Trop. Med. Infect. Dis., Volume 9, Issue 6 (June 2024) – 8 articles

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