Travel-related respiratory symptoms and infections in travellers (2000-22): a systematic review and meta-analysis

BACKGROUND

Respiratory tract infections (RTIs) are common in travellers due to the year-round or seasonal presence of respiratory pathogen and exposure to crowded environments during the itinerary. No study has systematically examined the burden of RTI infections among travellers. The aim of this systematic review and meta-analysis is to evaluate the prevalence of RTIs and symptoms suggestive of RTIs among travellers according to risk groups and/or geographic region, and to describe the spectrum of RTIs.

METHODS

The systematic review and meta-analysis was registered in PROSPERO (CRD42022311261). We searched Medline, Embase, Scopus, Cochrane Central, Web of Science, Science Direct and preprint servers MedRxiv, BioRxiv, SSRN and IEEE Xplore on 1 February 2022. Studies reporting RTIs or symptoms suggestive of RTIs in international travellers after 1 January 2000 were eligible. Data appraisal and extraction were performed by two authors, and proportional meta-analyses were used to obtain estimates of the prevalence of respiratory symptoms and RTIs in travellers and predefined risk groups.

FINDINGS

A total of 429 articles on travellers' illness were included. Included studies reported 86 841 symptoms suggestive of RTIs and 807 632 confirmed RTIs. Seventy-eight percent of reported respiratory symptoms and 60% of RTIs with available location data were acquired at mass gatherings events. Cough was the most common symptom suggestive of respiratory infections, and the upper respiratory tract was the most common site for RTIs in travellers. The prevalence of RTIs and respiratory symptoms suggestive of RTIs were 10% [8%; 14%] and 37% [27%; 48%], respectively, among travellers. Reporting of RTIs in travellers denoted by publication output was found to correlate with global waves of new respiratory infections.

INTERPRETATION

This study demonstrates a high burden of RTIs among travellers and indicates that travellers' RTIs reflect respiratory infection outbreaks. These findings have important implications for understanding and managing RTIs among travellers.

A meta-analysis and mapping of global mpox infection among children and adolescents

Monkeypox (mpox) is a significant health concern affecting children and adolescents globally. This systematic review and meta-analysis aims to synthesise the available evidence on the proportion of children and adolescents affected by the mpox virus. A comprehensive search was conducted in seven electronic databases (PubMed, Scopus, Web of Science, EMBASE, ProQuest, EBSCOHost, and Cochrane) to identify the original reports on mpox cases in children and adolescents till 15 January 2023. Descriptive reports on probable or laboratory-confirmed mpox in children and adolescents (0-17 years old) were considered eligible. Studies not providing separate data for the above age group and case-control studies were excluded. The primary outcome was pooled proportion of mpox cases among children and adolescents. Proportion meta-analysis and heterogeneity between studies were determined using a restricted maximum likelihood estimator, and a random-effects model was fitted to the data. Sensitivity analysis and subgroup analysis were also conducted. A drapery plot was also provided as a complementary figure to the forest plot. The protocol was prospectively registered with PROSPERO (CRD42023392475). A total of 440 studies were identified, of which 37 were included in the review and 25 in the meta-analysis (62,701 participants with 3306 children and adolescents). The pooled proportion of children and adolescents was 0.46 (95% CI: 0.30-0.63, I2 :100%). The proportion of children and adolescents was significantly lower (p < 0.001) in the ongoing pandemic 0.04 (95% CI: 0.00-0.32) than before 2022 0.62 (95% CI: 0.49-0.74). The meta-regression showed that the higher the study's sample size, the lower the proportion of children among the mpox cases. Both overall and subgroup heterogeneity were high. Adolescents and children below 5 years are commonly affected by the ongoing pandemic. In conclusion, the high proportion of children affected by the mpox virus highlights the need for increased research and targeted interventions to prevent and control the spread of the virus in this population.

Hair concentrations of anti-malarials in returned travellers-the HAIR study: Proof of principle analysis

BACKGROUND

Hair analysis to identify substance use is an established methodology. This could also be a method to monitor adherence to antimalarial drugs. We aimed to establish a methodology to determine hair concentrations of atovaquone, proguanil and mefloquine in travellers using chemoprophylaxis.

METHODS

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous analysis of the antimalarial drugs -atovaquone (ATQ), proguanil (PRO) and mefloquine (MQ), in human hair. The hair samples from five volunteers were used for this proof-of-concept analysis. Three volunteers were taking daily atovaquone/proguanil (ATQ/PRO) chemoprophylaxis and two volunteers were using weekly mefloquine (MQ) chemoprophylaxis.

RESULTS

With this proof-of-principle analysis, we could show that ATQ/PRO and MQ are integrated into the hair matrix. Chemoprophylaxis could be quantified with the established method. In hair segments, maximal concentrations of 3.0 ng/mL/20 mg hair proguanil, 1.3 ng/mL/20 mg hair atovaquone and 78.3 ng/mL/20 mg hair mefloquine were measured. Moreover, malaria drug concentration changes correlated with the time interval since finishing the chemoprophylaxis regimen.

CONCLUSIONS

The validated method was used successfully for the analysis of antimalarial-drug positive hair samples containing atovaquone, proguanil or mefloquine. This research shows that hair can be used for adherence monitoring of chemoprophylaxis and paves the way for larger studies and optimized procedures.

Spotted fever group rickettsiae and Anaplasma phagocytophilum in Borrelia burgdorferi sensu lato seropositive individuals with or without Lyme disease: A retrospective analysis

Background

The Ixodes ricinus tick is the main vector of Borrelia burgdorferi and tick-borne encephalitis virus in Switzerland. Spotted fever group Rickettsiae (SFG) and Anaplasma phagocytophilum have been detected in Swiss ticks, however, information about the extent and clinical presentation of these infections in humans is scant.

Methods

Indirect fluorescent antibody tests for SFG rickettsiae and Anaplasma phagocytophilum were performed on serum samples of 121 Borrelia burgdorferi seropositive patients with and without Lyme disease and 43 negative controls.

Results

Out of 121 Borrelia burgdorferi seropositive individuals, 65 (53.7%) were seropositive for IgG and 15 (12.4%) for IgM antibodies to SFG rickettsiae. IgM antibodies were detected more frequently in early-than in late-stage of Lyme disease (12 out of 51 and 2 out of 49; respectively; p ​= ​0.0078). Significantly higher IgG antibody titers against SFG rickettsiae were found in patients with late-stage compared to patients with early-stage Lyme disease (mean titer 1:261 and 1:129, respectively; p ​= ​0.038). This difference was even more pronounced in patients with acrodermatitis chronica atrophicans compared to patients with early stage of Lyme disease (mean titer 1:337 and 1:129, respectively; p ​= ​0.009).In patients presenting with fatigue, headache and myalgia, the prevalence of IgG antibodies against SFG rickettsiae was significantly higher (7 out of 11; 63.6%) than in Borrelia burgdorferi seropositive individuals without clinical illness (1 out of 10; 10%; p ​= ​0.024). IgG antibodies to Anaplasma phagocytophilum were detected in 12 out of 121 individuals (9.9%), no IgM antibodies were found.

Conclusion

Infections with SFG rickettsiae and Anaplasma phagocytophilum are underdiagnosed and should be ruled out after a tick bite. Further studies are needed to elucidate the possible causative role of SFG rickettsiae for myalgia, headache and long-lasting fatigue after a tick bite and to determine the necessity for an antibiotic treatment.

Healthcare seeking during travel: an analysis by the GeoSentinel surveillance network of travel medicine providers

BACKGROUND

International travellers may seek care abroad to address health problems that arise during their trip or plan healthcare outside their country of residence as medical tourists.

METHODS

Data were collected on travellers evaluated at GeoSentinel Network sites who reported healthcare during travel. Both unplanned and planned healthcare were analysed, including the reason and nature of healthcare sought, characteristics of the treatment provided and outcomes. Travellers that presented for rabies post-exposure prophylaxis were described elsewhere and were excluded from detailed analysis.

RESULTS

From May 2017 through June 2020, after excluding travellers obtaining rabies post-exposure prophylaxis (n= 415), 1093 travellers reported care for a medical or dental issue that was an unanticipated part of the travellers' planned itinerary (unplanned healthcare). Travellers who sought unplanned healthcare abroad had frequent diagnoses of acute diarrhoea, dengue, falciparum malaria and unspecified viral syndrome, and obtained care in 131 countries. Thirty-four (3%) reported subsequent deterioration and 230 (21%) reported no change in condition; a third (n = 405; 37%) had a pre-travel health encounter. Forty-one travellers had sufficient data on planned healthcare abroad for analysis. The most common destinations were the US, France, Dominican Republic, Belgium and Mexico. The top reasons for their planned healthcare abroad were unavailability of procedure at home (n = 9; 19%), expertise abroad (n = 9; 19%), lower cost (n = 8; 17%) and convenience (n = 7; 15%); a third (n = 13; 32%) reported cosmetic or surgical procedures. Early and late complications occurred in 14 (33%) and 4 (10%) travellers, respectively. Four travellers (10%) had a pre-travel health encounter.

CONCLUSIONS

International travellers encounter health problems during travel that often could be prevented by pre-travel consultation. Travellers obtaining planned healthcare abroad can experience negative health consequences associated with treatments abroad, for which pre-travel consultations could provide advice and potentially help to prevent complications.

COVID-19 impact on EuroTravNet infectious diseases sentinel surveillance in Europe

BACKGROUND

The COVID-19 pandemic resulted in a sharp decline of post-travel patient encounters at the European sentinel surveillance network (EuroTravNet) of travellers' health. We report on the impact of COVID-19 on travel-related infectious diseases as recorded by EuroTravNet clinics.

METHODS

Travelers who presented between January 1, 2019 and September 30, 2021 were included. Comparisons were made between the pre-pandemic period (14 months from January 1, 2019 to February 29, 2020); and the pandemic period (19 months from March 1, 2020 to September 30, 2021).

RESULTS

Of the 15,124 visits to the network during the 33-month observation period, 10,941 (72%) were during the pre-pandemic period, and 4183 (28%) during the pandemic period. Average monthly visits declined from 782/month (pre-COVID-19 era) to 220/month (COVID-19 pandemic era). Among non-migrants the top-10 countries of exposure changed after onset of the COVID-19 pandemic; destinations such as Italy and Austria, where COVID-19 exposure peaked in the first months, replaced typical travel destinations in Asia (Thailand, Indonesia, India). There was a small decline in migrant patients reported, with little change in the top countries of exposure (Bolivia, Mali). The three top diagnoses with the largest overall decreases in relative frequency were acute gastroenteritis (-5.3%), rabies post-exposure prophylaxis (-2.8%), and dengue (-2.6%). Apart from COVID-19 (which rose from 0.1% to 12.7%), the three top diagnoses with the largest overall relative frequency increase were schistosomiasis (+4.9%), strongyloidiasis (+2.7%), and latent tuberculosis (+2.4%).

CONCLUSIONS

A marked COVID-19 pandemic-induced decline in global travel activities is reflected in reduced travel-related infectious diseases sentinel surveillance reporting.

[Rising temperatures and the threat of malaria in Europe: an unwelcome return?]

Rising temperatures pose a threat to malaria transmission in Europe. Anopheles vectors are becoming more stable and widespread, putting some areas at increased risk of transmission for extended periods. By 2030 or 2050, the period of susceptibility is expected to extend to 3-6 months in some European countries and Anopheles mosquitoes are expected to migrate northward. In addition, climate change has led to a substantial increase in the number of climate refugees in Europe, increasing the risk of spread of the disease from endemic areas to susceptible regions. Urgent action is needed to prevent the transmission of malaria and other climate change-related diseases in Europe.

Analysis of Optical Coherence Tomography (OCT) and Optical Coherence Tomography Angiography (OCTA) Parameters in Young Adults after SARS-CoV-2 Infection (COVID-19) Compared with Healthy Young Controls

Purpose: To compare retinal changes in young adults with previous SARS-CoV-2 infection with healthy young controls using optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA). Methods: This prospective single-center study was conducted at the University Hospital of Zurich, Zurich, Switzerland. Participants were imaged from May to November 2021 using the SOLIX device (Visionix International SAS, Pont-de-l’Arche, France). We performed 12 mm × 12 mm, 6.4 mm × 6.4 mm, 6 mm × 6 mm and 3 mm × 3 mm OCT and OCTA scans, as well as fundus photography of each participant’s eyes. Results: In total, 466 participants were imaged. Of these, 233 were healthy controls with negative RT-PCR tests for SARS-CoV-2, 168 were young adults who had a SARS-CoV-2 infection at least 180 days previously, 19 were participants who had a SARS-CoV-2 infection < 180 days previously, and 46 were participants with asymptomatic SARS-CoV-2 infection (i.e., serologically positive but with no symptoms). Compared with healthy controls, statistically significant differences were found for OCTA recordings of the optic disc for the whole image (WI) and WI capillary vessel density, with both being higher in the SARS-CoV-2 group. Conclusion: Statistically significant results were only observed for selected variables, and in parts, only unilaterally, with relatively large p values (p = 0.02–0.03). Thus, we did not interpret these as clinically significant, leading to the conclusion that young and otherwise healthy individuals (mainly men) seem to recover from mild COVID-19 infections with no ophthalmological residues.

On the potential for discontinuing atovaquone-proguanil (AP) ad-hoc post-exposure and other abbreviated AP-regimens: Pharmacology, pharmacokinetics and perspectives

According to current guidelines, atovaquone-proguanil (AP) malaria chemoprophylaxis should be taken once daily starting one day before travel and continued for seven days post-exposure. However, drug-sparing regimens, including discontinuing AP after leaving malaria-endemic areas are cost-saving and probably more attractive to travelers, and may thus enhance adherence. AP has causal prophylactic effects, killing malaria parasites during the hepatic stage. If early hepatic stages were already targeted by AP, AP could possibly be discontinued upon return. Pharmacokinetic data and studies on drug-sparing AP regimens suggest this to be the case. Nevertheless, the evidence is weak and considered insufficient to modify current recommendations. Field trials require large numbers of travelers and inherently suffer from the lack of a control group. Safely-designed controlled human malaria infection trials could significantly reduce study participant numbers and safely establish an effective AP abbreviated regimen which we propose as the optimal trial design to test this concept.

Persistence, prevalence, and polymorphism of sequelae after COVID-19 in unvaccinated, young adults of the Swiss Armed Forces: a longitudinal, cohort study (LoCoMo)

BACKGROUND

Persistent COVID-19 sequelae could have global, public health ramifications. We therefore aimed to describe sequelae presenting more than 180 days after COVID-19-focussing on several organ systems, general health, and laboratory parameters-in non-hospitalised, unvaccinated, young adults.

METHODS

We did a longitudinal cohort study of all army bases in Switzerland. Eligible participants were personnel of the Swiss Armed Forces (SAF) who were aged 18-30 years with a positive or negative RT-PCR test for SARS-CoV-2 during their service between March 1, 2020, and Dec 31, 2020. Exclusion criteria were unwillingness to participate in testing. Females or men with a known reproductive anomaly were excluded from the optional component of male fertility testing. COVID-19 was defined as a positive diagnostic RT-PCR test result for SARS-CoV-2 with concurrent symptoms compatible with COVID-19. Participants were subdivided into four groups: control group (ie, serologically negative), asymptomatic infection group (ie, serologically positive but with no symptoms), non-recent COVID-19 group (>180 days since positive PCR test), and recent COVID-19 group (≤180 days since positive PCR test). Outcomes of interest were part of a comprehensive, intensive test battery that was administered during a single day. The test battery quantified the effect of SARS-CoV-2 infection on cardiovascular, pulmonary, neurological, renal, ophthalmological, male reproductive, psychological, general health, and laboratory parameters. This study was registered with ClinicalTrials.gov, number NCT04942249.

FINDINGS

Between May 20, 2021, and Nov 26, 2021, we enrolled 501 participants. 29 (6%) of 501 were female and 464 (93%) were male, and the median age was 21 years (IQR 21-23). Eight (2%) of 501 had incomplete data and were not included into the study groups. 177 participants had previous COVID-19 that was more than 180 days (mean 340 days) since diagnosis (ie, the non-recent COVID-19 group) compared with 251 serologically negative individuals (ie, the control group). We included 19 participants in the recent COVID-19 group and 46 in the asymptomatic infection group. We found a significant trend towards metabolic disorders in participants of the non-recent COVID-19 group compared with those in the control group: higher BMI (median 24·0 kg/m² [IQR 22·0-25·8] vs 23·2 kg/m² [27·1-25·0]; p=0·035), lower aerobic threshold (39% [36-43] vs 41% [37-46]; p=0·012), and higher blood cholesterol (4·2 μM [3·7-4·7] vs 3·9 μM [3·5-4·5]; p<0·0001) and LDL concentrations (2·4 μM [1·9-2·9] vs 2·2 μM [1·7-2·7]; p=0·001). The only significant psychosocial difference was found in the results of the Chalder Fatigue scale with the non-recent COVID-19 group reporting higher fatigue scores than the control group (median 12 points [IQR 11-15] vs 11 [9-14]; p=0·027). No significant differences in other psychosocial questionnaire scores, ophthalmological outcomes, and sperm quality or motility were reported between the control group and non-recent COVID-19 group.

INTERPRETATION

Young, previously healthy, individuals largely recover from SARS-CoV-2 infection. However, the constellation of higher BMI, dyslipidaemia, and lower physical endurance 180 days after COVID-19 is suggestive of a higher risk of developing metabolic disorders and possible cardiovascular complications. These findings will guide future investigations and follow-up management.

FUNDING

Swiss Armed Forces.

Discontinuing atovaquone/proguanil prophylaxis ad-hoc post-exposure and during-travel dose-sparing prophylactic regimens against P. falciparum malaria: An update with pointers for future research

BACKGROUND

Atovaquone/proguanil (AP) is a highly effective malaria chemoprophylaxis combination. According to current guidelines, AP is taken once daily during, and continued for seven days post exposure. A systematic review by Savelkoel et al. summarised data up to 2017 on abbreviated AP regimens, and concluded that discontinuing AP upon return may be effective, although the available data was insufficient to modify current recommendations. The same applies to other studies evaluating during-travel dose-sparing regimens.

METHODS

A literature search in Pubmed and Embase was performed including search terms related to AP prophylaxis and pharmacokinetics to search for recent studies on abbreviated AP regimens published since 2017.

RESULTS

Since the 2017 review, no new studies assessing discontinuing AP ad-hoc post-exposure prophylaxis have been published. Two new studies were identified assessing other abbreviated AP regimens; one investigated a twice-weekly AP regimen in 32 travellers, and one a three-day AP course in therapeutic dose (1000/400 mg) prior to exposure in 215 travellers. No malaria cases were detected in the study participants adhering to these regimens.

CONCLUSIONS

Further research would be needed if the research question is considered of sufficient importance to facilitate evidence-based decision-making to modify current guidelines, as efficacy studies in travellers are fraught with confounders. We recommend human challenge trials to study abbreviated AP regimens pertaining to malaria chemoprophylaxis as they allow for rational, subject number, time- and cost-saving trial designs.

Illness tracking in SARS-CoV-2 tested persons using a smartphone app: a non-interventional, prospective, cohort study

There are few data on the range and severity of symptoms of SARS-CoV-2 infection or the impact on life quality in infected, previously healthy, young adults such as Swiss Armed Forces personnel. It is also unclear if an app can be used to remotely monitor symptoms in persons who test positive. Using a smartphone app called ITITP (Illness Tracking in Tested Persons) and weekly pop-up questionnaires, we aimed to evaluate the spectrum, duration, and impact of symptoms reported after a positive SARS-CoV-2 test according to sex, age, location, and comorbidities, and to compare these to responses from persons who tested negative. We followed up 502 participants (57% active participation), including 68 (13.5%) positive tested persons. Hospitalisation was reported by 6% of the positive tested participants. We found that positives reported significantly more symptoms that are typical of COVID-19 compared to negatives. These symptoms with odds ratio (OR > 1) were having difficulty breathing (OR 3.35; 95% CI: 1.16, 9.65; p = 0.03), having a reduced sense of taste (OR 5.45; 95% CI: 1.22, 24.34; p = 0.03) and a reduced sense of smell (OR 18.24; 95% CI: 4.23, 78.69; p < 0.001). Using a random forest model, we showed that tiredness was the single symptom that was rated as having a significant impact on daily activities, whereas the other symptoms, although frequent, had less impact. The study showed that the use of an app was feasible to remotely monitor symptoms in persons infected with SARS-CoV-2 and could be adapted for other settings and new pandemic phases such as the current Omicron wave.

Imported malaria in Switzerland, (1990-2019): A retrospective analysis

BACKGROUND

Malaria is a life-threatening, mosquito-borne parasitic disease, caused by Plasmodium spp. It is a major public health issue. Malaria in Switzerland is primarily "imported" by infected international travellers, migrants, and asylum-seekers.

METHOD

We investigated the epidemiology and characteristics of imported malaria in Switzerland in the period between 1990 and 2019 using data from the Swiss Federal Office of Public Health (BAG). We also obtained traveller statistics from the World Tourism Organization (UNWTO).

RESULTS

During the last thirty years a total of 8'439 malaria cases and 52 deaths were reported in Switzerland. The main origin of infection was West Africa, followed by Central Africa and East Africa. The profile of malaria in migrants in Switzerland has changed, reflecting variation in migrant flows. The estimated risk of malaria in travellers sank significantly over the time frame of the study (p < 0.001, 95% CI -0.076 to -0.043).

CONCLUSIONS

Travel medicine should focus on West Africa, the main source of malaria in Switzerland. Despite most cases and all but one death being caused by Plasmodium falciparum, Plasmodium vivax remains a threat for travellers and is associated with complex prevention and therapy regimens. Public health authorities need to pre-empt the need for malaria screening, prevention and treatment based on the profile of migrant waves from malaria endemic areas including Eritrea and Afghanistan arriving in Europe.

Ayahuasca and the traveller: A scoping review of risks and possible benefits

BACKGROUND

Ayahuasca is a psychotropic drink made from the Amazonian vine Banisteriopsis caapi. Active components include beta-carboline alkaloids and the hallucinogen N-N-dimethyltryptamine (DMT). This review aimed to identify and summarize the literature on the safety and effectiveness of ayahuasca among recreational users.

METHOD

A comprehensive literature search was done on November 1, 2019 in the following six databases: PubMed(MEDLINE), Ovid Embase, Ovid International Pharmaceutical Abstracts, LILACS, Scopus, and Web of Science. Articles were included if they were original research published in English, Spanish, or Portuguese, among human participants using oral ayahuasca for neuropsychiatric effects. Chemical or pharmacological analyses, brain imaging studies, and studies examining the use of ayahuasca within a religious context were excluded.

RESULTS

5750 unique titles were identified through the database searches, with an additional 19 titles identified through manual searches. Ultimately, 39 met all the criteria for inclusion. Articles were organized into 4 themes: (1) Case reports and case series; (2) The use of ayahuasca for depression or grief; (3) The use of ayahuasca and other psychiatric or neuropsychological outcomes; and (4) Studies examining ayahuasca use and physiologic outcomes. Ayahuasca use is associated with a risk of both psychiatric and non-psychiatric events including hallucinations, agitation or aggression, vomiting, seizure, and rhabdomyolysis. Five fatalities have been reported in the literature following ayahuasca use. Open-label studies assessing ayahuasca use in depression found favorable results persisting across 21 days. Ayahuasca was also found to influence the MINDSENS scale for mindfulness, with mixed results observed for impact of ayahuasca on cognitive function and creativity, and benefits observed for measures of self-acceptance and overall wellbeing.

CONCLUSIONS

To date, evidence on benefits for the management of depression, anxiety, and other mental health disorders is mixed, with some evidence suggesting improvements in mindfulness measures and creativity that are generally short-lived, and multiple case reports suggesting the potential for harm and interactions.

Assessment and management of asymptomatic COVID-19 infection: A systematic review

Background

COVID-19 can be asymptomatic in a substantial proportion of patients. The assessment and management of these patients constitute a key element to stop dissemination.

Aim

To describe the assessment and treatment of asymptomatic infection in patients with a confirmed diagnosis of COVID-19.

Methods

We searched five databases and search engines for preprints/preproofs, up to August 22, 2020. We included cohort, cross-sectional, and case series studies, reporting the assessment and management of asymptomatic individuals. We extracted data on total discharges with negative PCR, length of hospitalization, treatment, and number of patients who remained asymptomatic. A random-effects model with inverse variance method was used to calculate the pooled prevalence.

Results

41 studies (nine cross-sectional studies, five retrospective studies and 27 reports/case series; 647 asymptomatic individuals), were included, of which 47% were male (233/501). The age of patients was between 1month and 73 years. In patients who became symptomatic, length of hospitalization mean was 13.6 days (SD 6.4). Studies used lopinavir/ritonavir, hydroxychloroquine plus ritonavir/lopinavir, hydroxychloroquine with and without azithromycin, ribavirin plus interferon and interferon alfa. The proportion of individuals who remained asymptomatic was 91% (463/588 patients; 95%CI: 78.3%–98.7%); and asymptomatic individuals discharged with negative PCR was 86% (102/124 individuals; 95%CI: 58.4%–100%).

Conclusions

There is no standard treatment for asymptomatic COVID-19 individuals. There are no studies of adequate design to make this decision. It has been shown that most asymptomatic individuals who were followed have recovered, but this cannot be attributed to standard treatment.

COVID-19 sequelae in adults aged less than 50 years: A systematic review

BACKGROUND

There is emerging evidence of long-term sequelae in a considerable proportion of COVID-19 patients after recovery and the spectrum and severity of such sequelae should be systematically reviewed. This review aims to evaluate the available evidence of all intermediate and long-term COVID-19 sequelae affecting formerly healthy adults.

METHODS

A systematic literature search of Embase, WHO, Scopus, Pubmed, Litcovid, bioRxiv and medRxiv was conducted with a cutoff date of the 17th September 2020 according to PRISMA guidelines and registered in PROSPERO (CRD42020208725). Search terms included "COVID-19", "coronavirus disease 2019", "SARS-CoV-2", "sequelae" and "consequence*". Publications on adult participants, with a confirmed SARS-CoV-2 infection were included. Elderly (>50 years old) and children (<18 years old) were excluded. Bias assessment was performed using a modified Newcastle-Ottawa Scale.

RESULTS

A total of 31 papers were included. Study types included prospective and retrospective cohort studies, cross-sectional studies and case reports. Sequelae persistence since infection spanned 14 days to three months. Sequelae included persistent fatigue (39-73% of assessed persons), breathlessness (39-74%), decrease in quality of life (44-69%), impaired pulmonary function, abnormal CT findings including pulmonary fibrosis (39-83%), evidence of peri-/perimyo-/myocarditis (3-26%), changes in microstructural and functional brain integrity with persistent neurological symptoms (55%), increased incidence of psychiatric diagnoses (5.8% versus 2.5-3.4% in controls), incomplete recovery of olfactory and gustatory dysfunction (33-36% of evaluated persons).

CONCLUSIONS

A variety of organ systems are affected by COVID-19 in the intermediate and longer-term after recovery. Main sequelae include post-infectious fatigue, persistent reduced lung function and carditis. Careful follow-up post COVID 19 is indicated to assess and mitigate possible organ damage and preserve life quality.

Reprint of: Air travel and COVID-19 prevention in the pandemic and peri-pandemic period: A narrative review

Air travel during the COVID-19 pandemic is challenging for travellers, airlines, airports, health authorities, and governments. We reviewed multiple aspects of COVID peri-pandemic air travel, including data on traveller numbers, peri-flight prevention, and testing recommendations and in-flight SARS-CoV-2 transmission, photo-epidemiology of mask use, the pausing of air travel to mass gathering events, and quarantine measures and their effectiveness.

Flights are reduced by 43% compared to 2019. Hygiene measures, mask use, and distancing are effective, while temperature screening has been shown to be unreliable. Although the risk of in-flight transmission is considered to be very low, estimated at one case per 27 million travellers, confirmed in-flight cases have been published. Some models exist and predict minimal risk but fail to consider human behavior and airline procedures variations. Despite aircraft high-efficiency filtering, there is some evidence that passengers within two rows of an index case are at higher risk. Air travel to mass gatherings should be avoided. Antigen testing is useful but impaired by time lag to results. Widespread application of solutions such as saliva-based, rapid testing or even detection with the help of “sniffer dogs” might be the way forward. The “traffic light system” for traveling, recently introduced by the Council of the European Union is a first step towards normalization of air travel. Quarantine of travellers may delay introduction or re-introduction of the virus, or may delay the peak of transmission, but the effect is small and there is limited evidence. New protocols detailing on-arrival, rapid testing and tracing are indicated to ensure that restricted movement is pragmatically implemented. Guidelines from airlines are non-transparent. Most airlines disinfect their flights and enforce wearing masks and social distancing to a certain degree. A layered approach of non-pharmaceutical interventions, screening and testing procedures, implementation and adherence to distancing, hygiene measures and mask use at airports, in-flight and throughout the entire journey together with pragmatic post-flight testing and tracing are all effective measures that can be implemented.

Ongoing research and systematic review are indicated to provide evidence on the utility of preventive measures and to help answer the question “is it safe to fly?“.

After SARS-CoV-2, will H5N6 and other influenza viruses follow the pandemic path?

While the world is focused on attending, controlling, and mitigating the current pandemic of COVID-19, caused by the SARS-CoV-2, other viral threats are possibly emerging and reemerging especially in Asia, posing a risk for the spread in that region and beyond. A predictable threat is the avian influenza virus, especially H5N6, which has recently led to significant outbreaks in China and the Philippines, deserving more attention and control. In the current review, we assess the history of this highly pathogenic reemerging virus, as well as the contemporary implications of poultry outbreaks occurring in some Asian countries. We also look at outbreaks due to other strains not only in Asia but also across Europe and Africa, according to recent reports from the World Organization of Animal Health (OIE).

Efficacy and safety of tafenoquine for malaria chemoprophylaxis (1998-2020): A systematic review and meta-analysis

BACKGROUND

In 2018, tafenoquine was approved for malaria chemoprophylaxis. We evaluated all available data on the safety and efficacy of tafenoquine chemoprophylaxis.

METHODS

This systematic review followed the PRISMA guidelines and was registered on PROSPERO (CRD42019123839). We searched PubMed, Embase, Scopus, CINAHL and Cochrane databases. Two authors (JDM, PS) screened all papers.

RESULTS

We included 44 papers in the qualitative and 9 in the quantitative analyses. These 9 randomized, controlled trials included 2495 participants, aged 12-60 years with 27.3% women. Six studies were conducted in Plasmodium spp.-endemic regions; two were human infection studies. 200 mg weekly tafenoquine and higher dosages lead to a significant reduction of Plasmodium spp. infection compared to placebo and were comparable to 250 mg mefloquine weekly with a protective efficacy between 77.9 and 100% or a total risk ratio of 0.22 (95%-CI: 0.07-0.73; p = 0.013) in favour of tafenoquine. Adverse events (AE) were comparable in frequency and severity between tafenoquine and comparator arms. One study reported significantly more gastrointestinal events in tafenoquine users (p ≤ 0.001). Evidence of increased, reversible, asymptomatic vortex keratopathy in subjects with prolonged tafenoquine exposures was found. A single, serious event of decreased macular sensitivity occurred.

CONCLUSION

This systematic review and meta-analysis of trials of G6PD-normal adults show that weekly tafenoquine 200 mg is well tolerated and effective as malaria chemoprophylaxis focusing primarily on Plasmodium falciparum but also on Plasmodium vivax. Our safety analysis is limited by heterogenous methods of adverse events reporting. Further research is indicated on the use of tafenoquine in diverse traveller populations.

Air travel and COVID-19 prevention in the pandemic and peri-pandemic period: A narrative review

Air travel during the COVID-19 pandemic is challenging for travellers, airlines, airports, health authorities, and governments. We reviewed multiple aspects of COVID peri-pandemic air travel, including data on traveller numbers, peri-flight prevention, and testing recommendations and in-flight SARS-CoV-2 transmission, photo-epidemiology of mask use, the pausing of air travel to mass gathering events, and quarantine measures and their effectiveness. Flights are reduced by 43% compared to 2019. Hygiene measures, mask use, and distancing are effective, while temperature screening has been shown to be unreliable. Although the risk of in-flight transmission is considered to be very low, estimated at one case per 27 million travellers, confirmed in-flight cases have been published. Some models exist and predict minimal risk but fail to consider human behavior and airline procedures variations. Despite aircraft high-efficiency filtering, there is some evidence that passengers within two rows of an index case are at higher risk. Air travel to mass gatherings should be avoided. Antigen testing is useful but impaired by time lag to results. Widespread application of solutions such as saliva-based, rapid testing or even detection with the help of "sniffer dogs" might be the way forward. The "traffic light system" for traveling, recently introduced by the Council of the European Union is a first step towards normalization of air travel. Quarantine of travellers may delay introduction or re-introduction of the virus, or may delay the peak of transmission, but the effect is small and there is limited evidence. New protocols detailing on-arrival, rapid testing and tracing are indicated to ensure that restricted movement is pragmatically implemented. Guidelines from airlines are non-transparent. Most airlines disinfect their flights and enforce wearing masks and social distancing to a certain degree. A layered approach of non-pharmaceutical interventions, screening and testing procedures, implementation and adherence to distancing, hygiene measures and mask use at airports, in-flight and throughout the entire journey together with pragmatic post-flight testing and tracing are all effective measures that can be implemented. Ongoing research and systematic review are indicated to provide evidence on the utility of preventive measures and to help answer the question "is it safe to fly?".

Traveller exposures to animals: a GeoSentinel analysis

BACKGROUND

Human coexistence with other animals can result in both intentional and unintentional contact with a variety of mammalian and non-mammalian species. International travellers are at risk for such encounters; travellers risk injury, infection and possibly death from domestic and wild animal bites, scratches, licks and other exposures. The aim of the present analysis was to understand the diversity and distribution of animal-related exposures among international travellers.

METHODS

Data from January 2007 through December 2018 from the GeoSentinel Surveillance Network were reviewed. Records were included if the exposure was non-migration travel with a diagnosis of an animal (dog, cat, monkey, snake or other) bite or other exposure (non-bite); records were excluded if the region of exposure was not ascertainable or if another, unrelated acute diagnosis was reported.

RESULTS

A total of 6470 animal exposures (bite or non-bite) were included. The majority (71%) occurred in Asia. Travellers to 167 countries had at least one report of an animal bite or non-bite exposure. The majority (76%) involved dogs, monkeys and cats, although a wide range of wild and domestic species were involved. Almost two-thirds (62.6%) of 4395 travellers with information available did not report a pretravel consultation with a healthcare provider.

CONCLUSIONS

Minimizing bites and other animal exposures requires education (particularly during pretravel consultations) and behavioral modification. These should be supplemented by the use of pre-exposure rabies vaccination for travellers to high-risk countries (especially to those with limited access to rabies immunoglobulin), as well as encouragement of timely (in-country) post-exposure prophylaxis for rabies and Macacine alphaherpesvirus 1 (herpesvirus B) when warranted.

COVID-19 in the least developed, fragile, and conflict-affected countries - How can the most vulnerable be protected?

The relentless spread of coronavirus disease 2019 (COVID-19) and its penetration into the least developed, fragile, and conflict-affected countries (LDFCAC) is a certainty. Expansion of the pandemic will be expedited by factors such as an abundance of at-risk populations, inadequate COVID-19 mitigation efforts, sheer inability to comply with community mitigation strategies, and constrained national preparedness. This situation will reduce the benefits achieved through decades of disease control and health promotion measures, and the economic progress made during periods of global development. Without interventions, and as soon as international travel and trade resume, reservoirs of COVID-19 and other vaccine-preventable diseases in LDFCAC will continue ‘feeding’ developed countries with repeated infection seeds. Assuring LDFCAC equity in access to medical countermeasures, funds to mitigate the pandemic, and a paradigm change in the global development agenda, similar to the post-World War II Marshall Plan for Europe, are urgently needed. We argue for a paradigm change in strategy, including a new global pandemic financing mechanism for COVID-19 and other future pandemics. This approach should assist LDFCAC in gaining access to and membership of a global interdisciplinary pandemic taskforce to enable in-country plans to train, leverage, and maintain essential functioning and also to utilize and enhance surveillance and early detection capabilities. Such a task force will be able to build on and expand research into the management of pandemics, protect vulnerable populations through international laws/treaties, and reinforce and align the development agenda to prevent and mitigate future pandemics. Lifting LDFCAC from COVID-related failure will offer the global community the best economic dividends of the century.

Self-diagnosis and self-treatment of Plasmodium spp. infection by travellers (1989-2019): A systematic review and meta-analysis

BACKGROUND

Standby emergency self-treatment (SBET) is often recommended as an anti-malaria strategy for travellers to low-risk endemic areas. This self-treatment enables competent malaria therapy, if medical assistance is unavailable. The World Health Organization (WHO) recommends performing reliable diagnostic tests before starting antimalarial treatment. For the self-diagnosis of malaria in travellers, rapid diagnostic tests (RDT) can be used to confirm the infection before SBET is used. The aim of this research is to assess the use of RDT and/or SBET in travellers.

METHODS

We searched the databases (PubMed, Scopus, Embase, CINAHL) using terms and synonyms for 'self-diagnosis' and 'self-treatment' combined with 'malaria' and 'travel'. Articles in English, French and German were included. Potential articles were screened and extracted by two authors (KU and PS). Only original articles and case reports documenting the self-use of RDT and/or SBET in travellers were included. Data were extracted using a standardised approach. We defined 'correct use' of RDT and SBET. Data on number and performance of RDT and SBET use, as well as malaria verification were collected in an Excel table. Five meta-analyses were performed using a random effects model and calculating pooled proportions. This systematic review was conducted according to the PRISMA guidelines and registered in PROSPERO (CRD42018108874).

RESULTS

The research resulted in 867 articles of possible relevance on RDT and 955 articles on SBET. After screening, a total of 4 articles on RDT use and 17 articles for SBET use in travellers were included in the systematic review. Most of the RDT were performed and interpreted properly by the travellers (pooled proportion 88%, 95% confidence interval (CI) from 64% to 97%), whereby the proportion of correct performance was increased after a pre-travel test run (97%). Major problems in the implementation such as pricking finger, placing blood drop, identifying lines and interpreting results could be discovered. We found data on 1025 SBET uses in studies of travellers to high-risk African countries. In these studies, the pooled proportion of SBET uses was 6% (95% CI from 2% to 13%). We found 545 SBET uses in studies of travellers to countries of mixed malaria risk. In these studies, the pooled proportion of SBET uses was 2% (95% CI from 1% to 7%). Furthermore, the evaluation showed a high proportion of correct SBET use (pooled proportion 69%, 95% CI from 35% to 90%). As a cause for incorrect use, errors in dosage (under- or overdose), disregard of minimal incubation period (< 7 days since first possible malaria exposure) and absence of fever were identified. Four cases of post-SBET severe adverse events were documented. In a third of travellers who used SBET, a Plasmodium spp. infection could be detected (pooled proportion 31%, 95% CI from 16% to 51%).

CONCLUSIONS

This systematic review and meta-analysis showed that the majority of travellers were able to use RDT and SBET correctly. Standardised pre-travel instructions and specific training are indicated to increase the proportions of correct RDT and SBET use. With improved and user-friendly technology, RDT may become an integral part of SBET malaria recommendations for travellers. Combined use of RDT and SBET could be an appropriate strategy for selected subgroups of travellers to low-risk, remote malaria areas. Future research should focus on combined RDT and SBET strategies.

Travel-associated chikungunya acquired in Myanmar in 2019

Eighteen cases of chikungunya virus infection in travellers returning from Myanmar were reported to the GeoSentinel Surveillance Network, its subnetwork EuroTravNet and TropNet in 2019, reflecting an ongoing local outbreak. This report reinforces the importance of travellers as sentinels of emerging arboviral outbreaks and highlights the importance of vigilance for imported cases, due to the potential for dissemination of the virus into areas with competent local vectors and conducive environmental conditions.

Zika among international travellers presenting to GeoSentinel sites, 2012-2019: implications for clinical practice

INTRODUCTION

International travellers contribute to the rapid spread of Zika virus (ZIKV) and its sentinel identification globally. We describe ZIKV infections among international travellers seen at GeoSentinel sites with a focus on ZIKV acquired in the Americas and the Caribbean, describe countries of exposure and traveller characteristics, and assess ZIKV diagnostic testing by site.

METHODS

Records with an international travel-related diagnosis of confirmed or probable ZIKV from January 2012 through December 2019 reported to GeoSentinel with a recorded illness onset date were included to show reported cases over time. Records from March 2016 through December 2019 with an exposure region of the Americas or the Caribbean were included in the descriptive analysis. A survey was conducted to assess the availability, accessibility and utilization of ZIKV diagnostic tests at GeoSentinel sites.

RESULTS

GeoSentinel sites reported 525 ZIKV cases from 2012 through 2019. Between 2012 and 2014, eight cases were reported, and all were acquired in Asia or Oceania. After 2014, most cases were acquired in the Americas or the Caribbean, a large decline in ZIKV cases occurred in 2018-19.Between March 2016 and December 2019, 423 patients acquired ZIKV in the Americas or the Caribbean, peak reporting to these regions occurred in 2016 [330 cases (78%)]. The median age was 36 years (range: 3-92); 63% were female. The most frequent region of exposure was the Caribbean (60%). Thirteen travellers were pregnant during or after travel; one had a sexually acquired ZIKV infection. There was one case of fetal anomaly and two travellers with Guillain-Barré syndrome. GeoSentinel sites reported various challenges to diagnose ZIKV effectively.

CONCLUSION

ZIKV should remain a consideration for travellers returning from areas with risk of ZIKV transmission. Travellers should discuss their travel plans with their healthcare providers to ensure ZIKV prevention measures are taken.

Rising temperature and its impact on receptivity to malaria transmission in Europe: A systematic review

BACKGROUND

Malaria is one of the most life-threatening vector-borne diseases globally. Recent autochthonous cases registered in several European countries have raised awareness regarding the threat of malaria reintroduction to Europe. An increasing number of imported malaria cases today occur due to international travel and migrant flows from malaria-endemic countries. The cumulative factors of the presence of competent vectors, favourable climatic conditions and evidence of increasing temperatures might lead to the re-emergence of malaria in countries where the infection was previously eliminated.

METHODS

We performed a systematic literature review following PRISMA guidelines. We searched for original articles focusing on rising temperature and the receptivity to malaria transmission in Europe. We evaluated the quality of the selected studies using a standardised tool.

RESULTS

The search resulted in 1'999 articles of possible relevance and after screening we included 10 original research papers in the quantitative analysis for the systematic review. With further increasing temperatures studies predicted a northward spread of the occurrence of Anopheles mosquitoes and an extension of seasonality, enabling malaria transmission for annual periods up to 6 months in the years 2051-2080. Highest vector stability and receptivity were predicted in Southern and South-Eastern European areas. Anopheles atroparvus, the main potential malaria vector in Europe, might play an important role under changing conditions favouring malaria transmission.

CONCLUSION

The receptivity of Europe for malaria transmission will increase as a result of rising temperature unless socioeconomic factors remain favourable and appropriate public health measures are implemented. Our systematic review serves as an evidence base for future preventive measures.

Can dengue virus be sexually transmitted?

It has been well documented that Zika virus (ZIKV) can be sexually transmitted. Dengue virus (DENV) shows many similarities with ZIKV; both belong to the genus Flavivirus and share the same main vector route of transmission. Moreover, they share overall architectural features on a molecular level, with a highly similar structure and distinctive insertions, deletions and mutations of their respective E proteins, and it has been suggested that they use a common pathophysiological pathway. In view of similarities with other sexually transmissible viruses, the question arises as to whether DENV could also be sexually transmissible. Limited animal model data do not suggest otherwise. The presence of dengue virus in - and human-to-human, non-vector transmission from - various bodily fluids other than semen or vaginal secretions has been documented anecdotally. Several anecdotal reports described prolonged presence of DENV in semen, urine and vaginal secretions. In 2019, two cases of likely sexual transmission were reported from Spain and South Korea, respectively. We discuss the evidence for and against a relevant DENV sexual transmission potential, highlight controversies and propose a future research agenda on this issue.

The safety and applicability of synthetic pyrethroid insecticides for aircraft disinsection: A systematic review

BACKGROUND

Air travel contributes to the global spread of vectors and vector-borne infections. Although WHO provides guidance on methods for disinsection of aircraft, there is currently no harmonized or standardized decision-making process to decide when disinsection of an aircraft should be conducted. It is however compulsory for flights arriving in certain countries. Concerns have been expressed about the usefulness of disinsection for preventing the international spread of vectors and vector-borne diseases via air travel and possible toxicity for passengers and flight crew.

METHODS

We performed a systematic literature review using the databases PubMed, Embase, Medline, Scopus and CINAHL to evaluate all research findings about the applicability and safety of chemical-based, aircraft disinsection. Official reports from the WHO were also screened. This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and meta-analysis (PRISMA) statement. The literature search strategy included "disinsection, airplane/plane/aviation/aircraft" and several other search items including d-phenothrin, permethrin, insecticide. Papers in English, French and German were reviewed. Reports of adverse events attributed to the disinsection of aircraft were also searched. AMP and PS screened all papers of relevance and agreed on a final selection.

RESULTS

Our search resulted in 440 papers of possible relevance. After screening, we included a total of 25 papers in this systematic review. Ten papers reported possible human toxicity and 17 papers addressed the applicability of disinsection and 2 papers addressed both topics. Chemical disinsection at recommended insecticide concentrations was found to be highly effective against a broad range of arthropods. Three papers reported passenger or crew illness possibly associated with insecticide spraying in passenger cabins - one describing a single passenger, the other two papers describing occupational illness of 12 and 33 aircrew members respectively, possibly due to aircraft disinsection. Another paper evaluating exposure of flight attendants to permethrin found higher levels of urinary metabolites in those working in planes that had recently been sprayed but this could not be linked to adverse health outcomes.

CONCLUSION

Our analysis confirmed that disease vectors are carried on international flights and can pose a threat particularly to island populations and certain airport hub areas. Disinsection with permethrin or d-phenothrin was shown to be highly effective against vectors. Despite several hundred million passenger and crew exposures to chemical disinsection, very few proven cases of toxicity have been reported. There is limited evidence linking exposure to insecticide spraying with negative health impact.