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Given widespread unreported SARS-CoV-2 infections, variable immunologic response based on host immunogenicity, vaccine type, viral strain, timing and sequence of vaccine or viral exposure, and humoral waning, the global SARS-CoV-2 [...]

The global elimination of lymphatic filariasis (LF) is a major focus of the World Health Organization. One key challenge is locating residual infections that can perpetuate the transmission cycle. We show how a targeted sampling strategy using predictions from a geospatial model, combining random forests and geostatistics, can improve the sampling efficiency for identifying locations with high infection prevalence. Predictions were made based on the household locations of infected persons identified from previous surveys, and environmental variables relevant to mosquito density. Results show that targeting sampling using model predictions would have allowed 52% of infections to be identified by sampling just 17.7% of households. The odds ratio for identifying an infected individual in a household at a predicted high risk compared to a predicted low risk location was 10.2 (95% CI 4.2-22.8). This study provides evidence that a 'one size fits all' approach is unlikely to yield optimal results when making programmatic decisions based on model predictions. Instead, model assumptions and definitions should be tailored to each situation based on the objective of the surveillance program. When predictions are used in the context of the program objectives, they can result in a dramatic improvement in the efficiency of locating infected individuals.

Background: Lymphatic filariasis (LF), a mosquito-borne helminth infection, is an important cause of chronic disability globally. The World Health Organization has validated eight Pacific Island countries as having eliminated lymphatic filariasis (LF) as a public health problem, but there are limited data to support an evidence-based approach to post-validation surveillance (PVS). Tonga was validated as having eliminated LF in 2017 but no surveillance has been conducted since 2015. This paper describes a protocol for an operational research project investigating different PVS methods in Tonga to provide an evidence base for national and regional PVS strategies. Methods: Programmatic baseline surveys and Transmission Assessment Surveys conducted between 2000–2015 were reviewed to identify historically 'high-risk' and 'low-risk' schools and communities. 'High-risk' were those with LF antigen (Ag)-positive individuals recorded in more than one survey, whilst 'low-risk' were those with no recorded Ag-positives. The outcome measure for ongoing LF transmission will be Ag-positivity, diagnosed using Alere™ Filariasis Test Strips. A targeted study will be conducted in May-July 2024 including: (i) high and low-risk schools and communities, (ii) boarding schools, and (iii) patients attending a chronic-disease clinic. We estimate a total sample size of 2,010 participants. Conclusions: Our methodology for targeted surveillance of suspected 'high-risk' populations using historical survey data can be adopted by countries when designing their PVS strategies. The results of this study will allow us to understand the current status of LF in Tonga and will be used to develop the next phase of activities. [ABSTRACT FROM AUTHOR]

Background: To monitor the progress of lymphatic filariasis (LF) elimination programmes, field surveys to assess filarial antigen (Ag) prevalence require access to reliable, user-friendly rapid diagnostic tests. We aimed to evaluate the performance of the new Q Filariasis Antigen Test (QFAT) with the currently recommended Filariasis Test Strip (FTS) for detecting the Ag of Wuchereria bancrofti, the causative agent of LF, under field laboratory conditions. Methodology/Principal findings: During an LF survey in Samoa, 344 finger-prick blood samples were tested using FTS and QFAT. Microfilariae (Mf) status was determined from blood slides prepared from any sample that reported Ag-positive by either Ag-test. Each test was re-read at 1 hour and the next day to determine the stability of results over time. Overall Ag-positivity by FTS was 29.0% and 30.2% by QFAT. Concordance between the two tests was 93.6% (kappa = 0.85). Of the 101 Mf slides available, 39.6% were Mf-positive, and all were Ag-positive by both tests. Darker test line intensities from Ag-positive FTS were found to predict Mf-positivity (compared to same/lighter line intensities). QFAT had significantly higher reported test result changes than FTS, mostly reported the next day, but fewer changes were reported between 10 minutes to 1-hour. The field laboratory team preferred QFAT over FTS due to the smaller blood volume required, better usability, and easier readability. Conclusion/Significance: QFAT could be a suitable and user-friendly diagnostic alternative for use in the monitoring and surveillance of LF in field surveys based on its similar performance to FTS under field laboratory conditions. Author summary: Lymphatic filariasis (LF) is a debilitating tropical disease caused by infection with parasitic filarial worms that are transmitted by mosquitoes. Long-term infection can lead to stigmatising chronic conditions like lymphoedema and elephantiasis. The World Health Organization initiated the global programme to eliminate lymphatic filariasis (GPELF) in 2000, focusing on mass drug administration (MDA) of anti-LF drugs to stop transmission in endemic countries. However, to monitor the success of this programme and to make informed decisions to stop costly MDA, it is crucial to have access to accurate and reliable rapid diagnostics. Here, we evaluated the performance of a new rapid antigen test called the Q Filariasis antigen test and compared it to the currently recommended filariasis test strip under field laboratory conditions in Samoa. This study showed that the new rapid test could be a suitable alternative to the currently recommended test for use in GPELF-related activities with more user-friendly features. [ABSTRACT FROM AUTHOR]

Background: Lymphatic filariasis (LF) remains a significant global issue. To eliminate LF as a public health problem, the World Health Organization (WHO) recommends multiple rounds of mass drug administration (MDA). In certain scenarios, including when elimination targets have not been met with two-drug MDA, triple-drug MDA (using ivermectin, diethylcarbamazine and albendazole) is recommended. In this study, we report on antigen (Ag) and microfilaria (Mf) prevalence in eight primary sampling units (PSUs) in Samoa 4.5 years after one round of triple-drug MDA. Methodology: In 2023, community surveys were conducted in eight PSUs that had been surveyed previously in 2018 (between 1.5 and 3.5 months post triple-drug MDA) and 2019 (six to eight-months post triple-drug MDA). Fifteen houses were randomly selected in each PSU with household members aged ≥ 5 years invited to participate. Blood samples were tested for Ag and Mf. Principal findings: Ag-positive participants were observed in six of the eight PSUs, and Ag prevalence was significantly above the 1% threshold in four PSUs. The presence of Mf-positive participants in five PSUs confirms the presence of residual active infections. Conclusions/Significance: This study provides evidence of persistent LF transmission in Samoa 4.5 years after one round of triple-drug MDA, confirming that one round was insufficient for interruption of transmission in this setting. Our findings highlight the negative impact of delaying MDA rounds, for example, due to public health emergencies. Author summary: The World Health Organization (WHO) recommends triple-drug mass drug administration (MDA) for the elimination of lymphatic filariasis (LF) as a public health problem for countries where targets have not been achieved using two-drug MDA, and where onchocerciasis is non-endemic. In 2018, Samoa was the first country to implement a national triple-drug MDA. This study surveyed 623 randomly selected participants across eight primary sampling units (PSUs) in Samoa, 4.5 years after the first round of triple-drug MDA. These results support the current WHO recommendations that multiple rounds of triple-drug MDA are required to interrupt transmission. A gap of 4.5 years between rounds of triple-drug MDA can result in a resurgence, with persistence of LF transmission and burden levels comparable to those observed before the MDA. [ABSTRACT FROM AUTHOR]

Measles in persons with secondary vaccination failure (SVF) may be less infectious than cases in unvaccinated persons. Our systematic review aimed to assess transmission risk for measles after SVF. We searched PubMed, Embase, and Web of Science databases from their inception dates. Inclusion criteria were articles describing persons who were exposed to measles-infected persons who had experienced SVF. Across the included 14 studies, >3,030 persons were exposed to measles virus from SVF cases, of whom 180 were susceptible, indicating secondary attack rates of 0%–6.25%. We identified 109 cases of SVF from the studies; 10.09% (n = 11) of case-patients transmitted the virus, resulting in 23 further cases and yielding an effective reproduction number of 0.063 (95% CI 0.0–0.5). These findings suggest a remarkably low attack rate for SVF measles cases, suggesting that, In outbreak situations, public health management of unvaccinated persons could be prioritized over persons with SVF. [ABSTRACT FROM AUTHOR]

Background Malaria continues to pose a significant burden in endemic countries, many of which lack access to molecular surveillance. Insights from malaria cases in travellers returning to non-endemic areas can provide valuable data to inform endemic country programmes. To evaluate the potential for novel global insights into malaria, we examined epidemiological and molecular data from imported malaria cases to Australia. Methods We analysed malaria cases reported in Australia from 2012 to 2022 using National Notifiable Disease Surveillance System data. Molecular data on imported malaria cases were obtained from literature searches. Results Between 2012 and 2022, 3204 malaria cases were reported in Australia. Most cases (69%) were male and 44% occurred in young adults aged 20–39 years. Incidence rates initially declined between 2012 and 2015, then increased until 2019. During 2012–2019, the incidence in travellers ranged from 1.34 to 7.71 per 100 000 trips. Cases were primarily acquired in Sub-Saharan Africa (n  = 1433; 45%), Oceania (n  = 569; 18%) and Southern and Central Asia (n  = 367; 12%). The most common countries of acquisition were Papua New Guinea (n  = 474) and India (n  = 277). Plasmodium falciparum accounted for 58% (1871/3204) of cases and was predominantly acquired in Sub-Saharan Africa, and Plasmodium vivax accounted for 32% (1016/3204), predominantly from Oceania and Asia. Molecular studies of imported malaria cases to Australia identified genetic mutations and deletions associated with drug resistance and false-negative rapid diagnostic test results, and led to the establishment of reference genomes for P. vivax and Plasmodium malariae. Conclusions Our analysis highlights the continuing burden of imported malaria into Australia. Molecular studies have offered valuable insights into drug resistance and diagnostic limitations, and established reference genomes. Integrating molecular data into national surveillance systems could provide important infectious disease intelligence to optimize treatment guidelines for returning travellers and support endemic country surveillance programmes. [ABSTRACT FROM AUTHOR]

Background: International travel can increase the risk of exposure to infectious diseases including sexually transmissible infections (STI). Pre-travel medical consultation provides an opportunity for travel-related health risk assessments and advice. This study explored how travel medicine clinicians integrate sexual and reproductive health (SRH) services into clinical practice. Methods: A convenience sample of travel medicine clinicians completed a cross-sectional survey online or via hard-copy disseminated at an annual national Australian travel medicine conference. Results: Of the 67 respondents, most (n , 51; 76.1%) had a postgraduate qualification relevant to travel medicine and 55.2% (n , 37) had worked in travel medicine for over 10 years. Only 22.4% (n , 15) reported conducting a SRH history/STI risk assessment for all travel patients. STI testing pre-departure was conducted on patient request (48, 71.6%), if symptomatic (32, 47.8%) or based on risk history (28, 41.8%). SRH information pre-departure was most frequently provided if prompted by patient questions (n , 42; 62.7%), or based on the patient's history (n , 37; 55.2%). Over half the sample (n , 40; 59.7%) expressed interest in further training in SRH. Conclusion: Providing and engaging with additional training may assist travel medicine clinicians to take a more proactive approach to SRH consultations and STI testing. Additional research is needed to explore models of care that will allow comprehensive SRH and STI services to be integrated into standard pre- and post-travel care. International travel can increase the risk of exposure to infectious diseases including sexually transmissible infections and human immunodeficiency virus. This study explored how travel medicine clinicians integrate sexual and reproductive health (SRH) services into clinical practice. Our findings highlighted gaps in the provision of pre-travel consultation and training needs for SRH among travel medicine clinicians, and the potential for improved promotion of sexual health among travellers to provide important public health benefits for individuals and the wider community. [ABSTRACT FROM AUTHOR]

Zika virus and chikungunya virus (CHIKV) have caused outbreaks in several tropical regions, including the Pacific (1). The first known Zika virus outbreak occurred in Yap Island (Federated States of [...]

Ross River virus (RRV) is an Alphavirus of the family Togaviridae and is transmitted to humans by Aedes and Culexmosquitoes (1). Marsupials are considered important reservoirs of RRV (1). Clinical [...]

The article discusses the growing concern of arboviral diseases such as dengue and chikungunya in travelers. The United States has recently approved the world's first chikungunya vaccine, which has shown promising results in terms of seroresponse and clinical benefit. The article also highlights the increasing incidence of dengue in travelers and the availability of a new dengue vaccine. The recommendations for the use of these vaccines vary among different expert groups, but the authors argue for broader recommendations to address the high burden of these diseases. Further research is needed to gather more data on the vaccines' effectiveness, safety, and duration of protection. [Extracted from the article]