Persistence of Trypanosoma cruzi vector-borne transmission among school-age children in the Bolivian Chaco documented by 24-month longitudinal serosurveillance.

BACKGROUND: Chagas disease represents a major public health concern in several Latin American countries, including Bolivia. METHODS: We present a longitudinal serosurvey for Trypanosoma cruzi antibodies among a cohort of 120 school-age children from rural communities in the Bolivian Chaco at three time points between 2017 and 2019. Serum samples extracted from dry blood spots collected on filter paper were tested for T. cruzi antibodies by enzyme-linked immunosorbent assay and rapid diagnostic test. RESULTS: T. cruzi antibodies were detected in 7/120 (5.8%), 8/120 (6.7%) and 11/120 (9.2%) samples in 2017, 2018 and 2019, respectively. An average incidence of 1.76 per 100 person-years was observed. CONCLUSIONS: Our findings support the persistence of vector-borne T. cruzi transmission in this area, highlighting the need for strengthening multidisciplinary efforts against Chagas disease.

Long-Standing International Cooperation in Parasitology Research: A Summary of 35 Years of Activities in the Bolivian Chaco.

The Bolivian Chaco is a semiarid region with a low population density, situated in the southeast part of the Plurinational State of Bolivia. Here, despite the improvements of the last 15 years, poverty remains high in rural areas, where social vulnerability is widespread. The Guaraní ethnic group often lives in isolated communities with a low standard of hygiene and sanitation. This epidemiological scenario favors the spread of transmissible diseases, including several parasitic infections belonging to the neglected tropical diseases (NTDs) group. In this area, a long-standing research activity, built upon the synergism between local and foreign institutions, has been established since the late 1980s and helps to fill in the knowledge gap about the epidemiology dynamics of soil-transmitted helminths, vector-borne parasites, and other parasitic diseases. A 35-year history of cooperation programs in parasitology research has contributed to informing local health authorities of the NTD burden in the Bolivian Chaco and, ultimately, supports local healthcare providers in the management of parasitic diseases.

Relevant increase of CTX-M-producing Escherichia coli carriage in school-aged children from rural areas of the Bolivian Chaco in a three-year period.

OBJECTIVES: The aim of this study was to perform two cross-sectional surveys on the fecal carriage of CTX-M-producing Enterobacterales in school-aged children from rural areas of the Bolivian Chaco (2016 vs 2019). METHODS: A total of 757 fecal samples were collected from school-aged children living in nine indigenous communities (n=337, 2016; n=420, 2019). After a first passage onto MacConkey agar (MCA), samples were plated onto MCA plus cefotaxime 2 µg/mL (MCA-CTX), and a loopful of the bacterial growth was used as a template for the detection of group 1, 2, 8/25, and 9 blaCTX-M variants by multiplex reverse transcriptase polymerase chain reaction . Positive samples were tested again for detecting, identifying, and characterizing CTX-M-positive isolates. RESULTS: Growth onto MCA-CTX was obtained with 208 samples (27.5%; 62/337, 2016; 146/420, 2019), of which 201 (96.6%) were positive for blaCTX-M genes. Overall, a relevant increase of fecal carriage of CTX-M-producing Enterobacterales was observed in the study period: 17,5% (59/337) in 2016 compared with 33,8% (142/420) in 2019, p<0.01. Nonetheless, the relative group distribution of CTX-M groups remained stable, with group 1 being the prevalent, followed by group 9 and group 8/25. Group 2 was not detected. CONCLUSIONS: The present study demonstrated an alarming spread of CTX-M enzymes in rural areas of the Bolivian Chaco, where antibiotics consumption is limited. Further studies are encouraged to better understand the dissemination dynamics of such relevant resistance determinants.

Trypanosoma cruzi infection in the human population of the Bolivian Chaco: four serosurveys over a 26-year period (1987-2013).

INTRODUCTION: Chagas disease (CD) remains a public health concern in several Latin American countries. At global level, Bolivia has the highest CD burden and the Chaco region, in the southeast of the country, is the most affected area. We report the results of four serosurveys for Trypanosoma cruzi antibodies, carried out approximately ten years apart from each other, during the lapse 1987-2013, in different localities of the Bolivian Chaco. METHODOLOGY: Four cross-sectional surveys were conducted in various localities, mostly rural, of the Bolivian Chaco, during the period 1987-2013. RESULTS: Although a reliable analysis of CD epidemiological trend is challenging, a partial reduction of anti-T. cruzi seroprevalence over the past four decades in the Bolivian Chaco may be assumed. In particular, in 1987 the exposure to T. cruzi in rural setting was universal since the first years of life, while it resulted gradually lower and age-dependent thereafter. Moreover, T. cruzi seroprevalence among women of reproductive age (15-45 years) has been persistently high in rural areas. CONCLUSIONS: T. cruzi transmission is still active and CD remains a concern throughout the Bolivian Chaco. More efforts are needed in order to achieve a sustainable interruption of vector-borne CD transmission in this area.

Hymenolepis nana-An Emerging Intestinal Parasite Associated with Anemia in School Children from the Bolivian Chaco.

Tropical anemia can have multiple causes, whether socioeconomic, dietary, or infectious. In the Bolivian Chaco, soil-transmitted helminthiases (STH), malaria, and Chagas disease are potential infectious causes of anemia among school-aged children (SAC). Following years of preventive chemotherapy with mebendazole, the prevalence of STH among SAC living in that area is now negligible, whereas protozoan infections are still highly prevalent (81%); Hymenolepis nana is the most frequent intestinal helminth (∼13%). We present results of hemoglobin (Hb) assessment and the association between parasitic infections and Hb levels of that SAC population. Overall, 511 SAC (girls:boys ratio 1:1, mean age 9.4 years [95% confidence interval {CI}: 9.3-9.5]) had Hb levels measured by using a point of care testing (HemoCue® Hb 301 System; HemoCue, Angelhome, Sweden). The prevalence of anemia was 23% (117/511), with mean and median Hb level = 12.2 g/dL (95% CI: 12.1-12.3; range 9.2-15.4 g/dL). By multivariate analysis, H. nana infection was associated with an increased risk of anemia (odds ratio 2.9, 95% CI: 1.5-5.7, P = 0.002). Two samples (0.5%) were positive for Trypanosoma cruzi and none for Plasmodium spp. by polymerase chain reaction of the 439 children tested. Anemia is still a concern among SAC living in the Bolivian Chaco. Our findings call for a greater attention to fecal-oral emerging pathogens, such as H. nana, and highlight the importance of water, sanitation, and hygiene improvements for disadvantaged population such as those living in the Bolivian Chaco.

Seroprevalence of Taenia solium antibodies in a cohort of Bolivian immigrants in Italy.

We conducted a retrospective study aimed at estimating the seroprevalence of anti-cysticercus antibodies in a Bolivian community settled in Italy. Seroprevalence of 9% was found, testing 495 sera with immunoblot. This study contributes to outline the epidemiological scenario of cysticercosis in immigrants living in Europe.

Scaling down of a deworming programme among school-age children after a thirty-year successful intervention in the Bolivian Chaco.

OBJECTIVE: Preventive chemotherapy is the WHO-recommended control method for soil-transmitted helminthiases. In the Bolivian Chaco, 6-monthly single-dose mebendazole delivery to school-age children achieved a dramatic decrease in soil-transmitted helminthiases prevalence between 1987 and 2013. Consequently, in September 2016, preventive chemotherapy delivery was interrupted in nine rural communities. In compliance with WHO recommendations, we intensified surveillance to monitor soil-transmitted helminthiases prevalence and detect potential changes that would require interventions. METHODS: We conducted two cross-sectional parasitology surveys 12 months apart (September 2016-2017) among school-age children living in the communities where preventive chemotherapy delivery had been halted. Study design, methods of sampling and sample analysis technique (direct microscopy, Kato-Katz technique) followed WHO recommendations, aiming to obtain data representative of the Bolivian Chaco ecological zone. RESULTS: We collected 426 samples in 2016 and 520 in 2017. Soil-transmitted helminthiasis prevalence was unremarkable: 0.7% (95% CI 0-1.5%) in 2016 and 0.8% (0-1.5%) in 2017. Conversely, the prevalence of tapeworms (13% in 2016, 12% in 2017) and intestinal protozoan infections (81% in 2016 and 75% in 2017) continued to be high. CONCLUSIONS: Our findings support the role of preventive chemotherapy in reducing soil-transmitted helminthiases transmission, as otherwise poor hygienic and health conditions persist in the Bolivian Chaco. A national survey, involving areas from all the ecological zones of Bolivia, is now warranted.

Seroprevalence of Hepatitis A Virus, Hepatitis E Virus, and Helicobacter pylori in Rural Communities of the Bolivian Chaco, 2013.

In the Bolivian Chaco, south-east of Bolivia, studies conducted over the past three decades reported hepatitis A virus (HAV) and Helicobacter pylori seroprevalences above 90% and 60%, respectively. Hepatitis E virus (HEV) prevalence was previously found to be 6-7% but is probably an underestimate because of the poor sensitivity of the assays used. In November 2013, we conducted a cross-sectional study of 263 healthy volunteers from two rural communities of the Bolivian Chaco, aiming to reassess HAV, HEV, and H. pylori seroprevalence 10-20 years following the previous surveys. Hepatitis A virus seroprevalence was 95%, with universal exposure after the first decade of life; HEV seroprevalence was considerably higher (31-35%) than that previously reported; H. pylori seroprevalence was 59%, with an age-dependent distribution. The high prevalence of these infections suggests that major efforts are still needed to reduce fecal-oral transmission and to improve human health in the Bolivian Chaco.

A screening questionnaire for convulsive seizures: A three-stage field-validation in rural Bolivia.

INTRODUCTION: Epilepsy is one of the most common neurological diseases in Latin American Countries (LAC) and epilepsy associated with convulsive seizures is the most frequent type. Therefore, the detection of convulsive seizures is a priority, but a validated Spanish-language screening tool to detect convulsive seizures is not available. We performed a field validation to evaluate the accuracy of a Spanish-language questionnaire to detect convulsive seizures in rural Bolivia using a three-stage design. The questionnaire was also administered face-to-face, using a two-stage design, to evaluate the difference in accuracy. METHODS: The study was carried out in the rural communities of the Gran Chaco region. The questionnaire consists of a single screening question directed toward the householders and a confirmatory section administered face-to-face to the index case. Positive subjects underwent a neurological examination to detect false positive and true positive subjects. To estimate the proportion of false negative, a random sample of about 20% of the screened negative underwent a neurological evaluation. RESULTS: 792 householders have been interviewed representing a population of 3,562 subjects (52.2% men; mean age 24.5 ± 19.7 years). We found a sensitivity of 76.3% (95% CI 59.8-88.6) with a specificity of 99.6% (95% CI 99.4-99.8). The two-stage design showed only a slightly higher sensitivity respect to the three-stage design. CONCLUSION: Our screening tool shows a good accuracy and can be easily used by trained health workers to quickly screen the population of the rural communities of LAC through the householders using a three-stage design.

Antimicrobial susceptibility and emerging resistance determinants (blaCTX-M, rmtB, fosA3) in clinical isolates from urinary tract infections in the Bolivian Chaco.

BACKGROUND: Bolivia is among the lowest-resourced South American countries, with very few data available on antibiotic resistance in bacterial pathogens. The phenotypic and molecular characterization of bacterial isolates responsible for urinary tract infections (UTIs) in the Bolivian Chaco are reported here. METHODS: All clinical isolates from UTIs collected in the Hospital Basico Villa Montes between June 2010 and January 2014 were analyzed (N=213). Characterization included susceptibility testing, extended-spectrum beta-lactamase (ESBL) detection, identification of relevant resistance determinants (e.g., CTX-M-type ESBLs, 16S rRNA methyltransferases, glutathione S-transferases), and genotyping of CTX-M producers. RESULTS: Very high resistance rates were observed. Overall, the lowest susceptibility was observed for trimethoprim-sulphamethoxazole, tetracycline, nalidixic acid, amoxicillin-clavulanic acid, ciprofloxacin, and gentamicin. Of E. coli and K. pneumoniae, 11.6% were ESBL producers. Resistance to nitrofurantoin, amikacin, and fosfomycin remained low, and susceptibility to carbapenems was fully preserved. CTX-M-15 was the dominant CTX-M variant. Four E. coli ST131 (two being H30-Rx) were identified. Of note, isolates harbouring rmtB and fosA3 were detected. CONCLUSIONS: Bolivia is not an exception to the very high resistance burden affecting many South American countries. Optimization of alternative approaches to monitor local antibiotic resistance trends in resource-limited settings is strongly encouraged to support the implementation of effective empiric treatment guidelines.

Methicillin-resistant Staphylococcus aureus in hospitalized patients from the Bolivian Chaco.

OBJECTIVES: Information is lacking on the methicillin-resistant Staphylococcus aureus (MRSA) clonal lineages circulating in Bolivia. We investigated the prevalence and molecular epidemiology of S. aureus colonization in hospitalized patients from the Bolivian Chaco, and compared their features with those of the few clinical isolates available from that setting. METHODS: S. aureus nasal/inguinal colonization was investigated in 280 inpatients from eight hospitals in two point prevalence surveys (2012, n=90; 2013, n=190). Molecular characterization included genotyping (spa typing, multilocus sequence typing, and pulsed-field gel electrophoresis), detection of virulence genes, and SCCmec typing. RESULTS: Forty-one inpatients (14.6%) were S. aureus nasal/inguinal carriers, of whom five were colonized by MRSA (1.8%). MRSA isolates mostly belonged to spa-type t701, harboured SCCmec IVc, and were negative for Panton-Valentine leukocidin (PVL) genes. However, a USA300-related isolate was also detected, which showed the characteristics of the USA300 Latin American variant (USA300-LV; i.e., ST8, spa-type t008, SCCmec IVc, presence of PVL genes, absence of arcA). Notably, all the available MRSA clinical isolates (n=5, collected during 2011-2013) were also identified as USA300-LV. CONCLUSIONS: Overall, MRSA colonization in inpatients from the Bolivian Chaco was low. However, USA300-LV-related isolates were detected in colonization and infections, emphasizing the importance of implementing control measures to limit their further dissemination in this resource-limited area.

Low prevalence of methicillin-resistant Staphylococcus aureus nasal carriage in urban and rural community settings in Bolivia and Peru.

OBJECTIVE: To investigate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage in rural and urban community settings of Bolivia and Peru. METHODS: MRSA nasal carriage was investigated in 585 individuals living in rural and urban areas of Bolivia and Peru (one urban area, one small rural village, and two native communities, one of which was highly isolated). MRSA isolates were subjected to molecular analysis for the detection of virulence genes, characterization of the staphylococcal cassette chromosome mec (SCCmec), and genotyping (multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE)). RESULTS: An overall very low prevalence of MRSA nasal carriage was observed (0.5%), with MRSA carriers being detected only in a small rural village of the Bolivian Chaco. The three MRSA isolates showed the characteristics of community-associated MRSA (being susceptible to all non-beta-lactam antibiotics and harboring the SCCmec type IV), were clonally related, and belonged to ST1649. CONCLUSIONS: This study provides an insight into the epidemiology of MRSA in community settings of Bolivia and Peru. Reliable, time-saving, and low-cost methods should be implemented to encourage continued surveillance of MRSA dissemination in resource-limited countries.

Quinolone resistance in absence of selective pressure: the experience of a very remote community in the Amazon forest.

BACKGROUND: Quinolones are potent broad-spectrum bactericidal agents increasingly employed also in resource-limited countries. Resistance to quinolones is an increasing problem, known to be strongly associated with quinolone exposure. We report on the emergence of quinolone resistance in a very remote community in the Amazon forest, where quinolones have never been used and quinolone resistance was absent in 2002. METHODS: The community exhibited a considerable level of geographical isolation, limited contact with the exterior and minimal antibiotic use (not including quinolones). In December 2009, fecal carriage of antibiotic resistant Escherichia coli was investigated in 120 of the 140 inhabitants, and in 48 animals reared in the community. All fluoroquinolone-resistant isolates were genotyped and characterized for the mechanisms of plasmid- and chromosomal-mediated quinolone resistance. PRINCIPAL FINDINGS: Despite the characteristics of the community remained substantially unchanged during the period 2002-2009, carriage of quinolone-resistant E. coli was found to be common in 2009 both in humans (45% nalidixic acid, 14% ciprofloxacin) and animals (54% nalidixic acid, 23% ciprofloxacin). Ciprofloxacin-resistant isolates of human and animal origin showed multidrug resistance phenotypes, a high level of genetic heterogeneity, and a combination of GyrA (Ser83Leu and Asp87Asn) and ParC (Ser80Ile) substitutions commonly observed in fluoroquinolone-resistant clinical isolates of E. coli. CONCLUSIONS: Remoteness and absence of antibiotic selective pressure did not protect the community from the remarkable emergence of quinolone resistance in E. coli. Introduction of the resistant strains from antibiotic-exposed settings is the most likely source, while persistence and dissemination in the absence of quinolone exposure is likely mostly related with poor sanitation. Interventions aimed at reducing the spreading of resistant isolates (by improving sanitation and water/food safety) are urgently needed to preserve the efficacy of quinolones in resource-limited countries, as control strategies based only on antibiotic restriction policies are unlikely to succeed in those settings.

Access to health care in relation to socioeconomic status in the Amazonian area of Peru.

BACKGROUND: Access to affordable health care is limited in many low and middle income countries and health systems are often inequitable, providing less health services to the poor who need it most. The aim of this study was to investigate health seeking behavior and utilization of drugs in relation to household socioeconomic status for children in two small Amazonian urban communities of Peru; Yurimaguas, Department of Loreto and Moyobamba, Department of San Martin, Peru. METHODS: Cross-sectional study design included household interviews. Caregivers of 780 children aged 6-72 months in Yurimaguas and 793 children of the same age in Moyobamba were included in the study. Caregivers were interviewed on health care seeking strategies (public/private sectors; formal/informal providers), and medication for their children in relation to reported symptoms and socio-economic status. Self-reported symptoms were classified into illnesses based on the IMCI algorithm (Integrated Management of Childhood Ilness). Wealth was used as a proxy indicator for the economic status. Wealth values were generated by Principal Component Analysis using household assets and characteristics. RESULTS: Significantly more caregivers from the least poor stratum consulted health professionals for cough/cold (p < 0.05: OR = 4.30) than the poorest stratum. The poorest stratum used fewer antibiotics for cough/cold and for cough/cold + diarrhoea (16%, 38%, respectively) than the least poor stratum (31%, 52%, respectively). For pneumonia and/or dysentery, the poorest used significantly fewer antibiotics (16%) than the least poor (80%). CONCLUSION: The poorest seek less care from health professionals for non-severe illnesses as well as for severe illnesses; and treatment with antibiotics is lacking for illnesses where it would be indicated. Caregivers frequently paid for health services as well as antibiotics, even though all children in the study qualified for free health care and medicines. The implementation of the Seguro Integral de Salud health insurance must be improved.

Antibiotic resistance in a very remote Amazonas community.

In a very remote human community of the Peruvian Amazonas with minimal antibiotic exposure, high levels of acquired resistance to the oldest antibiotics (ampicillin, tetracycline, trimethoprim/sulfamethoxazole, streptomycin and chloramphenicol) were detected in commensal Escherichia coli, with remarkable diversity of resistant clones and of resistance genes and plasmids. This pattern was similar overall to that previously observed in a very remote community of Bolivia. It was also similar to that observed in the nearest urban area, except for a lower dominance of resistant isolates and the absolute lack of quinolone resistance in the remote community. Present findings suggest that antibiotic resistance observed in remote communities with minimal antibiotic exposure is a general phenomenon contributed by complex mechanisms and provide new insights into the mechanisms involved in this phenomenon.

Multidrug-resistant commensal Escherichia coli in children, Peru and Bolivia.

Using a rapid screening method, we investigated the prevalence of fecal carriage of antimicrobial drug-resistant Escherichia coli in 3,174 healthy children from 4 urban settings in Peru and Bolivia. High resistance rates were observed for ampicillin (95%), trimethoprim-sulfamethoxazole (94%), tetracycline (93%), streptomycin (82%), and chloramphenicol (70%). Lower resistance rates were observed for nalidixic acid (35%), kanamycin (28%), gentamicin (21%), and ciprofloxacin (18%); resistance to ceftriaxone and amikacin was uncommon (<0.5%). In a random sample of 1,080 resistant E. coli isolates, 90% exhibited a multidrug-resistance (MDR) phenotype. The 2 most common MDR phenotypes (ampicillin/tetracycline/trimethoprim-sulfamethoxazole and ampicillin/tetracycline/trimethoprim-sulfamethoxazole/chloramphenicol) could be transferred en bloc in conjugation experiments. The most common acquired resistance genes were blaTEM, tet(A), tet(B), drfA8, sul1, sul2, and catI. These findings underscore the magnitude of the problem of antimicrobial drug resistance in low-resource settings and the urgent need for surveillance and control of this phenomenon.

Evaluation of a rapid screening method for detection of antimicrobial resistance in the commensal microbiota of the gut.

The assessment of antimicrobial resistance among commensal bacteria is an indicator of the spread of antimicrobial resistance. Rapid screening methods for detection of antimicrobial-resistant faecal Escherichia coli directly on MacConkey plates have been successfully adopted but suffer from lack of standardisation. The purpose of this study was to evaluate a direct plating method (DPM) for detection of antimicrobial-resistant faecal E. coli and to compare it with a conventional method. Faecal samples were collected from 71 healthy children from Peru and Bolivia. In the DPM, a faecal swab was directly plated onto a MacConkey agar plate and antimicrobial disks were applied onto the seeded plate. Raw data were obtained by direct reading of the plate and were subjected to confirmatory analysis. Good concordance between the DPM and a conventional method was observed in detecting carriage of resistant E. coli, with a higher sensitivity for the DPM. Analysis of the results allowed interpretive criteria to be defined for DPM raw data. The DPM showed good sensitivity and specificity at very low cost (ten times cheaper than the conventional method) to investigate the faecal carriage of drug-resistant E. coli. It may represent a useful tool to conduct large-scale resistance surveillance studies and to monitor resistance control programmes cost effectively, particularly in low-resource countries.

High prevalence of acquired antimicrobial resistance unrelated to heavy antimicrobial consumption.

In a very remote rural Bolivian community where the use of antimicrobials has been minimal and where exchanges with the exterior are very limited, 67% of subjects were found to be carriers of fecal Escherichia coli with acquired resistance to >/=1 antimicrobial agent(s); the highest rates were observed for tetracycline (64%), ampicillin (58%), trimethoprim-sulfamethoxazole (50%), and chloramphenicol (41%). The most relevant implication of these findings is that, in certain settings, the spread and maintenance of antimicrobial resistance can occur, regardless of whether selective pressure generated by the use of antimicrobials is present.