Molecular surveillance of dengue virus in Bahia State, Brazil

Dengue is an important emerging viruses, posing a threat to one-third of the global human population. In 2002, the introduction of DENV-3 in the state of Bahia produced massive epidemic (about 35,000 cases detected) and the first cases of dengue hemorrhagic fever. To understand the nature of the virus circulating at Bahia, E/NS1 sequence was determined for 31 DENV viruses isolated in Bahia during the 2006 and 2007 transmission season, from patients presenting with different degrees of severity. The carboxi-terminal region of the E gene (220 nt) of 31 viruses, isolated from dengue patients with clinical diagnosis of dengue infection were used to determine the genetic variability of dengue 2 (DENV-2) and dengue 3 (DENV-3). Sequence data were used in phylogenetic comparisons with global samples of DENV-2 and DENV-3. DENV-2 sample grouped in the South East Indian genotype, while DENV-3 samples were grouped within Indian genotype. This study is the first report on Bahia isolates during two transmission seasons. Our data confirms reports from other parts of Brazil and different countries showing the DENV-3 (geno-type III) strains circulating in the Americas are closely related, and cluster within the genotype that has been associated with DHF epidemics in different conti-nents.

Apparent soil electrical conductivity in the delineation of management zones for cocoa cultivation

Apparent electrical conductivity is an important parameter for describing the spatial vari-ability of physical and chemical attributes of the soil and for the delineation of manage-ment zones.The objective of this work is to outline management zones for the cocoa cultivation based on the spatial variability of the productivity and the apparent electrical conductivity(ECa)of the soil.Data collection was performed in a regular sample grid con-taining 120 points in an area cultivated with cocoa trees,located in the municipality of Ilhe´us,state of Bahia,Brazil.At each sampling point(cocoa tree),soil samples were col-lected to determine chemical attributes.Productivity was measured for one year,counting,monthly,the number of fruits,which were classified into off-season cocoa,harvest and annual production.Measurements of the apparent electrical conductivity of the soil were performed at different times of the year using a portable conductivity meter.The data were analyzed using classical statistics and geostatistics.The management zones were delin-eated using the fuzzy k-means algorithm.The ideal number of class was defined using the fuzziness performance index(FPI)and the entropy of the modified partition(MPE)indexes.The Kappa coefficient was used to validate the management zones,assessing their agreement with the chemical attributes of the soil.The ECa of the soil values pre-sented moderate temporal variation,with maximum amplitude of 19.37 mS m1 and min-imum of 0.82 mS m1 between measurement periods;higher averages of the ECa coincided with the highest levels of water in the soil.The measurements of the ECa of the soil carried out in April and October showed greater correlation with the chemical attributes of the soil,with significant values for 11 and 8 of the 17 attributes evaluated,respectively.The man-agement zones from the ECa measured in April showed:a)reduced number of classes;b)spatial continuity between classes,and;c)agreement from reasonable(kappa between 0.20 and 0.40)to good(kappa>0.41)with most of the chemical attributes of the soil.The ECa of the soil measured in April is, individually, the variable recommended for the man-agement of soil fertility in tropical areas cultivated with cocoa trees.