PLoS Neglected Tropical Diseases最新文献

Background: Snakebite envenoming remains a neglected health issue in many countries, including Gabon, where the limited availability of snakebite-specific training, clinical guidelines, and essential resources at health facilities may lead to gaps in healthcare workers' knowledge and confidence and the use of non-recommended treatment practices. This study aimed to assess healthcare workers' knowledge of snakebite management in the Ogooué et des Lacs department of Moyen-Ogooué province in Gabon.

Methods: From June to August 2023, we conducted a cross-sectional survey targeting all healthcare workers in Ogooué et des Lacs who may be involved in snakebite management. We collected information on prior training, self-perceived knowledge of snakebite management, symptom recognition, clinical management practices, and snake identification. Knowledge was assessed using 10 true/false symptom questions and 12 management questions, with one point assigned for each correct response. Generalised linear binomial regression modelling was used to evaluate associations between knowledge and participant characteristics.

Results: A total of 171 healthcare workers (78% of those eligible) participated. Overall, 40% (68/171) scored below 50% on symptom questions, and 66% (113/171) scored below 50% on management questions. Inappropriate practices were frequently recommended, including tourniquet use (70%, 120/171) and venom aspiration (73%, 125/171). Nurse assistants and nurses had a lower odds of correct responses than doctors (OR: 0.68, 95% confidence interval (CI): 0.55-0.84, and OR: 0.78, 95% CI: 0.62-0.98, respectively), while healthcare workers at secondary health facilities performed better than those at primary health facilities (OR: 1.23, 95% CI: 1.04-1.46). Venomous snakes were correctly identified as such in 74% (109/148) of responses, compared with 28% (42/148) for non-venomous snakes.

Conclusion: Gaps in snakebite knowledge and management were identified among healthcare workers in the study region. Targeted training, national clinical guidelines, and improved access to antivenom are needed to strengthen snakebite management in Ogooué et des Lacs and potentially more broadly in Gabon.

Helminths have co-evolved with humans and developed sophisticated mechanisms to manipulate the host immune system, allowing them to persist for years. During chronic disease, helminths typically shift immune responses toward a Th2 profile-supporting antibody production and tissue repair-while suppressing Th1/Th17 responses that are crucial for combating viruses and intracellular pathogens. Additionally, they elevate regulatory T cells and anti-inflammatory cytokines such as IL-10 and TGF-β, dampening inflammation, compromising host immunity to other infections, and, in some cases, reducing vaccine efficacy. Further, both experimental and clinical studies have shown that anthelminthic treatment can reverse parasite host immunomodulation. However, there is evidence that helminth-induced immune changes may persist months after parasite clearance. With the widespread rollout of preventive chemotherapy via mass drug administration (MDA) across the continent, many African populations have now received at least one round of deworming treatment. This raises critical questions about the nature, persistence, and public health significance of anthelminthic treatment-related immunological shifts in endemic settings with repeated exposures. In Africa, which bears a disproportionate share of the global helminth burden, there is growing interest in how these factors shape immune responses. In this review, we summarise current knowledge and key research gaps regarding mechanisms that contribute to immune variation in helminth-endemic populations and the broader implications for disease control, vaccine response, and health policy in endemic settings.

Background: Zoonotic diseases pose a significant public health threat in low- and middle-income countries (LMICs). This scoping review aimed to map the knowledge, attitudes, and practices (KAP) of abattoir workers and residents living near abattoirs regarding zoonotic diseases in LMICs.

Methodology/principal findings: A comprehensive search was conducted in SCOPUS, PubMed, Web of Science and Google Scholar for articles published between 2010 and 2023. Studies were included if they were conducted in LMICs, published in English, and focused on the KAP of zoonotic diseases among abattoir workers or nearby residents. Data extraction was conducted using a double-blind approach, and discrepancies were resolved by consensus. Of the 4,276 articles screened, 16 met the inclusion criteria. The studies were conducted in nine LMICs, with Nigeria (6; 38%) and Ethiopia (3; 19%) accounting for the highest number. Most studies reported on knowledge (10; 63%) and practices (12; 75%), while 4 (25%) addressed attitudes. Abattoir workers showed varied knowledge of zoonotic diseases, but substantial gaps in preventive practices were observed. Notably, no studies examined the KAP of residents living near abattoirs.

Conclusion/significance: This review underscores the need for targeted interventions to improve KAP among abattoir workers and to expand research to include nearby residents. A conceptual framework was developed to identify factors influencing KAP and guide future research, education, and policy development for zoonotic disease prevention in LMICs.

Background: Snake envenoming remains a major public health problem in Sri Lanka, disproportionately affecting rural children. Timely and appropriate pre-hospital management is crucial to reducing morbidity and mortality. Public Health Midwives (PHMs), as frontline community health workers, are strategically positioned to contribute to snakebite prevention and early management. However, their knowledge and confidence regarding paediatric snakebite care have not been systematically evaluated.

Methodology/principal findings: A cross-sectional, country-wide survey was conducted among PHMs across all 25 districts of Sri Lanka using a stratified random sampling approach. Data were collected through a validated, self-administered online questionnaire designed to assess knowledge and practices related to paediatric snakebite prevention, snake identification, and pre-hospital management. A total of 1,706 PHMs participated. Although most respondents correctly identified essential first-aid measures such as reassuring the patient (95.9%) and prompt hospital transfer (95.8%), a substantial proportion endorsed harmful practices, including sucking the venom (71.6%), applying herbs (73.2%), or cutting the bite site (64.4%). Only 48.7% recognized immobilisation as an appropriate first aid. Snake identification accuracy was high for the cobra (94%) but low for other medically significant species such as kraits and vipers. Awareness of national guidelines (14.7%) and emergency contact services (11.9%) was also poor. PHMs with prior training, awareness of national information services, or previous experience providing first aid demonstrated significantly higher knowledge scores (p < 0.001).

Conclusions/significance: Despite their key role in community health, PHMs in Sri Lanka exhibit major knowledge gaps in evidence-based first aid, snake identification, and awareness of national support systems for snakebite management. These deficits, coupled with widespread misconceptions and low confidence, highlight the need for structured training, curriculum integration, and ongoing professional development. Strengthening PHMs' capacity in snakebite prevention and early management can significantly enhance community preparedness and reduce the burden of paediatric snakebite envenoming in Sri Lanka.

Obligately intracellular rickettsiae cause a broad spectrum of disease in humans and animals, ranging from mild illness to life-threatening infections. Multiple species co-circulate along the southern United States of America-northern Mexico border, yet their seroprevalence in susceptible hosts remains incompletely understood. Dogs serve as key amplifying hosts for several of these pathogens, including Rickettsia rickettsii and Rickettsia massiliae, and have been shown to be infected by flea-borne Rickettsia typhi and Rickettsia felis. To better characterize exposure and potential co-infection patterns, we conducted a large binational seroepidemiologic study of 779 dogs from urban households and shelter settings across seven subregions along both sides of the border. Using a custom multiplex micro-immunofluorescence assay, we simultaneously screened for antibodies to R. rickettsii, R. massiliae, R. typhi, and R. felis. Overall, 41.2% of dogs were seroreactive to at least one pathogen, with the highest seroprevalence for R. felis (19.3%), followed by R. massiliae (15.7%), R. typhi (14.5%), and R. rickettsii (9.8%). Co-seroreactivity was common, particularly between R. typhi and R. felis, with 34.2% of R. typhi-seroreactive samples also seroreactive to R. felis, and 16.7% exhibiting high titers to both. In contrast, R. rickettsii and R. massiliae showed limited overlap (15.2% co-seroreactive; 6.4% with high titers), suggesting possible cross-protection or competitive exclusion. Spatial analyses revealed distinct geographic patterns: R. massiliae predominated in western Baja California, R. rickettsii was concentrated in Mexicali and the Rio Grande Valley, and R. felis was widely distributed. Seroreactivity patterns were generally consistent across age and sex but varied modestly between shelter and neighborhood dogs, particularly for R. typhi. These findings highlight the complex ecology of rickettsial pathogens in a binational context, underscore the importance of dogs as sentinels for human risk, and provide a foundation for future studies on vector-host-pathogen interactions, cross-protective immunity, and spatial epidemiological risk.

Background: Dengue and chikungunya, both transmitted by Aedes mosquitoes, continue to pose significant public health concerns in Thailand, particularly during the rainy season. Despite ongoing vector control efforts, the incidence of infection remains high, with an increasing trend observed in chikungunya. This underscores the need for additional control measures, including vaccination, to reduce disease burden and morbidity. This study aims to assess the seroprevalence of dengue and chikungunya infections among children aged 10-15 years in Bangkok and to evaluate the knowledge, attitudes, and practices (KAP) related to mosquito-borne disease prevention.

Methodology: A cross-sectional descriptive study was conducted across 12 schools in Bangkok. Children aged 10-15 years were included. Seroprevalence was determined using rapid diagnostic tests (Abbott DENGUE IgG/IgM and Citest Chikungunya IgG/IgM) based on the immunochromatography technique, using fingertip blood samples. Parents completed KAP questionnaires, including factors influencing vaccination decisions.

Principal findings: From June to August 2024, 937 participants were enrolled, with a mean (SD) age of 11 (1.6) years; 67% were aged 10-12 years, and 33% were aged 13-15 years. The seroprevalence of dengue was 28.1% (95% CI 25.2-31.0), while that of chikungunya was 6.3% (95% CI 4.7-7.9). KAP assessments revealed a high level of awareness regarding symptoms and transmission; however, notable deficiencies in preventive behaviors were identified. Only 14.8% of respondents reported consistent use of mosquito repellent, and 17.5% routinely inspected and removed mosquito larvae from their homes.

Conclusion: The substantial seroprevalence of dengue and the emerging trend of chikungunya among children in Bangkok highlights the urgent need to enhance community education and strengthen vector control interventions. Expanding dengue vaccination coverage and raising awareness about chikungunya prevention, including consideration for future vaccine implementation, are essential to mitigating future outbreaks and reducing the disease burden.

Trial registration: Thai Clinical Trials under the number TCTR20240404002 (https://www.thaiclinicaltrials.org/show/TCTR20240404002).

Background: Cystic echinococcosis (CE), caused by Echinococcus granulosus sensu lato, remains a significant public health concern in endemic areas of Kazakhstan. Despite global control efforts, CE persists due to insufficient deworming of dogs, the absence of control programs, and low public awareness.

Methods: A cross-sectional study was conducted between September 2023 and June 2024 in 51 remote villages across two endemic regions of Kazakhstan. Participants underwent abdominal ultrasound screening and completed a structured questionnaire to assess potential risk factors. Cyst staging was performed according to the WHO - Informal Working Group on Echinococcosis guidelines. Statistical analyses included both univariate and multivariate models to identify significant predictors of infection.

Results: The prevalence of CE was 0.34%, with higher rates observed in young people (82.1%) than in adults (17.9%), particularly among those aged 9-14 years. Major potential risk factors included dog ownership (OR = 3.17, p = 0.012), failure to deworm dogs (OR = 11.12, p = 0.018), feeding raw offal to dogs (OR = 3.06, p = 0.012), and consumption of unwashed vegetables and fruits among women (OR = 5.25, p = 0.005). All identified CE cases were newly diagnosed. Of these, 92.85% were active cysts, predominantly found in young individuals, while inactive cysts accounted for 7.14%, distributed equally between adults and youths.

Conclusions: These findings underscore the urgent need for regular deworming programs for dogs, public education on hygiene practices, and stricter management of livestock offal. Further research is needed to investigate transmission through water and environmental contamination.

The absence of an established in vitro platform is a major obstacle in research on parasitic flatworms, including Fasciola flukes. Fasciola flukes cause zoonotic infections that primarily affect the liver and the bile ducts. Infected juveniles can cause severe liver damage in animals, occasionally leading to sudden death. Although resistance to the only drug for the acute liver stage has been reported worldwide, the search for new drugs has been unsuccessful owing to the critical limitations of previous in vitro cultures. Previous studies have been unable to reproduce liver-stage development in vitro, hindering research on this stage. This study aimed to provide a novel in vitro research platform using a laboratory strain of Fasciola hepatica/gigantica hybrid. Juveniles derived from the livers of mice at 7 and 11 days post-infection (dpi) survived for nearly 100 days in the basic medium consisting of Roswell Park Memorial Institute (RPMI) 1640 supplemented with 50% fetal bovine serum. Bovine red blood cells (RBC) and sex-inducing substances (SIS) that induce sexualization in a free-living flatworm (planarian) were supplemented to examine their effects on the developmental processes in the liver stage, including growth, body shape change, and reproductive development. SIS induced all three processes, although the last was incomplete, suggesting that the sex-inducing ability of SIS is conserved between free-living and parasitic flatworms. However, RBC was somewhat toxic and less effective than SIS for both growth and reproductive development and could not alter body shape. Furthermore, the combined effects of the two supplements were not observed. In this study, the reproducibility of the development was carefully confirmed, and it was shown that a single SIS supplementation is currently the best condition and more closely mimics liver-stage development. This study provides a preliminary but outstanding in vitro research platform for liver-stage juveniles and will facilitate further drug development.

Background: The invasive mosquito species Anopheles stephensi plays a critical role in malaria transmission, particularly in urban environments. Its ability to thrive in such settings has raised public health concerns, especially as it expands its geographical range. The resurgence of malaria in Iran underscores the challenges posed by this vector, which is further complicated by factors such as climate change and the movement of populations. Understanding the ecological niches of An. stephensi is essential for developing targeted malaria control strategies. This study aims to assess the current and projected distribution of An. stephensi in Hormozgan Province, Iran, under varying climatic conditions.

Method: The study was conducted in Hormozgan Province, Iran, characterized by a hot, arid climate. A database of 96 occurrence points for An. stephensi was compiled through literature searches, which were refined to 72 points to ensure data quality. Environmental and bioclimatic data were sourced from the WorldClim v2.1 database, with a focus on various Shared Socioeconomic Pathways (SSPs). The MaxEnt modeling technique was employed to assess the impact of climate change on the species' distribution, with model performance evaluated using the two metrics, Area Under the Curve (AUC) and True Skill Statistic (TSS). The analysis aimed to map shifts in suitable habitats under different climate scenarios.

Results: The MaxEnt model predicts a significant decline in environmental suitability for An. stephensi under future climate scenarios, particularly in western and central Hormozgan Province. Habitat loss is prevalent, with stable areas primarily located in Bashagard County. Factors such as altitude and precipitation patterns significantly influence species distribution, with altitude showing the highest impact. The model's performance, indicated by an average AUC of 0.765 and a TSS of 0.519, demonstrates moderate predictive accuracy for identifying suitable habitats.

Discussion: Despite advancements in malaria control, An. stephensi remains a significant threat in Iran, particularly due to its invasive nature and adaptability to climate change. The study indicates a projected decline in suitable habitats, especially in coastal areas, highlighting the need for adaptive vector control strategies. Bashagard County may serve as a stable refuge, warranting further investigation. The findings emphasize the importance of continuous monitoring and integrating climate projections into public health interventions to effectively combat malaria transmission. Overall, ongoing research is crucial to refining understanding and enhancing malaria control efforts in response to shifting environmental conditions.

Background: Bubonic plague, caused by Yersinia pestis, is characterised by painful, enlarged lymph nodes ("buboes"). Despite centuries of clinical recognition, bubo morphology has been described only through observation and palpation. This study aimed to characterise the sonographic features of buboes over time in confirmed bubonic plague and evaluate the validity of digital calliper measurements compared to ultrasound.

Methods/principle findings: We conducted a prospective cohort study at three rural health centres in Madagascar between January and March 2024. Participants with suspected bubonic plague underwent ultrasound imaging and digital calliper measurements of enlarged lymph nodes at inclusion (D1), and follow-up on D4 and D11. Bubo size and morphology were assessed by clinicians - who received targeted ultrasound training for the study - using portable ultrasound devices, with expert radiologist oversight. Neither clinicians or radiologists were blind to clinical information or outcomes. Final diagnoses were retrospectively assigned using WHO criteria and national laboratory results. Of 16 enrolled participants, 12 were confirmed plague cases. Most buboes exhibited normal morphology on D1, with limited change over time despite clinical improvement. No association was found between bubo size or morphology and clinical status. Digital calliper measurements differed substantially from ultrasound. Study sonographers achieved good agreement with radiologists on bubo size, but lower agreement on structural features.

Conclusions/significance: Bubo morphology and size do not appear to correlate with clinical status, challenging their use as indicators of treatment response. Digital callipers introduce significant measurement error. Newly trained clinicians can perform size measurements reliably, but further training is needed for accurate sonographic characterisation.