RESUMO

O experimento foi realizado no setor de avicultura/UFRRJ, utilizando 348 galinhas semipesadas (linhagem Dekalb Brown), com 52 semanas de idade, criadas sob dois sistemas de produção: cage-free e em gaiolas. Os dados obtidos pela análise físico-química e microbiológica dos ovos e a resistência óssea à quebra foram submetidos à análise de variância. No caso de ocorrerem efeitos dos diferentes sistemas de produção, foi aplicado o teste de Tukey a 5% de probabilidade para comparação das médias. A qualidade físico-química foi igualmente favorecida pelos dois sistemas de produção, indicando que as circunstâncias experimentais propiciaram condições adequadas para a formação de ovos de boa qualidade. O sistema de gaiola não desfavoreceu as características ósseas das galinhas, apontando que, em densidades adequadas, a gaiola pode não exercer um fator prejudicial para a qualidade óssea. O sistema de produção cage-free piorou a contaminação da casca, comprovando que ovos postos em ninhos são mais contaminados em comparação aos produzidos em gaiolas.(AU)

The experiment was carried out in the poultry sector / UFRRJ, using 348 semi-heavy hens (Dekalb Brown line), 52 weeks old, raised under two cage-free production systems and cages. The data obtained by the physical-chemical and microbiological analysis of the eggs and the bone resistance to the break were submitted to analysis of variance, in case of effects of the different production systems, the Tukey's test was applied at 5% of probability for comparison of the means. The physical-chemical quality was also favored by the two production systems, indicating that the experimental circumstances provided adequate conditions for the formation of good quality eggs. The cage system did not disfavor the bony characteristics of the hens, indicating that at suitable densities, the cage may not exert a detrimental factor to bone quality. The cage-free production system worsened shell contamination by proving that nesting eggs are more contaminated compared to those produced in cages.(AU)

Assuntos

RESUMO

O experimento foi realizado no setor de avicultura/UFRRJ, utilizando 348 galinhas semipesadas (linhagem Dekalb Brown), com 52 semanas de idade, criadas sob dois sistemas de produção: cage-free e em gaiolas. Os dados obtidos pela análise físico-química e microbiológica dos ovos e a resistência óssea à quebra foram submetidos à análise de variância. No caso de ocorrerem efeitos dos diferentes sistemas de produção, foi aplicado o teste de Tukey a 5% de probabilidade para comparação das médias. A qualidade físico-química foi igualmente favorecida pelos dois sistemas de produção, indicando que as circunstâncias experimentais propiciaram condições adequadas para a formação de ovos de boa qualidade. O sistema de gaiola não desfavoreceu as características ósseas das galinhas, apontando que, em densidades adequadas, a gaiola pode não exercer um fator prejudicial para a qualidade óssea. O sistema de produção cage-free piorou a contaminação da casca, comprovando que ovos postos em ninhos são mais contaminados em comparação aos produzidos em gaiolas.(AU)

The experiment was carried out in the poultry sector / UFRRJ, using 348 semi-heavy hens (Dekalb Brown line), 52 weeks old, raised under two cage-free production systems and cages. The data obtained by the physical-chemical and microbiological analysis of the eggs and the bone resistance to the break were submitted to analysis of variance, in case of effects of the different production systems, the Tukey's test was applied at 5% of probability for comparison of the means. The physical-chemical quality was also favored by the two production systems, indicating that the experimental circumstances provided adequate conditions for the formation of good quality eggs. The cage system did not disfavor the bony characteristics of the hens, indicating that at suitable densities, the cage may not exert a detrimental factor to bone quality. The cage-free production system worsened shell contamination by proving that nesting eggs are more contaminated compared to those produced in cages.(AU)

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RESUMO

The role of Proechimys semispinosus as reservoir of Leishmania (Viannia) panamensis on the Colombian Pacific coast was experimentally evaluated. The susceptibility to L. chagasi also was assessed to determine the utility of this rodent as a model for studying reservoir characteristics in the laboratory. Wild-caught animals were screened for natural trypanosomatid infections, and negative individuals were inoculated intradermally (ID) in the snout or feet with 10(7) promastigotes of L. panamensis. L. chagasi was inoculated intracardially (10(7) promastigotes) or ID in the ear (10(8) promastigotes). PCR-hybridization showed that 15% of 33 spiny rats were naturally infected with L. Viannia sp. Animals experimentally infected with L. panamensis developed non-ulcerated lesions that disappeared by the 7th week post-infection (p.i.) and became more resistant upon reinfection. Infectivity to sand flies was low ((1/2)0-(1/4)8 infected/fed flies) and transient, and both culture and PCR-hybridization showed that L. panamensis was cleared by the 13th week p.i. Animals inoculated with L. chagasi became subclinically infected and were non-infective to sand flies. Transient infectivity to vectors of spiny rats infected with L. panamensis, combined with population characteristics, e.g., abundance, exploitation of degraded habitats and high reproductive rates, could make them epidemiologically suitable reservoirs.

Assuntos

RESUMO

The role of Proechimys semispinosus as reservoir of Leishmania (Viannia) panamensis on the Colombian Pacific coast was experimentally evaluated. The susceptibility to L. chagasi also was assessed to determine the utility of this rodent as a model for studying reservoir characteristics in the laboratory. Wild-caught animals were screened for natural trypanosomatid infections, and negative individuals were inoculated intradermally (ID) in the snout or feet with 10(7) promastigotes of L. panamensis. L. chagasi was inoculated intracardially (10(7) promastigotes) or ID in the ear (10(8) promastigotes). PCR-hybridization showed that 15 percent of 33 spiny rats were naturally infected with L. Viannia sp. Animals experimentally infected with L. panamensis developed non-ulcerated lesions that disappeared by the 7th week post-infection (p.i.) and became more resistant upon reinfection. Infectivity to sand flies was low (1/20-1/48 infected/fed flies) and transient, and both culture and PCR-hybridization showed that L. panamensis was cleared by the 13th week p.i. Animals inoculated with L. chagasi became subclinically infected and were non-infective to sand flies. Transient infectivity to vectors of spiny rats infected with L. panamensis, combined with population characteristics, e.g., abundance, exploitation of degraded habitats and high reproductive rates, could make them epidemiologically suitable reservoirs

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RESUMO

Canine visceral leishmaniasis (VL), caused by Leishmania infantum (Leishmania chagasi in the New World), is a zoonotic, endemic disease in Western Europe and Latin America. The potential spreading to new regions was suggested by the appearance of canine VL among foxhounds in the US. Although the sand fly vectors in the major foci of transmission have been described, no information exists on other sand flies that could propagate the infection outside endemic areas. We evaluated the capacity of Lutzomyia shannoni (Dyar) and Lutomyia youngi (Feliciangeli & Murillo), which are widely distributed in the New World, to acquire L chagasi (Cunha and Chagas) infections. A high proportion of L youngi were infected after feeding on an oligosymptomatic dog (51 per cent) or a polysymptomatic individual (95 per cent), but the intensity of infection was low (< 200 promastigotes/fly). L shannoni became infected only by feeding on the polysymptomatic dog, and the infection rate was lower (9 per cent) than in Lutzomyia longipalpis (36 per cent), and Lutzomyia evansi (Nunez-Tovar) (Lutz and Neiva) (38 per cent), but the intensity of infection (200 to > 500 promastigotes/fly) was comparable (L longipalpis) or higher (L evansi) than in the New World vectors. It is hypothesised that the presence of infected dogs in areas where L shannoni or L youngi occur could initiate new endemic cycles of VL in both South and North America.

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The manner in which terrestrial ecosystems are regulated is controversial. The "top-down" school holds that predators limit herbivores and thereby prevent them from overexploiting vegetation. "Bottom-up" proponents stress the role of plant chemical defenses in limiting plant depredation by herbivores. A set of predator-free islands created by a hydroelectric impoundment in Venezuela allows a test of these competing world views. Limited area restricts the fauna of small (0.25 to 0.9 hectare) islands to predators of invertebrates (birds, lizards, anurans, and spiders), seed predators (rodents), and herbivores (howler monkeys, iguanas, and leaf-cutter ants). Predators of vertebrates are absent, and densities of rodents, howler monkeys, iguanas, and leaf-cutter ants are 10 to 100 times greater than on the nearby mainland, suggesting that predators normally limit their populations. The densities of seedlings and saplings of canopy trees are severely reduced on herbivore-affected islands, providing evidence of a trophic cascade unleashed in the absence of top-down regulation.

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The infection rate with Leishmania chagasi and the population dynamics of small mammals were studied in an undisturbed forest reserve (Colosó) and an area of highly degraded forest (San Andrés de Sotavento [SAS]) in northern Colombia, both endemic for visceral leishmaniasis. Live trapping of mammals was done every month, and species, age, sex and reproductive status determined. L. chagasi was detected in samples of skin or spleen by the polymerase chain reaction, after extraction of deoxyribonucleic acid using specific primers (DB8/AJS3), and dot blood hybridization. Didelphis marsupialis was found to be infected in Colosó (3/21, 14.3%) and SAS (13/137, 9.5%); its relative abundance was higher in SAS (93/113, 82% of the captures). Although Proechimys canicollis was also found to be infected in Colosó (3/34, 8.8%) and SAS (2/4), its relative abundance was much lower (4%) in SAS than in Colosó (56% of 77 animals captured). Sciurus granatensis, Marmosa robinsoni, Heteromys anomalus, Zygodontomys brevicauda and Metachirus nudicaudatus were less common, and no L. chagasi infection was detected in them.

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The small mammal fauna of coffee plantations in SW Colombia was surveyed to determine which of the species present were infected with parasites of the Leishmania (Viannia) braziliensis complex and might therefore act as reservoirs of human cutaneous leishmaniasis. Fifty animals of seven different species were captured. Tissue samples were taken from the ears of specimens from each of the seven species. Thirty three samples were analysed by polymerase chain reaction (PCR) using oligonucleotide primers directed against conserved regions of L. (V) braziliensis complex kinetoplast DNA. Three of the samples (two from mouse opossums Micoureus demerarae, and one from a pygmy rice at Microryzomys minutus) gave positive results based on PCR analysis. When the samples were subjected to DNA hybridization (dot blot) analysis using the B18 (L. (V.) braziliensis complex-specific) probe, a total of ten specimens belonging to six species (the opossums M. demerarae and Didelphis marsupilalis, the rodents Melanomys caliginosus, Mi. minutus and Rattus rattus, and a rabbit Sylvilagus brasiliensis) gave positive results, indicating that all these animals had flies of species occurring in the same habitat by allowing them to feed on infected animals.

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