RS), Brasil, onde a DC é endêmica. O grupo 2 foi formado por estudantes que frequentam três escolas públicas localizadas na zona rural de Pinheiro Machado, RS. Dois questionários com perguntas sobre conhecimentos sobre triatomíneos e DC foram aplicados, antes e depois da exibição do documentário. Após a exibição do vídeo, houve um aumento significativo no conhecimento dos indivíduos (em ambos os grupos) sobre "triatomíneos", sua notificação, a doença e sua prevenção. Além disso, os observadores consideraram que a qualidade do material era satisfatória. Como o "Documentário DC" pode ser facilmente acessado na Internet e ser eficaz no ensino à população que vive em áreas endêmicas, seu uso deve ser incentivado em locais e reuniões relacionadas à saúde, que visam combater os triatomíneos e exibir uma informação atualizada sobre a DC.

Avaliação da toxicidade pré-natal: estudo de teratogenicidade do inseticida piriproxifeno em ratos Wistar / Prenatal toxicity assessment: teratogenicity study of the insecticide pyriproxyfen in Wistar rats

Este estudo investigou a toxicidade pré-natal do inseticida piriproxifeno em ratos Wistar, de forma a detectar possíveis alterações no desenvolvimento fetal da progênie exposta durante o período organogênico. Três doses de piriproxifeno (100, 300 e 500mg.kg-1) foram administradas por via oral às progenitoras, do sexto ao 15º dia de gestação. Os fetos foram submetidos à técnica de diafanização modificada descrita por Taylor e Van Dyke, para avaliação de malformações e alterações esqueléticas. Os resultados não demonstraram a ocorrência de toxicidade materna sistêmica ou alterações nos índices reprodutivos avaliados. Malformações ou alterações teratogênicas não foram detectadas, no entanto alterações esqueléticas sugestivas de retardo no desenvolvimento foram observadas especialmente nas doses mais altas testadas (300mg.kg-1 e 500mg.kg-1). Considerando-se a situação complexa de risco para a saúde humana, mostra-se importante a execução de investigações adicionais, de modo a contribuir para a adequada avaliação de risco do piriproxifeno em água potável.(AU)

This study investigated the prenatal toxicity of the insecticide pyriproxyfen in Wistar rats to detect the possible changes in the fetal development of the progeny exposed during the organogenic period. Three doses of pyriproxyfen (100, 300, and 500mg.kg-1) were administered orally to the progenitors, from day 6 to 15 of gestation. The fetuses were processed using the Taylor and Van Dyke modified diaphanization technique to evaluate malformations and skeletal changes. The results did not demonstrate the occurrence of systemic maternal toxicity or changes in the reproductive indexes evaluated. Malformations or teratogenic changes were not detected, however, skeletal changes suggestive of developmental delay were observed, especially in the highest doses tested (300 mg.kg-1 and 500 mg.kg-1). Owing to the potentially complex situation regarding its risk to human health, it is important that further studies be performed to contribute to the risk assessment of the addition of pyriproxyfen in drinking water.(AU)

Plant antiherbivore defenses in Fabaceae species of the Chaco / Defesas das plantas anti-herbivoria em espécies de Fabaceae do Chaco

Abstract The establishment and maintenance of plant species in the Chaco, one of the widest continuous areas of forests in the South American with sharp climatic variations, are possibly related to biological features favoring plants with particular defenses. This study assesses the physical and chemical defenses mechanisms against herbivores of vegetative and reproductive organs. Its analyses of 12 species of Fabaceae (Leguminosae) collected in remnants of Brazilian Chaco shows that 75% present structural defense characters and 50% have chemical defense - defense proteins in their seeds, like protease inhibitors and lectins. Physical defenses occur mainly on branches (78% of the species), leaves (67%), and reproductive organs (56%). The most common physical characters are trichomes and thorns, whose color represents a cryptic character since it does not contrast with the other plant structures. Defense proteins occur in different concentrations and molecular weight classes in the seeds of most species. Protease inhibitors are reported for the first time in seeds of: Albizia niopoides, Anadenanthera colubrina, Mimosa glutinosa, Prosopis rubriflora, and Poincianella pluviosa. The occurrence of physical and chemical defenses in members of Fabaceae indicate no associations between defense characters in these plant species of the Chaco.

Resumo O estabelecimento e a manutenção de espécies no Chaco, uma planície semi-árida da América do Sul com variações climáticas importantes, possivelmente estão relacionados a características biológicas que favorecem as plantas detentoras de defesas particulares. Este estudo teve como objetivos avaliar os mecanismos de defesa física e química anti-herbivoria em órgãos vegetativos e reprodutivos. Analisamos 12 espécies da família Fabaceae (Leguminosae) obtidas em remanescentes de Chaco brasileiro. Observamos que 75% das espécies estudadas apresentam atributo de defesa física e 50% possuem defesa química - proteínas de defesa nas sementes, como inibidores de protease e lectinas. As defesas físicas ocorrem principalmente nos ramos (78% das espécies), nos órgãos reprodutivos (56% das espécies) e nas folhas (67%). Os atributos físicos mais frequentes são tricomas e espinhos, cuja coloração não contrastante com as demais estruturas das plantas representa um caráter críptico. Proteínas de defesa ocorrem nas sementes da maioria das espécies, com diferentes concentrações e classes de pesos moleculares. Inibidores de protease nas sementes estão sendo relatados pela primeira vez em: Albizia niopoides, Anadenanthera colubrina, Mimosa glutinosa, Prosopis rubriflora e Poincianella pluviosa. A ocorrência de defesas física e química entre os membros de Fabaceae indica que não há associações entre as características de defesa das espécies de plantas avaliadas no Chaco.

Validation of a documentary on Chagas disease by a population living in an endemic area

Abstract Educational interventions may trigger actions that contribute to prevent parasitic diseases, such as Chagas disease (CD). This study aimed at investigating the impact of an instructional video named Documentary on Chagas Disease on knowledge about CD and its vectors displayed by a population that lives in an endemic area in Brazil, so as to validate it as an educational tool. The video was shown to 226 subjects, divided into two groups. Group 1 was composed of users of Basic Health Units (BHU) in Pelotas and Pinheiro Machado, cities located in Rio Grande do Sul (RS) state, Brazil, where CD is endemic. Group 2 consisted of students who attend three public schools located in the rural area in Pinheiro Machado, RS. Two questionnaires with questions about their knowledge about triatomines and CD were applied, before and after the documentary was shown. After the video was shown, there was significant increase in individuals knowledge (in both groups) about kissing bugs, their notification, the disease and its prevention. Besides, watchers considered that the quality of the material was satisfactory. Since the Documentary on CD can be easily accessed on the internet and was effective in teaching the population that lives in endemic areas, its use should be encouraged in places and meetings connected to health that aim at fighting against triatominae and at exposing an updated view of CD.

Resumo Intervenções educacionais podem desencadear ações que contribuam para a prevenção de doenças parasitárias, como a doença de Chagas (DC). Este estudo teve como objetivo investigar o impacto de um vídeo instrucional denominado Documentário Doença de Chagas no conhecimento sobre DC e seus vetores exibidos a uma população que vive em área endêmica no Brasil, para validá-lo como uma ferramenta educacional. O vídeo foi exibido para 226 indivíduos, divididos em dois grupos. O grupo 1 foi composto por usuários das Unidades Básicas de Saúde (UBS) de Pelotas e Pinheiro Machado, cidades do estado do Rio Grande do Sul (RS), Brasil, onde a DC é endêmica. O grupo 2 foi formado por estudantes que frequentam três escolas públicas localizadas na zona rural de Pinheiro Machado, RS. Dois questionários com perguntas sobre conhecimentos sobre triatomíneos e DC foram aplicados, antes e depois da exibição do documentário. Após a exibição do vídeo, houve um aumento significativo no conhecimento dos indivíduos (em ambos os grupos) sobre triatomíneos, sua notificação, a doença e sua prevenção. Além disso, os observadores consideraram que a qualidade do material era satisfatória. Como o Documentário DC pode ser facilmente acessado na Internet e ser eficaz no ensino à população que vive em áreas endêmicas, seu uso deve ser incentivado em locais e reuniões relacionadas à saúde, que visam combater os triatomíneos e exibir uma informação atualizada sobre a DC.

Cell-free antigens from precocious Paracoccidioides brasiliensis culture induce a typical delayed-type hypersensitivity reaction

Cell-free antigens (CFAg) derived from Paracoccidioides brasiliensis have typically been used in immunodiffusion reactions for serodiagnosis or therapeutic follow-up of paracoccidioidomycosis patients. Thus, we investigated the usefulness of CFAg obtained from cultures at different ages, to evaluate cellular immunity by the footpad test, in experimental murine paracoccidioidomycosis. Male mice infected with P. brasiliensis 265 strain were challenged in the footpad with CFAg obtained from four- (4d CFAg) or 11-day-old cultures (11d CFAg). The increase in footpad swelling provoked by 4d CFAg and 11d CFAg was similar and showed significant difference in relation to control groups. However, the infiltrate pattern was strikingly different: 4d CFAg induced a predominant mononuclear infiltrate whereas 11d CFAg provoked a predominant polymophonuclear infiltrate. These different inflammatory patterns were associated with distinct electrophoretic characteristics. By comparison with 11d CFAg, 4d CFAg showed more numerous and intense bands, including a strong one of 43 kDa (gp43). These results suggest that CFAg derived from Pb 265 isolate can be used as a reagent to evaluate cellular immunity; however, the culture's age is critical because only young cultures are able to induce a typical mononuclear infiltrate. The efficacy of this new paracoccidioidin to assay the cellular immunity in infections caused by other P. brasiliensis isolates is under investigation.

Impact of malnutrition on immunity and infection

Malnutrition may be a consequence of energy deficit or micronutrient deficiency. It is considered the most relevant risk factor for illness and death, particularly in developing countries. In this review we described the magnitude of this problem, as well as its direct effect on the immune system and how it results in higher susceptibility to infections. A special emphasis was given to experimental models used to investigate the relationship between undernutrition and immunity. Malnutrition is obviously a challenge that must be addressed to health authorities and the scientific community.(AU)

Th1 polarized response induced by intramuscular DNA-HSP65 immunization is preserved in experimental atherosclerosis

We previously reported that a DNA vaccine constructed with the heat shock protein (HSP65) gene from Mycobacterium leprae (DNA-HSP65) was protective and also therapeutic in experimental tuberculosis. By the intramuscular route, this vaccine elicited a predominant Th1 response that was consistent with its protective efficacy against tuberculosis. It has been suggested that the immune response to Hsp60/65 may be the link between exposure to microorganisms and increased cardiovascular risk. Additionally, the high cholesterol levels found in atherosclerosis could modulate host immunity. In this context, we evaluated if an atherogenic diet could modulate the immune response induced by the DNA-HSP65 vaccine. C57BL/6 mice (4-6 animals per group) were initially submitted to a protocol of atherosclerosis induction and then immunized by the intramuscular or intradermal route with 4 doses of 100 mug DNA-HSP65. On day 150 (15 days after the last immunization), the animals were sacrificed and antibodies and cytokines were determined. Vaccination by the intramuscular route induced high levels of anti-Hsp65 IgG2a antibodies, but not anti-Hsp65 IgG1 antibodies and a significant production of IL-6, IFN-g and IL-10, but not IL-5, indicating a Th1 profile. Immunization by the intradermal route triggered a mixed pattern (Th1/Th2) characterized by synthesis of anti-Hsp65 IgG2a and IgG1 antibodies and production of high levels of IL-5, IL-6, IL-10, and IFN-g. These results indicate that experimentally induced atherosclerosis did not affect the ability of DNA-HSP65 to induce a predominant Th1 response that is potentially protective against tuberculosis.

Interleukin-15: its role in microbial infections

Interleukin-15 (IL-15) is a pleiotropic cytokine which regulates the proliferation, survival and the secretory activities of many distinct cell types in the body. This cytokine is produced by macrophages and many other cell types in response to infectious agents; it controls growth and differentiation of T and B lymphocytes, activation of Natural Killer (NK) and phagocytic cells, and contributes to the homeostasis of the immune system. The present review focuses on the biological and modulatory effects of IL-15 in microbial infections and shows that this cytokine may play a role in the host defense against infections by inducing activation of effector cells from both innate and adaptive immune system.(AU)

Produção deficiente de citocinas Th1 em camundongos BALB/c jovens / Deficient production of Th1 cytokines in young BALB/c mice

O objetivo do presente estudo foi comparar a produção de IFN-gama , IL-12 e IL-4 entre camundongos jovens (5, 12e 19 dias de idade) e adultos (30 dias de idade). As avaliações foram feitas por estimulação, in vitro, de células esplênicas com Concanavalina A (ConA) , Staphylococcus aureus (S. aureus) e lipopolissacarídeo (LPS). Diferentes concentrações de cada estímulo foram testadas e os sobrenadantes das culturas foram coletados após 48 horas de incubação e as concentrações de IFN-gama IL-12 e IL-4 determinadas por ELISA. Células de camundongos jovens e adultos produziram níveis igualmente elevados de IFN-gama após estímulo com ConA. Somente animais adultos produziram IFN-gama em resposta ao estímulo com S. aureus. Em culturas estimuladas com LPS, a produção desta citocina foi baixa e similar nos animais jovens e significativamente elevada nos animais adultos. Somente células de animais adultos estimuladas com S. aureus foram capazes de produzir IL-12. O único estímulo capaz de induzir níveis detectáveis de IL-4 foi ConA, sendo que estes níveis foram mais elevados nos animais com 12 e 19 dias de idade em comparação com animais neonatos e adultos. A diminuição das doses ótimas dos estímulos não mudou o perfil de produção de cada citocina nos animais jovens. Estes resultados permitem concluir que a idade afeta a produção de citocinas: ocorre maior produção de IL-4 em camundongos jovens e maior produção de IL-12 e IFN-gama em animais adultos. Estas informações são importantes devido ao papel destas citocinas na polarização das respostas imunes nos sentidos Th1 e Th2.

Interval between first dose and booster affected antibody production in cattle vaccinated against rabies

In this study, we compared the levels of neutralizing antibodies induced by inactivated rabies vaccine in cattle by using three alternative immunization procedures. Forty-five bovines (breed nelore) were then organized in three groups (A, B and C, with 15 animals/group). Group A received only one vaccine dose at day zero and Group B received the first dose at day zero and then another dose at day 30 (early booster). Group C was also immunized with two doses; however, the booster was postponed until day 180 after the first dose (delayed booster). Blood samples were withdrawn at days zero (before the first dose) and 30, 210, 390, and 540 after the beginning of immunization and the antibody titers were evaluated by mouse neutralization test. The protocol used to immunize Group C (booster at day 180) was clearly more efficient. In this group, antibody levels were higher and also remained higher for longer periods in comparison with the other two groups. These results show that booster timing significantly affected antibody levels. Therefore, programs addressed to control this disease in cattle should consider not only the use of a booster but also its administration time

Detection and neutralization of venom by ovine antiserum in experimental envenoming by Bothrops jararaca

In this study we optimized an enzyme-linked immunosorbent assay (ELISA) to evaluate bothropic venom levels in biological samples. These samples were obtained by two distinct protocols. In the first one, Swiss mice were injected with 1 LD50 of Bothrops jararaca (B. jararaca) venom and 15 minutes later, animals were treated with ovine antibothropic serum. Blood and spleen homogenate samples were obtained 6 hours after antiserum therapy. Ovine antibothropic serum significantly neutralized venom levels in serum and spleen. In the second protocol, BALB/c mice were injected with 1 LD50 of bothropic venom by either intraperitoneal (IP) or intradermal (ID) route and venom levels were evaluated 1, 3 and 6 hours after, in blood, spleen homogenates and urine. Serum and splenic venom levels were significantly higher in animals envenomed by IP route comparing with animals envenomed by ID route. Higher venom levels were also detected in urine samples from animals envenomed by IP route. However, these differences were not statistically significant. These results demonstrated that the optimized ELISA was adequate to quantify venom levels in different biological samples. This assay could, therefore, substitute the in vivo neutralizing assay and also be useful to evaluate the severity of human and experimental envenomations.

Assessment of the neutralizing potency of ovine antivenom in a swiss mice model of Bothrops jararaca envenoming

Alternative sources of anti-ophidic serum are being investigated due to the secondary effects associated with types I and II hypersensitivity reactions. In the present study we raised and evaluated the protective effect of an ovine antibothropic serum in a Swiss mice envenoming model. Ovine antiserum was obtained by immunization with seven increasing doses of bothropic venom associated with adjuvants. The neutralizing ability was tested by the lethal activity (2 LD50) neutralization and serum and splenic venom levels after antivenom administration to experimentally envenomed mice. The antiserum effect on local edema was also tested by injection of venom/antivenom mixtures into the mice footpads. Ovine antiserum neutralized lethal activity and also significantly decreased serum and splenic venom levels. However, this antiserum was not able to mediate any protective effect on edema triggered by bothropic venom

Down-modulation of lymphoproliferation and interferon-gamma production by beta-glucan derived from Saccharomyces cerevisiae

Beta-glucan, one of the major cell wall components of Saccharomyces cerevisiae, has been found to enhance immune functions. This study investigated in vivo and in vitro effects of beta-glucan on lymphoproliferation and interferon-gamma (IFN-gamma) production by splenic cells from C57BL/6 female mice. All experiments were performed with particulate beta-glucan derived from S. cerevisiae. Data demonstrated that both, i.p administration of particulate beta-glucan (20 or 100 µg/animal) and in vitro stimulation of splenic cells (20 or 100 µg/ml of culture) decreased lymphoproliferation and IFN-gamma production induced by concanavalin A. These results suggest that beta-glucan can trigger a down-modulatory effect regulating a deleterious immune system hyperactivity in the presence of a strong stimulus.

Neonatal rat exposure to pyrethroid and organophosphate insecticides: a physiological and biochemical trial of progeny

A manufactured product (Ectoplus R) composed by a cypermethrin (44,7 por cento) and dichlorvos (4,2 por cento) mixture was administered (10mg-day, orally, by gavage) to pregnant rats, during the periods of gestation+lactation, gestation, and lactation. Controlmothers received vehicle aqueous solution during the gestation+lactation period. With the progeny, in the 1-15 post-natal days (PND1-15) there were observed alterations in the periods of occurrence of teeth, hair, unfolding of ears, and in the developmental period for following reflexes: postural, palmar grasp, negative geotaxis, and acoustic startle reflex. After weaning (PND21), there were observed the presence of cypermethrin and dichlorvos in the blood brain and liver, decrease in weight of liver, of cholinesterase activity in the plasma, liver, and brain, and hepatic metabolizing activity of drugs, alterations of levels of gamma glutamyl transferase enzymes, of creatinine, and of potassium in the serum of the animals. In conclusion, neonatal exposure to a formulated mixture of cypermethrin and dichlorvos is inductive to alterations in characteristics that indicate somatic and neuromuscular development of the progeny, and in certain biochemical parameters. The results suggest that enzymatic assessment associated with somatic and neuromotor assessment can be important markers of developmental characteristics in neonatal toxicity by pesticide formulations based on mixtures of insecticides.

Parasitemia por Trypanosoma cruzi em pacientes com doenca de Chagas cronica co-infectados por virus da imunodeficiencia humana (HIV) / Trypanosoma cruzi parasitemia in patients with chronic Chagas' disease and human immunodeficiency virus (HIV) coinfection

Avaliar a parasitemia por T.cruzi em individuos com doenca de Chagas cronica, comparando pacientes co-infectados pelo HIV e soronegativos para HIV; investigar a relacao entre a parasitemia e o numero de celulas T CD4+ no sangue, a carga viral de HIV no plasma e o diagnostico de aids; avaliar se ha um nivel de parasitemia indicativo da reativacao da tripanosomiase. Foram estudados 110 pacientes com doenca de Chagas cronica: 29 soropositivos e 81 soronegativos para HIV, com idade entre 25 e 61 anos. Os pacientes foram submetidos a tres avaliacoes seriadas com realizacao de xenodiagnostico in vitro, hemocultura para T.cruzi e pesquisa microscopica direta do prasito no sangue. A parasitemia foi significativamente mais frequente nos pacientes co-infectados por HIV(80,9 porcento) do que nos pacientes soronegativos para HIV (35,3 porcento). Os pacientes co-infectados por HIV apresentaram tambem niveis mais elevados de parasitemia. Nao foi observada correlacao entre a parasitemia e a contagem de celulas T CD4+, a carga viral de HIV ou o diagnostico de aids. Reativacao da doenca de Chagas foi diagnosticada em 17,2 porcento (5/29) dos pacientes co-infectados, tendo sido observadas formas oligossintomaticas. Diante de xenodiagnostico com mais de 20 porcento de ninfas positivas, deve-se considerar a possibilidade de reativacao da tripanosomiase. A co-infeccao por HIV resulta em exacerbacao da parasitemia por T.cruzi em pacientes com doenca de Chagas cronica.

Digestibilidade aparente dos fenos de rami (Boehmeria nivea, G.), guandu (Cajanus cajan, L.), soja perene (Glycine wightii, V.) e da palha de feijäo (Phaseolus vulgaris, L) em coelhos na fase de crescimento / Apparent digestibility of ramie hay (Boehmeria nivea, G), pigeon pea hay (Cajanus cajan, L.), perennial soybean hay (Glycine wightii, V.) and bean husk (Phaseolus vulgaris, L.) on growing rabbits

Determinaram-se a composiçäo química, a digestibilidade aparente dos nutrientes e os valores energéticos do feno de rami (FR), feno de guandu (FG), feno de soja perene (FSP) e palha de feijäo (PF) para coelhos em crescimento. No ensaio biológico foram distribuídos 20 coelhos machos da raça Nova Zelândia Branca, em 20 gaiolas de metabolismo, segundo um delineamento inteiramente ao acaso, em cinco tratamentos e quatro repetiçöes. Os tratamentos constaram de cinco dietas, sendo uma basal e quatro dietas experimentais, em que as forragens avaliadas aubstituíram 40 por cento da dieta basal em referência à matéria seca. Adotou-se o sistema de coleta total de fezes de cada animal. Os coeficientes aparentes da digestibilidade (por cento) da MS, PB, FB, EE, ENN e EB do feno de rami foram, respectivamente, 49,80; 59,49; 22,78; 36,14; 63,04 e 47,93; de feno de guandu, na mesma ordem de citaçäo, foram 24,00; 25,64; 27,41; 32,26; 20,98 e 24,62; do feno de soja perene, 34,22; 46,38; 8,34; 85,27; 62,71 e 33,68; e da palha de feijäo 30,24; 54,41; 28,00; 60,16; 39,22 e 27,58. Os resultados revelam que os alimentos testados foram utilizados diferentemente pelos coelhos, provavelmente, devido às particularidades químicas da parede celular vegetal

Use of an ELISA assay to evaluate venom, antivenom, IgG and IgM human antibody levels in serum and cerebrospinal fluid from patients bitten by Crotalus durissus terrificus in Brazil

A sandwich-type ELISA technique for specific and sensitive detection of Crotalus durissus terrificus venom antigens, horse-antivenom, human IgG and IgM antibodies was set up. Sixteen patients, 13 males and 3 females aged between 13 to 63 years (mean 33 ñ 15) bitten by Crotalus durissus terrificus snakes were studied. Of the 15 patiens, 6 had previously received anti-Crotalus venom and no seric venom was detected. For the other 9 patients studied, the venom levels ranged from 2 to 108mg/ml according to the severity of each case. Seric antivenom was detected up to 44 days after the bite. IgM human antibody levels against Crotalus venom were higher between 3 and 18 days after specific treatment. IgG human antibody levels against Crotalus venom were detected between 30 and 90 days after envenoming. Venom and antivenom levels in cerebrospinal fluid were not observed 24 h after the bite. This suggests that neither the venom nor the antivenom is capable of crossing the blood-brain barrier. In addition, when either venom or the antivenom is presented to the immune system cells an immune response is prepared.