Trop. Med. Infect. Dis., Volume 9, Issue 6 (June 2024) – 14 articles

Leishmaniasis is a group of diseases caused by protozoa of the genus Leishmania and is transmitted by the bite female sand fly. The present work is characterized as a descriptive study in two areas: a forest area located in the Parque Estadual do Rio Doce, and another urban area located in the municipality of Timóteo-MG, with the objective of identifying the presence of Leishmania spp. and the blood source of the collected female sand flies. Part of the females were obtained from the Parque Estadual do Rio Doce, and part was collected using 19 ligth traps distributed in residences of Timóteo. For molecular studies of Leishmania spp. DNA, the ITS1 gene was used, and in the search for blood source, the CytB gene was used and positive samples were sequenced. The study demonstrated that there are at least three species of Leishmania circulating in the study areas: Leishmania (Viannia) braziliensis, Leishmania (Leishmania) amazonensis, and Leishmania (V.) guyanensis. Nyssomyia whitmani was the predominant sand fly species in the urban area of Timóteo with a positive diagnosis for the presence of Leishmania braziliensis DNA. We found the presence of blood from Gallus gallus (Chicken) and Sus scrofa (Pig) in sand flies. The present study demonstrates that Leishmania braziliensis is the main agent of cutaneous leishmaniasis in the study area, with the effective participation of Nyssomyia whitmani as the vector and both Gallus gallus and Sus scrofa acting as a food source for female sand flies, and helping maintaining the sand fly life. Full article

Neurological complications are frequent during the active course of infective endocarditis (IE), and they are associated with high in-hospital mortality rates. However, limited data exist on the prognostic value of these complications for late outcomes. This study aimed to assess the long-term impact of neurological complications in patients surviving an IE episode. A total of 263 consecutive IE patients admitted to a tertiary care center between 2007 and 2022 were prospectively included. Neurological complications at admission included transient ischemic attack (TIA), ischemic stroke, hemorrhagic stroke, intracerebral abscess, and meningitis. The primary outcome was a composite of overall mortality or heart valve surgery. Of the patients, 34.2% died in the hospital, leaving 173 survivors for long-term follow-up. Over a median of 3.5 years, 29 patients died, and 13 (9%) underwent cardiac surgery, resulting in an overall adverse event rate of 30%. Neurological complications independently predicted long-term adverse outcomes (hazard ratio (HR) 2.237; 95% CI 1.006–4.976), after adjusting for age, chronic kidney disease (CKD), and heart failure (HF) development. In an IE patient cohort, neurological complications at admission, which is a complication directly related to the IE process, were independent predictors of long-term outcomes. Full article

Background: Tuberculosis (TB) continues to be a serious public health threat that affects the most vulnerable populations. Patients who are lost to follow-up (LTFU) after TB diagnosis still represent one of the biggest challenges to TB control. Method: In this prospective observational study, we aimed to identify and analyse the risk factors associated with LTFU among TB patients who started first-line TB treatment in the Sanatorium Hospital in Luanda. Result: A total of 113 patients with TB (non-multidrug resistant) were included between August 2018 and September 2019. Seventy-six (67.3%) patients were cured, 27 (23.9%) were LTFU, 5 (4.4%) died, 4 (3.5%) were transferred and 1 (0.9%) presented treatment failure. After excluding those who died, were transferred or failed treatment, we observed that severe TB at the time of diagnosis (OR 9.24, 95% CI 2.18–39.04) and food insecurity were significantly associated with LTFU (OR 5.96, 95% CI 1.66–21.41). Conclusions: The findings of our study can contribute to understanding the reasons for the LTFU of patients with TB and can guide policies and facilitate designing measures to allow better adherence and, therefore, greater treatment success. Full article

Background: The study aimed to characterize patients with leprosy admitted to Fontilles throughout the 20th and 21st centuries, focusing on differences across three periods (I, II, and III). It also explored variables linked to patient survival. Methods: This was a retrospective descriptive study analyzing the medical records of Fontilles patients from 1909 to 2020. It assessed 26 clinical, sociodemographic, and temporal variables (n = 2652). Results: Most patients were male, single, multibacillary (MB), and farmers, from Andalusia and the Valencian Community. The origin of patients shifted over time towards being mostly foreign-born in period III. More than a half were previously admitted and had family members with leprosy. While leprosy reactions decreased over time, neurological symptoms were increasingly diagnosed. The age at onset, admission, and death increased progressively over time. The survival of patients with leprosy at Fontilles depended on the age at admission and the period. Conclusions: Improved knowledge, services, and awareness regarding leprosy led to increased age at onset and more favorable outcomes. The prolonged time between symptom onset and diagnosis indicates that leprosy is still a neglected disease. Although MB forms are more severe, leprosy classification did not significantly impact the survival rates of patients at Fontilles. Full article

L-arginine metabolism is strongly linked with immunity to mycobacteria, primarily through the antimicrobial activity of nitric oxide (NO). The potential to modulate tuberculosis (TB) outcomes through interventions that target L-arginine pathways are limited by an incomplete understanding of mechanisms and inadequate in vivo modeling. These gaps in knowledge are compounded for HIV and Mtb co-infections, where activation of arginase-1 due to HIV infection may promote survival and replication of both Mtb and HIV. We utilized in vitro and in vivo systems to determine how arginase inhibition using N^ω-hydroxy-nor-L-arginine (nor-NOHA) alters L-arginine pathway metabolism relative to immune responses and disease outcomes following Mtb infection. Treatment with nor-NOHA polarized murine macrophages (RAW 264.7) towards M1 phenotype, increased NO, and reduced Mtb in RAW macrophages. In Balb/c mice, nor-NOHA reduced pulmonary arginase and increased the antimicrobial metabolite spermine in association with a trend towards reduced Mtb CFU in lung. In humanized immune system (HIS) mice, HIV infection increased plasma arginase and heightened the pulmonary arginase response to Mtb. Treatment with nor-NOHA increased cytokine responses to Mtb and Mtb/HIV in lung tissue but did not significantly alter bacterial burden or viral load. Our results suggest that L-arginine pathway modulators may have potential as host-directed therapies to augment antibiotics in TB chemotherapy. Full article

Leptospirosis is a zoonotic disease caused by the spirochete bacteria Leptospira spp. From December 2017 to December 2023, a total of 34 canine leptospirosis cases were reported in urban Sydney, Australia. During the same spatio-temporal frame, one locally acquired human case was also reported. As it was hypothesised that human residents and companion dogs might both be exposed to pathogenic Leptospira in community green spaces in Sydney, an environmental survey was conducted from December 2023 to January 2024 to detect the presence of pathogenic Leptospira DNA in multipurpose, recreational public parks in the council areas of the Inner West and City of Sydney, Australia. A total of 75 environmental samples were collected from 20 public parks that were easily accessible by human and canine visitors. Quantitative PCR (qPCR) testing targeting pathogenic and intermediate Leptospira spp. was performed, and differences in detection of Leptospira spp. between dog-allowed and dog-prohibited areas were statistically examined. The global Moran’s Index was calculated to identify any spatial autocorrelation in the qPCR results. Pathogenic leptospires were detected in all 20 parks, either in water or soil samples (35/75 samples). Cycle threshold (Ct) values were slightly lower for water samples (Ct 28.52–39.10) compared to soil samples (Ct 33.78–39.77). The chi-squared test and Fisher’s exact test results were statistically non-significant (p > 0.05 for both water and soil samples), and there was no spatial autocorrelation detected in the qPCR results (p > 0.05 for both sample types). Although further research is now required, our preliminary results indicate the presence of pathogenic Leptospira DNA and its potential ubiquity in recreational parks in Sydney. Full article

Background: Fungal keratitis is an ophthalmic emergency that can cause visual impairment and blindness. We reviewed the epidemiology and clinical features of fungal keratitis in a tropical Australian setting. Objectives: To document the clinical and microbiological characteristics of fungal keratitis in an Australian tropical setting. Methods: A retrospective cohort study of patients with fungal keratitis from October 2014 to December 2022 was conducted at Royal Darwin Hospital, Northern Territory, Australia. We reviewed all patients with culture-proven fungal keratitis and their outcomes. Results: There were 31 patients identified. Aboriginal and Torres Strait Islander (ATSI) patients were of a significantly younger median age (28 years) compared to non-ATSI patients (42 years), and they also presented later to health care. Contact lens use and ocular trauma were the most common predisposing factors. Most patients presented with a corneal infiltrate and corneal epithelial defect, and the central visual axis was affected in 54% of patients. Curvularia spp. and Fusarium spp. were the commonest causative fungi (39% and 30% respectively). Conclusions: Our series is different and reveals a wider range of fungal species identified over the 7 years of the study, in particular, a range of Curvularia spp. were detected. Access to eye health services in rural and remote settings is important, particularly for ATSI patients, as morbidity remains high. Full article

The World Health Organization (WHO) recommends the use of annual mass drug administration (MDA) as the strategy for controlling and eliminating the five preventive chemotherapy neglected tropical diseases (PC-NTDs). The success of MDAs hinges on community acceptance, active participation, and compliance. This study aimed to explore the experiences and perceptions of community members, to obtain a more thorough understanding of their openness and willingness to participate in MDA and other NTD elimination activities. A mixed-methods approach was employed, utilizing qualitative and quantitative methods for comprehensive data collection. Eighteen key informant interviews (KIIs) and sixteen focus group discussions (FGDs) were conducted to explore community engagement, participation, medication utilization, and programme perception. Triangulation of findings from interviews and discussions with household survey results was performed to gain a deeper understanding of emerging themes. The household survey involved interviewing 1220 individuals (Abaji: 687; Bwari: 533). Audio tapes recorded KIIs and FGDs, with interview transcripts coded using Nvivo 12.0 software based on predefined themes. Descriptive analysis using SPSS version 21 was applied to quantitative data. Results indicated high awareness of mass drug administration (MDA) campaigns in both area councils (Abaji: 84.9%; Bwari: 82.9%), with a small percentage claiming ignorance (15.1%), attributed to lack of information or absence during health campaigns. Respondents primarily participated by taking medication (82.5%), with minimal involvement in other MDA campaigns. Perception of medicines was generally positive, with a significant association between participation level and performance rating (p < 0.05). The study recommends leveraging high awareness and community responsiveness to enhance engagement in various MDA activities, ensuring sustainability and ownership of the programme. Full article

Diverse larval habitats significantly influence female mosquito oviposition. Utilizing traps that simulate these habitats is helpful in the study of the bioecology and characteristics of pathogen-transmitting species during oviposition. This study evaluated the feasibility of different traps in natural environments by comparing sampling methods and detecting the oviposition of epidemiologically important mosquitoes, with emphasis on Haemagogus species, in a fragment of the Atlantic Forest in Silva Jardim, Rio de Janeiro State, Brazil. Monthly collections were conducted from March 2021 to October 2023 using four types of traps: plastic containers, tires, bamboo, and sapucaia. Immatures were collected from these traps using a pipette, placed in plastic bags, and transported to the laboratory. Tire was the most efficient trap, showing the highest mosquito abundance (n = 1239) and number of species (S = 11). Conversely, the plastic container trap exhibited the lowest diversity (H = 0.43), with only two species and a low mosquito abundance (n = 26). The bamboo trap captured six species and recorded the second-highest diversity index (H = 1.04), while the sapucaia trap captured five species and had the third-highest diversity index (H = 0.91). Of the total immatures collected, 1817 reached adulthood, comprising 13 species, two of which are vectors of the sylvatic yellow fever virus: Haemagogus leucocelaenus and Haemagogus janthinomys. In conclusion, detecting key vectors of the sylvatic yellow fever virus in Brazil highlights the need for ongoing entomological and epidemiological surveillance in the study area and its vicinity. These efforts are crucial for monitoring vector presence and activity, identifying potential transmission hotspots, and devising effective control and prevention strategies. Full article

Angiostrongylus cantonensis, a zoonotic parasite, can invade the human central nervous system (CNS) and cause acute eosinophilic meningitis or eosinophilic meningoencephalitis. Mice infected with A. cantonensis show elevated levels of pro-inflammatory cytokines, plasminogen activators, and matrix metalloproteinase-9, resulting in disruption of the blood–brain barrier (BBB) and immune cell infiltration into the CNS. Caveolin-1 (Cav-1) regulates the permeability of the BBB, which affects immune cells and cerebrospinal fluid. This intricate interaction ultimately fuels the progression of brain damage and edema. This study aims to investigate the regulatory role of Cav-1 in the pathogenesis of meningoencephalitis induced by A. cantonensis infection. We investigated pathological alterations by triphenyl-tetrazolium chloride, brain water content, BBB permeability, Western blot analysis, and gelatin zymography in BALB/c mice after A. cantonensis. The study evaluates the critical role of Cav-1 regulation through the TLR4/MyD88 signaling pathway, modulates tight junction proteins, influences BBB permeability, and contributes to brain damage in A. cantonensis-induced meningoencephalitis. Full article

Extraintestinal pathogenic Escherichia coli (ExPEC) strains are capable of causing various systemic infections in both humans and animals. In this study, we isolated and characterized 30 E. coli strains from the parenchymatic organs and brains of young (<3 months of age) camel calves which died in septicemia. Six of the strains showed hypermucoviscous phenotype. Based on minimum inhibitory concentration (MIC) values, seven of the strains were potentially multidrug resistant, with two additional showing colistin resistance. Four strains showed mixed pathotypes, as they carried characteristic virulence genes for intestinal pathotypes of E. coli: three strains carried cnf1, encoding cytotoxic necrotizing factor type 1, the key virulence gene of necrotoxigenic E. coli (NTEC), and one carried eae encoding intimin, the key virulence gene of enteropathogenic E. coli (EPEC). An investigation of the integration sites of pathogenicity islands (PAIs) and the presence of prophage-related sequences showed that the strains carry diverse arrays of mobile genetic elements, which may contribute to their antimicrobial resistance and virulence patterns. Our work is the first to describe ExPEC strains from camels, and points to their veterinary pathogenic as well as zoonotic potential in this important domestic animal. Full article

Despite the implementation of various control strategies aimed at eliminating canine-mediated rabies, the disease is still endemic in up to 150 countries across the world. Rabies remains endemic to South Africa, with various reservoir species (both wildlife species and domestic dogs) capable of maintaining rabies infection, and the epidemiology of the disease is yet to be adequately defined. As such, this study used surveillance data collected between 1998 and 2019 from the two diagnostic laboratories in the country for a statistical space–time analysis to determine regions where significant disease clusters could occur. In addition, the robustness of surveillance activities across the country was evaluated through the mathematical evaluation and visualization of testing rates based on the average number of samples tested per species group. In our study, various significant disease clusters were detected for domestic animals, wildlife and livestock. The significant disease clusters for domestic animals and livestock were primarily restricted to eastern South Africa, while the significant disease clusters in wildlife species were detected across northern and western South Africa. Furthermore, the testing rates identified districts from various provinces where surveillance activities could be considered inadequate, consequently influencing the geographical range of the observed clusters. These results could be used to direct intervention campaigns towards high-risk areas, while also allocating the required resources to improve surveillance in the surrounding areas where surveillance was deemed inadequate. Full article

Bulinus snails surviving drought play a key role in the seasonal transmission of urogenital schistosomiasis, although our knowledge of their adaptation to dry season is still limited. We investigated the survival dynamic and infestation by the Schistosoma haematobium of Bulinus snails during the dry and rainy seasons in a single pond in an area of seasonal schistosomiasis transmission in Senegal. During the rainy season, 98 (94.23%) B. senegalensis and six (5.76%) B. umbilicatus were collected, respectively. In the dry season, B. umbilicatus outnumbered B. senegalensis, but all five (100%) B. senegalensis collected were viable and alive after the interruption of aestivation by immersion in water, while only 7 of 24 (29.16%) B. umbilicatus collected emerged from their dormant state. The rate of infestation with S. haeamatobium during the rainy season was 18.2% (19/104), while all the viable snails collected during the dry season were negative. B. senegalensis and B. umbilicatus have different seasonal dynamics with no evidence of maintaining S. haematobium infestation during the drought. Further studies including more survey sites and taking account both snails biology and ecological conditions are needed to better understand snail adaptation to seasonal changes and their ability to maintain S. haeamatobium infestation during drought. Full article

The objective of this study was to assess tobacco use (TU) behaviors among newly diagnosed pulmonary TB (PTB) patients and identify associated factors in Benin and Burkina Faso. A cross-sectional study was conducted in 20 randomly selected TB clinics. To ensure a representative study cohort, clinics were stratified during the sampling process. PTB patients were consecutively sampled in 20 of the clinics between 1 December 2021 and 30 September 2022. The study population comprised individuals aged 15 years and above who were newly diagnosed with PTB. Among the 1399 registered PTB patients, 564 (40.3%) reported a history of TU, including 392 (28.0%) current tobacco users and 172 ex-tobacco users. Cigarettes emerged as the predominant form of TU (86.2%), followed by smokeless tobacco (6.4%), and chicha smoking (2.6%). Factors independently associated with tobacco use were male gender (p < 0.001), being in Burkina Faso (p < 0.001), and an age of 25–59 years (p = 0.002). Our multicentric study reveals a substantial prevalence of tobacco use among TB patients, with cigarette smoking emerging as the predominant form. These findings underscore the imperative for implementing targeted cessation interventions within TB control programs. Special emphasis is warranted for male patients aged 25–59 years. Full article