The neglected tropical diseases of Latin America and the Caribbean: a review of disease burden and distribution and a roadmap for control and elimination

Pyrethroid resistance distribution in Triatoma infestans and environmental association along the Argentine endemic zone

Insecticide resistance is considered a barrier to chemical control of Triatoma infestans, the main vector of Chagas disease in the Southern Cone of South America. Although initiatives to reduce the incidence of the disease in the region have integrated different strategies, they have mainly relied on vector elimination using pyrethroid insecticides such as deltamethrin. Reports of pyrethroid resistance in connection with T. infestans control failures first emerged in northern Argentina and southern Bolivia. Recently, a mosaic pyrethroid-resistant focus has been described in the center of the Argentine Gran Chaco (Department of General Güemes, Chaco Province), characterized by the presence of susceptible and very highly resistant populations in the same area. The involvement of different resistance mechanisms has been proposed, together with the contribution of environmental variables that promote the toxicological heterogeneity described. In the endemic zone of Argentina, however, new questions arise: Are there any other clusters of resistance? Is there a relationship between the distribution of resistance and environmental variables (as has been observed at smaller scale)? We studied toxicological data from insects collected and analyzed at 224 localities between 2010 and 2020 as part of the resistance monitoring conducted by the Chagas National Program. The sites were classified according to the survival rate of insects exposed to a discriminant dose of deltamethrin: 0-0.19 were considered susceptible, 0.2-0.79 low-resistance, and 0.8-1 high-resistance. Localities were georeferenced to describe the spatial distribution of resistance and to identify environmental variables (demographics, land use, urbanization, connectivity, and climate) potentially associated with resistance. We used Generalized Linear Models (GLMs) to examine the association between resistance and environmental predictors, selecting error distributions based on the response variable definition. For the entire period, 197 susceptible localities were distributed across the endemic zone. Localities with different survival rates were found throughout the area; 9 high-resistance localities circled the two previously identified resistant foci, and 18 low-resistance in 6 provinces, highlighting their relevance for control planning. Precipitation variables were linked to resistance in all the GLMs evaluated. Presence/absence models were the most accurate, with precipitation, distance from the capital city, and land use contributing to the distribution of resistance. This information could be valuable for improving T. infestans control strategies in future scenarios characterized by unpredictable changes in land use and precipitation.

Overcoming Geographical Constraints: A Diagnostic and Therapeutic Challenge of Amebic Liver Abscess in a Non-Endemic Region

This case report provides data on unique challenges related to amoebiasis diagnostics and treatment in non-endemic regions. The presented case report is focused a 28-year-old male patient of Indian origin, temporarily living in Poland, who was diagnosed with an amoebic liver abscess. The patient presented with a range of non-specific symptoms including shortness of breath, chest pain, and fever. The differential diagnosis included cardio-pulmonary diseases, a range of tropical diseases such as malaria or typhoid fever, bacterial abscesses, and malignancies, necessitating a comprehensive, multi-modal diagnostic approach. This approach included an extensive review of patient history, physical examination, and various laboratory and imaging investigations. A further challenge in this case was the unavailability of standard cysticidal treatments in Poland, which required individualized therapeutic strategy. Despite these obstacles, the patient was successfully treated using an alternative regimen of intravenous metronidazole, ceftriaxone, doxycycline, chloroquine, and finally, trimethoprim/sulfamethoxazole (treatment with metronidazole was used as a base drug, due to the lack of typical cysticidal treatment, an alternative treatment was added: chloroquine is a recommended drug used in the treatment of pregnant patients, in addition, doxycycline showed in vitro activity against Entamoeba histolytica). This therapeutic journey underscored the value of adaptability in treatment protocols, particularly in regions where certain resources may not be readily available. This case report underlines the importance of broadening the differential diagnosis in non-endemic regions to include tropical diseases, particularly in the context of increasing global travel and migration. It also highlights the significance of employing comprehensive diagnostic strategies and adaptable treatment protocols in such scenarios. In addition, the report reiterates the need for global collaboration and education among healthcare providers to effectively manage tropical diseases, especially in non-endemic regions. Through its exploration of the complexities associated with diagnosing and managing amebiasis in a non-endemic region, this report offers valuable insights to clinicians worldwide.

Prevalence and transmission of the most relevant zoonotic and vector-borne pathogens in the Yucatan peninsula: A review

BACKGROUND

Habitat modification and land use changes impact ecological interactions and alter the relationships between humans and nature. Mexico has experienced significant landscape modifications at the local and regional scales, with negative effects on forest cover and biological biodiversity, especially in the Yucatan peninsula in southeastern Mexico. Given the close relationship between landscape modification and the transmission of zoonotic and vector-borne diseases, it is essential to develop criteria for identifying priority zoonoses in the south of the country.

METHODOLOGY/PRINCIPAL FINDINGS

We reviewed 165 published studies on zoonotic and vector-borne diseases in the region (2015-2024). We identified the most frequent vectors, reservoirs, and hosts, the most prevalent infections, and the factors associated with transmission risk and the anthropogenic landscape modification in urban, rural, ecotone, and sylvatic habitats. The most relevant pathogens of zoonotic risk included Trypanosoma cruzi, arboviruses, Leishmania, Rickettsia, Leptospira, and Toxoplasma gondii. Trypanosoma cruzi was the vector-borne agent with the largest number of infected vertebrate species across habitats, while Leishmania and arboviruses were the ones that affected the greatest number of people. Dogs, cats, backyard animals, and their hematophagous ectoparasites are the most likely species maintaining the transmission cycles in human settlements, while rodents, opossums, bats, and other synanthropic animals facilitate connection and transmission cycles between forested habitats with human-modified landscapes. Pathogens displayed different prevalences between the landscapes, T. cruzi, arbovirus, and Leptospira infections were the most prevalent in urban and rural settlements, whereas Leishmania and Rickettsia had similar prevalence across habitats, likely due to the diversity and abundance of the infected vectors involved. The prevalence of T. gondii and Leptospira spp. may reflect poor hygiene conditions. Additionally, results suggest that prevalence of zoonotic and vector-borne diseases is higher in deforested areas and agricultural aggregates, and in sites with precarious health and infrastructure services.

CONCLUSIONS

Some hosts, vectors, and transmission trends of zoonotic and vector-borne diseases in the YP are well known but others remain poorly recognized. It is imperative to reinforce practices aimed at increasing the knowledge, monitoring, prevention, and control of these diseases at the regional level. We also emphasize the need to perform studies on a larger spatio-temporal scale under the socio-ecosystem perspective, to better elucidate the interactions between pathogens, hosts, vectors, environment, and sociocultural and economic aspects in this and many other tropical regions.

The Role of Senescent CD8+T Cells in the Pathogenesis of Disseminated Leishmaniasis

Disseminated leishmaniasis (DL) caused by L. braziliensis is characterized by the presence of 10 to more than 1000 lesions spread on the body. While protection against Leishmania is mediated by macrophages upon activation by IFN-γ produced by CD4+T cells, the pathology of disseminated leishmaniasis (DL) could be mediated by macrophages, NK, and CD8+T cells. Herein, we evaluate the participation of senescent CD8+T cells in the pathogenesis of DL. Methods: Peripheral blood mononuclear cells (PBMCs), biopsies, co-cultures of CD8+T cells with uninfected and infected macrophages (MØ), and PBMC cultures stimulated with soluble L. braziliensis antigen (SLA) for 72 h from patients with cutaneous leishmaniasis (CL) and DL were used to characterize senescent CD8+T cells. Statistical analysis was performed using the Mann-Whitney and Kruskal-Wallis tests, followed by Dunn's. Results: Patients with DL have an increase in the frequency of circulating CD8+T cells that present a memory/senescent phenotype, while lesions from DL patients have an increase in the frequency of infiltrating CD8+T cells with a senescent/degranulation phenotype. In addition, after specific stimuli, DL patients' circulating CD8+T with memory/senescent profile, showing degranulation characteristics, increased upon SLA stimuli, and those specific CD8+T cells from DL patients had an increased degranulation phenotype, causing more apoptosis of infected target cells. Conclusions: DL patients show a higher frequency of cytotoxic senescent CD8+T cells compared to CL patients, and that could promote the lysis of infected cells, although without parasite killing, releasing Leishmania to the extracellular compartment, contributing to the spread of parasites.

Chagas Disease: Comparison of Therapy with Nifurtimox and Benznidazole in Indigenous Communities in Colombia

Background: For indigenous people in Colombia, high infection rates with Chagas disease (CD) are known. Methods: In 2018 and 2020, nine villages were screened for CD. CD-positive patients could enter a drug observed treatment. While, in 2018, Benznidazole (BNZ) was provided as the first-line drug by the government, nifurtimox (NFX) was administered in 2020. Results: Of 121 individuals treated with BNZ, 79 (65%) suffered from at least one adverse event (AE). Of 115 treated with NFX, at least one AE occurred in 96 (84%) patients. In 69% of BNZ cases, the side effects did not last longer than one day; this applied to 31% of NFX cases. Excluding extreme outlier values, average duration of AEs differed highly significantly: BNZ (M = 0.7, SD = 1.4) and NFX (M = 1.7, SD = 1.5, p < 0.001). Using an intensity scale, AEs were highly significantly more severe for NFX (M = 2.1, SD = 0.58) compared to BZN (M = 1.1, SD = 0.38), p < 0.001. When analyzing the duration in relation to the intensity, the burden of AEs caused by NFX was significantly more pronounced. Dropouts (n = 2) due to AEs were in the NFX-group only. Conclusions: Side effects caused by BNZ were significantly fewer, as well as milder, shorter in duration, and more easily treatable, compared to NFX.

Human Trypanosoma cruzi infection in the Argentinean Chaco: risk factors and identification of households with infected children for treatment

BACKGROUND

Chagas disease is a neglected tropical disease (NTD). Cost-effective strategies for large-scale implementation of diagnosis and etiological treatment are urgently needed to comply with NTD control goals. We determined the seroprevalence of Trypanosoma cruzi infection and associated risk factors in a well-defined rural population of Pampa del Indio municipality including creole and indigenous (Qom) households and developed two indices to identify houses harboring infected children.

METHODS

We serodiagnosed and administered a questionnaire to 1337 residents (48.2% of the listed population) in two sections of the municipality (named Areas II and IV) 6-9 years after deploying sustained vector control interventions. Multiple logistic regression models were used to evaluate the relationship between human infection and a priori selected predictors. Two risk indices were constructed based on environmental and serostatus variables, and we used spatial analysis to test whether households harboring T. cruzi-seropositive children were randomly distributed.

RESULTS

The global seroprevalence of T. cruzi infection was 24.8%. Human infection was positively and significantly associated with exposure time to triatomines, the household number of seropositive co-inhabitants, maternal seropositivity for T. cruzi, recent residence at the current house and the presence of suitable walls for triatomine colonization in the domicile. The pre-intervention mean annual force of infection (FOI) was 1.23 per 100 person-years. Creoles from Area IV exhibited the highest seroprevalence and FOI; Qom people from both areas displayed intermediate ones and creoles from Area II the lowest. Three hotspots of infected children were spatially associated with hotspots of triatomine abundance at baseline and persistent house infestation. No child born after vector control interventions was T. cruzi seropositive except for one putative transplacental case. Two simple risk indices (based on self-reported inhabiting an infested house and suitable walls for triatomines or maternal serostatus) identified 97.3-98.6% of the households with at least one T. cruzi-seropositive child.

CONCLUSIONS

We showed strong heterogeneity in the seroprevalence of T. cruzi infection within and between ethnic groups inhabiting neighboring rural areas. Developed indices can be used for household risk stratification and to improve access of rural residents to serodiagnosis and treatment and may be easily transferred to primary healthcare personnel.

Syphilis epidemic among men who have sex with men: A global systematic review and meta-analysis of prevalence, incidence, and associated factors

Background

We aimed to estimate the prevalence and incidence of syphilis at global, regional and national levels for human immunodeficiency virus (HIV)-positive and HIV-negative men who have sex with men (MSM) and explore the association between demographic and social behavioural factors and syphilis infection.

Methods

We searched PubMed, Embase, and the Cochrane Library from 1 January 2012 to 31 December 2022 for studies of reported crude syphilis prevalence or incidence in MSM or with sufficient data to calculate prevalence or incidence rate in MSM.

Results

We included 376 articles reporting on 409 records from 62 countries to calculate syphilis prevalence and incidence in MSM. The pooled prevalence of syphilis in MSM was 10.4%, with substantial differences between countries and regions. Syphilis prevalence was substantially higher in HIV-positive than in HIV-negative MSM. The pooled incidence of syphilis in MSM was 76.4 per 1000 person-years. Older age, lower education, nitrite or recreational drug use, group sex, and multiple sexual partners were identified as risk factors for syphilis infection.

Conclusions

A disproportionate geographic pattern of syphilis infection in MSM and significant threats of syphilis infection were revealed. The 'hidden risk' in specific regions and the inadequately elucidated drivers of high-risk behaviours, need to be fully acknowledged and addressed.

Registration

PROSPERO: CRD42023422218.

Characterization of Novel Trypanosoma cruzi-Specific Antigen with Potential Use in the Diagnosis of Chagas Disease

Chagas disease is caused by the parasite Trypanosoma cruzi. In humans, it evolves into a chronic disease, eventually resulting in cardiac, digestive, and/or neurological disorders. In the present study, we characterized a novel T. cruzi antigen named Tc323 (TcCLB.504087.20), recognized by a single-chain monoclonal antibody (scFv 6B6) isolated from the B cells of patients with cardiomyopathy related to chronic Chagas disease. Tc323, a ~323 kDa protein, is an uncharacterized protein showing putative quinoprotein alcohol dehydrogenase-like domains. A computational molecular docking study revealed that the scFv 6B6 binds to an internal domain of Tc323. Immunofluorescence microscopy and Western Blot showed that Tc323 is expressed in the main developmental forms of T. cruzi, localized intracellularly and exhibiting a membrane-associated pattern. According to phylogenetic analysis, Tc323 is highly conserved throughout evolution in all the lineages of T. cruzi so far identified, but it is absent in Leishmania spp. and Trypanosoma brucei. Most interestingly, only plasma samples from patients infected with T. cruzi and those with mixed infection with Leishmania spp. reacted against Tc323. Collectively, our findings demonstrate that Tc323 is a promising candidate for the differential serodiagnosis of chronic Chagas disease in areas where T. cruzi and Leishmania spp. infections coexist.

Phylogenomics of Leptospira santarosai, a prevalent pathogenic species in the Americas

BACKGROUND

Leptospirosis is a complex zoonotic disease mostly caused by a group of eight pathogenic species (L. interrogans, L. borgpetersenii, L. kirschneri, L. mayottensis, L. noguchii, L. santarosai, L. weilii, L. alexanderi), with a wide spectrum of animal reservoirs and patient outcomes. Leptospira interrogans is considered as the leading causative agent of leptospirosis worldwide and it is the most studied species. However, the genomic features and phylogeography of other Leptospira pathogenic species remain to be determined.

METHODOLOGY/PRINCIPAL FINDINGS

Here we investigated the genome diversity of the main pathogenic Leptospira species based on a collection of 914 genomes from strains isolated around the world. Genome analyses revealed species-specific genome size and GC content, and an open pangenome in the pathogenic species, except for L. mayottensis. Taking advantage of a new set of genomes of L. santarosai strains isolated from patients in Costa Rica, we took a closer look at this species. L. santarosai strains are largely distributed in America, including the Caribbean islands, with over 96% of the available genomes originating from this continent. Phylogenetic analysis showed high genetic diversity within L. santarosai, and the clonal groups identified by cgMLST were strongly associated with geographical areas. Serotype identification based on serogrouping and/or analysis of the O-antigen biosynthesis gene loci further confirmed the great diversity of strains within the species.

CONCLUSIONS/SIGNIFICANCE

In conclusion, we report a comprehensive genome analysis of pathogenic Leptospira species with a focus on L. santarosai. Our study sheds new light onto the genomic diversity, evolutionary history, and epidemiology of leptospirosis in America and globally. Our findings also expand our knowledge of the genes driving O-antigen diversity. In addition, our work provides a framework for understanding the virulence and spread of L. santarosai and for improving its surveillance in both humans and animals.

Environmental health risk factors and cutaneous leishmaniasis (CL): A case-control study in northeastern Iran

Background & objectives

Cutaneous leishmaniasis (CL) is one of the main causes of vector-born diseases in younger population. To evaluate the association of environmental health factors on the odds of CL incidence, a case-control study was conducted in northeastern Iran.

Methods

This study was conducted within 2020-2021 based on individual and household data from a tertiary referral center. Cases were patients diagnosed with CL by PCR method; controls were selected among the patients' relatives, and information was obtained from a health registry system. Demographic and socioeconomic data of 1871 subjects, included age, sex, household information and environmental health factors. Multivariable models with environmental factors in various conditions and CL were separately fit by univariate and mixed multiple unconditional logistic regression.

Results

Participants included 617 cases (mean [SD] age, 13.62[13.72] years; 58.20% male) and 1264 controls (mean [SD] age, 16.45[15.44] years; 50.40% male). Results revealed that the use of well-water sources compared to surface water is significantly associated with CL (odds ratio [OR]=0.204; 95%CI, 0.13-0.33;P<0.001). Muddy houses, ruined buildings or wastelands and stagnant water, canals and rivers near the houses were also associated with CL (OR=3.85; 95%CI, 1.66-8.89; P=.002; OR=2.47; 95%CI, 1.76-3.47; P<.001). Besides, existence of pine tree was found to be a risk factor (OR=3.25; 95%CI, 2.12-4.99; P<.001) and similarly for the use of waste collection system (OR=4.43; 95%CI, 3.32-7.51; P<.001).

Interpretation & conclusion

Environmental factors related to houses were significantly associated with CL and may represent the modifiable risk factors of CL disease.

Ten years follow-up of the largest oral Chagas disease outbreak: Cardiological prospective cohort study

BACKGROUND

Chagas disease (ChD) is the most important endemy in Latin America. Some patients, develop chronic Chagasic cardiopathy (CCC) years after the acute phase. It is unknown if patients infected by the oral route have higher risk of developing early CCC.

METHODS AND FINDINGS

A prospective cohort study was conducted to assess morbidity and mortality during 10 years observation in 106 people simultaneously infected and treated in the largest known orally transmitted ChD outbreak in 2007. A preschooler died during the acute phase, but thereafter was no mortality associated to ChD. All acute phase findings improved in the first-year post-treatment. Each person was evaluated 8.7 times clinically, 6.4 by electrocardiogram (ECG)/Holter, and 1.7 by echocardiogram. Based on prevalence, the number of people who had any abnormalities (excluding repolarization abnormalities and atrial tachycardia which decreased) was higher than 2007, since they were found at least once between 2008-2017. However, when we evaluated incidence, except for clinical bradycardia and dizziness, it was observed that the number of new cases of all clinical and ECG findings decreased at the end of the follow-up. Between 2008-2017 there was not incidence of low voltage complex, 2nd degree AV block, long QT interval, left bundle branch block or left ventricular dysfunction that allowed the diagnosis of CCC. Total improvement prevailed over the persistence of all clinical and ECG/Holter findings, except for sinus bradycardia. Incomplete right bundle branch block, sinus bradycardia and/or T-wave inversion were diagnosed persistently in 9 children. The second treatment did not have significant influence on the incidence of clinical or ECG/Holter findings.

CONCLUSIONS

At the end of the 10-year follow-up, there were not clinical or ECG/Holter criteria for classifying patients with CCC. The incidence of arrhythmias and repolarization abnormalities decreased. However, special attention should be paid on findings that not revert as sinus bradycardia, or those diagnosed persistently in all ECG as sinus bradycardia, incomplete right bundle branch block or T-wave inversion. Early diagnosis and treatment may have contributed to the rapid improvement of these patients. In ChD follow-up studies prevalence overestimates the real dimension of abnormalities, the incidence looks as a better indicator.

Seroprevalence of Equine Leptospirosis in the State of Goiás, Brazil

Leptospirosis, caused by Leptospira, is a zoonotic disease that, in horses, is linked to abortions, uveitis, and sporadic occurrences of liver and kidney disease, often resulting in significant economic losses for farmers. Research on the prevalence of leptospirosis in horses in the central-west region of Brazil has been relatively scarce. Thus, the present study aimed to determine the prevalence of leptospirosis in equine herds in the state of Goiás (Central Brazil). Blood samples were collected from 894 equids at 294 randomly selected farms divided into three different strata according to their herd characteristics. The microscopic agglutination test for the detection of anti-Leptospira agglutinins was carried out and the results showed that among the 294 sampled farms, 213 (72.9%; CI 95% 71.7-78.9) had one or more animals positive for leptospirosis, and of the 894 horses sampled, 513 (61.6%; CI 95% 54.3-69.0) were seropositive for leptospirosis. Djasiman, Icterohaemorrhagiae, and Australis were the most prevalent serogroups. The results showed a high prevalence of seropositive animals and a widespread distribution of positive farms in the state of Goiás. Thus, environmental sanitation measures and health education to prevent and control equine leptospirosis in the state are required.

Phylogenetic description of Trypanosoma cruzi isolates from Dipetalogaster maxima: Occurrence of TcI, TcIV, and TcIV-USA

Trypanosoma cruzi is the parasite responsible for Chagas disease. The parasite has been classified into six taxonomic assemblages: TcI-TcVI and TcBat (aka Discrete Typing Units or Near-Clades). No studies have focused on describing the genetic diversity of T. cruzi in the northwestern region of Mexico. Within the Baja California peninsula lives Dipetalogaster maxima, the largest vector species for CD. The study aimed to describe the genetic diversity of T. cruzi within D. maxima. A total of three Discrete Typing Units (DTUs) were found (TcI, TcIV, and TcIV-USA). TcI was the predominant DTU found (∼75% of samples), in concordance with studies from the southern USA, one sample was described as TcIV while the other ∼20% pertained to TcIV-USA, which has recently been proposed to have enough genetic divergence from TcIV, to merit its own DTU. Potential phenotype differences between TcIV and TcIV-USA should be assessed in future studies.

Promiscuity in drug discovery on the verge of the structural revolution: recent advances and future chances

INTRODUCTION

Promiscuity denotes the ability of ligands and targets to specifically interact with multiple binding partners. Despite negative aspects like side effects, promiscuity is receiving increasing attention in drug discovery as it can enhance drug efficacy and provides a molecular basis for drug repositioning. The three-dimensional structure of ligand-target complexes delivers exclusive insights into the molecular mechanisms of promiscuity and structure-based methods enable the identification of promiscuous interactions. With the recent breakthrough in protein structure prediction, novel possibilities open up to reveal unknown connections in ligand-target interaction networks.

AREAS COVERED

This review highlights the significance of structure in the identification and characterization of promiscuity and evaluates the potential of protein structure prediction to advance our knowledge of drug-target interaction networks. It discusses the definition and relevance of promiscuity in drug discovery and explores different approaches to detecting promiscuous ligands and targets.

EXPERT OPINION

Examination of structural data is essential for understanding and quantifying promiscuity. The recent advancements in structure prediction have resulted in an abundance of targets that are well-suited for structure-based methods like docking. In silico approaches may eventually completely transform our understanding of drug-target networks by complementing the millions of predicted protein structures with billions of predicted drug-target interactions.

Clinical and Demographic Features of Paracoccidioidomycosis in Argentina: A Multicenter Study Analysis of 466 Cases

Information on paracoccidioidomycosis (PCM) in Argentina is fragmented and has historically been based on estimates, supported only by a series of a few reported cases. Considering the lack of global information, a national multicentric study in order to carry out a more comprehensive analysis was warranted. We present a data analysis including demographic and clinical aspects of a historical series of 466 cases recorded over 10 years (2012-2021). Patients were aged from 1 to 89 years. The general male: female (M:F) ratio was 9.5:1 with significant variation according to the age group. Interestingly, the age range 21-30 shows an M:F ratio of 2:1. Most of the cases (86%) were registered in northeast Argentina (NEA), showing hyperendemic areas in Chaco province with more than 2 cases per 10,000 inhabitants. The chronic clinical form occurred in 85.6% of cases and the acute/subacute form occurred in 14.4% of cases, but most of these juvenile type cases occurred in northwestern Argentina (NWA). In NEA, the incidence of the chronic form was 90.6%; in NWA, the acute/subacute form exceeded 37%. Diagnosis by microscopy showed 96% positivity but antibody detection displays 17% of false negatives. Tuberculosis was the most frequent comorbidity, but a diverse spectrum of bacterial, fungal, viral, parasitic, and other non-infectious comorbidities was recorded. This national multicenter registry was launched in order to better understand the current status of PCM in Argentina and shows the two endemic zones with a highly diverse epidemiology.

Taenia solium taeniasis and Cysticercosis Prevalence and Control Practice in China

Taenia solium taeniasis/cysticercosis is an important global food-borne zoonosis transmitted between humans and pigs. In China, the prevalence of Theridion solium taeniasis/cysticercosis has been marked decline in recent decades based on the data revealed by both national surveys and field prevalence investigations. Health education and promotion, meat inspection, and chemotherapy are unquestionably the main control measures for diseases. It is worth noting that a variety of socio-ecological variables have been identified in the process of controlling T. solium taeniasis/cysticercosis. It has become difficult for pigs to come into direct or indirect contact with or consume human excreta as pig farming practices have been shifted from traditional backyard farms to large-scale commercial pig raising systems that are still in progress. The human toilet revolution in rural areas of China has ensured hygienic separation of human excreta from contact, and thereby preventing human excreta from polluting the soil, feeds, and water. These two important fundamental preventive measures are crucial to establishing an environmental restriction between humans and pigs cannot be overlooked for interrupting or limiting T. solium transmission. In this chapter, we reviewed the epidemiology, traditional measures, and ecological determinants that significantly contributed to the dramatic decline of taeniasis/cysticercosis in China.

A review of ancestrality and admixture in Latin America and the caribbean focusing on native American and African descendant populations

Genomics can reveal essential features about the demographic evolution of a population that may not be apparent from historical elements. In recent years, there has been a significant increase in the number of studies applying genomic epidemiological approaches to understand the genetic structure and diversity of human populations in the context of demographic history and for implementing precision medicine. These efforts have traditionally been applied predominantly to populations of European origin. More recently, initiatives in the United States and Africa are including more diverse populations, establishing new horizons for research in human populations with African and/or Native ancestries. Still, even in the most recent projects, the under-representation of genomic data from Latin America and the Caribbean (LAC) is remarkable. In addition, because the region presents the most recent global miscegenation, genomics data from LAC may add relevant information to understand population admixture better. Admixture in LAC started during the colonial period, in the 15th century, with intense miscegenation between European settlers, mainly from Portugal and Spain, with local indigenous and sub-Saharan Africans brought through the slave trade. Since, there are descendants of formerly enslaved and Native American populations in the LAC territory; they are considered vulnerable populations because of their history and current living conditions. In this context, studying LAC Native American and African descendant populations is important for several reasons. First, studying human populations from different origins makes it possible to understand the diversity of the human genome better. Second, it also has an immediate application to these populations, such as empowering communities with the knowledge of their ancestral origins. Furthermore, because knowledge of the population genomic structure is an essential requirement for implementing genomic medicine and precision health practices, population genomics studies may ensure that these communities have access to genomic information for risk assessment, prevention, and the delivery of optimized treatment; thus, helping to reduce inequalities in the Western Hemisphere. Hoping to set the stage for future studies, we review different aspects related to genetic and genomic research in vulnerable populations from LAC countries.

Intersections of climate change, migration, and health: experiences of first-generation migrants from Latin America to the Atlanta-metropolitan area

Climate change is an important driver of migration, but little research exists on whether migrant communities in the U.S. identify climate change-related factors as reasons for migrating. In 2021, we conducted a multidisciplinary, collaborative project to better understand the nexus of climate change and immigrant health in the Atlanta area. This paper presents one arm of this collaboration that explored both the role of climate change in decisions to immigrate to Georgia and the ways that climate change intersects with other possible drivers of migration. First generation migrants from Latin America were recruited primarily through CPACS Cosmo Health Center and were invited to participate in an intake survey and an in-depth interview. Results were analyzed using descriptive statistics and thematic analysis. Findings suggest that while participants may not have explicitly identified climate change as a primary reason for migration, in both surveys and in-depth interviews, participants reported multiple and intersecting social, economic, political, and environmental factors that are directly or indirectly influenced by climate change and that are involved in their decisions to migrate. The narratives that emerged from in-depth interviews further contextualised survey data and elucidated the complex nexus of climate change, migration, and health.

Prevalence of Geohelminthic Infection and Its Risk Factors Among School Children in Thiruvananthapuram, Kerala, India

Introduction Geohelminthic infections are the most common infections worldwide and affect the poorest and most deprived communities. School-age children typically have the highest intensity of worm infection. Currently, information on the prevalence of geohelminthic infestations among schoolchildren is scarce in Kerala. As a result, it would be worthwhile to investigate the prevalence and risk factors of a geohelminthic infestation among schoolchildren in Kerala's Thiruvananthapuram district. Materials and methods A community-based cross-sectional study was conducted among 454 primary school children (5-10 years) in the Thiruvananthapuram district. Samples were selected by stratified multi-stage sampling, and the data were collected using a pre-tested, semi-structured questionnaire. The stool examination was performed for each study subject, and the data were recorded. Results The overall prevalence of geohelminthic infections was 9.69% (95% confidence interval: 5.62-14.61), with Ascaris (A.) lumbricoides accounting for 5.7%, Trichuris (T.) trichiura accounting for 3.3%, and hookworm accounting for 0.7%. Children residing in rural areas (odds ratio (OR): 40.16; 95% confidence interval (CI): 5.28-305.3), studying in government schools (OR: 3.06 with 95% CI: 1.55-6.05), and using piped water as a source of drinking water (OR: 1.96; 95% CI: 1.01-3.77) were found to be significant and had emerged as risk factors for geohelminthic infestation. Children wearing footwear while playing outside (OR: 0.77; 95% CI: 0.39-1.5) and having personal hygiene class in school (OR: 0.34; 95% CI: 0.14-0.83) were found to be significant and had emerged as protective factors for geohelminthic infestations. Conclusion The prevalence of geohelminthic infestations among schoolchildren in this study was 9.7%. The individual species prevalence of A. lumbricoides, T. trichiura, and hookworm were 5.7%, 3.3%, and 0.7%, respectively. In addition to geohelminthic infestation, this study discovered a prevalence of 0.9% with Enterobius vermicularis. The factors found to be significantly associated with geohelminthic infestation after doing multivariate analysis were children belonging to government schools, residing in rural areas, and using piped water as a source of drinking water.

3-phenacylideneoxindoles as a new class of antifungal compounds against Paracoccidioides spp

Aims: Considering the need to identify new compounds with antifungal action, the activity of five 3-phenacylideneoxindoles compounds was evaluated. Materials & methods: The compounds were synthesized, and their antifungal activity was elucidated through minimum inhibitory concentration tests and interaction assay with other antifungals. Potential targets of compounds were predicted in silico. Results: 3-phenacylideneoxindoles compounds inhibited fungal growth with minimum inhibitory concentration and minimum fungicidal concentration ranging from 3.05 to 12.26 μM. The compounds demonstrated high selectivity index and presented a synergistic effect with itraconazole. In silico prediction revealed the pentafunctional AROM polypeptide, enolase, superoxide dismutase, catalase and kinases as proteins targets of the compound 4a. Conclusion: The results demonstrate that 3-phenacylideneoxindoles is a potential new class of antifungal compounds for paracoccidioidomycosis treatment.

Seroprevalence of human leptospirosis in a rural community from Tandil, Argentina. Assessment of risk factors and spatial analysis

Leptospirosis is a neglected zoonosis that is widely distributed in the world. Although it is endemic in Argentina, prevalence remains unknown. The aims of the study were: (i) to determine the prevalence of leptospirosis in humans from a rural community in Tandil Argentina, (ii) to identify infecting Leptospira spp. serogroups, (iii) to identify factors associated with the infection, (iv) to estimate the population attributable fraction (PAF) of the risk factors and (v) to determine the spatial patterns of disease presentation and related risk factors. Blood samples from 202 participants were collected. A survey was conducted to obtain clinical and epidemiological data. Serological testing was performed by the microscopic agglutination test (MAT). Univariate and multivariate methods were applied to evaluate associations. Spatial clusters were investigated for seroprevalence and risk factors. Antibodies were found in 32.2% of participants (95% CI: 25.8-39.1). The most prevalent serogroup was Hebdomadis followed by Sejroe; Icterohaemorrhagiae; Tarassovi and Canicola. Living at lower altitudes (OR: 13.04; 95% CI: 2.60-65.32); not having access to water supply network (OR: 2.95; 95% CI: 1.30-6.69); living close to flooded streets (OR: 2.94; 95% CI: 1.14-7.69) and practicing water sports (OR: 3.12; 95% CI: 1.12-8.33) were associated with seropositivity. Factors related with housing characteristics, services and infrastructure had the higher PAF (from 17% to 81%). A spatial cluster with higher rates of positivity and of the main risk factors was determined. This work contributes useful data for specific preventive measures that should be implemented for the control of the disease.

Leishmania kinetoplast DNA contributes to parasite burden in infected macrophages: Critical role of the cGAS-STING-TBK1 signaling pathway in macrophage parasitemia

Leishmania parasites harbor a unique network of circular DNA known as kinetoplast DNA (kDNA). The role of kDNA in leishmania infections is poorly understood. Herein, we show that kDNA delivery to the cytosol of Leishmania major infected THP-1 macrophages provoked increased parasite loads when compared to untreated cells, hinting at the involvement of cytosolic DNA sensors in facilitating parasite evasion from the immune system. Parasite proliferation was significantly hindered in cGAS- STING- and TBK-1 knockout THP-1 macrophages when compared to wild type cells. Nanostring nCounter gene expression analysis on L. major infected wild type versus knockout cells revealed that some of the most upregulated genes including, Granulysin (GNLY), Chitotriosidase-1 (CHIT1), Sialomucin core protein 24 (CD164), SLAM Family Member 7 (SLAMF7), insulin-like growth factor receptor 2 (IGF2R) and apolipoprotein E (APOE) were identical in infected cGAS and TBK1 knockout cells, implying their involvement in parasite control. Amlexanox treatment (a TBK1 inhibitor) of L. major infected wild type cells inhibited both the percentage and the parasite load of infected THP-1 cells and delayed footpad swelling in parasite infected mice. Collectively, these results suggest that leishmania parasites might hijack the cGAS-STING-TBK1 signaling pathway to their own advantage and the TBK1 inhibitor amlexanox could be of interest as a candidate drug in treatment of cutaneous leishmaniasis.

Biological characteristics of the Trypanosoma cruzi Arequipa strain make it a good model for Chagas disease drug discovery

Trypanosoma cruzi, the causative agent of Chagas disease (CD), is a genuine parasite with tremendous genetic diversity and a complex life cycle. Scientists have studied this disease for more than 100 years, and CD drug discovery has been a mainstay due to the absence of an effective treatment. Technical advances in several areas have contributed to a better understanding of the complex biology and life cycle of this parasite, with the aim of designing the ideal profile of both drug and therapeutic options to treat CD. Here, we present the T. cruzi Arequipa strain (MHOM/Pe/2011/Arequipa) as an interesting model for CD drug discovery. We characterized acute-phase parasitaemia and chronic-phase tropism in BALB/c mice and determined the in vitro and in vivo benznidazole susceptibility profile of the different morphological forms of this strain. The tropism of this strain makes it an interesting model for the screening of new compounds with a potential anti-Chagas profile for the treatment of this disease.

Biodiversity in Times of COVID-19 and its Relationship with the Socio-Economic and Health Context: A Look from the Digital Media

The COVID-19 pandemic has caused a pause in people's activities and a socio-economic crisis worldwide due to confinement. This situation is an unprecedented opportunity to understand how these changes may impact biodiversity and its conservation, as well as to study human-nature interaction. Biodiversity plays an essential role in conservation and economic activities, and in countries with greater inequality and low gross domestic product (GDP), biodiversity could have a low priority. Moreover, how biodiversity is prioritized in a society impacts how the citizens view it, and digital news tends to shape biodiversity narratives. The aim of this work was to determine the main trends in biodiversity-related news categories during the COVID-19 pandemic in countries with terrestrial and marine hotspots and relate them to the socioeconomic and public health context of each country. For this, we searched for news on biodiversity and Covid-19 in the first 6 months of the pandemic and related them to GDP, Gini-index, deaths, and infections by Covid-19. Results showed that conservation, public policies, and use of natural resources stood out as the main news categories across countries, with a positive narrative and mostly related to terrestrial rather than marine environments. On the other hand, the socio-economic and public health characteristics of each country had an influence on which aspect of the biodiversity was reflected in the media. For example, countries with greater inequality were associated with tourism news, additionally, countries with low GDP, high cases, and deaths by Covid-19 were associated with news about cultural diversity. In contrast, countries with high GDP and low inequality were associated with news about zoonosis, research and development, public policies, and alien and invasive species.

The long-term impact of an Ecohealth intervention: Entomological data suggest the interruption of Chagas disease transmission in southeastern Guatemala

Triatoma dimidiata is the main vector of Chagas disease in southern Mexico, Central America and northern South America. As a native vector, it moves readily among domestic, peri-domestic and sylvatic environments, making it difficult to control only using insecticide as this requires regular application, and re-infestation frequently occurs. Other social innovation alternatives such as those based on Ecohealth principles can be used to tackle the dynamics of the disease in an integral way. We asked whether an Ecohealth intervention, implemented beginning in 2001 in a highly infested village, 41.8%, in southeastern Guatemala, was sustainable in the long term. This intervention included initial insecticide treatments, followed by making low-cost house improvements to eliminate transmission risk factors such as repairing cracked walls, covering dirt floors with a cement-like substance and moving domestic animals outside. We assessed the long-term sustainability through entomological and house condition surveys, as well as an analysis of community satisfaction. We found over a 19-year period, infestation with T. dimidiata was reduced to 2.2% and maintained at a level below the level (8%) where vector transmission is unlikely. This long-term maintenance of low infestation coincided with a large proportion of villagers (88.6%) improving their houses and completing other aspects of the Ecohealth approach to maintain the village at low risk for Chagas transmission. There was unanimous satisfaction among the villagers with their houses, following improvements using the Ecohealth method, which likely played a role in the long-term persistence of the modifications. Although the infestation has remained low, 11 years following the last intervention and as the population grew there has been an increase in the proportion of "at-risk" houses, to 33%, pointing out the necessity of maintaining vigilance. The Ecohealth approach is a low-cost, sustainable approach for the long-term control of vector-borne Chagas disease. We recommend this approach including ongoing community monitoring and institutional response for the long-term, integrated control of Chagas disease.

Spotted Fever Group Rickettsioses in Central America: The Research and Public Health Disparity among Socioeconomic Lines

Simple Summary

Tick-borne diseases are an important public health issue globally. Spotted fever group rickettsioses (SFGR), a group of related tick-borne pathogens, can cause significant disease, but is widely underreported and likely misdiagnosed. In Central America, there is little known about SFGR, and there seems to be a socioeconomic-related difference between the most-developed and least-developed countries in the region. The least-developed countries (El Salvador, Guatemala, Honduras, and Nicaragua) disproportionately underreport research or studies regarding SFGR disease compared to the most-developed countries (Belize, Panama, and Costa Rica). We compared human development and poverty indicators among Central American countries for this review of SFGR Rickettsia-related articles. The least-developed countries are at a higher risk or are more vulnerable to SFGR disease than the most-developed countries in this region.

Abstract

Tick-borne diseases including rickettsial diseases are increasing in incidence worldwide. Many rickettsial pathogens can cause disease which is commonly underdiagnosed and underreported; Rickettsia pathogens in the spotted fever group (SFGR) are thus classified as neglected bacterial pathogens. The Central American region shoulders a large proportion of the global neglected disease burden; however, little is known regarding SFGR disease here. Although development varies, four of the seven countries in this region have both the highest poverty rates and SFGR disease burdens (El Salvador, Honduras, Guatemala, and Nicaragua), compared to Belize, Panama, and Costa Rica. Utilizing the Human Development Index (HDI), we compared published articles related to SFGR Rickettsia prevalence in the lowest-HDI-scoring countries to the highest-HDI-scoring countries. Our analysis identified a distinct dichotomy in publication, and by proxy, potentially awareness and knowledge of SFGR tick-borne disease in Central America, where the least-developed countries are at the highest risk for, yet the most vulnerable to, SFGR disease.

Leishmania braziliensis causing human disease in Northeast Brazil presents loci with genotypes in long-term equilibrium

Background

Leishmaniases are neglected tropical diseases that inflict great burden to poor areas of the globe. Intense research has aimed to identify parasite genetic signatures predictive of infection outcomes. Consistency of diagnostic tools based on these markers would greatly benefit from accurate understanding of Leishmania spp. population genetics. We explored two chromosomal loci to characterize a population of L. braziliensis causing human disease in Northeast Brazil.

Methodology/Principal findings

Two temporally distinct samples of L. braziliensis were obtained from patients attending the leishmaniasis clinic at the village of Corte de Pedra: (2008–2011) primary sample, N = 120; (1999–2001) validation sample, N = 35. Parasites were genotyped by Sanger’s sequencing of two 600 base pairs loci starting at nucleotide positions 3,074 and 425,451 of chromosomes 24 and 28, respectively. Genotypes based on haplotypes of biallelic positions in each locus were tested for several population genetic parameters as well as for geographic clustering within the region. Ample geographic overlap of genotypes at the two loci was observed as indicated by non-significant Cusick and Edward’s comparisons. No linkage disequilibrium was detected among combinations of haplotypes for both parasite samples. Homozygous and heterozygous genotypes displayed Hardy-Weinberg equilibrium (HWE) at both loci in the two samples when straight observed and expected counts were compared by Chi-square (p>0.5). However, Bayesian statistics using one million Monte-Carlo randomizations disclosed a less robust HWE for chromosome 24 genotypes, particularly in the primary sample (p = 0.04). Fixation indices (Fst) were consistently lower than 0.05 among individuals of the two samples at both tested loci, and no intra-populational structuralization could be detected using STRUCTURE software.

Conclusions/Significance

These findings suggest that L. braziliensis can maintain stable populations in foci of human leishmaniasis and are capable of robust genetic recombination possibly due to events of sexual reproduction during the parasite’s lifecycle.

Leishmania braziliensis affects poor human populations in the tropics, may cause face disfiguring lesions and may also resist treatment. There has been intense research for markers in these parasites genetic contents for helping predict if an infected human being would be of greater chance of severe disease or treatment failure. The consistent identification of such markers requires a deep understanding of how genes circulate within these parasites’ natural populations. We explored two small segments of DNA (i.e. loci), one on chromosome 24, the other on chromosome 28 of L. braziliensis to characterize a population that causes human disease in Northeast Brazil. We employed two samples of parasites obtained from lesions of patients diagnosed from 1999 to 2001, and from 2008 to 2011. We sequenced the DNA of those loci in each parasite of the two samples. Then, we evaluated the status of several population genetics parameters among them. Based on our findings to that region, we concluded that L. braziliensis can maintain populations that are genetically stable for several years in foci of human leishmaniasis and are capable of robust recombination of their genetic contents, probably due to events of sexual reproduction during its lifecycle.

Spatial epidemiology and adaptive targeted sampling to manage the Chagas disease vector Triatoma dimidiata

Widespread application of insecticide remains the primary form of control for Chagas disease in Central America, despite only temporarily reducing domestic levels of the endemic vector Triatoma dimidiata and having little long-term impact. Recently, an approach emphasizing community feedback and housing improvements has been shown to yield lasting results. However, the additional resources and personnel required by such an intervention likely hinders its widespread adoption. One solution to this problem would be to target only a subset of houses in a community while still eliminating enough infestations to interrupt disease transfer. Here we develop a sequential sampling framework that adapts to information specific to a community as more houses are visited, thereby allowing us to efficiently find homes with domiciliary vectors while minimizing sampling bias. The method fits Bayesian geostatistical models to make spatially informed predictions, while gradually transitioning from prioritizing houses based on prediction uncertainty to targeting houses with a high risk of infestation. A key feature of the method is the use of a single exploration parameter, α, to control the rate of transition between these two design targets. In a simulation study using empirical data from five villages in southeastern Guatemala, we test our method using a range of values for α, and find it can consistently select fewer homes than random sampling, while still bringing the village infestation rate below a given threshold. We further find that when additional socioeconomic information is available, much larger savings are possible, but that meeting the target infestation rate is less consistent, particularly among the less exploratory strategies. Our results suggest new options for implementing long-term T. dimidiata control.

Effective public health interventions for the control and elimination of neglected tropical diseases require an efficient use of resources while still causing long-term disease reduction at the community level. To use resources to best effect, areas most in need of control efforts must be identified. However, strategies for correctly identifying these areas are rarely known due to the complex environmental, biological, and cultural factors shaping disease spread. In turn, incorrect prioritization of control targets can cause the intervention to have no lasting effect. We address this tradeoff between efficiency and efficacy by adapting control priorities throughout an intervention, targeting areas of high uncertainty during the initial stages while shifting to areas of greatest risk at later stages. In the context of controlling Triatoma dimidiata, the primary vector of Chagas disease in several countries in Latin America, our methods provide a means of targeting only a subset of homes for insecticide and housing improvements, while still reducing a village’s overall infestation rate below the critical threshold.

Global burden and trends of neglected tropical diseases from 1990 to 2019

BACKGROUND

An updated analysis of neglected tropical diseases (NTDs) from a global perspective is missing from the literature. We aimed to assess the global burden and trends of NTDs from 1990 to 2019.

METHODS

Yearly incident case, mortality and disability-adjusted life years (DALYs) data for NTDs were extracted from the Global Burden of Disease Study 2019 (GBD 2019) based on global, regional, country, social development index (SDI), age and sex categories. The age-standardized rate (ASR) and number of incident cases, mortality and DALYs were computed from 1990 to 2019. The estimated annual percentage change (EAPC) in the ASR was calculated to quantify the changing trend.

RESULTS

Globally, the age-standardized incidence rate (ASIR) and the number of incident cases of total NTDs increased between 1990 and 2019, whereas the age-standardized mortality rate (ASMR), mortality, age-standardized DALY rate and DALYs of total NTDs decreased. Although tropical Latin America, South Asia, Southeast Asia and Oceania had the highest ASIR for total NTDs in 2019, tropical Latin America was the only region to experience a decreasing trend in ASIR from 1673.5 per 100 000 in 2010 to 1059.2 per 100 000 in 2019. The middle, high-middle and high SDI regions experienced increasing ASIR trends between 1990 and 2019, whereas the low-middle SDI region remained stable, and the low SDI region presented a decreasing trend. Children and older adults were vulnerable to dengue, rabies and leishmaniasis (cutaneous and mucocutaneous). Females had a higher ASIR but a lower ASMR and age-standardized DALY rate than males.

CONCLUSIONS

NTDs still represent a serious problem for public health, and the increasing ASIR and incident cases globally may require more targeted strategies for prevention, control and surveillance, especially among specific populations and endemic areas.

Leptospirosis: Morbidity, mortality, and spatial distribution of hospitalized cases in Ecuador. A nationwide study 2000-2020

Background

In Ecuador, leptospirosis surveillance involves a mandatory notification of all cases and a hospitalization for severe illness. Morbidity and mortality are, nevertheless, underestimated and contribute directly to the status of leptospirosis as a neglected disease. Leptospira spp. is zoonotic in Ecuador with established endemic transmission in the Tropics. Here, we review retrospective national data within the country to aid in control strategies.

Methodology/Principal findings

In a population-based nationwide study, we analysed morbidity, mortality, and spatial distribution on confirmed hospital-discharged leptospirosis cases from 2000–2020 from a publicly accesible National Database, including males and females of all ages. We computed data for the 24 provinces across the four-geoclimatic regions of Ecuador based on seasonal and monthly variations and calculated rates according to age and sex. The spatial distribution was estimated at the level of ecoregions, provinces, and cantons. A total of 2,584 hospitalizations were recorded over all three continental regions in 22 provinces, except Carchi province and the Galapagos Islands. The annual incidence varied from 0.27 to 2.45 cases per 100,000 inhabitants with ages ranging from 1 to 98 years-old and an overall male/female ratio of 1.92:1. Most hospitalizations and deaths occurred in males ages 25–34 years. We registered 79 fatalities (3.06%); the highest mortality rate was 0.05 per 100,000 inhabitants. More cases clustered in the tropical cantons of central and north of the Coast and in the southern Amazon when compared to the Andes.

Conclusions and significance

Our findings evidence leptospirosis endemicity and pinpoint the highest incidence within resource-poor tropical settings. The highest incidence occurred in males of adult age, with those also exhibiting the highest mortality. The national incidence rate was stable, but peaks occurred intermittently during the rainy seasons. Thus, strategies aimed at leptospirosis monitoring and control involving the application of preventive measures should consider this season and the aforementioned high-risk groups.

Leptospirosis is a neglected tropical disease poorly characterized in Latin American countries like Ecuador. Although this zoonotic disease is considered by the Epidemiology Department of the Ministry of Public Health to be of mandatory notification, an updated document on the patterns of morbidity and mortality or a control strategy do not yet exist. In the present study, we carried out a retrospective analysis of Ecuadorian national data (INEC) on hospitalized cases and deaths from 2000 through 2020 to estimate the trends of morbidity and mortality, and the spatial distribution of this disease throughout its four geoclimatic regions (Pacific coastal, Andes, Amazon, and the Galapagos Islands). The INEC recorded only hospitalized cases, meaning those with severe illness. The spatial distribution was estimated at the ecoregion, province, and canton levels. With a total number of 2,584 hospitalizations, an annual incidence ranging from 0.27 to 2.45 cases per 100,000 inhabitants, and a fatality rate of 3.06% during the period of study. Our findings evidence the endemicity of leptospirosis, particularly within the neglected tropical settings in the Ecuadorian Coast and Amazon regions. Despite the wide geographic distribution of leptospirosis and its severity in terms of incidence, morbidity, and mortality, leptospirosis is not yet considered a “tool-ready” disease for control/elimination and research initiatives.

Epidemiological and Clinical Characteristics of Acute Dengue Virus Infections Detected through Acute Febrile Illness Surveillance, Belize 2020

The Acute Febrile Illness (AFI) Surveillance Network in Belize is a country-wide active surveillance program aimed at diagnosing vector-borne, respiratory, and enteric pathogens among patients presenting to 11 participating hospitals and clinics with new onset fever. This study describes the epidemiology of dengue virus (DENV) infections in Belize diagnosed through AFI surveillance in 2020. Of the 894 patients enrolled and PCR-tested for DENV in this period, 44 DENV-positive cases (5%) were identified. All four DENV serotypes were detected, with two cases testing positive for DENV serotype 4, which is the first report of this serotype in Belize since 2004. The majority of DENV cases (66%) were diagnosed in the Belize District, which contains the largest urban center in the country (Belize City). Positive cases were detected between January 2020 and September 2020, with the majority (89%) diagnosed during the dry season between January and April, unlike years prior when cases were more often diagnosed during the wet season. Clinical signs and symptoms varied slightly between DENV serotypes. Active surveillance of DENV among AFI cases provides insight into the epidemiologic and clinical characteristics of DENV in Belize. This information is important for informing public health interventions to mitigate DENV transmission.

The status of schistosomiasis japonica control in the Philippines: The need for an integrated approach to address a multidimensional problem

Schistosomiasis japonica remains a public health concern in many areas of the Philippines. Adequate and updated information is essential to enhance policy and service delivery toward control and elimination. Despite the efforts on schistosomiasis control in the Philippines, some challenges remain in these dimensions. An integrated surveillance system is recommended to determine the prevalence of infection in humans, animal reservoirs, and snail intermediate hosts, allowing the identification of high-priority areas for targeted interventions. This will entail the enhancement of laboratory diagnosis capacity through the use of more sensitive techniques, complemented by capacity building of concerned human and animal health professionals. Given the zoonotic nature of schistosomiasis japonica, adopting the One Health approach is essential to influence policies and interventions that may accelerate control and elimination. This can be achieved through the attainment of mass drug administration coverage targets and intensified case finding and management, robust implementation and integration of veterinary public health activities, the conduct of snail control measures, provision of safe water, sanitation, and hygiene services, and health promotion and education into the national schistosomiasis control and elimination program. This review aimed to describe the status of schistosomiasis japonica control in the Philippines in the context of human health, animal health, vector ecology and management, environmental health, and sociocultural dimensions.

Could combination chemotherapy be more effective than monotherapy in the treatment of visceral leishmaniasis? A systematic review of preclinical evidence

From a systematic review framework, we assessed the preclinical evidence on the effectiveness of drug combinations for visceral leishmaniasis (VL) treatment. Research protocol was based on the PRISMA guideline. Research records were identified from Medline, Scopus and Web of Science. Animal models, infection and treatment protocols, parasitological and immunological outcomes were analysed. The SYRCLE's (SYstematic Review Center for Laboratory Animal Experimentation) toll was used to evaluate the risk of bias in all studies reviewed. Fourteen papers using mice, hamster and dogs were identified. Leishmania donovani was frequently used to induce VL, which was treated with 23 drugs in 40 different combinations. Most combinations allowed to reduce the effective dose, cost and time of treatment, in addition to improving the parasitological control of Leishmania spp. The benefits achieved from drug combinations were associated with an increased drug's half-life, direct parasitic toxicity and improved immune defences in infected hosts. Selection, performance and detection bias were the main limitations identified. Current evidence indicates that combination chemotherapy, especially those based on classical drugs (miltefosine, amphotericin B antimony-based compounds) and new drugs (CAL-101, PAM3Cys, tufisin and DB766), develops additive or synergistic interactions, which trigger trypanocidal and immunomodulatory effects associated with reduced parasite load, organ damage and better cure rates in VL.

Computer-Assisted Discovery of Alkaloids with Schistosomicidal Activity

Schistosomiasis is a chronic parasitic disease caused by trematodes of the genus Schistosoma; it is commonly caused by Schistosoma mansoni, which is transmitted by Bioamphalaria snails. Studies show that more than 200 million people are infected and that more than 90% of them live in Africa. Treatment with praziquantel has the best cost–benefit result on the market. However, hypersensitivity, allergy, and drug resistance are frequently presented after administration. From this perspective, ligand-based and structure-based virtual screening (VS) techniques were combined to select potentially active alkaloids against S. mansoni from an internal dataset (SistematX). A set of molecules with known activity against S. mansoni was selected from the ChEMBL database to create two different models with accuracy greater than 84%, enabling ligand-based VS of the alkaloid bank. Subsequently, structure-based VS was performed through molecular docking using four targets of the parasite. Finally, five consensus hits (i.e., five alkaloids with schistosomicidal potential), were selected. In addition, in silico evaluations of the metabolism, toxicity, and drug-like profile of these five selected alkaloids were carried out. Two of them, namely, 11,12-methylethylenedioxypropoxy and methyl-3-oxo-12-methoxy-n(1)-decarbomethoxy-14,15-didehydrochanofruticosinate, had plausible toxicity, metabolomics, and toxicity profiles. These two alkaloids could serve as starting points for the development of new schistosomicidal compounds based on natural products.

Pulmonary, liver and cerebral paragonimiasis: An unusual clinical case in Colombia

BACKGROUND

Mainly affecting poorer populations in remote (sub)tropical areas, paragonimiasis is considered one of the world's most neglected tropical diseases by the World Health Organization. It is usually acquired by consuming undercooked freshwater crustaceans and primarily affects the lungs, but may ectopically migrate to other organs to produce a multisystemic clinical presentation. This study details what appears to be the first documented case in South America and particularly in Colombia of cerebral paragonimiasis and infection by the crab Moreirocarcinus emarginatus.

CASE PRESENTATION

After consuming this crab, a 32-year-old Colombian male developed dyspnea and headache. A chest X-ray revealed tension pneumothorax (TPT) and a thoracoscopic lung biopsy bronchiolitis, eosinophilia, and granulomatous reaction due to Paragonimus parasites.

RESULTS

Brain tomography and MRI also showed a configuration typical of Paragonimus parasites, namely a predominantly cystic area near the left cuneus with diffusion restriction, a hemosiderin halo, and linear enhancement characteristic of the tunnel sign, indicating an adult worm moving in the brain.

CONCLUSIONS

Cerebral paragonimiasis can occur in the Colombian population and Moreirocarcinus emarginatus can be its cause. In rural areas, education about raw crab consumption would be beneficial, and physicians addressing lung-related complaints should bear paragonimiasis in mind and ask about raw crab consumption.

Challenges in the control of neglected insect vector diseases of human importance in the Anglo-Caribbean

INTRODUCTION

Neglected tropical diseases (NTDs) in developing countries like the Caribbean, negatively affect multiple income-generating sectors, including the tourism industry upon which island states are highly dependent. Insect-transmitted NTDs include, but are not limited to, malaria, dengue and lymphatic filariasis. Control measures for these disease, are often ignored because of the associated cost. Many of the developing country members are thus retained in a financially crippling cycle, balancing the cost of prophylactic measures with that of controlling an outbreak.The purpose of the paper is to bring awareness to NTDs transmitted by insects of importance to humans, and to assess factors affecting such control, in the English-speaking Caribbean.

METHOD

Comprehensive literature review on reports pertaining to NTDs transmitted by insects in the Caribbean and Latin America was conducted. Data search was carried out on PubMed, and WHO and PAHO websites.

RESULTS AND CONCLUSION

Potential risk factors for NTDs transmitted by arthropods in the English-speaking Caribbean are summarised. The mosquito appears to be the main insect-vector of human importance within the region of concern. Arthropod-vectors of diseases of veterinary importance are also relevant because they affect the livelihood of farmers, in highly agriculture based economies. Other NTDs may also be in circulation gauged by the presence of antibodies in Caribbean individuals. However, routine diagnostic tests for specific diseases are expensive and tests may not be conducted when diseases are not prevalent in the population. It appears that only a few English-speaking Caribbean countries have examined secondary reservoirs of pathogens or assessed the effectivity of their insect control methods. As such, disease risk assessment appears incomplete. Although continuous control is financially demanding, an integrated and multisectoral approach might help to deflect the cost. Such interventions are now being promoted by health agencies within the region and various countries are creating and exploring the use of novel tools to be incorporated in their insect-vector control programmes.

A retrospective study of Taenia spp. in Cuban patients: what does molecular analysis tell us?

Taeniosis is a neglected disease, particularly in developing countries, and is caused by infection with the adult tapeworm of either Taenia solium, Taenia saginata, and Taenia asiatica. Of these, T. solium is of primary concern due to the potential for cysticercosis should T. solium eggs be ingested. In Cuba, all cases of taeniosis are assumed to be caused by T. saginata, although some cases of cysticercosis have been documented. It is therefore important to gain further insights regarding the species causing taeniosis in Cuba, especially as diagnostic records indicate an increasing incidence, with the highest number of cases reported in 2020. In this study, we analysed 37 Taenia-positive faecal samples (or proglottids isolated from faecal samples) from the period 2001 until 2020 from all regions of the country. Genomic DNA was extracted from the samples, which had been stored in 10% formalin, using the QIAamp Tissue Kit. Species identification was carried out by duplex real-time PCR targeting the mitochondrial DNA. All cases were found to be T. saginata, and sequence analysis of three isolates confirmed the identification of this species. Our data do not provide any evidence that T. solium currently occurs in Cuba. However, given the relatively low number of samples analysed here, that the parasite may be imported with visitors or travellers who have been in endemic countries, and that taeniosis has relatively mild symptoms and thus infected patients may not seek medical attention, we recommend species determination for all taeniosis cases reported in Cuba.

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The incidence of taeniosis cases in Cuba is rising, with 2020 being a peak year

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Although assumed to be Taenia saginata, this has not been confirmed

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We investigated 37 samples from 2001 until 2020 that had been stored in formalin

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Duplex real-time PCR indicated T. saginata; 3 cases were confirmed by sequencing

Diversity of Trypanosoma cruzi parasites infecting Triatoma dimidiata in Central Veracruz, Mexico, and their One Health ecological interactions

Triatoma dimidiata is the main vector of Trypanosoma cruzi parasites in Veracruz, Mexico, and its association with human housing appears variable. Also, in spite of a high seroprevalence of T. cruzi infection in humans, parasite transmission remains poorly understood. Therefore, we aimed to identify T. dimidiata blood feeding sources and its parasite and microbial diversity to reconstruct T. cruzi parasite transmission ecology in central Veracruz, Mexico, within a One Health/Ecohealth framework. We used a metabarcoding and deep sequencing approach of specific markers for the simultaneous identification of T. dimidiata haplogroup (ITS-2), vertebrate blood meals (12 s gene), T. cruzi parasites (mini-exon gene), and gut microbiota (bacterial 16 s). Twelve species of domestic/synanthropic animals and humans were identified as blood sources, with multiple feeding on 4.2 ± 0.4 hosts per bug. The feeding/parasite transmission network was strongly centered on humans, emphasizing a significant risk of infection. We also unambiguously confirmed the presence of TcI, TcII, TcV and TcVI DTUs in T. dimidiata, and sequences from Veracruz tended to cluster apart from parasites from other regions, suggesting some level of local differentiation. Analysis of T. dimidiata microbiota suggested that several bacterial families may be associated with the presence/absence of T. cruzi, and some of these associations may also be parasite DTU-specific. Such integrative approaches within the EcoHealth/One Health framework provide key insights on T. cruzi transmission and potential novel strategies for disease control.

Influence of Intestinal Helminth Burden on Clinical Manifestations, Therapeutic Response, and Leishmania braziliensis Load in Patients with New World Cutaneous Leishmaniasis

Leishmania braziliensis is the most important cause of cutaneous leishmaniasis (CL) in the Americas. A Th1-type immune response is required to control Leishmania infection, but an exaggerated inflammatory response leads to the development of ulcers seen in CL. Infection with intestinal helminths has the potential to inhibit the Th1 response in a manner that depends both on the species of helminth present as well as the burden of helminthiasis. We conducted a prospective cohort study of CL patients from an endemic area between January and December 2017 with either negative or high intestinal helminth burden to characterize relationships between helminth burden, L. braziliensis quantification within CL lesions, clinical aspects of CL, and therapeutic response. Of 234 participants with leishmaniasis who underwent stool examination at the time of diagnosis, 45% had detectable helminth infection. The overall cure rate after 90 days was 66%, with a median time to resolution of disease of 40 days (interquartile range: 30-65 days). There was no significant association between the type of helminth infection or the magnitude of intestinal helminth burden at the time of diagnosis and L. braziliensis genomic DNA (gDNA) detected in biopsies from CL lesions. Likewise, there was no association between helminth burden and response to treatment after 90 days. Considering quantification of parasite DNA in CL lesions, participants who were cured at 90 days had a median of 0.017 ng/mg gDNA, and participants who failed therapy had a median of 0.091 ng/mg gDNA (P = 0.03). The results indicate that cutaneous Leishmania load may influence therapeutic response in CL.

Economic costs of biological invasions in Ecuador: the importance of the Galapagos Islands

Biological invasions, as a result of human intervention through trade and mobility, are the second biggest cause of biodiversity loss. The impacts of invasive alien species (IAS) on the environment are well known, however, economic impacts are poorly estimated, especially in mega-diverse countries where both economic and ecological consequences of these effects can be catastrophic. Ecuador, one of the smallest mega-diverse countries, lacks a comprehensive description of the economic costs of IAS within its territory. Here, using "InvaCost", a public database that compiles all recorded monetary costs associated with IAS from English and Non-English sources, we investigated the economic costs of biological invasions. We found that between 1983 and 2017, the reported costs associated with biological invasions ranged between US$86.17 million (when considering only the most robust data) and US$626 million (when including all cost data) belonging to 37 species and 27 genera. Furthermore, 99% of the recorded cost entries were from the Galapagos Islands. From only robust data, the costliest identified taxonomic group was feral goats (Capra hircus; US$20 million), followed by Aedes mosquitoes (US$2.14 million) while organisms like plant species from the genus Rubus, a parasitic fly (Philornis downsi), black rats (Rattus rattus) and terrestrial gastropods (Achatina fulica) represented less than US$2 million each. Costs of "mixed-taxa" (i.e. plants and animals) represented the highest (61% of total robust costs; US$52.44 million). The most impacted activity sector was the national park authorities, which spent about US$84 million. Results from robust data also revealed that management expenditures were the major type of costs recorded in the Galapagos Islands; however, costs reported for medical losses related to Aedes mosquitoes causing dengue fever in mainland Ecuador would have ranked first if more detailed information had allowed us to categorize them as robust data. Over 70% of the IAS reported for Ecuador did not have reported costs. These results suggest that costs reported here are a massive underestimate of the actual economic toll of invasions in the country.

Knowledge, attitudes, and practices regarding vector-borne diseases in central Mexico

BACKGROUND

While vector-borne diseases (VBDs) pose an important public health problem worldwide, there is a limited and conflicting knowledge about such illnesses in rural or urban settings. The present study aimed to explore the social representations (SRs) held by people in the state of Puebla, Mexico on insects and the diseases they transmit. Understood as the group of ideas held and shared by a group of human beings which enable them to understand and interpret the world, SRs constitute what could be called a collective science or knowledge of everyday life.

METHODS

The present study was conducted in six municipalities in the state of Puebla, wherein an open-ended questionnaire was applied with three age ranges. A total of 360 questionnaires were applied with people dedicated to a variety of activities. The survey data was analyzed to identify the SR's structure (the central nucleus of the SR and its peripheral system) and the level of organization in order to explore the degree to which the ideas that constitute it are shared and based on consensus. To describe the structure of the SR, a network analysis was conducted and complemented by a correspondence analysis, which also enables the differences between social groups to be identified.

RESULTS

Popular knowledge on insects and VBDs is often limited, even in communities in which more than one-vector insect is found. The elements that were most frequently mentioned in the data, as pertaining to the insect-disease relationship, were mosquitoes and dengue fever, with scorpions (which are arachnids and not insects) receiving the second-highest number of mentions, while other insects such as kissing bugs, flies, and cockroaches were also mentioned as transmitting VBDs. While television was the main information source on VBDs for the residents of these communities, biology books were also mentioned. Chemical control measures (insect repellents) were the most used prevention method, and traditional medicine was the remedy most commonly used to treat insect bites and transmitted diseases. Entomophobia was the main cause for the respondents' fear and rejection of insects. Beyond the deleterious effects of many insects, those surveyed also recognized a positive relationship with insects due to economic and nutritional benefits they provide.

CONCLUSIONS

The present study provides relevant information on how insects and the diseases they transmit are perceived by rural and urban communities. Although the population is aware of dengue fever and the role of mosquitoes in transmitting it, information campaigns are required for other historically neglected VBDs, such as leishmaniasis, Chagas disease, and, even, rickettsiosis. As it is important to understand the impact that these illnesses have on communities further research is required to ensure that better information and guidance is provided on VBDs in order to develop a culture of illness prevention in not only the rural but also the metropolitan communities of the state of Puebla.

γ-Lactones from Persea americana and Persea fulva - in Vitro and in Silico Evaluation of Trypanosoma cruzi Activity

In the present study, five known γ-lactones (majoranolide B - 1, majorenolide - 2, majorynolide - 3, lincomolide D - 4, and isolinderanolide E - 5), as well as a new one (perseanolide - 6), were isolated from Persea fulva and P. americana. All isolated compounds exhibited potential activity against trypomastigote forms of Trypanosoma cruzi, whereas compounds 2 (EC₅₀ of 4.8 μM) and 6 (EC₅₀ of 3.6 μM) displayed superior activity than the positive control benznidazole (EC₅₀ of 16.4 μM), with selectivity index (SI) values of 17.8 and >55.6, respectively (benznidazole, SI>12.2). Molecular docking studies were performed for 1-6 against six T. cruzi molecular targets. Using this approach, we observed that, even though perseanolide (6) showed favorable docking to several studied targets, the results were especially promising for hypoxanthine phosphoribosyl transferase (PDB 1TC1). As PDB 1TC1 is associated to the transference of a monophosphorylated ribose from phosphoribosylpyrophosphate (PRPP) in the ribonucleotide synthesis pathway, this interaction may affect the survival of T. cruzi in mammalian cells. The data herein also indicate that possible intermolecular interactions between 6 and PDB 1TC1 derive from (i) hydrogen bonds in the α,β-unsaturated-γ-lactone unity and (ii) hydrophobic interactions in the long-chain alkyl group. Based on our results, perseanolide (6), reported for the first time in this work, can auspiciously contribute to future works regarding new trypanocidal agents.

Stunting in pre-school and school-age children in the Peruvian highlands and its association with Fasciola infection and demographic factors

Fascioliasis is a zoonotic trematode infection that is endemic in the highlands of Peru. Chronic fascioliasis can be asymptomatic and remain undiagnosed for years. Chronic malnutrition in children, as manifested by stunting, leads to delayed cognitive development and lost productivity. We hypothesized that fascioliasis is among the factors associated with stunting in children from endemic areas. We conducted a cross-sectional study among children attending pre-school and school in 26 communities in the Anta province in the Cusco region of Peru. We conducted interviews to collect information on demographic, socioeconomic, and medical history. Blood was collected and tested for complete cell count and FAS2 ELISA for Fasciola antibodies. Three stool samples per participant were tested for parasites by Kato-Katz and Lumbreras rapid sedimentation methods. Chronic fascioliasis was determined by the presence of ova in stool. Children's height, weight, and age were recorded and used to calculate height for age Z scores (HAZ). Three thousand children participated in the study. Nine percent (264) of children had at least one positive test for Fasciola infection, 6% (164) had chronic fascioliasis, and 3% (102) had only positive antibody tests. The median HAZ was -1.41 (IQR: -2.03 to -0.81) and was similar in males and females. Twenty six percent (776) of children had stunting with HAZ < -2. Children with chronic fascioliasis had a lower median HAZ than children without Fasciola (-1.54 vs. -1.4, p = 0.014). History of treatment for malnutrition, history of treatment for anemia, having other helminths in stool, lower socioeconomic score, living at a higher elevation, and fewer years of schooling of both parents were associated with a lower HAZ score. In a multiple regression analysis, older age and a lower socioeconomic score were associated with a lower HAZ score. While fascioliasis and other helminths were associated with lower HAZ, they were not independent of the socioeconomic score.

Molecular ecology of Triatoma dimidiata in southern Belize reveals risk for human infection and the local differentiation of Trypanosoma cruzi parasites

OBJECTIVE

In Belize, the main vector for Trypanosoma cruzi, the agent of Chagas disease, is Triatoma dimidiata, but transmission cycles and the risk for human infection are unclear. Therefore, the aim of this study was to identify T. dimidiata blood feeding sources and its parasite and microbial diversity, in order to reconstruct T. cruzi parasite transmission ecology in southern Belize.

METHODS

A metabarcoding approach based on deep sequencing of markers was used for bug taxonomy, blood meal sources, T. cruzi genotypes, and microbiota composition. Bugs were collected in 13 villages of Toledo district.

RESULTS

Bugs fed on at least 13 species, from domestic hosts such as humans, dogs, cows, and pigs, to synanthropic species such as mice, rats, and opossums, and sylvatic species such as deer, peccary, and kinkajou, in agreement with an opportunistic feeding behavior. Nonetheless, most feeding focused on a few species, including humans. Infection with T. cruzi was detected in 24 of 39 bugs (62%), and the analysis of 242 T. cruzi mini-exon sequences (average 10 ± 5 haplotypes per bug) indicated the presence of TcI and TcIV parasite discrete typing units (DTUs). However, for both DTUs, sequences from Belize mostly clustered apart from sequences from North and South America, suggesting the local differentiation of parasites. T. dimidiata also harbored a diverse bacterial microbiota, with ontogenic changes suggesting microbiota maturation during nymphal development.

CONCLUSIONS

Together, these results indicate a significant risk for T. cruzi infection in humans. They also highlight the need to better characterize the diversity of T. cruzi strains in the region and its impact on disease epidemiology.