737. Geographic Clustering of Travel-acquired Infections in Ontario, Canada, 2008-2020

Background As rates of international travel increase, more individuals are at risk of travel-acquired infections (TAIs). We aimed to review all microbiologically confirmed cases of malaria, dengue, chikungunya, and enteric fever (Salmonella enterica serovar Typhi/Paratyphi) in Ontario, Canada between 2008-2020 to identify high-resolution geographical clusters that could be targeted for pre-travel prevention. Methods Retrospective cohort study of over 174,000 unique tests for the four above TAIs from Public Health Ontario Laboratories. Test-level data were processed to calculate annual case counts and crude population-standardized incidence ratios (SIRs) at the forward sortation area (FSA) level. Moran’s I statistic was used to test for global spatial autocorrelation. Smoothed SIRs and 95% posterior credible intervals (CIs) were estimated using a spatial Bayesian hierarchical model, which accounts for statistical instability and uncertainty in small-area incidence. Posterior CIs were used to identify high- and low-risk areas, which were described using sociodemographic data from the 2016 Census. Finally, a second model was used to estimate the association between drivetime to the nearest travel clinic and risk of TAI within high-risk areas. Results There were 5962 cases of the four TAIs across Ontario over the study period. Smoothed FSA-level SIRs are shown in Figure 1a, with an inset for the Greater Toronto Area (GTA) in 1b. There was spatial clustering of TAIs (Moran’s I=0.61, p< 2.2e-16). Identified high- and low-risk areas are shown in panels c and d. Compared to low-risk areas, high-risk areas were significantly more likely to have higher proportions of immigrants (p< 0.0001), lower household after-tax income (p=0.04), more university education (p< 0.0001), and were less knowledgeable of English/French (p< 0.0001). In the high-risk GTA, each minute increase in drivetime to the closest travel clinic was associated with a 4% reduction in TAI risk (95% CI 2 - 6%). Bayesian hierarchical model (BHM) smoothed standardized incidence ratios (SIRs) for travel-acquired infections (TAIs) and estimated risk levels (a and c) with insets for the Greater Toronto Area (b and d). High-risk areas are defined as those with smoothed SIR 95% CIs greater than 2, and low-risk areas with smoothed SIR 95% CIs less than 0.25. Conclusion Urban neighbourhoods in the GTA had elevated risks of becoming ill with TAIs. However, geographic proximity to a travel clinic was not associated with an area-level risk reduction in TAI, suggesting other barriers to seeking and adhering to pre-travel advice. Disclosures Isaac Bogoch, MD, MSc, BlueDot (Consultant)National Hockey League Players' Association (Consultant) Andrea Boggild, MSc MD DTMH FRCPC, Nothing to disclose Shaun Morris, MD, MPH, DTM&H, FRCPC, FAAP, GSK (Speaker's Bureau)Pfizer (Advisor or Review Panel member)Pfizer (Grant/Research Support)

Catch-up immunization for adolescents and young adults during pre-travel consultation in Japan

Rubella and measles outbreaks in adults occur because of unimmunized or partially immunized status. Travel clinics play an important role in catch-up measles, rubella, mumps, and varicella immunization for adults. We evaluated the need for catch-up measles, rubella, mumps, and varicella immunization by young adults at our travel clinic. This retrospective observational study was conducted at the National Center for Global Health and Medicine from June 1, 2017 to May 31, 2018. Adults aged 16–49 years who received pre-travel consultation and had childhood immunization records were included. Individuals who fully or partially received planned measles, rubella, mumps, and varicella catch-up immunization were classified as “immunized.” We calculated the proportion of “immunized” individuals and analyzed the factors associated with catch-up measles, rubella, mumps, and varicella immunization at pre-travel consultation using logistic regression analysis. Overall, 3,456 individuals received pre-travel consultations during the study period; 827 (336 men, median age 22 years) had childhood immunization records. The most common trip purposes were study (33%) and tourism (24%). The most common destination was Asia (39%). Catch-up immunization of any measles, rubella, mumps, and varicella vaccine was needed by 755 individuals. After consultation, 20–46% of these participants who needed catchup immunization received at least one dose of immunization. Factors that are negatively associated with measles, rubella, mumps, and varicella catch-up immunization were tourism (odds ratio 0.37 to 0.58), yellow fever vaccination (0.45 to 0.50) (excluding varicella), and each disease history (0.13 to 0.40) (excluding rubella and varicella). Further studies are needed to identify barriers to catch-up immunization.

Increased primaquine total dose prevents Plasmodium vivax relapses in patients with impaired CYP2D6 activity: report of three cases

Background The relapsing nature of Plasmodium vivax infection is a major barrier to its control and elimination. Factors such as adequate dosing, adherence, drug quality, and pharmacogenetics can impact the effectiveness of radical cure of P. vivax and need to be adequately evaluated. CYP2D6 pathway mediates the activation of primaquine (primaquine) into an active metabolite(s) in hepatocytes, and impaired activity has been linked to a higher risk of relapse. Cases presentation Three patients diagnosed with P. vivax malaria presented repeated relapses after being initially treated with chloroquine (25 mg/kg) and primaquine (3.5 mg/kg in 14 days) at a non-endemic travel clinic. Recurring episodes were subsequently treated with a higher dose of primaquine (7 mg/kg in 14 days), which prevented further relapses in two patients. However, one patient still presented two episodes after a higher primaquine dose and was prescribed 300 mg of chloroquine weekly to prevent further episodes. Impaired CYP2D6 function was observed in all of them. Conclusion Lack of response to primaquine was associated with impaired CYP2D6 activity in three patients presenting multiple relapses followed in a non-endemic setting. Higher primaquine dosage was safe and effectively prevented relapses in two patients and should be further investigated as an option in Latin America. It is crucial to investigate the factors associated with unsuccessful radical cures and alternative therapeutic options.

Pretravel consultation on COVID-19 testing before international travel: lessons learnt from the Thai Travel Clinic, Bangkok, Thailand

The demand for COVID-19 testing has been on the rise after many countries have eased travel restrictions for essential travel to aid their economy. Thus, we discuss our lessons learnt of the crucial points that need to be considered by the clinicians when dealing with individuals seeking COVID-19 testing before international travel.

If I told you that there is no need for yellow fever vaccine booster would you still come to the travel clinic?: a cross-sectional study

Background Yellow Fever (YF) immunization required a single dose vaccine with boosters every 10 years. After International Health Regulation (IHR) amendment annex 7 (July 2016), it was accepted that a single dose confers lifelong immunity. Since pre-travel advice is as important as vaccination when traveling, it is essential to clarify why travelers come to a travel health consultation, with the possibility of IHR amendment having a negative impact on travelers’ health. This study aims to describe travelers’ reasons to come to a pre-travel consultation in Lisbon and if they would return if they wouldn’t need the YF vaccine booster. Methods An observational cross-sectional study was conducted during 5 months in the waiting room of Instituto de Higiene e Medicina Tropical travel clinic in Lisbon, Portugal. Travelers were asked about sociodemographic characteristics, destination country, travel duration and reasons to travel in an anonymous self-administered questionnaire. Results A total of 1043 travelers agreed to participate in the study. Although 61.0% (627/1028) did not come to the clinic to get the YF vaccine, from those who did, 36.7% (133/362) would not come and 12.9% (47/362) didn’t knew if they would come if the vaccine would not be necessary. Conclusion The IHR amendment may have a negative impact on travel clinic attendance and on travelers´ health.

Health Problems During and After Travel: A Prospective Observational Study in a Travel Clinic in Portugal

Introduction: In order to improve the health of travellers during travel it is important to better understand the health problems faced by travellers in different destinations. The main objective of this study was to characterise the perceived health problems of travellers during and up to six months after travel on a pre-travel clinic in Lisbon, Portugal.Material and Methods: This is a prospective observational study. Participants were recruited among those travellers attending a pretravel clinic between May 2016 and April 2017, meeting the inclusion criteria (age over 18 years old and predicted time of stay from five to 90 days). Structured questionnaires were applied by telephone interviews, three and six months after arrival. Associations and their magnitude were sought between travel and traveller’s characteristics with total and specific health problems, using multiple logistic regression models.Results: Out of 364 participants who completed the study, 60% were under 37 years of age, and 87.9% presented a higher educationaldegree. Africa and Asia were travel destinations for 89.1% of travellers. Three months after travel, 39.3% confirmed some travel-acquired health problem, namely diarrhoea (26.6%) and unmeasured fever (12.4%). A malaria case was diagnosed, occurring 3.5 months after return. From a total of 189 travellers to countries with high risk of malaria and chemoprophylaxis recommendation, 65.6% adhered completely and 6.9% of those presenting fever during travel sought healthcare.Discussion: The proportion of travellers that became ill was lower compared to other published studies. Failure to follow a randomsampling method and the characteristics of the travel consultation with a particular profile of travellers in terms of level of education and ability to pay, challenges the external validity of the study.Conclusion: Health problems during or after travel occurred in 39.3% of travellers with diarrhoeal disease being the most common (26.6%). From our findings, the need for taking chemoprophylaxis for malaria or seeking health care in the presence of fever is not translated into appropriate action. The reasons are unclear and should be the subject of further research. Furthermore, research is needed with inclusion of other centres practicing travel medicine in Portugal, both in the pre-travel setting and others, in order to better understand the health risks associated with Portuguese traveller’s characteristics and destinations.

Increased Primaquine Total Dose in Patients with Multiple Plasmodium vivax Relapses Associated with Impaired CYP2D6 Activity: Report of Three Cases

BackgroundThe relapsing nature of Plasmodium vivax infection is a major barrier to its control and elimination. Factors such as adequate dosing, adherence, drug quality, and pharmacogenetics can impact the effectiveness of radical cure of P. vivax and need to be properly evaluated. CYP2D6 pathway mediates the activation of primaquine (PQ) into an active metabolite(s) in hepatocytes, and impaired activity has been linked to higher risk of relapse. Cases presentationThree patients diagnosed with P. vivax malaria presented repeated relapses after being initially treated with chloroquine (25mg/kg) and primaquine (3.5mg/kg in 14 days) at a non-endemic travel clinic. Recurring episodes were subsequently treated with higher dose of primaquine (7mg/kg in 14 days), which prevented further relapses in two patients. However, one patient still presented 2 episodes after higher primaquine dose and was prescribed 300mg of chloroquine weekly to prevent further episodes. Impaired CYP2D6 function was observed in all of them. ConclusionLack of response to PQ was associated with impaired CYP2D6 activity in three patients presenting multiple relapses followed in a non-endemic setting. Higher PQ dosage was a safe and effectively prevented relapses in two patients and should be further investigated as an option in Latin America. It is important to investigate the factors associated with unsuccessful radical cure and alternative therapeutic options.

International travel is not a significant risk of exposure for patients at a Midwestern United States travel clinic

The Novel Coronavirus (SARS-CoV-2) was introduced into the United States via travel from Asia and Europe, although the extent of the spread of the disease was limited in the early days of the pandemic. Consequently, international travel may have played a role in the transmission of the disease into Iowa. This study seeks to determine how preferences for international travel changed as novel Coronavirus Disease (COVID-19) spread throughout the world and if any of these returning travelers developed COVID-19 as a result of their trips. This is a retrospective chart review of patients presenting to a travel clinic in Bettendorf, Iowa for pre-travel advice and vaccinations. From October 2019 to March 2020, four hundred twelve (n = 412) patients presented to the clinic. Intended travel to the Western Pacific region (China, Japan, Korea, etc.) decreased dramatically during the study period. All 412 patients were followed in the electronic medical record for the period after their planned travel and only three (3) presented for COVID-19 testing. Two (2) tested positive, and both of these infections were linked to workplace exposures and not due to travel. News of the growing pandemic and travel warnings likely altered patients’ travel plans and decreased travel to the most affected regions of the world in the early months of the COVID-19 pandemic. Based on our study, travel was not a significant source of COVID-19 exposure for patients seen at this clinic.