Cutaneous allergic reactions to Triatoma infestans after xenodiagnosis

We determined the frequency of cutaneous allergic reactions to bites of Triatoma infestans during xenodiagnosis in a rural community where Panstrongylus megistrus is the only domestic vector of Trypanosoma cruzi. Localized urticaria or more intense cutaneous allergic reactions at 48 and 72 hours were observed in 86.7% and 82.1% respectively of the individuals in our study. Urticaria was more severe in children and older adults and in women than in men. The high frequency of reactions suggests either cutaneous reactivity to T. infestans without prior sensitization or cross reactivity between P. megistus and T. infestans. A single application of topical corticosteroid or antihistamine medication did not reduce the cutaneous reactions.

O vaso dorsal de Triatoma infestans

Descreve-se a anatomia do coração e da aorta de Triatoma infestans, material criado durante alguns anos em cativeiro. O principal resultado das observações é o fato de que, em vez de três pares de ostíolos, o coração possui apenas um único ostíolo em cada uma das suas últimas câmaras. Material capturado no campo (Panstrongylus megistrus) possui normalmente três pares de ostíolos, porém diferentes em tamanho e localização.

Studies in search of a suitable experimental insect model for xenodiagnosis of hosts with Chagas' disease. 1 - Comparative xenodiagnosis with nine triatomine species of animals with acute infections by Trypanosoma cruzi

In search of a suitable vector species for xenodiagnosis of humans and animals with chronic Chagas' disease we first investigated the reactions of different vector species to acute infection with Trypanosoma cruzi. Vector species utilized in this study were: Triatoma infestans, Rhodnius prolixus and Triatoma dimidiata, all well adapted to human habitats; Triatoma rubrovaria and Rhodnius neglectus both considered totally wild species; Panstrongylus megistus, Triatoma sordida, Triatoma pseudomaculata and Triatoma brasiliensis, all essentially sylvatic but some with domiciliary tendencies and others restricted to peridomestic biotopes with incipient colonization of human houses after successful eradication of T. infestans. Results summarized in Table IV suggest the following order of infectivity among the 9 studied vector species: P. megistus with 97.8% of infected bugs, T. rubrovaria with 95% of positive bugs a close second followed by T. Pseudomaculata with 94.3% and R. neglectus with 93.8% of infected bugs, almost identical thirds. R. prolixus, T. infestans and T. dimidiata exhibited low infection rates of 53.1%, 51.6% and 38.2% respectively, coupled with sharp decreases occuring with aging of infection (Fig. 1). The situation was intermediate in T. brasiliensis and T. sordida infection rates being 76.9% and 80% respectively. Results also point to the existence of a close correlation between prevalence and intensity of infection in that, species with high infection rates ranging from 93.8% to 97.8% exhibited relatively large proportions of insects (27.3% - 33.5%) harbouring very dense populations of T. cruzi. In species with low infection rates ranging from 38.2% to 53.1% the proportion of bugs demonstrating comparable parasite densities was at most 6%. No differences attributable to blood-meal size or to greater susceptibility of indigenous vector species to parasites of their own geographical area, as suggested in earlier...

Helminths parasites of freshwater fishes from Pirassununga, SP, Brazil

Twelve species of parasitic helminths, seven trematodes, four nematodes and one acanthocephalan are reported from various hosts. Creptotrema lynchi, a parasite from Bufo marinus in Colombia, is described for the first time in fish and from Brazil, parasitizing two different species. A list of the host species, measurements and figures of most parasites are included with particular reference to the tegument of Bellumcorpus major recovered from a new host. The genus Zonocotyloides Padilha, 1978 is considered a synonym of Zonocotyle and the new combination: Zonocotyle haroltravassosi is proposed to the species Zonocotyloides haroltravassosi Padilha, 1978. The nematodes Cucullanus pinnai and Procamallanus (Spirocamallanus) inopinatus and the trematode Pararhipidocotyle jeffersoni are reported in new hosts. The description of the acanthocephalan Neoechinorhynchus curemais (new locality record) is supplemented. Other parasites recovered include the nematodes Travnema travnema (new locality record), Rondonia rondoni and the digenetic trematodes Cladocystis intestinalis, Pseudosellacotyla lutzi (new locality record), Teratotrema sp. and Zonocotyle bicaecata.

Studies in search of a suitable experimental insect model for xenodiagnosis of hosts with Chagas' disease: 2 - Attempts to upgrade the reliability and the efficacy of xenodiagnosis in chronic Chagas' disease

In order to upgrade the reliability of xenodiagnosis, attention has been directed towards population dynamics of the parasite, with particular interest for the following factors: 1. Parasite density which by itself is not a research objective, but by giving an accurate portrayal of parasite development and multiplication, has been incorporated in screening of bugs for xenodiagnosis. 2. On the assumption that food availability might increase parasite density, bugs from xenodiagnosis have been refed at biweekly intervals on chicken blood. 3. Infectivity rates and positives harbouring large parasite yields were based on gut infections, in which the parasite population comprised of all developmental forms was more abundant and easier to detect than in fecal infections, thus minimizing the probability of recording false negatives. 4. Since parasite density, low in the first 15 days of infection, increases rapidly in the following 30 days, the interval of 45 days has been adopted for routine examination of bugs from xenodiagnosis. By following the enumerated measures, all aiming to reduce false negative cases, we are getting closer to a reliable xenodiagnostic procedure. Upgrading the efficacy of xenodiagnosis is also dependent on the xenodiagnostic agent. Of 9 investigated vector species, Panstrongylus megistus deserves top priority as a xenodiagnostic agent. Its extraordinary capability to support fast development and vigorous multiplication of the few parasites, ingested from the host with chronic Chagas' disease, has been revealed by the strikingly close infectivity rates of 91.2% vs. 96.4% among bugs engorged from the same host in the chronic and acute phase of the disease respectively (Table V), the latter comporting an estimated number of 12.3 x 10[raised to the power of 3] parasites in the circulation at the time of xenodiagnosis, as reported previously by the authors (1982).

The hemocytes of Panstrogyllus Megistus (Hemiptera: Reduviidae)

Five hemocyte types were identified in the hemolymph of Panstrongylus megistus by phase contrast and common light microscopy using some histochemical methods. These are: Prohemocytes, small cells presenting a great nucleus/cytoplasm ratio; Plasmatocytes, the most numerous hemocytes, are polymorphic cells mainly characterized by a large amount of lysosomes; Granulocytes, hemocytes very similar to plasmatocytes which contain cytoplasmic granules and are especially rich in polysaccharides; Oenocytoids, cells presenting a small nucleus and a thick cytoplasm; they show many small round vacuoles when observed in Giemsa smears and many cytoplasmic granules under phase microscopy; Adipohemocytes, very large hemocytes, presenting many fat droplet inclusions which could correspond to free fat bodies which entered the hemolymph. Only prohemocytes and plasmatocytes can be clearly classified; all the other hemocyte types have a more ambiguous classification.

Estudo anatômico e morfométrico dos folículos testiculares de algumas espécies de Triatominae (Hemiptera: Reduviidae)

Os folículos testiculares nas ordens dos insetos, vêm demonstrando papel relevante sob o ponto de vista da Sistemática e Filogenia. Nos triatomíneos, os folículos testiculares são em número de sete, sendo que o comprimento e a espesura variam consideravelmente entre os gêneros, e pouco entre as espécies. Verificou-se que em Rhodnius spp existem dois folículos longos e grossos e cinco curtos e fuinnos; em Triatoma spp existem dois longos e finos, dois médios e grossos e três curtos e finos; e em Panstrongylus spp existem sete aproximadamente iguais. Através das medições do comprimento dessas estruturas, evidenciou-se que os valores das médias e desvios padrão das médias, foram muito próximos entre as espécies do mesmo gênero, tornando-se inviável estabelecer limites que pudessem caracterizá-las. Em busca de resultados mais precisos, fizeram-se comparações interespecíficas através da análise de variância: entre as diferentes espécies do mesmo gênro (comparação simultânea); entre cada duas espécies do mesmo gênro (comparação aos pares); e entre espécies iguais de procedência diferentes. Os resultados obtidos não demostraram possibilidades de utilização na Sistemática, contudo foram promissores no que concerne à Filogenia, desde que seja observado um número maior de espécies.

Natural lectin activity in the haemolymph of Panstrogylus megistus (Heteroptera: Reduvidae)

The haemolymph of Panstrongylus megistus showed a natural lectin activity for a wide range of vertebrate erythocytes. Agglutination was observed against all vertebrate erythrocytes tested (human ABO, duck, rabbit, mouse, sheep, chicken and cow). Cow erythrocytes showed the lowest titre. Concerning human erythrocytes, the lectin activity was similar in the types A+,B+ and AB+ while the highest activity was observed in the type O+. Determination of minimal inhibitory concentrations was carried out with human erythrocytes type O+. Agglutination was inhibited by several carbohydrates (rhamnose. D-galatose, raffinose, D-lactose and D-fucose). Rhamnose wasreported as the strongest inhibitor (0.78mM). The results suggest the presence of more than one lection in the haemolymph of P. megistus.

Isolamento de amostras do Trypanosoma cruzi por xenodiagnóstico e hemocultura de pacientes na fase crônica da doença de Chagas

Cinquenta e nove pacientes chagásicos crônicos foram submetidos a xenodiagnósticos e hemocultura concomitantes para isolamento de amostras de Trypanosoma cruzi. O xenodiagnóstico foi composto de 40 ninfas de Panstrongylus megistrus, Triatoma infestans e Dipetalogylus megistus, Triatoma infestans e Dipetalogaster maximus num total de 120 triatomíneos. Os insetos foram dissecados em grupo de 10 por espécie e o conteúdo intestinal, agrupado, examinado após prévia trituração e homogeneização. O material negativo ao microscópio foi semeado em meio LIT e examinado após 20 dias. Vinte e nove pacientes foram parasitologicamente comprovados, sendo 15 apenas no xenodiagnóstico, quatro apenas com a hemocultura e 10 por ambos os métodos. Discutem-se as dificuldades para a comprovação parasitológica dos pacientes chagásicos crônicos, o valor da utilização simultânea de diferentes espécies de triatomíneos no xenodiagnóstico e a hemocultura, numa associação positiva favorável ao aumento da sensibilidade para o diagnóstico da doença de Chagas. A positividade de 49,2% obtida neste grupo de pacientes visualiza abordagens do tipo ensaio clínico-terapêutico e/ou epidemiológico (tipo caso-controle) com a finalidade de investigar uma possível associação entre amostras do T. cruzi e diferentes formas clínicas da doença de Chagas.

Estudo comparado do ciclo evolutivo de triatomíneos a duas temperaturas

We studied the life cicle of several triatominae species: Dipetalogaster maximus (Uhler, 1894); Panstrongylus herreri Wygodzinsky, 1948; Panstrongylus megistus (Burmeister, 1835); Rhodnius ecuadoriensis Lent & Leon, 1958; Rhodnius nasutus Stal, 1859; Rhodnius neglectus Lent, 1954; Rhodnius pictipes Stal, 1872; Rhodnius prolixus Stal, 1859; Rhodnius robustus Larrousse, 1927; Triatoma brasiliensis Neiva, 1911; Triatoma infestans (Klug, 1834); Triatoma maculata (Erichson, 1848); Triatoma matogrossensis Leite & Barbosa, 1953; Triatoma platensis Neiva, 1913; Triatoma protracta (Uhler, 1894); Triatoma sordida (Stal, 1859); Triatoma tibiamaculata (Pinto, 1926) e Triatoma vitticeps (Stal, 1859) (Hemiptera, Reduviidae). The main purpose of the study was to obtain information to improve control measures specially in those peridomiciliar species. The experiments were performed in two climatized chambers, both with an humidity of 70 ± 5% and photoperiod of 12 hours. One was maintained at 25 ± 0,5ºC and the other at 30 ± 1ºC.

Histogical and ultrastructural aspects of the brindley's glands of pantrongylus megistus (Burmeister, 1835) (Hemiptera: Reduviidae)

The Brindley's glands of Panstrongylus megistus were studied under the antomic, histologic and ultrastructural point of view. These glands located in the insect's methatorax are paired and have an opening near the third parir of the feet. Beside this aperture, ther are evaporation areas. Shape, sixe and aspect of the gland vary according to the feeding status. The glands are composed by a tubular part corresponding to the duct and a sack-like portion corrsponding to the secretory part. By electron microscopy we observed that the basal part of the epithelium has many interdigitations associated with mitochondria. On the apical surface where epicuticular foldings are located an electonlucent space is often seen. The glands are composed of the following elements: 1) superficial epithelial cells, located just below the apical surface foldings; 2) secretory cells; which are long and have an intracellular canalicule which changes according to the functional state of the cell; 3) a collecting duct to the secretory cells and covered with an epicuticle, reaching up to the gland's lumen; and 4) cells around the duct.

Aspects of classification of Hemiptera hemocytes from six triatomine species

The objective of this work was to characterize, and compare different morphological types of hemocytes of Rhodnius prolixus, Rhodnius, Rhodnius neglectus, Triatoma infestans, Panstrongylus megistus, and Dipetalogaster maximus. This information provides the basis for studying the cellular immune systems of these insects. Seven morphological hemocyte types wereidentified by phase-contrast microscopy: prohemocytes, plasmatocytes, granular cells, cytocytes, oenocytoids, adipohemocytes and giant cells. All seven types of hemocytes are not present in every species. For example, adipohemocytes and oenocytoids were not observed in P. megistus and P. infestans, and giant cells were rarely found in any of the species studied. The hemocytes of rhodnius and Dipetalogaster are more similar to each other than those from Triatoma and Panstrongylus which in turn closely resemble each other. Emphasis is placed on methodological problems arising in this work wicah are discussed in detail.

The importance of the opossum (Didelphis albiventris) as a reservoir for Trypanosoma cruzi in Bambuí, Minas Gerais state

In a survey realized on the sylvatic and peridomestic environment at Bambuí county, Minas Gerais State, 44 (37.9%) out of 116 opossums (Didelphis albiventris) captured were found to be naturally infected with Trypanosoma cruzi. One handred and forty three parasite samples were obtanied from 43 infected opossums using simultaneously hemoculture, xenodiagnosis (Triatoma infestans, Panstrongylus megistus and Rhodnius neglectus) and examination of anal glands contents. The parasite samples were characterized according to six isoenzyme patterns. All samples, independently of the method of isolation, presented an isoenzyme pattern similar to the standard T. cruzi Z1, showing that either xenodiagnosis or hemoculture can used without selecting parasite subpopulation from naturally infected opossums. Preveous isoenzyme patterns reported for human T.cruzi isolates from same region were completely different. This isoenzyme dissimilarity between sylvatic and domiciliar environments suggests the existence of two independent T. cruzi transmission cycles in Bambuí. The epidemiological implicatinos of these results are discussed.

Sexual distinction between 5th instar nymphs of six species of Triatominae (Hemiptera, Reduviidae)

The aim of this paper is to present the analysis of sexual morphological differences observed in 5th instar nymphs of the following species: Panstrongylus megistus; Rhodnius neglectus; Triatoma brasiliensis; T. infestans; T. matogrosensis and T. tibiamaculata. Male and female nymphs were examined and photographed with a Scanning Electron Microscope. The 9th segment dimensions of dorsal and ventral faces were determined through a Profile Projector. Results and statistical analysis showed significant differences: the 9th sternite is significantly broader in male than female nymphs, while in five species; tergites in female nymphs are broad and in male are narrow.

On Thelazia anolabiata (Molin, 1860) Railliet & Henry, 1910 (Nematoda, Thelazioidea): a new host record and systematic considerations

Thelazia anolabiata (Molin, 1860) Raillet & Henry, 1910, parasite of eyes of birds, is reported in s new host, Ortalis canicolis pantanalensis Cher & Reich from Salobra, Mato Grosso do Sul State; T. digitata Travassos, 1918 and T. lutzi Travassos, 1918 are considered its synonyms.