Molecular Prevalence and Subtypes Distribution of Blastocystis spp. in Humans of Latin America: A Systematic Review

Blastocystis spp. are among the few enteric parasites with a prevalence that can reach up to approximately 80% in communities of developing countries. This systematic review updates and summarizes available literature on the molecular prevalence and subtype distribution of Blastocystis spp. in Latin American people. This work follows the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The literature revised covers from 1 January 2015 to 6 October 2023 in seven different scientific databases, and the material was selected through inclusion and exclusion criteria. According to data found in the 36 selected articles, the prevalence of Blastocystis spp. in Latin America ranged between 5.8% (Bolivian rural communities) and 94.0% (Colombian general public). Generally, genomic DNA was extracted from approximately 200 mg fecal sediments using commercial kits, such as the QIAamp Stool Mini Kit (QIAGEN, Hilden, Germany) or the Norgen Stool DNA Isolation Kit (Norgen Biotek Corporation, Thorold, ON, Canada). Subtype-specific primers (such as the couple of primers BhRDr-RD5) developed from unique sequences of the SSU rRNA gene were applied to Blastocystis subtyping. Ten specific subtypes (STs) were found as well as various mixed infections, and the most circulating Blastocystis STs were in the order ST3, ST1, ST2, and ST4. The most recent data about Blastocystis spp. molecular epidemiology and the STs in communities of Latin America are limited to studies from specific countries. Novel scientific data from the other countries are required to obtain a complete picture and truly understand the distribution and prevalence of Blastocystis spp. and the STs.

Burden and Epidemiology of Human Intestinal Giardia duodenalis Infection in Colombia: A Systematic Review

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.

Molecular identification of Giardia spp. in Latin America: An updated systematic review on reports from 2017 to 2021

Background: Giardia spp. is the most common protozoan found in coproparasitoscopic tests; it is the cause of gastrointestinal discomfort, with a high prevalence in children and in low-income areas. This systematic review updates available literature on molecular identification of Giardia spp. in Latin America during 2017 to 2021. Methodology: The guidelines established in Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) were used; the study covers the period from January 1, 2017 to October 03, 2021; the search focused on the “molecular identification of Giardia spp. in Latin America” in six different scientific databases. The material found was reviewed to select only those papers that met the inclusion and exclusion criteria. Results: The search yielded 1036 publications, but only 19 investigations in 6 countries (Brazil, Colombia, Cuba, Ecuador, Mexico, and Venezuela) met the selection criteria. Most were cross-sectional studies carried out in school-age children, the dominant assemblages were A and B while the most frequent subassemblages were AII, BIII and BIV, the most used target genes were tpi and gdh, the prevalence by molecular methods was higher regarding microscopy, the countries with the highest prevalence percentages for Giardiosis were Brazil and Cuba. Conclusions: More Latin America countries need to generate data of prevalence, incidence, and intensity of Giardiosis. Studies are also needed to estimate the costs of Giardiosis on economic productivity and public health. The present systematic review offers evidence based on the current literature available for the molecular identification of Giardia spp. in Latin America during 2017 to 2021.

Using demographic data to understand the distribution of H1N1 and COVID-19 pandemics cases among federal entities and municipalities of Mexico

Background

The novel coronavirus disease (COVID-19) pandemic is the second global health emergency the world has faced in less than two decades, after the H1N1 Influenza pandemic in 2009–2010. Spread of pandemics is frequently associated with increased population size and population density. The geographical scales (national, regional or local scale) are key elements in determining the correlation between demographic factors and the spread of outbreaks. The aims of this study were: (a) to collect the Mexican data related to the two pandemics; (b) to create thematic maps using federal and municipal geographic scales; (c) to investigate the correlations between the pandemics indicators (numbers of contagious and deaths) and demographic patterns (population size and density).

Methods

The demographic patterns of all Mexican Federal Entities and all municipalities were taken from the database of “Instituto Nacional de Estadística y Geografía” (INEGI). The data of “Centro Nacional de Programas Preventivos y Control de Enfermedades” (CENAPRECE) and the geoportal of Mexico Government were also used in our analysis. The results are presented by means of tables, graphs and thematic maps. A Spearman correlation was used to assess the associations between the pandemics indicators and the demographic patterns. Correlations with a p value < 0.05 were considered significant.

Results

The confirmed cases (ccH1N1) and deaths (dH1N1) registered during the H1N1 Influenza pandemic were 72.4 thousand and 1.2 thousand respectively. Mexico City (CDMX) was the most affected area by the pandemic with 8,502 ccH1N1 and 152 dH1N1. The ccH1N1 and dH1N1 were positively correlated to demographic patterns; p-values higher than the level of marginal significance were found analyzing the % ccH1N1 and the % dH1N1 vs the population density. The COVID-19 pandemic data indicated 75.0 million confirmed cases (ccCOVID-19) and 1.6 million deaths (dCOVID-19) worldwide, as of date. The CDMX, where 264,330 infections were recorded, is the national epicenter of the pandemic. The federal scale did not allow to observe the correlation between demographic data and pandemic indicators; hence the next step was to choose a more detailed geographical scale (municipal basis). The ccCOVID-19 and dCOVID-19 (municipal basis) were highly correlated with demographic patterns; also the % ccCOVID-19 and % dCOVID-19 were moderately correlated with demographic patterns.

Conclusion

The magnitude of COVID-19 pandemic is much greater than the H1N1 Influenza pandemic. The CDMX was the national epicenter in both pandemics. The federal scale did not allow to evaluate the correlation between exanimated demographic variables and the spread of infections, but the municipal basis allowed the identification of local variations and “red zones” such as the delegation of Iztapalapa and Gustavo A. Madero in CDMX.

Knowledge, Attitude and Practices (KAP) towards COVID-19 pandemic in America: A preliminary systematic review

INTRODUCTION

On the eleventh of March 2020, the World Health Organization (WHO) declared the novel coronavirus disease 2019 (COVID-19) a pandemic by the number of cases and deaths worldwide: more than 91.1 million confirmed cases and approx. 1.9 million deaths globally, as of date. The aims of this systematic review were to identify and to evaluate the reports associated on Knowledge, Attitude and Practices (KAP) towards COVID-19 pandemic in America.

METHODOLOGY

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were adopted for searching reports published from December 2019 to September 2020, regarding "COVID-19 KAP" across six electronic databases. Inclusion and exclusion criteria were taken up to select the articles and focus to the topic.

RESULTS

Thirteen scientific papers were finally eligible and included in this systematic review. The surveys were directed to common citizens, healthcare workers and patients with chronic conditions. General public acquired information about COVID-19 mainly through social media; several misconceptions due to falsehoods circulating on-line were identified. The pandemic COVID-19 has severely affected the physical and emotional health of many people in America. Nevertheless, many American citizens do not recognize or have poor knowledge about COVID-19 risks.

CONCLUSIONS

This systematic review brings information for governments and scientific community that may be useful in the development of official awareness and prevention campaigns aiming mainly at marginated groups of the society.

Soil microbial diversity drops with land-use change in a high mountain temperate forest: a metagenomics survey

Land-use change has been identified as the most severe threat to biodiversity. Soils are important biodiversity reservoirs, but to what extent conversion of high-altitude temperate forest to arable land affects taxonomic and functional soil biodiversity is still largely unknown. Shotgun metagenomics was used to determine the taxonomic and functional diversity of bacteria, archaea and DNA virus in terms of effective number of species in high-altitude temperate oak and pine-oak forest and arable soils from Mexico. Generally, the soil ecosystem maintained its microbial species richness notwithstanding land-use change. Archaea diversity was not affected by land-use change, but the bacterial diversity decreased with 45-55% when the oak forest was converted to arable land and 65-75% when the pine-oak forest was. Loss in bacterial diversity as a result of land-use change was positively correlated (R² = 0.41) with the 10-25% loss in functional diversity. The archaeal communities were evener than the bacterial ones, which might explain their different response to land-use change. We expected a decrease in DNA viral communities as the bacterial diversity decreased, i.e. their potential hosts. However, a higher viral diversity was found in the arable than in the forest soils. It was found that converting high altitude oak and pine-oak forests to arable land more than halved the bacterial diversity, but did not affect the archaeal and even increased the viral diversity.

Land use is the main driver of soil organic carbon spatial distribution in a high mountain ecosystem

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.

Bacterial and archaeal spatial distribution and its environmental drivers in an extremely haloalkaline soil at the landscape scale

Background

A great number of studies have shown that the distribution of microorganisms in the soil is not random, but that their abundance changes along environmental gradients (spatial patterns). The present study examined the spatial variability of the physicochemical characteristics of an extreme alkaline saline soil and how they controlled the archaeal and bacterial communities so as to determine the main spatial community drivers.

Methods

The archaeal and bacterial community structure, and soil characteristics were determined at 13 points along a 211 m transect in the former lake Texcoco. Geostatistical techniques were used to describe spatial patterns of the microbial community and soil characteristics and determine soil properties that defined the prokaryotic community structure.

Results

A high variability in electrolytic conductivity (EC) and water content (WC) was found. Euryarchaeota dominated Archaea, except when the EC was low. Proteobacteria, Bacteroidetes and Actinobacteria were the dominant bacterial phyla independent of large variations in certain soil characteristics. Multivariate analysis showed that soil WC affected the archaeal community structure and a geostatistical analysis found that variation in the relative abundance of Euryarchaeota was controlled by EC. The bacterial alpha diversity was less controlled by soil characteristics at the scale of this study than the archaeal alpha diversity.

Discussion

Results indicated that WC and EC played a major role in driving the microbial communities distribution and scale and sampling strategies were important to define spatial patterns.

Upper gastrointestinal motor abnormalities in children with active celiac disease

Although from the clinical point of view a GI motor disorder can be suspected in celiac disease, objective evidence for this is still lacking. We therefore conducted a study on children with active celiac disease to detect possible GI motor abnormalities in this disease. Fourteen children (age range, 1-13 years) were studied; they underwent fasting and fed manometric recordings in the gastroduodenojejunal area. Four patients were restudied after a 6-month gluten-free diet. Data were compared with those obtained in eight control children. As compared with controls, celiac disease patients showed a shorter duration of activity fronts (p < 0.01) and a significant (p < 0.01) reduction of the postprandial antral motility index; furthermore, > 90% of the patients displayed marked fasting and/or fed motor abnormalities, suggesting a neuropathic disorder. Interestingly, gut dysmotilities disappeared in the four subjects reassessed after the gluten-free diet. It is concluded that celiac disease frequently affects the motor behavior of the gut and that its effects may be reversed by appropriate diet.

Abnormal gastrointestinal motility in patients with celiac sprue

No study to date has objectively investigated whether the motor behavior of the small bowel is abnormal in celiac sprue. The purpose of this study was to systematically address this topic by means of intraluminal pressure recordings in a series of such patients. Sixteen subjects (nine adults, seven children, age range 2-69 years) with celiac sprue were recruited and studied while untreated. Manometric examination was carried out for 6 hr during fasting and 3 hr after a meal. Adult celiac patients displayed a significantly (mean +/- SEM) greater frequency of migrating motor complexes in comparison to controls during fasting (4.44 +/- 1.6 vs 2.45 +/- 0.20, P < 0.01), whereas no differences were found in the pediatric group with respect to this variable. Fasting motor abnormalities, chiefly represented by discrete clustered contractions, giant jejunal contractions, and bursts of nonpropagated contractions, were discovered in a high percentage in both groups of celiac subjects (89% in adults and 44% in children, respectively). Similar abnormalities were observed in the postprandial period, especially in adults. In conclusion, patients with celiac sprue frequently display discrete gastrointestinal motor abnormalities, which though perhaps nonspecific may account for several symptoms complained of by such patients.

Anorectal manometric abnormalities and colonic propulsive impairment in patients with severe chronic idiopathic constipation

Idiopathic chronic constipation is a frequent and disabling symptom, but its pathophysiological grounds are still poorly understood. In particular, there is little knowledge about the relationships between distal (anorectal area) and proximal (colonic area) motor abnormalities in this condition, especially concerning high-amplitude propagated colonic activity. For this purpose, we studied 25 patients complaining of severe idiopathic constipation and categorized them as normal- or slow-transit constipation according to colonic transit time. Twenty-five age-matched controls were also studied. Investigations included standard anorectal motility testing and prolonged (24-hr) colonic motility studies. Analysis of results showed that both groups of constipated patients displayed significantly different (P < 0.05) minimum relaxation volumes of the internal anal sphincter, defecatory sensation thresholds, and maximum rectal tolerable volumes with respect to controls. Patients with normal-transit constipation also showed lower internal anal sphincter pressure with respect to slow-transit constipation and controls (P < 0.001 and P < 0.02, respectively). The daily number of high-amplitude propagated contractions (mass movements) as well as their amplitude and duration, was significantly reduced in both subgroups of constipated patients (P < 0.02 vs controls). We conclude that (1) in normal-transit constipation, motor abnormalities are not limited to the anorectal area; (2) patients with slow-transit constipation probably have a severe neuropathic rectal defect; (3) prolonged colonic motility studies may highlight further the functional abnormalities in constipated subjects; and (4) an approach taking into account proximal and distal colon motor abnormalities might be useful to understand pathophysiological grounds of chronic constipation and lead to better therapeutic approaches.

[Abnormal synthesis of 1,25-dihydroxyvitamin D and hypercalcemia in children with tuberculosis]

Three children with tuberculosis and hypercalcemia are reported. Before antitubercular treatment 1,25-dihydroxyvitamin D serum levels and urinary calcium excretion were elevated for age in all patients; vitamin D and 25-hydroxyvitamin D were in normal range whereas serum intact parathyroid hormone concentrations were suppressed. Low calcium diet and antitubercular treatment caused a normalization of serum calcium levels and urinary calcium excretion; 1,25-dihydroxyvitamin D concentrations returned in normal range after three months of antituberculosis therapy. When 1,25-dihydroxyvitamin D was normal, a reintroduction of a diet with normal calcium content did not determine new hypercalcemic episodes. These data suggest that an abnormal 1,25-dihydroxyvitamin D production sustains the hypercalcemia of children with tuberculosis. An ectopic and unregulated synthesis of 1,25-dihydroxyvitamin D by macrophages of granulomatous tissue is proposed.

[Selective deficit of IgA and infantile rheumatoid arthritis. Case reports]

Three children with selective deficiency of serum IgA associated with oligoarticular juvenile rheumatoid arthritis (JRA) are presented. Before the appearance of JRA, all 3 children had shown frequently some respiratory infections. Indeed IgA deficiency may be asymptomatic or may cause a higher frequency of respiratory, gastrointestinal, allergic or autoimmune diseases, among which, JRA is one of the most important conditions.

[Dynamic tests for calcium-regulating hormones in childhood. Evaluation of the incremental response in normal subjects]

Some tests to study the dynamic secretion of calcium-regulating hormones in childhood are presented. A low-calcium diet (less than or equal to 2 mg/kg/daily) for 1,25-dihydroxyvitamin D [1.25-(OH)-2D], ASU-eel-CT i.m. injection (80 U MRC/1.73 mq) for parathyroid hormone (PTH), and calcium infusion (2 mg/kg in 5') for calcitonin (CT) are employed. A significant increase in 1,25-(OH)-2D level (1 degree day: 47.0 +/- 6.7 pg/ml; 3 degree day: 73.2 +/- 6.9 pg/ml; p less than 0.001; n = 19), intact PTH values (basal: 29.7 +/- 7.5 pg/ml; +120': 68.2 +/- 7.8 pg/ml; p less than 0.001; n = 10) and monomeric CT concentrations (basal: 5.2 +/- 2.3 pg/ml; +10': 26.2 +/- 4.4 pg/ml; p less than 0.001; n = 18) have been observed. The employed tests are able to show a significant increase in calcium-regulating hormones in healthy children. These tests are a simple and reliable method without side-effects that may provide further information on the pathogenesis of some pediatric diseases with altered mineral homeostasis.

Autonomic functions in type 1 (insulin-dependent) diabetes

In juvenile type 1 diabetes a computer-aided orthoclinostatic test, giving information on central autonomic reactivity, shows a significant difference, vs control subjects, only in the ortho-to-clino transition (not in clino-to-ortho), while no differences emerge in peripheral autonomic functions. The correlations between the mean values of heart rate in lying and standing positions seem to indicate a different response of the baroceptor reflex in the two groups.

Size at onset of sexual maturity and growth rate in crustacean populations

The size at which crustaceans become mature can be a useful gauge in the study of environmental effects on field populations. The use of probability paper in rigorously defining the mean size at onset of sexual maturity avoids some of the confusion inherent in other methods of assessing size at maturity and permits an objective comparison of differences between discrete populations. Both logical and mathematical considerations in the use of probability paper for analyzing field data have been treated; and some sample data reveal how one might detect environmental effects on population structure. In this case the data indicated that mole crabs (Emerita analoga) may have grown at different rates in proximate populations.