Revista Cubana de Medicina Tropical最新文献

Introduction: in the last few years, a lot of importance has been given to natural predators against Aedes aegypti. Several organisms have been studied both in lab and in the field so as to find out their capacity to devour mosquito larvae. High densities of Macrobrachium tenellum are found in natural conditions, it is not aggressive and may stand wide ranges of temperature, rates of salinity and oxygen concentrations.

Objective: to evaluate the predatory capacity of Macrobrachium tenellum on Aedes aegypti larvae in lab conditions.

Methods: very young Macrobrachium tenellum prawns measuring A(3.0-3.5cm) and B (4.5-5 cm) were used. The mosquito larvae were obtained after hatching of egss from adult females kept in entomological cages. Five, ten, fifteen and twenty Aedes aegypti larvae were placed per treatment per rank, whereas the second bioassays adjusted the number of larvae to 30, 40, 50 and 80 larvae per treatment per rank.

Results: Macrobrachium tenellum showed high rate of larval consumption for the two ranks and treatments. In the highest density (80 larvae), the consumption was 95% of larvae at 24 hours for rank A and 100% for rank B.

Conclusions: Macrobrachium tenellum may be considered as a potential biological control agent, due to its abundant presence in natural conditions, its resistance to different environmental conditions and to its voraciousness seen in this study.

Introduction: Bacillus thuringiensis H-14 has shown high efficacy on Aedes aegypti larvae. But a number of factors could affect its effectiveness. Knowing these factors is of vital importance for improving the application parameters in real conditions in order to guarantee the treatment's efficiency and to reduce environmental impact.

Objective: to evaluate the influence of some biotic factors on Bacillus thuringiensis H-14 efficacy against Aedes aegypti (Rockefeller).

Methods: an experimental study was conducted following the WHO guidelines. The influence of the food availability, the larval density and the larval staging was evaluated on laboratory bioassays. A commercial Bacillus thuringiensis H-14 formulation against a reference Aedes aegypti strain was used.

Results: the efficacy of Bacillus thuringiensis H-14 decreased in a linear manner with increasing larval density and development stage. This could be related to food intake and availability of the active principle. Competition in food intake resulted in lower efficacy of Bacillus thuringiensis H-14 applications.

Conclusions: the Bacillus thuringiensis H-14 efficacy was affected for the availability of food, the larval development stage and the larval density, so all this should be borne in mind when applying the biolarvicide in situ.

Introduction: schistosomiasis is kept under epidemiolotical surveillance in some areas of Brazil.

Objective: to evaluate the epidemiological situation of schistosomiasis in the city of Belo Horizonte in Minas Gerais, Brazil, through epidemiological indicators.

Methods: a descriptive study was conducted by using the System of Information and Notification of Grievances (SINAN) that contains the cases occurred in the residents of Belo Horizonte in the period of January-2007 to July-2011. Four hundred ninety six lab confirmed cases of schistosomiasis(Kato-Katz technique) were recorded.

Results: in this period, there was a considerable increase of the number of cases in 2007 when the incidence was 1.96/100 000 habitants; the incidence was 7.29/100 000 habitants until July, 2011.

Conclusions: the increasing number of recent cases points to the need of developing new strategies to control this endemic disease in our region.

Introduction: development of new antituberculosis vaccines requires the characterization of the cell-mediated immune responses induced by mycobacterial antigens.

Objective: to determine the immunogenic potential of 'Mycobacterium habana' TMC-5135 when using subcutaneous vaccine in Balb/c mice.

Methods: in this study, Balb/c mice were inoculated subcutaneously with live 'Mycobacterium habana' TMC-5135. The production of IFN gamma in cell suspensions obtained from the lungs, the spleen and the lymph nodes after stimulation with mycobacterial antigens Ag85b or culture filtrate antigens (CFA) was recorded.

Results: the production of IFN gamma after stimulation with CFA and Ag85b was higher in mice vaccinated with 'M. habana' than in animals immunized with BCG.

Conclusions: these results encourage new research on 'M. habana' as vaccinal candidate against tuberculosis.

Introduction: some physioecological responses from rodents may be registered through the study of morphological indexes, which is an important factor for the control of rodents.

Objectives: to compare the morphophysiological variables in two rat populations and relate them to the ectoparasite loads.

Methods: this study was carried out from 2007 to 2008 in two sites of La Habana province. Specially prepared traps to catch rats alive were used. Four morphophysiological indexes were studied and then compared through a variance analysis for the two sites.

Results: one hundred four Rattus rattus (83.6 %) and Rattus norvegicus (16.4 %) were analyzed. The relative kidney index showed highly significant different between the rat populations. The morphophysiological indexes were lower in parasitized animals. The ecological importance and the implications of these indexes for the control of obtained results were discussed in this paper.

Conclusions: the morphophysiological analysis proved that the necessary resources for the survival of these species are available, which favors that both rat sexes bear the ectoparasite load in a better way, and thus they represent parasite reservoirs and a permanent transmission risk.

Introduction: the studies on population's knowledge and perceptions of infectious diseases contribute to develop more effective communication processes.

Objective: to evaluate the knowledge and the perception of the residents in Habana Vieja municipality about tuberculosis, and to identify the ways for obtaining information about aspects of this disease.

Methods: a cross-sectional study was carried out. A questionnaire was applied on a sample of 86 persons from five health areas of the municipality. A descriptive analysis was made. Odds ratios were calculated to determine association between ways for obtaining information and knowledge on the existence of the disease, symptoms and transmission forms.

Results: the respondents know about tuberculosis as a disease, its symptoms, and its presence in Cuba, but the percentages corresponding to the truly significant symptoms are low, including incorrect identifications of towel, comb and mosquitoes as transmission ways of the disease. Television, radio and friends were the most mentioned sources of information.

Conclusions: the population from Habana Vieja municipality knows about the existence of TB. However, specific knowledge about symptoms of the disease and ways of transmissions are insufficient. Changing this situation requires the strengthening of the role of the mass media role and the development of local communication strategies suited to local characteristics.

Introduction: viral DNA levels in serum samples are a useful marker to monitor the disease progression and the treatment response in patients with chronic hepatitis B. Commercial kits for this purpose are available, but they are considerably expensive.

Objectives: to evaluate the analytical performance of a real-time polymerase chain reaction (RT-PCR) assay for Hepatitis B virus DNA quantification.

Methods: specific primers to the gene C and TaqMan chemistry in a LightCycler 1.5 equipment was used. A standard curve was made and evaluated. Two hundred and seventy-two serum samples were used to assess the clinical and analytical specificity, the genotypic accuracy and specificity, the intra-assay and interassay coefficients of variation and the comparison with a commercial assay and with the qualitative PCR.

Results: the standard curve showed a strong linear correlation (r= -1) and low error values in the tested target DNA concentration. Analytical and clinical specificities were 100 %. Genotype accuracy and specificity showed that the differences between the results obtained by RT-PCR assay and those of the reference assay were less than 0.5 Log10. The 95% HBV DNA detection end-point assessed by Probit analysis was 16.41 IU/microL with a dynamic range of quantification of 10(8) IU/mL. Intra-assay and interassay coefficients of variation ranged from 0.16 to 1.45 % and 0.9 to 2.62 % respectively. The RT-PCR assay correlated well with those from a commercial assay (r= 0.964 and r2= 0.929) and with the HBV qualitative PCR, thus confirming its better sensitivity and advantages.

Conclusions: the RT-PCR assay is well suited to monitoring HBV DNA levels showing to be sensitive, specific and reproducible. Its application in the clinical practice ensures a better diagnosis and management of patients with chronic hepatitis B in Cuba.

Introduction: the integration of chemical and biological methods is one of the strategies for the vector control, due to the existing environmental problems and the concerns of the community as a result of the synthetic organic insecticide actions. The bacterium called Bacillus thuringiensis var. israelensis in liquid formulation has been widely used in the vector control programs in several countries and has shown high efficacy at lab in Cuba.

Objective: to determine the susceptibility of Aedes aegypti collected in the municipalities of La Habana province to Bacillus thuringiensis var. israelensis.

Methods: fifteen Aedes aegypti strains, one from each municipality, were used including larvae and pupas collected in 2010 and one reference strain known as Rockefeller. The aqueous formulation of Bacillus thuringiensis var. israelensis (Bactivec, Labiofam, Cuba) was used. The bioassays complied with the World Health Organization guidelines for use of bacterial larvicides in the public health sector. The larval mortality was read after 24 hours and the results were processed by the statistical system SPSS (11.0) through Probit analysis.

Results: the evaluated mosquito strains showed high susceptibility to biolarvicide, there were no significant differences in LC50 values of Ae. aegypti strains, neither in the comparison of these values with those of the reference strain.

Conclusions: the presented results indicate that the use of Bacillus thuringiensis var. israelensis continues to be a choice for the control of Aedes aegypti larval populations in La Habana province.

Introduction: the search of new antimalarial compounds comprises, among its challenges, the development of therapeutic alternatives for cerebral malaria; due to the high mortality and neurological deficiencies that persist after treatment with recommended drugs.

Objectives: to evaluate the activity of organic fractions of Mycale laxissima and Clathria echinata in the cerebral malaria model of infection of C57BL/6 mice with Plasmodium berghei ANKA.

Methods: preparative fractions of both species were obtained by reverse-phase flash chromatography. In order to detect the presence of saponins, triterpenods/steroids and alkaloids, a qualitative chemical analysis was performed. The schyzontocidal effect of the extracts was determined by the suppression test at the beginning of the infection. Survival, neurological symptoms and body weight changes were evaluated in subsequent days.

Results: the organic fractions of Mycale laxissima at 200 mg/kg and Clathria echinata at 100 mg/kg showed neither substantial reductions of body weights, nor deaths of animals until day 4; but caused significant reductions of median parasitemia of 45 % and 53 % respectively. The fraction of Mycale laxissima at 200 mg/kg caused a significant increase in the median survival time up to day 20, whereas animals treated with Clathria echinata at 100 mg/kg presented a survival of 16 days. Both increases the survival time 7 days. Neurological alterations were not observed in the groups treated with organic fractions when compared to the control group. This survival extension was similar to the effect of administration of 7.5 mg/kg of chloroquine.

Conclusions: the organic fractions of Mycale laxissima and Clathria echinata exhibited promising antimalarial activities in the infection model of C57BL/6 mice with Plasmodium berghei ANKA. This indicates that their active chemical constituents should be studied.