Un brote de dermatitis producido por picaduras de Sclerodermus sp. (Hymenoptera, Bethylidae) en Costa Rica, América Central / An outbreak of dermatitis produced by the stings of Sclerodermus sp. (Hymenoptera, Bethylidae) in Costa Rica. Central America

Resumen:Se describe un brote de dermatitis producido por la picadura de una pequeña avispa áptera Sclerodermus sp. (Hymenoptera, Bethylidae), en un grupo de estudiantes de un colegio de San José, capital de Costa Rica. Se encontró también al escarabajo xilófago Calymmaderus pupatus (Coleoptera, Ptinidae), que sirve de huésped a la avispita, la cual necesita depositar sus huevos, como parasitoide, en las larvas del coleóptero para su reproducción. Casos autóctonos de esta dermatitis se conocen en los cinco continentes y esto contrasta con la ausencia de reportes procedentes de América Central.Los lugares en donde se observaron las lesiones, a veces numerosas en la misma persona, fueron: brazos, cuello, piernas, espalda, abdomen, pecho, cara y codos. El tipo de lesión se caracteriza por dolor y ardor en el momento de la picadura, seguido de una pápula eritematosa de tamaño variable, hasta un centímetro de diámetro e intenso prurito, con una duración de una a dos semanas. Se observaron cuadros urticariformes y angioedematosos e inclusive infecciones secundarias como consecuencia del rascado.El problema se atacó con una fumigación dirigida al coleóptero, con un insecticida capaz de penetrar la madera llena de galerías del escarabajo y sus larvas. Pocos días después de la fumigación, se encontraron numerosos ptínidos adultos muertos, así como gran cantidad de betílidos, en los muebles dañados por el escarabajo.

Abstract:This article describes an outbreak of dermatitis caused by stings from a small apterous wasp, Sclerodermus sp. (Hymenoptera: Bethylidae), among a group of students attending a school in San José, of Costa Rica. Also present was the xylophagous beetle, Calymmaderus pupatus (Coleoptera: Ptinidae), which serves as a host for this parasitic wasp and on which the wasp depends for its reproduction. The female wasps lay their eggs on the beetle larvae in the wood and the wasp larvae develop as parasitoids. Autochthonous cases of dermatitis caused by bethylid wasps are known from all other five continents but, as far as we are aware, this is the first report from Latin America, and the first report of Sclerodermus from Central America.The sites in which the lesions were located, sometimes numerous in the same person, were: arms, neck, legs, back, abdomen, breast, face and elbows. The type of lesionwas characterized by being painful, with a burning sensation, at the moment of the sting, followed by an erythematous papule lesion of variable size, up to one centimeter in diameter and with intense pruritus, lasting from one to two weeks. Urticariform lesions and angioedema were observed, as well as secondary infections consequence of the scratching of the lesions.The problem was solved by a fumigation directed against the coleoptera beetle, with an insecticide capable of penetrating the wood that was filled with tunnels made by the adult beetles and larvae. A few days after the fumigation numerous dead beetles and bethylid wasps were found in the furniture damaged by the beetles.

Influencia del sexo en la susceptibilidad de ratones Swiss a Trypanosoma cruzi / Sex influence on the susceptibility of Swiss mice to Trypanosoma cruzi

Algunos estudios han reportado que los ratones hembras son más resistentes al trypanosoma cruzi que los machos. Para probar lo anterior, se realizo un estudio comparativo con cuatro cepas de T. cruzi de Costa Rica midiendo parámetros como niveles de parasitemia, porcentajes de mortalidad e histopatología, en un total de 240 ratones (160 para parasitemia y mortalidad y 80 para histopatología). Todas las cepas correspondieron al genotipo TcI. En todos los casos los ratones machos resultaron más susceptibles a la infección (P<0,001). Se observaron parasitemias hasta cinco veces más altas en los machos que, en general, mueren antes que las hembras. La cepa Oswaldo fue la que presentó una mayor mortalidad y niveles de parasitemia más altos. El tejido cardiaco fue el más afectado tanto en los ratones machos como en las hembras, con las cepas bolita y capitán el número de nidos en el miocardio fue significativamente mayor en los machos que en las hembras. Una vez concluido el análisis comparativo se eligió la cepa humana GA, para determinar su efecto en ratones machos y hembras castrados, al lado de ratones normales (150 ratones en total). Las hembras normales se mostraron como las más resistentes, con parasitemias menores que las castradas (P<0,001), y los machos normales como los más susceptibles, con parasitemias significativamente más altas (P<0,001) y supervivencias menores (P<0.01), que los ratones castrados. No se observó diferencia significativa en cuanto al número de nidos en los tejidos entre ratones normales y castrados. Se concluye que el sexo tiene influencia en la resistencia a la infección experimental por T. cruzi.

Some authors have reported that female mice are more resistant to Trypanosoma cruzi infections than male mice. In order to test this hypothesis we did a comparative study using four isolates of T. cruzi from Costa Rica in a total of 160 mice, and observed several parameters such as: parasitemia levels, percent mortality and histopathology. All isolates were identified as genotype TcI. Male mice were more susceptible to infection (P<0.001). Parasitemias reached levels up to five times higher in males and shorter survival periods were observed in males than in females. The Oswaldo isolate showed the highest parasitemias and mortality rates. The heart tissue was the most affected in both males and females. In two isolates the number of parasites in the heart was significantly higher in males than in females. In separate experiments, the human GA isolate was selected in order to observe its effect in castrated male and female mice. Non-castrated females were the most resistant, with lower parasitemias than castrated females, and non-castrated males were the most susceptible with higher parasitemias (P<0.001) and lower survival periods than castrated males (P<0.01). There was no significant difference in the number of parasites in tissues between normal and castrated mice. The final conclusion is that there is a marked sex influence in the susceptibility of mice to T. cruzi experimental infections.

Life cycle of Triatoma ryckmani (Hemiptera: Reduviidae) in the laboratory, feeding patterns in nature and experimental infection with Trypanosoma cruzi

A cohort initiated with 121 eggs, yielding 105 first instar nymphs (eclosion rate: 86.78 percent), allowed us to observe the entire life cycle of Triatoma ryckmani under laboratory conditions (24ºC and 62 percent relative humidity), by feeding them on anesthetized hamsters. It was possible to obtain 62 adults and the cycle from egg to adult took a mean of 359.69 days with a range of 176-529 days (mortality rate of nymphs: 40.95 percent). Mean life span of adults was of 81 days for females and 148 days for males. The developmental periods of 4th and 5th nymphs were longer than those of the other instars. This suggests that young siblings have a better chance of taking a hemolymph meal from older ones, in order to survive during fasting periods during prolonged absences of vertebrate hosts from natural ecotopes. The stomach contents of 37 insects showed blood from rodents (15 cases), lizards (7 cases), birds (6 cases) and insect hemolymph (7 cases). Out of 10 insects fed by xenodiagnosis on a Trypanosoma cruzi infected mouse, all but one became infected with the parasite.

In vitro activity of thienyl-2-nitropropene compounds against Trypanosoma cruzi

The in vitro activity of four 2-nitropropene derivatives, 1-(3-benzothienyl)-2-nitropropene (N1), 1-(3-thienyl)-2-nitropropene (N2), 1-(5-bromo-2-thienyl)-2-nitropropene (N3) and 1-(4-bromo-2-thienyl)-2-nitropropene (N4), were tested against cultures of the parasite Trypanosoma cruzi. Cytotoxicity studies were performed using Vero cells. The blood trypomastigotes, amastigotes and epimastigotes showed differential degrees of sensitivity towards the four tested compounds; the highest activity against the epimastigotes and blood tripomastigotes was exhibited by N1, followed by N3, N4 and finally N2. In contrast, whereas the compounds N1, N3 and N4 exerted similar magnitudes of activity against amastigotes, N2 was found to be a much less potent compound. According to our results, the compound N1 had the highest level of activity (IC50: 0.6 ìM) against epimastigotes.

Susceptibilidad de trypanosoma cruzi a diferentes venenos de serpientes de Costa Rica / Susceptibility of Trypanosoma cruzi to different Costa Rican snake venoms

Se evaluaron los efectos tóxicos de los venenos de cinco serpientes costarricenses en cuanto a su capacidad tripanocida contra dos cepas de trypanosoma cruzi y sus efectos en cuanto a los mecanismos de muerte celular. Los venenos de bothrops asper, bothriechis schlegelii, crotalus durissus durissus, atropoides nummifer y A. picadoi, mostraron actividad tripanocida contra las formas de epimastigoto, amastigoto y tripomastigoto. Los venenos de b. asper y de A. nummifer presentaron la más alta citotoxicidad para las células Vero. Los de b. asper y b. schlegelii presentaron la más alta actividad en los epimastigotos de la cepa CL, mientras que los venenos de b. asper y el de A. nummifer fueron más eficientes contra los epimastigotos de la cepa Jennifer. El veneno de b. schlegelii produce un efecto proliferativo en las células Vero; mientras que el de C. d. durissus produce el mismo efecto en los epimastigotos de la cepa CL, ambos a la concentración de 2,5 Ig/mL. Los valores de CI50 mostraron que se requieren menores cantidades contra los amastigotos en relación con los epimastigotos. Los venenos de b. asper y B. schlegelii presentan la más alta actividad contra los amastigotos de ambas cepas. Con los tripomastigotos sanguíneos de la cepa GA, los cinco venenos ocasionaron una disminución de la motilidad en los diferentes tiempos de exposición, pero el veneno de A. nummifer, en las concentraciones más bajas, mostró una actividad más marcada en comparación con los otros veneno. En cuanto a los efectos de los venenos, mediados por los grados de apoptosis, necrosis o proliferación celular, se observó que estos fenémenos se presentan y tienen relación con el tipo de veneno, su concentración y el tiempo de exposición.

The trypanocide effect of venoms from five Costa Rican species of snakes was evaluated against two strains of trypanosoma cruzi and their cellular toxic effects were likewise observed. The venoms of Bothrops asper, bothriechis schlegelii, crotalus durissus durissus, atropoide nummifer and A. picadoi showed evident trypanocide action against epimastigotes, amastigotes and trypomastigotes. The venoms of b. asper and b. schlegelii were shown to be the most active against the epimastigotes of the CL strain, whereas those of b. asper and A. nummifer were more effective against the epimastigotes of the Jennifer strain. The venoms of b. schlegelii and C.d. durissus, at the lowest concentrations of 2.5 Ig/mL, were able to trigger a proliferative effect on Vero cells and epimastigotes of the CL strain, respectively. The IC50 values showed that lower amounts of venoms are necessary in order to inhibit amastigotes as compared to epimastigotes. The venoms of b. asper and b. schlegelii exhibited the highest activity against amastigotes of both T. cruzi strains. All venoms were able to arrest motility of blood trypomastigotes of the GA strain at different times and the most active in this case was A. nummifer venom. The toxic effects of the venoms measured by the degree of apoptosis, necrosis and cell proliferation that they produced showed that all these events occur and are related to the type of venom, its concentration and exposure time.

Environmental management for the control of Triatoma dimidiata (Latreille, 1811), (Hemiptera: Reduviidae) in Costa Rica: a pilot project

An ecological control method, using environmental management operations, based on biological and behavioral characteristics of Triatoma dimidiata (Latreille, 1811), was implemented as a pilot project in an area of Costa Rica where the bug is prevalent. The sample was represented by 20 houses with peridomestic colonies (two also had indoor infestation), divided in two equivalent groups of 10 each. In one group we intervened the houses, i.e. all objects or materials that were serving as artificial ecotopes for the bugs were removed, and the second group was used as control houses. After a year of periodic follow up, it became evident that in those houses with a modified environment the number of insects had decreased notoriously even after the first visits and this was more evident after a period of 12.5 to 13.5 months in which no insects were detected in eight of the houses. It also became clear that in this group of houses, recolonization by wild bugs from the surrounding areas, became more difficult, probably due to the absence of protection from bug predators. In the control houses, with the exception of three in which the inhabitants decided to intervene on their own, and another house with a peculiar situation, the insect populations remained the same or even showed a tendency to increase, as confirmed at the end of the experiment. We believe that the method is feasible, low costing and non contaminating. It could be used successfully in other places where T. dimidiata is common and also in countries where other species colonize peridomestic areas of homes. Environmental management of this kind should seek the participation of the members of the communities, in order to make it a more permanent control measure.

Distribution and ecological aspects of Rhodnius pallescens in Costa Rica and Nicaragua and their epidemiological implications

In light of the Central American Initiative for the control of Chagas disease, efforts were made on the part of Costa Rican and Nicaraguan teams, working separately, to determine the present status of Rhodnius pallescens in areas close to the common border of the two countries, where the insect has appeared within the last few years. The opportunity was also used to establish whether R. prolixus, a vector present in some areas of Nicaragua, has been introduced in recent years into Costa Rica with Nicaraguan immigrants. It became evident that wild adults of R. pallescens are common visitors to houses in different towns of a wide area characterized as a humid, warm lowland, on both sides of the frontier. Up to the present, this bug has been able to colonize a small proportion of human dwellings only on the Nicaraguan side. There was strong evidence that the visitation of the adult bug to houses is related to the attraction of this species to electric lights. There were no indications of the presence of R. prolixus either in Nicaragua or in Costa Rica in this area of the Caribbean basin. Triatoma dimidiata, a widespread domestic species in both countries, was totally absent in the explored areas of Costa Rica but occasionally occurs on the Nicaraguan side. Serological surveys in children of both areas showed that transmission of Chagas disease takes place in a rather small degree in Costa Rica and more commonly in Nicaragua, indicating that R. pallescens could be a potential threat as a vector in this particular region.

The finding of Rhodnius pallescens Barber, 1932 (Reduviidae: Triatominae) in palm trees (Attalea butyracea ) in north Costa Rica

A total of 167 nymphs and adults of Rhodnius pallescens was collected from the basal parts of dead fronds of two palm trees (Attalea butyracea ) in the town of Los Chiles, province of Alajuela, Costa Rica, close to the Nicaraguan border. Previous records of this species in the same habitat come from Panama and Colombia. A group of 32 insects examined for Trypanosoma cruzi revealed that all were infected. By examining their hemolymph, none of 24 of the insects was found infected with T. rangeli. Balb/c mice inoculated with the T. cruzi strain from infected insects showed a typical acute myocarditis reaction with numerous groups of parasites among the heart bers at autopsy. The geographical distribution of R. pallescens as well as its possible presence in other Central American countries and in Mexico where it is still unknown, coinciding with the distribution of the same species of palm tree, is discussed. Likewise, the potential of R. pallescens in becoming adapted to domestic environments is analyzed in light of recent information, and the epidemiological implications of the phenomenon are also discussed.

A survey on Triatoma dimidiata in an urban area of the province of Heredia, Costa Rica

Triatoma dimidiata has been found in several cities and towns of those countries where the insect is a domestic or peridomestic pest. In Central America, urban infestations occur in the capitals of at least five countries. During 2001 and 2002 a survey was carried out in the county of San Rafael, Heredia province, located 15 km northwest of San José, capital of Costa Rica, in order to determine the degree of infestation by T. dimidiata in an entire city block. Six peridomestic colonies of the insect were detected in the backyards of eight households. The ecotopes occupied by the insects consisted of store rooms with old objects, wood piles or firewood, and chicken coops. A total of 1917 insects were found in the six foci, during two sampling periods, and a mean infection rate by Trypanosoma cruzi of 28.4 percent was found in 1718 insects examined. The largest colony found in one of the households yielded 872 insects that were thriving mainly at the expenses of two dogs. Opossums and adult insects were common visitors of the houses and it became evident that this marsupial is closely related to the peridomestic cycle of the Chagas disease agent. Lack of colonization of the insect inside the human dwellings is explained by the type of construction and good sanitary conditions of the houses, in contrast to the situation in most peridomiciliary areas. Stomach blood samples from the insects showed that the main hosts were, in order of decreasing frequency: rodents, dogs, fowl, humans, opossums, and cats. The fact that no indication of infection with Chagas disease could be detected in the human occupants of the infested houses, vis a vis the high infection rate in dogs, is discussed.

Enfermedad de Chagas aguda, en un adulto tratado con benznidazol (Rochagan) en Costa Rica / Disease acute Chagas, in a adult dealt with benznidazol (Rochagan) en Costa Rica

Se da a conocer un caso agudo de la enfermedad de Chagas en un adulto de 48 años con signo de Romaña, infectado a recibir un chorro de orina de una chince (T dimidiata), cuando trataba de destriparla con un palo de café. Es el primer adulto con enfermedad de Chagas aguda tratado en Costa Rica con Benznidazol. Se citan los síntomas encontrados, así como los aspectos epidemiológicos relacionados con su presentación. Se enfatizan el tratamiento y la evolución del caso. Se hace un llamado de atención a los clínicos, ya que este caso no fue diagnosticado apropiadamente desde un inicio, lo que evidencia el desconocimiento que existe de la enfermedad de Chagas como motivo de consulta. Descriptores: Chagas, agudo, benznidazol.

Chagas disease in dogs from endemic areas of Costa Rica

Dogs with the presumptive diagnosis of Chagas disease are commonly sent to our School of Veterinary Medicine by independent veterinarians. This prompted us to evaluate the prevalence of canine trypanosomiasis in some villages of the Central Valley of Costa Rica. A total of 54 dogs (21 males and 33 females) from five rural villages, with ages between 3 months and 10 years old, were bled and submitted to three serological tests: indirect immunofluorescence, indirect hemagglutination and ELISA. Among all animals, 15 (27.7 percent) revealed antibodies (6 pure bred and 9 mongrels) and in 3 of them the parasite was also demonstrated by xenodiagnosis. All positive animals except 1, and 9 negative animals (control group) were examined by X-rays and electrocardiography, revealing different degrees of cardiomegaly and ECG alteration, consistent with Chagas disease pathology in one dog (SA-11) of the infected ones. Examination of 50 inhabitants living in the houses where dogs and Triatoma dimidiata were found, yielded negative serological reactions. This was assumed to support the hypothesis that dogs are commonly infected by the oral route, a more effective means of infection compared with the vector transmission mechanism that occurs in humans

Entomological and ecological aspects of six sylvatic species of triatomines (Hemiptera, Reduviidae) from the collection of the National Biodiversity Institute of Costa Rica, Central America

A total of 797 specimens of wild adult triatomines, belonging to six species from the entomological collections of the Costa Rican National Biodiversity Institute, was studied from the standpoint of their relative abundance, as reflected by light traps, distribution in the country, seasonal variations and climatic and altitudinal preferences. Triatoma dimidiata was the most abundant species (32.9 percent of the total specimens), with a very extensive distribution in different ecological zones, being more common between 100 to 400 m above sea level mainly at the end of the dry season. T. dispar was the third in frequency (21.5 percent), with narrower distribution, more abundant between 600 to 800 m and scarce during the dry season. Panstrongylus geniculatus and P. rufotuberculatus, second and fourth in frequency (22.1 percent and 15.1 percent, respectively), were widely distributed on both the Pacific and Caribbean basins, the former being more common between 80 to 270 m all year round and the latter below 800 m mainly during the first semester. Eratyrus cuspidatus which represented only 4.9 percent of the insects, was also present on both basins mainly below 200 m with a tendency to be scarce during certain months of the year, and was found in all types of ecological zones. Finally, Rhodnius pallescens, the least abundant species (3.6 percent) was restricted to very humid areas below 20 m, on the north side and Caribbean basin. With the exception of R. pallescens, males were more commonly found than females. Some epidemiological implications related to the six species are discussed

Evidence of colonization of man-made ecotopes by Triatoma dimidiata (Latreille, 1811) in Costa Rica

Triatoma dimidiata adults have been frequently found, during the last five years, in a dog kennel and a chicken coop, in the back yard of a well-built house, 15 km from San José, the capital of Costa Rica. In the chicken coop nymphs were also found. Two of the 11 dogs from the kennel were serologically positive for Trypanosoma cruzi infection. The inhabitants of the house, three adults and two children, were negative. This type of colonization by the insect, which is attracted to lights, is becoming common in old and new settlements, with different degrees of success, a fact with epidemiological implications and great relevance in the control strategies that can be applied

Zymodene and serodeme characterization of Leishmania isolates obtained from Costa Rican patients

Third-four Leishmania isolates obtained from Costa Rican patients, from different geographical areas, were characterized by isoenzyne electrophoresis and indirect immunofluorescense with monoclonal antibodies. Thirty-two were characterized as L. panamensis strains and two were L. braziliensis variants. We confirm the evident predominance of L. panamensis as the main etiological agent of leishmaniasis in Costa Rica and the existence of L. braziliensis in the country.

Morfologia externa de Triatoma ryckmani Zeledón & Ponce, 1972 vista através da microscopia eletrônica de varredura / External morphology of triatoma rickmani Zeledón & Ponce, 1972 by scanning electron microscopy

A male of Triatoma ryckmani Zeledón & Ponce, 1972, was studied by scanning electron microscopy. Only few specimens of this species are known. In this paper, some structures from the head, thorax, abdomen and distal region of the second leg are shown. Some of them could have taxonomic importance, as the oculo-ocellar region, the buccula, the anterolateral angle of the collar, the scutellum with the process longer than the main body, the stridulatory sulcus with an unusual backward vermiform area and the tibia-tarsal articulation, with a spongy fossula. The last structure was absent in specimens previously studied (Lent & Wygodzinsky 1979). Differences between this specimen and others previously described by several authors are discussed.

Morphological evidence by scanning electron microscopy of excretion of metacyclic forms of Trypanosoma cruzi in vector's urine

Observando-se, em microscopia eletrônica de varedura, formas flageladas do Trypanosoma cruzi presas a cutícula da glândula retal de ninfas infectadas de Dipetalogaster maxima verificaram-se nítidas diferenças antes e depois da alimentaçäo. Antes, viam-se numerosos tripomastigotas metacíclicos entre os abundantes epimastigotas que formavam o tapete de flagelados, ao passo que nos insetos que urinavam dentro das 24 horas após o repasto os metacíclicos eram raros, indicando que haviam sido desprendidos pelo fluxo urinário. Foi notado, as vezes, um tipo assimétrico de divisäo celular, originando um epi e um tripomastigota. Nos flagelados dos epimastigotas a presença de dilataçöes a diferentes níveis sugere que lugares secundários de aderência podem ser comuns

Does a spontaneous cure for Chagas' diseases exist?

Um grupo de pacientes com doença de Chagas vem sendo acompanhado desde a fase aguda, na Costa Rica, com tempos de evoluçäo entre 14 e 44 anos (mediana de 32 anos). Em todos a doença aguda foi bem comprovada, näo sendo realizado tratamento específico em nenhum deles, contra o Trypanosoma cruzi. Todos apresentaram pelo menos uam sorologia positiva ao longo da fase crnica, mas em três deles as técnicas sorológicas convencionais se tornaram permanentemente negativas em diversos exames realizados em diferentes laboratórios, entre 1981 e1986. Nestes três pacientes também a pesquisa de anticorpos líticos foi negativa (um caso) ou negativo-duvidoso (dois casos), permanecendo consistentemente positiva nos três outros pacientes com sorologia convencional reagente. Atualmente todos os seis pacientes se apresentaram assintomáticos e com xenodiagnóstico negativo. Apenas um deles apresenta distúrbio eletrocardiográfico mínimo e inespecífico (bloqueio incompleto do ramo direito) e, um outro, pequeno retardo do trânsito esofagiano à prova de metacolina. Levanta-se a hipótese de cura espontânea da doença de Chagas, fato que deve ser raro e que merece maior investigaçäo