ABSTRACT
The genus Giardia is a unicellular protozoan able to parasitize both humans and animals. Cysts of Giardia can be found in soil samples, aquatic environments, food, and any surface that gets in contact with the feces of parasitized animals. The aim of this systematic review was to analyze the burden and epidemiology of Giardia infection in Colombia summarizing recent scientific reports and existing knowledge and to identify knowledge gaps that may be addressed in future investigations. This work follows the guidelines established by "Preferred Reporting Items for Systematic Reviews and Meta-Analyzes" (PRISMA). Published scientific literature from 1 January 2010 to 18 September 2022 was searched in six electronic scientific databases using the search terms: "Giardia" OR "Giardiasis" AND "Colombia". Twenty-three scientific articles were performed in 22 departments of Colombia at rural, urban, and a combination of rural and urban contexts. The prevalence of Giardia in the Colombian population was between 0.9 and 48.1% when the samples were analyzed with classical microscopy; the range of Giardia prevalence was even bigger (4.2-100%) when qPCR and nested PCR were used. The dominant Giardia assemblages found in Colombia were A and B, and most frequent subassemblages were AII, BIII, and BIV.
ABSTRACT
BACKGROUND: Terrestrial ecosystems play a significant role in carbon (C) storage. Human activities, such as urbanization, infrastructure, and land use change, can reduce significantly the C stored in the soil. The aim of this research was to measure the spatial variability of soil organic C (SOC) in the national park La Malinche (NPLM) in the central highlands of Mexico as an example of highland ecosystems and to determine the impact of land use change on the SOC stocks through deterministic and geostatistical geographic information system (GIS) based methods. METHODS: The soil was collected from different landscapes, that is, pine, fir, oak and mixed forests, natural grassland, moor and arable land, and organic C content determined. Different GIS-based deterministic (inverse distance weighting, local polynomial interpolation and radial basis function) and geostatistical interpolation techniques (ordinary kriging, cokriging and empirical Bayes kriging) were used to map the SOC stocks and other environmental variables of the top soil layer. RESULTS: All interpolation GIS-based methods described the spatial distribution of SOC of the NPLM satisfactorily. The total SOC stock of the NPLM was 2.45 Tg C with 85.3% in the forest (1.26 Tg C in the A horizon and 0.83 Tg C in the O horizon), 11.4% in the arable soil (0.23 Tg in the A horizon and only 0.05 Tg C in the O horizon) and 3.3% in the high moor (0.07 Tg C in the A horizon and <0.01 Tg C in the O horizon). The estimated total SOC stock in a preserved part of the forest in NPLM was 4.98 Tg C in 1938 and has nearly halved since then. Continuing this trend of converting all the remaining forest to arable land will decrease the total SOC stock to 0.52 Tg C. DISCUSSION: Different factors explain the large variations in SOC stocks found in this study but the change in land use (conversion of forests into agricultural lands) was the major reason for the reduction of the SOC stocks in the high mountain ecosystem of the NPLM. Large amounts of C, however, could be stored potentially in this ecosystem if the area was used more sustainable. The information derived from this study could be used to recommend strategies to reverse the SOC loss in NPLM and other high-altitude temperate forests and sequester larger quantities of C. This research can serve as a reference for the analysis of SOC distribution in similar mountain ecosystems in central part of Mexico and in other parts of the world.
