Prevalence of Toxoplasma gondii and Neospora caninum infections in sheep from Federal District, central region of Brazil

Serum samples from 1028 sheep were collected from 32 herds within Federal District, in the central region of Brazil. The samples were examined by indirect fluorescent antibody test (IFAT) using sera diluted 1:64 and 1:50 as cut-off values for the detection of antibodies against Toxoplasma gondii and Neospora caninum, respectively. The observed prevalence for T. gondii infection was 38.22% (26.81%< CI 0.95 < 49.62%), and the titers ranged from 64 to 65536. The observed prevalence for N. caninum infection was 8.81% (7.08%< CI 0.95 < 10.53%). The titers ranged from 50 to 51200. The reactant sera to both pathogens corresponded to 4.67% of the samples. The risk factors were not determined because of the absence of negative herds for T. gondii and the high proportion of positive herds for N. caninum (87.50%). The prevalence for T. gondii infection was significantly higher among males than in females. The present work is the first report on seroprevalence of T. gondii and N. caninum in sheep from Federal District and shows that infection by both parasites is widespread in the ovine population from this region.

Rickettsia in Synanthropic and Domestic Animals and Their Hosts from Two Areas of Low Endemicity for Brazilian Spotted Fever in the Eastern Region of Minas Gerais, Brazil

The aim of this study was to understand the current epidemiology of rickettsial diseases in two rickettsial-endemic regions in Brazil. In the municipalities of Pingo D`Agua and Santa Cruz do Escalvado, among serum samples obtained from horses and dogs, reactivity by immunofluorescent assay against spotted fever group rickettsiae was verified. In some serum samples from opossums (Didelphis aurita) captured in Santa Cruz do Escalvado, serologic response against rickettsiae was also verified. Polymerase chain reaction identified rickettsiae only in ticks and fleas obtained in Santa Cruz do Escalvado. Rickettsiae in samples had 100% sequence homology with Rickettsia fells. These results highlight the importance of marsupials in maintenance of the sylvatic cycle of rickettsial disease and potential integration with the domestic cycle. Our data also support the importance of horses and dogs as sentinels in monitoring circulation of rickettsiae in an urban area.

Carios fonsecai sp nov (Acari, Argasidae), a bat tick from the central-western region of Brazil

Males, females, and larvae of Carios fonsecai sp. nov. are described from free-living ticks collected in a cave at Bonito, state of Mato Grosso do Sul, Brazil. The presence of cheeks and legs with micromammillate cuticle makes adults of C. fonsecai morphologically related to a group of argasid species (mostly bat-associated) formerly classified into the subgenus Alectorobius, genus Ornithodoros. Examination of larvae indicates that C. fonsecai is clearly distinct from most of the previously described Carios species formerly classified into the subgenus Alectorobius, based primarily on its larger body size, dorsal setae number, dorsal plate shape, and hypostomal morphology. On the other hand, the larva of C. fonsecai is most similar to Carios peropteryx, and Carios peruvianus, from which differences in dorsal plate length and width, tarsal setae, and hypostome characteristics are useful for morphological differentiation. The mitochondrial 16S rDNA sequence of C. fonsecai showed to be closest (85-88% identity) to several corresponding sequences of different Carios species available in GenBank. Bats identified as Peropteryx macrotis and Desmodus rotundus were found infested by C. fonsecai larvae in the same cave where the type series was collected. C. fonsecai showed to be aggressive to humans in the laboratory.

Inquiry of antibodies anti-Neospora caninum in dairy cattle, dogs and rural workers of the south-west region of Mato Grosso State

Considering the importance of neosporosis in the animal health and production, the frequency of antibodies to Neospora caninum was evaluated in dairy cattle of the Southwestern region of Mato Grosso State, Brazil, in addition to serum samples obtained from dogs and humans living in the farms. A total of 1036 serum samples were analyzed, from which 932 were from dairy bovine females, 37 from dogs and 67 from humans, from 24 farms and examined by the indirect fluorescent antibody test (IFAT). Reactive human scrum samples were retested by Western-blotting to confirm the results. Antibodies to N. caninum were found in 499 cattle sera (53.5 %), with at least one positive in each farm, 25 dog sera (67.6 %) and seven human sera (10.5 %). There was no significant difference in the number of positive cattle sera according to age group. The results indicate a wide dissemination of N caninum in the studied region.

Seroepidemiology of Toxoplasma infection in a metropolitan region of Brazil

Seroprevalence data from a representative population were used to estimate the annual incidence of congenital toxoplasmosis in Sao Paulo Metropolitan Region (SPMR). Retrospective anti-toxoplasma IgG serological analysis was conducted to determine age-dependent seroprevalence, force of infection, average age of acquisition of infection and curve of decay of maternally derived antibodies. Seroprevalence was used to calculate the number of new infections. Toxoplasmosis in pregnant women was estimated by total number of deliveries in a given year as a proxy for the number of pregnancies per year. Toxoplasma seroprevalence was 64.9% in women of childbearing age. Average age of acquisition of toxoplasmosis was 10.74 years. The estimated annual incidence of congenital toxoplasmosis varied from 9.5 to 10.6/1000 births in the studied period. The toxoplasmosis seroprevalence model allowed a good incidence estimation of congenital disease in SPMR compared to other published data, indicating that this mathematical approach is useful in calculating the potential demand of congenital disease due to Toxoplasma gondii in a given community.

Ticks (Acari: Ixodidae) Infesting Birds in an Atlantic Rain Forest Region of Brazil

Brazil has the third richest bird diversity of the world; however, there are few data concerning ticks (Acari: Ixodidae) parazitizing birds. The aim of the study was to report tick infestations on wild birds from an Atlantic rain forest region of Brazil. During 2 yr, ticks were collected from birds and from the environment in 12 forest sites. A total of 1,725 birds were captured representing 80 species from 24 families. In total, 223 (13%) birds were found infested by immature stages of Amblyomma ticks: 1,800 larvae and 539 nymphs. The prevalence of ticks was higher among-birds from the families Thamnophilidae, Conopophagidae, and Momotidae. The most common tick parasitizing birds was Amblyomma nodosum Koch. Other tick species, Amblyomma coelebs Neumann, Amblyomma cajennense (F.), Amblyomma ovale Koch, Amblyomma longirostre (Koch), Amblyomma calcaratum Neumann, and Amblyomma naponense (Packard), were found sporadically. Among free-living ticks collected in the environment, A. cajennense was the most common, followed by A. coelebs, A. naponense, Amblyomma brasilense Aragao, and Hemaphysalis juxtakochi Cooley.

Prevalence and risk factors for anti-Toxoplasma gondii antibodies in goats of the Serido Oriental microregion, Rio Grande do Norte state, Northeast region of Brazil

The prevalence and risk factors for anti-Toxoplasma gondii antibodies were investigated in goats of the Serido Oriental microregion, Rio Grande do Norte state, Northeast region of Brazil. Three hundred and sixty-six blood samples from goats collected by jugular venopuncture were used. For the serologic diagnosis of Toxoplasma gondii infection, the indirect fluorescent-anti body test (IFAT) with cut-off value 1:64 was carried out. The prevalence of anti-T. gondii antibodies was 30.6% [95% CI = 25.9-35.6%] with titers ranging from 1:64 to 1: 16,384. The multivariate logistic regression analysis showed that the risk factors associated to anti-T. gondii antibodies were presence of cats in the herd, extensive/semi-intensive management systems and lack of mineral supplementation. (c) 2008 Elsevier B.V. All rights reserved.

Human twinning is not linked to the region of chromosome 4 syntenic with the sheep twinning gene FecB

The tendency to dizygotic (DZ) twinning is inherited in both humans and sheep, and a fecundity gene in sheep (FecB) maps to sheep chromosome 6, syntenic with human 4q21-25. Our aim was to see whether a gene predisposing to human DZ twinning mapped to this region. DNA was collected from 169 pairs and 17 sets of 3 sisters (trios) from Australia and New Zealand who had each had spontaneous DZ twins, mostly before the age of 35, and from a replication sample of 111 families (92 affected sister pairs) from The Netherlands. Exclusion mapping was carried out after typing 26 markers on chromosome 4, of which 8 spanned the region Likely to contain the human homologue of the sheep FecB gene. We used nonparametric affected sib pair methods for linkage analysis [ASPEX 2.2, Hinds and Risch, 1999]. Complete exclusion of linkage (lod < -2) of a gene conferring a relative risk for sibs as low as 1.5 ((s) > 1.5) was obtained for all but the p terminus region on chromosome 4. Exclusion in the syntenic region was stronger, down to lambda (s) = 1.3. We concluded that if there is a gene influencing DZ twinning on chromosome 4, its effect must be minor. (C) 2001 Wiley-Liss, Inc.

A single nucleotide polymorphism in the 5' untranslated region of RAD51 and risk of cancer among BRCA1/2 mutation carriers

RAD51 colocalizes with both BRCA1 and BRCA2, and genetic variants in RAD51 would be candidate BRCA1/2 modifiers. We searched for RAD51 polymorphisms by sequencing 20 individuals. We compared the polymorphism allele frequencies between female BRCA1/2 mutation carriers with and without breast or ovarian cancer and between population-based ovarian cancer cases with BRCA1/2 mutations to cases and controls without mutations. We discovered two single nucleotide polymorphisms (SNPs) at positions 135 g-->c and 172 g-->t of the 5' untranslated region. In an initial group of BRCA1/2 mutation carriers, 14 (21%) of 67 breast cancer cases carried a c allele at RAD51:135 g-->c, whereas 8 (7%) of 119 women without breast cancer carried this allele. In a second set of 466 mutation carriers from three centers, the association of RAD51:135 g-->c with breast cancer risk was not confirmed. Analyses restricted to the 216 BRCA2 mutation carriers, however, showed a statistically significant association of the 135 c allele with the risk of breast cancer (adjusted odds ratio, 3.2; 95% confidence limit, 1.4-40). BRCA1/2 mutation carriers with ovarian cancer were only about one half as likely to carry the RAD51:135 g-->c SNP. Analysis of the RAD51:135 g-->c SNP in 738 subjects from an Israeli ovarian cancer case-control study was consistent with a lower risk of ovarian cancer among BRCA1/2 mutation carriers with the c allele. We have identified a RAD51 5' untranslated region SNP that may be associated with an increased risk of breast cancer and a lower risk of ovarian cancer among BRCA2 mutation carriers. The biochemical basis of this risk modifier is currently unknown.

Liveweight gains of steers at different stocking rates on monospecific Gatton panic and Estrella grass pastures in the Chaco Central region of Paraguay

A grazing trial to study the effect of stocking rate on animal production and botanical composition of Gallon panic (Panicum maximum) and Estrella grass (Cynodon nlemfuensis) was conducted in the central region of the Paraguayan Chaco between 1992 and 1998. The experiment included 6 stocking rates (0.5, 0.8. 1.1, 1.4. 1.7 and 2.0 AU/ha) on individual 4-ha paddocks. The pasture treatments were continuously grazed by yearling steers. replaced annually, over a 4-year grazing period. No fertiliser was used. Botanical composition was recorded annually in autumn from 1992 to 1998 while animal production data were recorded monthly from 1992 to 1996. Relationships between animal productivity and stocking rates were determined by regression analysis. Gallon panic produced greater liveweight gains per head than Estrella grass at low and intermediate stocking rates. However, the slope of the linear relationship between liveweight gain per head and stocking rate increased each year in Gallon panic indicating that the productivity of this grass progressively declined at higher stocking rates over the period of observation. Estrella grass showed less sensitivity to stocking rate but was affected severely by periods of low rainfall.

Isolation of arboviruses from mosquitoes (Diptera : Culicidae) collected from the Gulf Plains region of northwest Queensland, Australia

As part of investigations into Japanese encephalitis (JE) virus and related flaviviruses in northern Australia, 153,529 mosquitoes were collected and processed for virus isolation from the Gulf Plains region of northwest Queensland. Collections front within 30 km of each of the townships of Croydon, Normanton and Karumba yielded 3,087 (2.0%), 66,009 (43.0%), and 84,433 (55.0%) mosquitoes, respectively, from which 16 viruses were isolated. Four isolates of Murray Valley encephalitis (MVE), two of Kunjin (KUN), three of Ross River (1111), and one of Sindbis (SIN) viruses were obtained from Culex sitiens subgroup mosquitoes. Molecular identification of the mosquito species composition of these virus positive pools revealed that most isolates were from pools containing mainly Culex annulirostris Skuse and low numbers of Cidex palpalis (Taylor). Only three pools, one each of MVE, KUN, and RR, were from mosquitoes identified exclusively as Cx. annulirostris. Other viruses isolated include one Edge Hill Virus from Ochlerotatus normanensis (Taylor), an isolate of SIN from Anopheles meraukensis Venhuis, two isolates of RR from Anopheles amictus Edwards, and single isolates of RR from Anopheles bancroftii Giles and Aedes lineatopennis (Ludlow). The isolate of RR from Ae. lineatopennis was the first reported from this species. The public health implications of these isolations in the Gulf Plains region are discussed briefly.

Epizootic activity of Murray Valley encephalitis virus in an aboriginal community in the southeast Kimberley region of western Australia: Results of cross-sectional and longitudinal serologic studies

Murray Valley encephalitis (MVE) virus is a mosquito-borne flavivirus causing severe encephalitis with a resultant high morbidity and mortality. In the period 1989-1993. we undertook a cross-sectional and longitudinal studs by annually screening members of a small remote Aboriginal community in northwestern Australia for MVE virus antibodies. Of the estimated 250-300 people in the community. 249 were tested, and 52.6% had positive serology to MVE. The proportion testing positive increased with increasing age group. and males were slightly more likely to be positive than females. During the study period. a high proportion of the population seroconverted to MVE: the clinical/subclinical ratio seems to be lower than previously reported. Although MVE is mostly asymptomatic, the devastating consequences of clinical illness indicate that advice should be provided regarding the avoidance of mosquito bites. Our longitudinal study showed that the risk of seroconversion was similar for each age group. not just the young.

Simulation of the micro-physics of rocks using LSMearth

The particle-based Lattice Solid Model (LSM) was developed to provide a basis to study the physics of rocks and the nonlinear dynamics of earthquakes (MORA and PLACE, 1994; PLACE and MORA, 1999). A new modular and flexible LSM approach has been developed that allows different microphysics to be easily included in or removed from the model. The approach provides a virtual laboratory where numerical experiments can easily be set up and all measurable quantities visualised. The proposed approach provides a means to simulate complex phenomena such as fracturing or localisation processes, and enables the effect of different micro-physics on macroscopic behaviour to be studied. The initial 2-D model is extended to allow three-dimensional simulations to be performed and particles of different sizes to be specified. Numerical bi-axial compression experiments under different confining pressure are used to calibrate the model. By tuning the different microscopic parameters (such as coefficient of friction, microscopic strength and distribution of grain sizes), the macroscopic strength of the material and can be adjusted to be in agreement with laboratory experiments, and the orientation of fractures is consistent with the theoretical value predicted based on Mohr-Coulomb diagram. Simulations indicate that 3-D numerical models have different macroscopic properties than in 2-D and, hence, the model must be recalibrated for 3-D simulations. These numerical experiments illustrate that the new approach is capable of simulating typical rock fracture behaviour. The new model provides a basis to investigate nucleation, rupture and slip pulse propagation in complex fault zones without the previous model limitations of a regular low-level surface geometry and being restricted to two-dimensions.

Single-chain antibodies produced by phage display against the C-terminal 19 kDa region of merozoite surface protein-1of Plasinodium yoelii reduce parasite growth following challenge

Antibodies have the potential to be therapeutic reagents for malaria. Here we describe the production of a novel phage antibody display library against the C-terminal 19 kDa region of the Plasmodium yoelii YM merozoite surface protein-1 (MSP1(19)). In vivo studies against homologous lethal malaria challenge show an anti-parasite effect in a dose dependent manner, and analysis by plasmon resonance indicates binding to the antigen is comparable to the binding of a protective monoclonal antibody. The data support the lack of a need for any antibody Fc-related function and hold great significance for the development of a therapeutic reagent for malaria. (C) 2002 Elsevier Science Ltd. All rights reserved.