Behavioral plasticity of Triatominae related to habitat selection in northeast Brazil.

Triatoma pseudomaculata Corrêa and Espínola, 1964 and Triatoma juazeirensis Costa and Felix, 2007 ( = T. brasiliensis Neiva, 1911 [part]), are sylvatic vectors of Trypanosoma cruzi (Chagas, 1909), the causative agent of Chagas disease, in northeast Brazil-especially in the caatinga region. In an area of caatinga in the State of Bahia, we compared the wild and peridomestic habitats of these two species of Triatominae to assess their behavioral plasticity in relation to habitat selection in different environments. In the sylvatic environment, the habitat of these two species is never shared. T. pseudomaculata is found in trees and bird nests, but without apparent preference for any particular tree species. In contrast, T. juazeirensis is exclusively rupicolous (found among rocks). Both species invade peridomestic structures but do not display a significant ability to colonize human dwellings. In the peridomestic area, they are highly adaptable to different habitats and can occupy substrates that they do not colonize in the sylvatic environment. This behavioral plasticity seems to be more striking in T. juazeirensis-rupicolous in sylvatic environments but colonizing wooden structures in the peridomicile in >80% of cases.

Wild habitat and related fauna of Panstrongylus lutzi (Reduviidae, Triatominae).

Although Panstrongylus lutzi (Neiva and Pinto) is currently the fifth most frequent species of Triatominae captured in artificial structures in Brazil, its silvatic habitat remains unknown. A survey of its natural ecotopes was performed in an area of Bahia State. P. lutzi nymphal instars and adults were detected in burrows of Dasypodidae. Silvatic habitat of four other endemic triatomine species of the caatinga (Triatoma pseudomaculata Correa and Espinola, Triatoma brasiliensis Neiva, Rhodnius neglectus Lent, and Psammolestes tertius Lent and Jurberg) was also recorded.

A follow-up of Beagle dogs intradermally infected with Leishmania chagasi in the presence or absence of sand fly saliva.

In this study, we compare the development of infection and/or disease in Beagle dogs intradermally infected with Leishmania chagasi, in the presence or absence of Lutzomyia longipalpis saliva, with those of intravenously infected animals. Spleen samples of all the animals inoculated with parasites had positive polymerase chain reaction tests for Leishmania DNA. Positive spleen cultures for Leishmania were detected earlier (P < or = 0.018) and were more frequent (five out of the five animals) in intravenously infected animals than in the intradermally infected animals, in presence (two out of the six animals) or absence (three out of the five animals) of salivary gland lysate of L. longipalpis. Significant increase in serum antibodies against Leishmania was observed only in the intravenously infected group (P = 0.004). In addition, dogs with infection confirmed by isolation of amastigotes or detection of parasite DNA were, nevertheless, negative for anti-Leishmania antibodies up to 5 months or more after infection. Only animals of the intravenously infected group developed progressive decreases in hematocrit (Pearson r = -0.8076, P = -0.0026) and hemoglobin (Pearson r = -0.8403, P = 0.0012) during the infection period. No significant difference in the course of infection was observed between groups of intradermally infected animals. The data presented herein confirms that the intradermal inoculation of dogs with Leishmania produces an asymptomatic form of infection. It also fails to show an advantage in using L. longipalpis saliva as an infection-enhancing agent in experimental canine leishmaniasis.

[Experimental infection of Equus asinus with Leishmania chagasi Cunha & Chagas, 1937]. / Inoculação experimental de Equus asinus com Leishmania chagasi Cunha & Chagas, 1937.

Four Equus asinus were challenged with promastigotes of Leishmania chagasi Cunha & Chagas, 1937, and followed up for 12 months. They were observed by means of direct testing for promastigotes in smears and culture of peripheral blood, fragments from inferior lip, bone marrow, spleen and liver and the immunological assays ELISA and TRALd. The post-necropsy histological examination demonstrated a small number of amastigotes in the liver of two animals. ELISA and TRALd tests were positive at the 8th, 10th and 12th month after inoculation. The results suggest that the donkeys were able to overcome the experimental leishmanial infection and did not infect the vector Lutzomyia longipalpis in the laboratory. Consequently they can not be considered an important reservoir in the epidemiological chain of transmission of visceral leishmaniasis, although they represent an important blood source for the vector and its proliferation.

[Visceral leishmaniasis among Indians of the State of Roraima, Brazil: clinical and epidemiologic aspects of the cases observed from 1989 to 1993]. / Leishmaniose visceral entre índios no Estado de Roraima, Brasil: aspectos clínicoepidemiológicos de casos observados no período de 1989 a 1993.

A description of the epidemiological profile of visceral leishmaniasis among Indians in the State of Roraima, Brazil, was based on the clinical characteristics of human and dog disease, ecological aspects of the area where the cases occurred and entomologic investigations performed from 1989 to 1993. The 82 human cases were reported in six out of eight Counties that existed then in the state; there was a 69.5% predominance of male cases among those registered and a greater (52.4%) occurrence of the disease in children from zero to ten years old. The rate of natural infection was 10.3% out of 3,773 dogs examined in 74 different locations. Lutzomyia longipalpis was found in 31 areas with greater prevalence of the disease. The human and animal cases as well as the vectors were concentrated in areas where mountains and arable soil predominate, typical locations for the occurrence of American visceral leishmaniasis.

[Vertical stratification of phlebotomine sandfly fauna (Diptera, Psychodidae) in a primary non-flooded forest of the Central Amazon, Amazonas State, Brazil]. / Estratificação vertical da fauna de flebótomos (Diptera, Psychodidae) numa floresta primária de terra firme da Amazônia Central, Estado do Amazonas, Brasil.

Studies on the vertical stratification of phlebotomine sandfly fauna were conducted in a non-flooded primary forest at a Tropical Forest Experimental Station of the National Institute of Amazonian Research from October 1998 to March 1999. CDC light traps were placed at one, 10, and 20 meters above ground. A total of 2,859 sandflies were captured, belonging to the Lutzomyia (99.93%) and Brumtomyia (0.07%) genera, represented by 38 species. In the Lutzomyia gender, the most frequent sub-gender was Nyssomyia (43.4%), followed by Psychodopygus (22.8%). Lutzomyia umbratilis, L. anduzei, L. rorotaensis, L. trichopyga, and L. olmeca nociva predominated at one meter above ground, while L. davisi, L. infraspinosa, L. umbratilis, L. trichopyga, and L. anduzei predominated at 10 meters. L. anduzei, L. tuberculata, L. dendrophyla, and L. dreisbachi were the most abundant species at 20 meters. L. umbratilis, which appeared at all three levels of vertical stratification, has great epidemic significance as a vector of Leishmania (Viannia) guyanensis.

Horizontal stratification of the sand fly fauna (Diptera: Psychodidae) in a transitional vegetation between caatinga and tropical rain forest, state of Bahia, Brazil.

A study about the horizontal stratification of the sand fly fauna in two distinct ecosystems, caatinga area, endemic for visceral leishmaniasis, and the tropical rain forest area, endemic for cutaneous leishmaniasis, was performed in the state of Bahia, Brazil. Lutzomyia longipalpis was predominant in the caatinga, and following it came the species L. capixaba and L. oswaldoi. In the tropical rain forest other species were found, such as L. intermedia, L. migonei, L. whitmani, L. yuilli, L.fischeri, L. damascenoi, L. evandroi, L. monticola, and L. lenti. It was found that the geographical limits of the vector species of visceral and cutaneous leishmaniasis are clearly defined by the biological and phytogeographic characteristics.

Trapping Triatominae in silvatic habitats.

Large-scale trials of a trapping system designed to collect silvatic Triatominae are reported. Live-baited adhesive traps were tested in various ecosystems and different triatomine habitats (arboreal and terrestrial). The trials were always successful, with a rate of positive habitats generally over 20% and reaching 48.4% for palm trees of the Amazon basin. Eleven species of Triatominae belonging to the three genera of public health importance (Triatoma, Rhodnius and Panstrongylus) were captured. This trapping system provides an effective way to detect the presence of triatomines in terrestrial and arboreal silvatic habitats and represents a promising tool for ecological studies. Various lines of research are contemplated to improve the performance of this trapping system.

Ecological interactions of visceral leishmaniasis in the State of Bahia, Brazil

The laboratory and field observations summarized in this paper on visceral leishmaniasis ecology in the State of Bahia, Brazil are based on the author's observations over the past 35 years in a number of state's foci, public health records and literature citations. The disease is endemic with epidemic outbreaks occuring every ten years and its geographical distribution is expanding rapidly in the last years. Leishmania chagasi is the main ethiologic agent of the visceral leishmaniasis but Le. amazonensis s. lato was the only leishmania isolated by other authors from some visceral leishmaniasis human cases in the state. Lutzomyia longipalpis (with one or two spots on tergites III and IV and two sized different populations) was epidemiologically incriminated as the main vector. It was found naturally infected with promastigotes, and it was infected with four species of leishmanias in the laboratory. Although the experimental transmission of Le. amazonensis by the bite of Lu. longipalpis to hamsters was performed, the author was not successful in transmitting Le. chagasi in the same way. The dog is the most important domestic source for infection of the vector, however it is not a primary reservoir. The opossum Deldelphis albiventris was found naturally infected with Le. chagasi but its role as reservoir is unknown. Foxes and rodents were nor found infected with leishmanias in Bahia .

Flebotomíneos (Díptera: Psychodidae) de uma Floresta Primária de Terra Firme da Estação Experimental de Silvicultura Tropical, Estado do Amazonas, Brasil

Studies about sand flies fauna were carried out in a non-flooded primary forest at the Experimental Station of Tropical Forest - National Institute of Amazon Research, between October 1998 and March 1999. CDC light traps were placed at 1m, 10m and 20 meters above ground level. 7.409 phlebotomines were collected, belonging to the genera, Lutzomyia (99,98%) and Brumptomyia (0,02%), represented by 39 species. In the genus Lutzomyia, the more frequent subgenus was Nyssomyia, with 39,43%, followed by Psychodopygus with 22,68%. The number of sandflies collected was increased, from the beginning of the rainy station.

Estudos sobre o levantamento da fauna de flebótomos foram realizados numa floresta primária de terra firme da Estação Experimental de Silvicultura Tropical (EEST) do Instituto Nacional de Pesquisas da Amazônia (INPA), durante os meses de outubro de 1998 a março de 1999. Utilizando-se de armadilhas luminosas CDC colocadas a 1m, 10m e 20 metros de altura do solo, foram coletados 7.409 flebótomos, pertencentes a dois gêneros, Lutzomyia (99,98 %) e Brumptomyia (0,02%), abrangendo 39 espécies. Dentro do gênero Lutzomyia, os subgêneros mais representados foram Nyssomyia, com 39,43%, e Psychodopygus com 22,68%. O número de flebotomíneos coletados foi crescente, a partir do início da estação chuvosa.

Sylvatic vectors invading houses and the risk of emergence of cases of Chagas disease in Salvador, State of Bahia, Northeast Brazil

During the last twenty years, several adults of Triatoma tibiamaculata infected with Trypanosoma cruzi have been spontaneously caught by inhabitants, inside their houses in the new habitational district of Pituaçu of Salvador, Bahia. In this communication the authors call attention to the necessity of studies about the possibility of occurrence of new human cases of Chagas disease, to clarify the obscure origin of some positive blood donors in Salvador.

Trypanosoma cruzi strains: behavior after passage into authoctonous or foreign species of treatomine (biological and biochemical patterns)

Foi estudada a influencia da passagem de cepas do T. cruzi de Sao Felipe - BA (19 SF, 21 SF e 22 SF), Tipo II, Zimodema 2, no vetor autoctone (P. megistus) e em vetores nao autoctones (T. infestans e R. prolixus). Para cada cepa, camundongos suicos de 10 a 12 g foram inoculados com I - formas sanguicolas (controles); II - metaciclicos do P. megistus; III - metaciclicos de T. infestans; IV - metaciclicos do R. prolixus. O inoculo para cada grupo foi de 10 a quarta potencia tripomastigotas. A obtencao dos metaciclicos foi feita 60 a 120 dias apos infeccao dos triatomineos...

Estratificação vertical da fauna de flebótomos (Diptera, Psychodidae) numa floresta primária de terra firme da Amazônia Central, Estado do Amazonas, Brasil / Vertical stratification of phlebotomine sandfly fauna (Diptera, Psychodidae) in a primary non-flooded forest of the Central Amazon, Amazonas State, Brazil

Studies on the vertical stratification of phlebotomine sandfly fauna were conducted in a non-flooded primary forest at a Tropical Forest Experimental Station of the National Institute of Amazonian Research from October 1998 to March 1999. CDC light traps were placed at one, 10, and 20 meters above ground. A total of 2,859 sandflies were captured, belonging to the Lutzomyia (99.93) and Brumtomyia (0.07) genera, represented by 38 species. In the Lutzomyia gender, the most frequent sub-gender was Nyssomyia (43.4), followed by Psychodopygus (22.8). Lutzomyia umbratilis, L. anduzei, L. rorotaensis, L. trichopyga, and L. olmeca nociva predominated at one meter above ground, while L. davisi, L. infraspinosa, L. umbratilis, L. trichopyga, and L. anduzei predominated at 10 meters. L. anduzei, L. tuberculata, L. dendrophyla, and L. dreisbachi were the most abundant species at 20 meters. L. umbratilis, which appeared at all three levels of vertical stratification, has great epidemic significance as a vector of Leishmania (Viannia) guyanensis.

Horizontal stratification of the sand fly fauna (Diptera: Psychodidae) in a transitional vegetation between caatinga and tropical rain forest, state of Bahia, Brazil

A study about the horizontal stratification of the sand fly fauna in two distinct ecosystems, caatinga area, endemic for visceral leishmaniasis, and the tropical rain forest area, endemic for cutaneous leishmaniasis, was performed in the state of Bahia, Brazil. Lutzomyia longipalpis was predominant in the caatinga, and following it came the species L. capixaba and L. oswaldoi. In the tropical rain forest other species were found, such as L. intermedia, L. migonei, L. whitmani, L. yuilli, L.fischeri, L. damascenoi, L. evandroi, L. monticola, and L. lenti. It was found that the geographical limits of the vector species of visceral and cutaneous leishmaniasis are clearly defined by the biological and phytogeographic characteristics

Development of Eosinophilia in dogs intradermically inoculated with sand fly saliva and Leishmania (Leishmania) chagasi stationary-phase promastigotes

Salivary glad lysates of the sand fly Lutzomia longipalpis have been shown to enhance the infectivity of Leishmania in mice. As shown herein, the simultaneous inoculation of Leishmania chagasi stationary-phase promastigotes and L. longipalpis salivary gland by the intradermal route in a group of mongrel dogs induced a statistically significant eosinophilia, in relation to dogs inoculated with Leishmania or with salivary gland lysate only. These dogs had no evidence of infection, in spite of the infectivity of the promastigotes when inoculated by the intravenous route

Inoculação experimental de Equus asinus com Leishmania chagasi Cunha & Chagas, 1937 / Experimental infection of Equus asinus with Leishmania chagasi Cunha & Chagas, 1937

Quatro Equus asinus foram inoculados com promastigotas de Leishmania chagasi Cunha & Chagas, 1937 e acompanhados durante 12 meses através de: pesquisa de amastigotas em esfregaços e culturas de sangue periférico em fragmentos de tecido do lábio inferior, medula óssea, baço e fígado e de testes de ELISA e TRALd. Estes foram positivos nos 8º, 10º e 12º meses após a inoculação. O exame histopatológico pós necropsia, demonstrou discreto número de amastigotas no fígado de dois dos eqüídeos inoculados. Apesar de desafiados com elevado número de promastigotas, os animais não desenvolveram infecções patentes e não infectaram experimentalmente a vetora Lutzomya longipalpis. Os resultados induzem a acreditar que os eqüídeos são desprovidos de importância como reservatórios na cadeia de transmissão da leishmaniose visceral, embora sirvam como boa fonte de alimentação sangüínea e proliferação da vetora Lutzomyia longipalpis.

Consideraçöes sobre pulga (Siphonaptera) da raposa Cerdocyon thous (Canidae) da área endêmica de leishmanioe visceral de Jacobina, Bahia, Brasil / Notes on fleas (Siphonaptera) of the fox Cerdocyon thous (Canidae) from the visceral leishmaniasis endemic area of Jacobina, Bahia, Brazil

No período de julho a setembro de 1998 foram coletadas 152 pulgas em 18 exemplares da raposa Cerdocyon thous capturados na área endêmica de leishmaniose visceral de Jacobina, Estado da Bahia. As pulgas foram identificadas como: 136 Rhopalopsyllus lutzi lutzi, 11 Pulex irritans, 2 Ctenocephalides canis, 1 Ctenocephalides felis felis e 2 Xenopsylla

Evaluation of Chagas' disease transmission through breast feeding

Foram estudadas, parasitologicamente, 100 amostras de leite ou colostro de 78 mäes chagásicas crônicas, através do exame direito e inoculaçäo em camundongos. Os animais foram submetidos a exame direito, três vezes por semana e, ao fim de 45 días, também, a xenodiagnóstico e a exame sorológico para pesquisa de anticorpos anti Trypanosoma cruzi. Näo houve evidência de parasitismo pelo T. cruzi nas amostras estudadas, muito embora em cinco mäes tivesse sido documentada parasitemia no momento da colheita do material. Foram, também, examinados, sorologicamente, através da pesquisa de anticorpos IgG anti-T. cruzi, filhos de chagásica crônicas, nos quais excluiu-se, ao nascer, infecçäo pelo T.cruzi. nestas crianças näo se comprovou infecçäo chagásica. Os autores concluem que näo se deve proibir a amamentaçäo nessas mäes, mas como apresentam parasitemia intermitente devem ser recomendadas a näo amamentar quando houver sangramento do mamilo

Leishmaniose visceral entre índios no Estado de Roraima, Brasil: aspectos clínicoepidemiológicos de casos observados no período de 1989 a 1993 / Visceral leishmaniasis among Indians of the State of Roraima, Brazil: clinical and epidemiologic aspects of the cases observed from 1989 to 1993

Descreve-se o perfil epidemiológico da leishmaniose visceral entre índios no estado de Roraima, Brasil, baseado na ocorrência de casos humanos observados e nos inquéritos caninos e entomológicos realizados no período de 1989 a 1993. Foram registrados 82 casos humanos de leishmaniose visceral em seis dos oito municípios então existentes no estado; houve predomínio de 69,5 por cento para o sexo masculino entre os casos observados. A maioria (52,4 por cento) dos casos foi entre crianças de zero a dez anos de idade. Registrou-se o índice de 10,3 por cento de infecção canina natural, entre 3.773 cães examinados em 74 localidades pesquisadas. A Lutzomyia longipalpis foi encontrada nas áreas de maior prevalência da doença, em 31 localidades diferentes. Os casos humanos, caninos e vetores estão concentrados em regiões onde predominam serras e lavrados, áreas características de ocorrência da leishmaniose visceral americana. A introdução e intensificação das atividades garimpeiras na região podem ter contribuído para a introdução da doença.

Dissociation between vasodilation and Leishmania infection-enhancing effects of sand fly saliva and maxadilan

In this study, the ability of maxadilan and Lutzomyia longipalpis salivary gland lysate to enhance the infection of CBA mice by Leishmania major and of BALB/c mice by L. braziliensis was tested. No difference was observed between sizes of lesion in CBA mice infected with L. major and treated or not with salivary gland lysate or maxadilan, although they were injected in concentrations that induced cutaneous vasodilation. Although parasites were more frequently observed in foot pads and spleens of animals treated with maxadilan than in the animals treated with salivary gland lysate or saline, the differences were small and not statistically significant. The lesions in BALB/c mice infected with L. braziliensis and treated with maxadilan were slightly larger than in animals that received Leishmania alone. Such differences disappeared 14 weeks after infection, and were statistically significant only in one of two experiments