Absence of asymptomatic malaria in schoolchildren of Quibdó, Chocó

Asymptomatic malaria is characteristic of high intensity transmission areas in Africa but unusual in low transmission areas in Latin America. Nevertheless, asymptomatic malaria has been reported to be frequent in areas in Latin America with high and moderate intensity of transmission. Asymptomatic malaria can affect both individuals who carry parasites and are cryptic carrier reservoirs for the community. Individuals chronically infected with malaria parasites are usually unidentifiable by most malaria control programmes. In order to identify whether asymptomatic individuals harboring malaria parasites are an important reservoir of infection in Quibdó, Chocó, the prevalence of asymptomatic malaria was assessed in schoolchildren. This study was part of a major study of the epidemiology of malaria in Quibdó. A total of 255 children from 5 schools were examined, of which 223 were included in the analysis. Children reported headache (34%), cough (32%), and diarrhoea (9%). None of the children presented a positive thick smear. In addition, IFA tests in a subsample of 25 children were negative. By these criteria, the prevalence of asymptomatic malaria in Quibdó schoolchildren is 0% (95%C.I.: 0.0-1.4). Although asymptomatic malaria in adults possibly occurs, a very low prevalence is predicted.     

Factors determining annual changes in bacterial photosynthetic pigments in holomictic lake cisó, Spain

The pigments and biomass of anoxygenic phototrophic bacteria were measured during a year cycle in Lake Cisó (Girona, Spain). Two genera, Chromatium and Chlorobium, accounted for most of the bacterial population. The bacteria were present throughout the year despite complete mixing of the lake during fall and winter. This was possible because the sulfide production in the sediment was high enough to make the lake anaerobic to the very surface. Solar radiation, temperature, and biomass of Chromatium sp. were found to be important in determining pigment concentrations by correlation analysis. Sulfide concentration and biomass of Chlorobium spp. were found to be unimportant. A path analysis was performed to determine what percentage of the variability of pigments could be explained by the variables studied. Since a high percentage could be explained, it was possible to conclude that solar radiation, temperature, and biomass of Chromatium sp. were the main variables.     

Trace metal contents in water and sediments in Samborombón Bay wetland,Argentina

Samborombón Bay is the most extensive myxohaline wetland of Argentina. This Ramsar site is considered a priority area for the conservation of biodiversity in the country. Numerous rivers and channels that drain the Pampean plain, such as the Salado River and the channels Lower Salado, 15, 9, A, 1, and 2, cross this wetland and flow into Samborombón Bay. Trace metal concentration (As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn) in water and sediments were determined in low and high water periods. In the first case, contents were higher than the Guide Levels for the Protection of the Aquatic Biota (GLPAB) in most of the sampling stations. In high water period, only As and Zn were detected. Relevant physico-chemical parameters were analyzed by a principal component analysis (PCA). Trace metal concentrations in sediments suggest, as a whole, that this wetland has been so far exposed to low to moderate levels of anthropic influence. It must be emphasized however, that the presence of metals in both the water and sediments of this bay might have negative effects on the biota and on the regional trophic web.     

High Blood Pressure among Students in Public and Private Schools in Maceió, Brazil

The prevalence of hypertension in childhood is increasing, and investigation of its distribution is important for planning timely interventions. This study assessed the prevalence of high blood pressure (HBP) and associated factors in students between 9 and 11 years of age enrolled in public and private schools in Maceió, Brazil. A cross-sectional study was performed in a probabilistic sample of students (10.3 ± 0.5 years). The students were selected from a systematic sampling of 80 schools (40 public and 40 private). To maintain similar proportions of students existing in public and private schools in Maceió, 21 and 14 students were randomly selected from each public and private school, respectively. The prevalence ratio (PR) was estimated using Poisson regression. A total of 1,338 students were evaluated (800 from public schools and 538 from private schools). No differences were observed between school types in terms of student age and gender (p > 0.05). The prevalence of obesity (19.9% vs. 9.0%; PR = 2.2; 95% CI = 1.67–2.92) and hypertension (21.2% vs. 11.4%; PR = 1.86; 95% CI = 1.45–2.40) were higher in private schools. The association between high blood pressure and type of school (public or private) remained statistically significant even after adjustment for obesity (PR = 1.53; 95% CI = 1.19–1.97). In conclusion: (a) students from private schools have higher socioeconomic status, BMI, and HBP prevalence compared to those of public school; (b) among the evaluated students, the prevalence of obesity only partially explained the higher prevalence of high blood pressure among students from private schools. Other factors related to lifestyle of children from private schools may explain the higher prevalence of HBP. This results show the need to implement measures to promote healthy lifestyles in the school environment, since children with HBP are more likely to become hypertensive adults. Therefore, early detection and intervention in children with HBP is an important action for the prevention of hypertension in adulthood.     

Isonymous structure in the white population of Córdoba, Argentina, in 1813

Surnames analysis is useful for populations in which only written documents remain, as is the case for historical populations. In Córdoba province, Argentina, census records contain nominal data of inhabitants, including information on sex, age, ethnosocial category, civil status, occupation, place of birth, and residence, that can be analyzed using surnames. Relationship indicators within and among ecclesiastic units in Córdoba were estimated by isonymy for the adult white population registered in the 1813 census. The Rii, Rij, and R(ST) coefficients and the surname abundance indicator (a) were calculated. Lasker's distances among categories of population units were used to cluster the 16 provincial population categories. Gradients for kinship within population and for surname diversity were in agreement with the principal areas and waves of original settlement in the province. The main population clusters reflect those areas, whereas minor clusters coincide with the network of roads existing in the territory by 1813. The structure of the white population in Córdoba province was determined by the geographic location of the original waves of settlement, and it followed a pattern of relationships conditioned by the routes connecting population units in the Colonial period.     

Vegetation in a high Andean transect between Turi and Cerro León in Northern Chile

This paper reports the results of a phytosociological and gradient analysis of the vegetation occurring along an altitudinal gradient from Turi (3100 m) to Cerro León (4250 m) on the western flank of the Andes in northern Chile (22°06′–22°22′ S; 68°15′–68°07′ W). Along the transect, the total cover of vegetation ranges from 2.5% at the lower end to 35.7% at 4000 m altitude. Four major physiognomic zones, including six associations are recognized within the transect studied: (1) The ‘Pre-Puna’ belt (2700–3150 m), characterized by a sparse cover of xerophytic subshrubs, including two associations: Acantholippia deserticola-Franseria meyeniana, which occurs over the sedimentary sands around Turi, and Franseria meyeniana-Helogyne macrogyne-Helianthocereus atacamensis, restricted to ravines and canyons. (2) The ‘Puna’ belt (3150–3850 m), physiognomically dominated by shrubs and presenting the highest vegetational cover, including the: Fabiana densa-Baccharis boliviensis, and Junellia seriphioides-Baccharis incarum-Lampaya medicinalis, associations. (3) The ‘High-Andean’ belt, localized above the ‘Puna’, including the Fabiana bryoides-Adesmia horrida and Oxalis exigua-Mulinum crassifolium associations. (4) The ‘Subnival’ belt, a high mountain semi-desert with a poorly developed vegetation. Only three species occur at the upper vegetational limit (4380 m). The phytosociological scheme proposed in this paper can be paralleled with that by Ruthsatz (1977) for the eastern flank of the Andes. A marked contrast in species richness and phytosociological complexity between these Andean regions is pointed out. Lower species richness of the Chilean transect is related to the presence of the Atacama desert, which extends from the coast up to 2700 m in the study area.     

Contact in the Andes: bioarchaeology of systemic stress in colonial Mórrope, Peru

The biocultural interchange between the Eastern and Western Hemispheres beginning in the late fifteenth century initiated an unprecedented adaptive transition for Native Americans. This article presents findings from the initial population biological study of contact in the Central Andes of Peru using human skeletal remains. We test the hypothesis that as a consequence of Spanish colonization, the indigenous Mochica population of Mórrope on the north coast of Peru experienced elevated systemic biological stress. Using multivariate statistical methods, we examine childhood stress reflected in the prevalence of linear enamel hypoplasias and porotic hyperostosis, femoral growth velocity, and terminal adult stature. Nonspecific periosteal infection prevalence and D(30+)/D(5+) ratio estimations of female fertility characterized adult systemic stress. Compared to the late pre-Hispanic population, statistically significant patterns of increased porotic hyperostosis and periosteal inflammation, subadult growth faltering, and depressed female fertility indicate elevated postcontact stress among both children and adults in Mórrope. Terminal adult stature was unchanged. A significant decrease in linear enamel hypoplasia prevalence may not indicate improved health, but reflect effects of high-mortality epidemic disease. Various lines of physiological, archaeological, and ethnohistoric evidence point to specific socioeconomic and microenvironmental factors that shaped these outcomes, but the effects of postcontact population aggregation in this colonial town likely played a fundamental role in increased morbidity. These results inform a model of postcontact coastal Andean health outcomes on local and regional scales and contribute to expanding understandings of the diversity of indigenous biological variation in the postcontact Western Hemisphere.     

Outbreak of Rocky Mountain spotted fever in Córdoba, Colombia

Rocky Mountain spotted fever (RMSF) is a tick-borne disease caused by the obligate intracellular bacterium Rickettsia rickettsii. Although RMSF was first reported in Colombia in 1937, it remains a neglected disease. Herein, we describe the investigation of a large cluster of cases of spotted fever rickettsiosis in a new area of Colombia.     

Ichthyoplankton from the pier area in Limón, Costa Rica

Four sampling stations were set 200-500 m off Limon Port, Costa Rica, at an average depth of 20 m. From October 1996 to May 1997 horizontal subsuperficial trawls were done for 12 minutes at a speed of about 2 Km/h, with a 1,000 microns plancton net. A total of 28 samples were processed and 104 physical-chemistry parameter measurements were taken. Average salinity was 30.1 +/- 3.7 and dissolved oxygen 6.9 +/- 0.6 mg l-1 reflecting good aeration throughout the sampling period. This suggests good mixture and a highly dynamic hydrography. Temperature showed no drastic variations (28.0 +/- 1.7 degrees C), possibly because of the constant mixing with shallow water. The highest larval counts were for November and early January and include families common to reefs and estuaries (Balistidae, Lutjanidae) and to coastal areas (Centropomidae, Gerreidae, Haemulidae, Carangidae, Engraulidae, Hemiramphidae, and representative Pleuronectiformes) existing in a common area.