Search

This paper discusses challenges in formulating and harmonizing malaria prevention recommendations for travellers. It explores diverse approaches used by advisory groups to assess malaria risk and shares insights from the 2023 International Expert Committee for Travel Medicine meeting. It also explores future prospects for enhancing malaria prevention recommendations for travellers., S.L.M. is supported by a National Health and Medical Research Council (NHMRC) Investigator Grant (2017229).

Background: The World Health Organization (WHO) recommends that when peripheral malarial parasitaemia is quantified by thick film microscopy, an actual white blood cell (WBC) count from a concurrently collected blood sample is used in calculations. However, in resource-limited settings an assumed WBC count is often used instead. The aim of this study was to describe the variability in WBC count during acute uncomplicated malaria, and estimate the impact of using an assumed value of WBC on estimates of parasite density and clearance. Methods: Uncomplicated malaria drug efficacy studies that measured WBC count were selected from the WorldWide Antimalarial Resistance Network data repository for an individual patient data meta-analysis of WBC counts. Regression models with random intercepts for study-site were used to assess WBC count variability at presentation and during follow-up. Inflation factors for parasitaemia density, and clearance estimates were calculated for methods using assumed WBC counts (8000 cells/mu L and age-stratified values) using estimates derived from the measured WBC value as reference. Results: Eighty-four studies enrolling 27,656 patients with clinically uncomplicated malaria were included. Geometric mean WBC counts (x 1000 cells/mu L) in age groups < 1, 1-4, 5-14 and >= 15 years were 10.5, 8.3, 7.1, 5.7 and 7.5, 7.0, 6.5, 6.0 for individuals with falciparum (n = 24,978) and vivax (n = 2678) malaria, respectively. At presentation, higher WBC counts were seen among patients with higher parasitaemia, severe anaemia and, for individuals with vivax malaria, in regions with shorter regional relapse periodicity. Among falciparum malaria patients, using an assumed WBC count of 8000 cells/mu L resulted in parasite density underestimation by a median (IQR) of 26% (4-41%) in infants < 1 year old but an overestimation by 50% (16-91%) in adults aged = 15 years. Use of age-stratified assumed WBC values removed systematic bias but did not improve pr

BACKGROUND Acute gastroenteritis (AGE) is a major medical condition for travellers worldwide, particularly travellers to low- and middle-income countries. Norovirus (NoV) is the most common cause of viral AGE in older children and adults, but data on prevalence and impact among travellers is limited. METHODS Prospective, multi-site, observational cohort study conducted 2015-2017, among adult international travellers from the US and Europe to areas of moderate to high risk of travel-acquired AGE. Participants provided self-collected pre-travel stool samples and self-reported AGE symptoms while travelling. Post-travel stool samples were requested from symptomatic subjects and a sample of asymptomatic travellers within 14days of return. Samples were tested for NoV by RT-qPCR, genotyped if positive, and tested for other common enteric pathogens by Luminex xTAG GPP. RESULTS Of the 1109 participants included, 437 (39.4%) developed AGE symptoms resulting in an overall AGE incidence of 24.7 per 100 person-weeks (95% CI: 22.4; 27.1). Twenty NoV-positive AGE cases (5.2% of those tested) were identified at an incidence of 1.1 per 100 person-weeks (95% CI: 0.7; 1.7). NoV-positive samples belonged mostly to genogroup GII (18, 85.7%); None of the 13 samples sequenced belonged to genotype GII.4. Clinical severity of AGE was higher for NoV-positive than for NoV-negative cases (mean modified Vesikari Score 6.8 vs 4.9) with more cases classified as severe or moderate (25% vs 6.8%). Eighty percent of NoV-positive participants (vs. 38.9% in NoV-negative) reported at least moderate impact on travel plans. CONCLUSIONS AGE is a prevalent disease among travellers with a small proportion associated with NoV. Post-travel stool sample collection timing might have influenced the low number of NoV cases detected; however, NoV infections resulted in high clinical severity and impact on travel plans. These results may contribute to targeted vaccine development and the design of future studies on

BACKGROUND The Ready-To-Go (R2G) Questionnaire is a tool for rapid assessment of health risks for travel consultation. This study aims to assess the utility of the R2G Questionnaire in identifying high-risk travellers and predicting health events and behaviour during travel in the TOURIST2 prospective cohort. METHODS TOURIST2 data were used to calculate the R2G medical and travel risk scores and categorize each participant based on their risk. The TOURIST2 study enrolled 1000 participants from Switzerland's largest travel clinics between 2017 and 2019. Participants completed daily smartphone application surveys before, during and after travel on health events and behaviours. We used regression models to analyse incidence of overall health events and of similar health events grouped into health domains (e.g. respiratory, gastrointestinal, accident/injury). Incidence rate ratios (IRR) are displayed with 95% confidence intervals (95% CI). RESULTS R2G high-risk travellers experienced significantly greater incidence of health events compared to lower-risk travellers (IRR = 1.27, 95% CI: 1.22-1.33). Both the medical and travel scores showed significant positive associations with incidence of health events during travel (IRR = 1.11, 95% CI: 1.07-1.16; IRR = 1.07, 95% CI: 1.03-1.12, respectively), with significant increases in all health domains except skin disorders. Medical and travel risk scores were associated with different patterns in behaviour. Travellers with chronic health conditions accessed medical care during travel more often (IRR = 1.16, 95% CI: 1.03-1.31), had greater difficulty in carrying out planned activities (IRR = -0.04, 95% CI: -0.05, -0.02), and rated their travel experience lower (IRR = -0.04, 95% CI: -0.06, -0.02). Travellers with increased travel-related risks due to planned travel itinerary had more frequent animal contact (IRR = 1.09, 95% CI: 1.01-1.18) and accidents/injuries (IRR = 1.28, 95% CI: 1.15-1.44). CONCLUSIONS The R2G Questionnaire is a

Background Reagent strip to detect microhematuria as a proxy for Schistosoma haematobium infections has been considered an alternative to urine filtration for individual diagnosis and community-based estimates of treatment needs for preventive chemotherapy. However, the diagnostic accuracy of reagent strip needs further investigation, particularly at low infection intensity levels. Methods We used existing data from a study conducted in Tanzania that employed urine filtration and reagent strip testing for S. haematobium in two villages, including a baseline and six follow-up surveys after praziquantel treatment representing a wide range of infection prevalence. We developed a Bayesian model linking individual S. haematobium egg count data based on urine filtration to reagent strip binary test results available on multiple days and estimated the relation between infection intensity and sensitivity of reagent strip. Furthermore, we simulated data from 3,000 hypothetical populations with varying mean infection intensity to infer on the relation between prevalence observed by urine filtration and the interpretation of reagent strip readings. Principal findings Reagent strip showed excellent sensitivity even for single measurement reaching 100% at around 15 eggs of S. haematobium per 10 ml of urine when traces on reagent strip were considered positive. The corresponding specificity was 97%. When traces were considered negative, the diagnostic accuracy of the reagent strip was equivalent to urine filtration data obtained on a single day. A 10% and 50% urine filtration prevalence based on a single day sampling corresponds to 11.2% and 48.6% prevalence by reagent strip, respectively, when traces were considered negative, and 17.6% and 57.7%, respectively, when traces were considered positive. Conclusions/Significance Trace results should be included in reagent strip readings when high sensitivity is required, but excluded when high, Background Reagent strip to detect microhematuria as a proxy for Schistosoma haematobium infections has been considered an alternative to urine filtration for individual diagnosis and communitybased estimates of treatment needs for preventive chemotherapy. However, the diagnostic accuracy of reagent strip needs further investigation, particularly at low infection intensity levels. Methods We used existing data from a study conducted in Tanzania that employed urine filtration and reagent strip testing for S. haematobium in two villages, including a baseline and six followup surveys after praziquantel treatment representing a wide range of infection prevalence. We developed a Bayesian model linking individual S. haematobium egg count data based on urine filtration to reagent strip binary test results available on multiple days and estimated the relation between infection intensity and sensitivity of reagent strip. Furthermore, we simulated data from 3,000 hypothetical populations with varying mean infection intensity to infer on the relation between prevalence observed by urine filtration and the interpretation of reagent strip readings. Principal findings Reagent strip showed excellent sensitivity even for single measurement reaching 100% at around 15 eggs of S. haematobium per 10 ml of urine when traces on reagent strip were considered positive. The corresponding specificity was 97%. When traces were considered negative, the diagnostic accuracy of the reagent strip was equivalent to urine filtration data obtained on a single day. A 10% and 50% urine filtration prevalence based on a single day sampling corresponds to 11.2% and 48.6% prevalence by reagent strip, respectively, when traces were considered negative, and 17.6% and 57.7%, respectively, when traces were considered positive. Conclusions/Significance Trace results should be included in reagent strip readings when high sensitivity is required, but excluded when high specificity is needed. The observed preva

Background There are no validated pre-travel self-assessment tools to stratify travellers' health risks and identify their needs for pre-travel medical preparation. This study presents a novel pre-travel risk stratification tool (Ready-To-Go Questionnaire). Methods The Ready-To-Go Questionnaire was developed by travel medical experts. It assesses information on travellers' itinerary and current health status, thereby assigning travellers to one out of four risk categories. To explore the Ready-To-Go Questionnaire's validity, we analysed the agreement between the risk categories resulting from the questionnaire and predefined validation criteria. This study was carried out at the Travel Clinic, University of Zurich, Switzerland. Results One hundred travellers attending a pre-travel consultation were included. 82% corresponded to the substantial-risk category, 17% to the high-risk category, 1% to the moderate-risk category and 0% to the low-risk category. The concordance between the risk categories and the consultants' risk assessment, was 0.39 and 0.29 (unweighted/weighted Cohen's Kappa). No significant concordance was found between the risk categories and additional validation criteria. Conclusion The Ready-To-Go Questionnaire is a medical triage tool developed to identify different levels of travel-related health risks. This tool assists in better understanding travellers' needs, shaping modern travel consultations and offering patient-centred travel medicine services.

BACKGROUND We used a mobile application to determine the incidence of health events and risk behaviours during travel by country and identify which health risks are significantly elevated during travel compared with at home. METHOD TOURIST2 is a prospective cohort study of 1000 adult travellers from Switzerland to Thailand, India, China, Tanzania, Brazil and Peru, planning travel of ≤4 weeks between 09/2017 and 04/2019. The incidence rate ratio (IRR) in each country was calculated. RESULTS All countries had significantly higher incidence of health events than at home. The most elevated symptoms were sunburn, itching from mosquitoes, and gastrointestinal disorders (e.g. vomiting, diarrhoea), corresponding with universally high food/drink risk behaviours. Peru had the highest incidence of both overall negative health events and severe health events (172.0/1000 travel-days). Traffic accidents were significantly higher in Peru (IRR: 2.4, 1.2, 4.7), although incidence of transportation risk was highest in India and Thailand. In Tanzania, incidence of negative mental health events was significantly lower than at home, although it was elevated in other countries. Sexual risk behaviours were high in Brazil. CONCLUSIONS Our study improves the understanding of the non-infectious disease related health challenges travellers face and provides evidence for more personalised traveller support.