Travel-associated diseases, Indian Ocean Islands, 1997-2010

Chikungunya: An Emerging Public Health Concern

Purpose of Review

The worldwide spread of chikungunya over the past two decades calls for greater knowledge and awareness of the virus, its route of transmission, methods of diagnosis, and the use of available treatment and prevention measures.

Recent Findings

Chikungunya virus infection, an Aedes mosquito-borne febrile disease, has spread from Africa and Asia to Europe and the Americas and from the tropics and subtropics to temperate regions. International travel is a pivotal influence in the emergence of chikungunya as a global public health threat, as evidenced by a growing number of published reports on travel-related chikungunya infections. The striking features of chikungunya are arthralgia and arthritis, and the disease is often mistaken for dengue. Although mortality is low, morbidity can be profound and persistent. Current treatment for chikungunya is supportive; chikungunya vaccines and therapeutics are in development. Travelers planning to visit areas where the mosquito vectors are present should be advised on preventive measures.

Summary

Chikungunya is an emerging disease in the Americas. Frequent travel, the presence of at least two competent mosquito species, and a largely naïve human population in the Western Hemisphere create a setting conducive to future outbreaks. Awareness of the disease and its manifestations is critical to effectively and safely manage and limit its impact. Vaccines in late-stage clinical trials offer a new pathway to prevention.

Dengue, chikungunya and Zika in GeoSentinel surveillance of international travellers: a literature review from 1995 to 2020

INTRODUCTION

GeoSentinel is a global surveillance network of travel medicine providers seeing ill-returned travellers. Much of our knowledge on health problems and infectious encountered by international travellers has evolved as a result of GeoSentinel surveillance, providing geographic and temporal trends in morbidity among travellers while contributing to improved pre-travel advice. We set out to synthesize epidemiological information, clinical manifestations and time trends for dengue, chikungunya and Zika in travellers as captured by GeoSentinel.

METHODS

We conducted a systematic literature search in PubMed on international travellers who presented with dengue, chikungunya or Zika virus infections to GeoSentinel sites around the world from 1995 until 2020.

RESULTS

Of 107 GeoSentinel publications, 42 articles were related to dengue, chikungunya and/or Zika. The final analyses and synthesis of and results presented here are based on the findings from 27 original articles covering the three arboviral diseases.

CONCLUSIONS

Dengue is the most frequent arboviral disease encountered in travellers presenting to GeoSentinel sites, with increasing trends over the past two decades. In Southeast Asia, annual proportionate morbidity increased from 50 dengue cases per 1000 ill returned travellers in non-epidemic years to an average of 159 cases per 1000 travellers during epidemic years. The highest number of travellers with chikungunya virus infections was reported during the chikungunya outbreak in the Americas and the Caribbean in the years 2013-16. Zika was first reported by GeoSentinel already in 2012, but notifications peaked in the years 2016-17 reflecting the public health emergency in the Americas at the time.

[Disease spectrum among guests and staff of an international luxury beach resort in the tropics]

BACKGROUND

Diseases of travelers upon returning home are described in numerous publications. However, we have limited data on the disease spectrum and the reasons for medical consultations during a trip.

METHODS

Over the period of one year, we analyzed all patient visits to the inhouse medical center of a major 5‑star beach resort of an international chain in the Maldives.

RESULTS

Around 6% of all guests sought medical consultation at least once during their stay. The main reasons for consultation were sea water induced external otitis and-in some cases-severe (2nd degree) sunburn. Staff presented mainly with viral nasopharyngitis in 20%, whereby guests had symptoms of the common cold in only 7% of all consultations. The occurrence of gastroenteritis was similar in both groups and was associated in most cases with seawater but was much lower compared to the region's epidemiological data. A high incidence of allergic reactions (7%) was recognized in both groups, being more than doubled among guests compared to staff. A considerable number of complaints caused by insects and sea organisms as well as a few drowning accidents were recorded.

CONCLUSION

Despite the high international 5‑star standards, there is a considerable probability for a medical consultation during the stay in a tropical beach hotel setting. However, environmental and behavioral factors are the main causes of sickness among guests.

Two Cases of Dengue Virus Type 2 (DENV-2) Infection in a Japanese Couple Returning from the Maldives during the 2018 Dengue Outbreak

Annually, more than 1.2 million travelers from other countries visit the Maldives for sightseeing, business, and honeymoon. In 2018, the largest dengue fever outbreak occurred, affecting more than 3,200 people. During this outbreak, we encountered a newly married Japanese couple returning from the Maldives on their honeymoon in October 2018, both were infected by the dengue virus type 2 during the travel. The number of imported dengue fever cases from the Maldives may increase; hence, physicians should stay up to date on dengue outbreak information worldwide.

Culicoides Latreille in the sun: faunistic inventory of Culicoides species (Diptera: Ceratopogonidae) in Mayotte (Comoros Archipelago, Indian Ocean)

BACKGROUND

The south-west insular territories of the Indian Ocean have recently received attention concerning the diversity of arthropods of medical or veterinary interest. While a recent study highlighted the circulation of Culicoides-borne viruses, namely bluetongue and epizootic hemorrhagic disease, with clinical cases in Mayotte (comprising two islands, Petite-Terre and Grand-Terre), Comoros Archipelago, no data have been published concerning the species diversity of Culicoides present on the two islands.

RESULTS

A total of 194,734 biting midges were collected in 18 sites, covering two collection sessions (April and June) in Mayotte. Our study reports for the first time livestock-associated Culicoides species and recorded at least 17 described Afrotropical species and one undescribed species. The most abundant species during the April collection session were C. trifasciellus (84.1%), C. bolitinos (5.4%), C. enderleini (3.9%), C. leucostictus (3.3%) and C. rhizophorensis (2.1%). All other species including C. imicola represented less than 1% of the total collection. Abundance ranged between 126-78,842 females with a mean and median abundance of 14,338 and 5111 individuals/night/site, respectively. During the June collection, the abundance per night was low, ranging between 6-475 individuals. Despite low abundance, C. trifasciellus and C. bolitinos were still the most abundant species. Culicoides sp. #50 is recorded for the first time outside South Africa.

CONCLUSIONS

Our study reports for the first time the Culicoides species list for Mayotte, Comoros Archipelago, Indian Ocean. The low abundance and rare occurrence of C. imicola, which is usually considered the most abundant species in the Afrotropical region, is unexpected. The most abundant and frequent species is C. trifasciellus, which is not considered as a vector species so far, but its role needs further investigation. Further work is needed to describe Culicoides sp. #50 and to carry on faunistic investigations on the other islands of the archipelago as well as in neighboring countries.

No chikungunya virus infections among Dutch long-term travellers to (sub)tropical countries: a prospective study 2008-2011

Background

Chikungunya is an arthropod-borne viral disease now identified in over 60 countries in Asia, Africa, Europe, and the Americas. Chikungunya virus (CHIKV) has spread in the last 15 years to many countries, causing large local outbreaks. CHIKV infection can be clinically misdiagnosed in areas where dengue and/or Zika infections occur. Prospective studies are necessary to calculate the true incidence rate of CHIKV infection in travellers. The aim of this study was to obtain the attack and incidence rates of CHIKV infection among long-term travellers and identify associated risk factors.

Methods

A previously collected prospective cohort of Dutch long-term travellers (12–52 weeks) to subtropical and tropical countries was tested. From December 2008 to September 2011, participants were recruited at the travel clinic of the Public Health Service Amsterdam. A weekly diary was kept during travel in which participants recorded their itinerary, symptoms, and physician visits. On return, their pre- and post-travel blood samples were tested for the presence of IgG antibodies to CHIKV antigen. Seroconversions were confirmed by an in-house CHIKV neutralisation test.

Results

The median age of 603 participants was 25 years (interquartile range [IQR]: 23–29); 35.7% were male; median travel duration was 20 weeks (IQR: 15–25), and purpose of travel was predominantly tourism (62%).

The presence of anti-CHIKV IgG in the pre-travel sample, suggestive of previous CHIKV infection, was found for 3/603 participants (0.5%); all three had been previously travelling in either Africa or Asia. In one traveler who visited Latin America, a seroconversion was found (0.2%) but the CHIKV neutralisation test was negative, making the incidence rate 0.

Conclusion

No chikungunya virus infections were found in this 2008–2011 prospective cohort of long-term travellers. We recommend the research be repeated, particularly as the sample size of our cohort might have been too small. Also, extensive spread of chikungunya virus has likely increased incidence rates among travellers since 2013.

Economic analysis of dengue prevention and case management in the Maldives

As tourism is the mainstay of the Maldives' economy, this country recognizes the importance of controlling mosquito-borne diseases in an environmentally responsible manner. This study sought to estimate the economic costs of dengue in this Small Island Developing State of 417,492 residents. The authors reviewed relevant available documents on dengue epidemiology and conducted site visits and interviews with public health offices, health centers, referral hospitals, health insurers, and drug distribution organizations. An average of 1,543 symptomatic dengue cases was reported annually from 2011 through 2016. Intensive waste and water management on a resort island cost $1.60 per occupied room night. Local vector control programs on inhabited islands cost $35.93 for waste collection and $7.89 for household visits by community health workers per person per year. Ambulatory care for a dengue episode cost $49.87 at a health center, while inpatient episodes averaged $127.74 at a health center, $1,164.78 at a regional hospital, and $1,655.50 at a tertiary referral hospital. Overall, the cost of dengue illness in the Maldives in 2015 was $2,495,747 (0.06% of gross national income, GNI, or $6.10 per resident) plus $1,338,141 (0.03% of GNI or $3.27 per resident) for dengue surveillance. With tourism generating annual income of $898 and tax revenues of $119 per resident, results of an international analysis suggest that the risk of dengue lowers the country's gross annual income by $110 per resident (95% confidence interval $50 to $160) and its annual tax receipts by $14 per resident (95% confidence interval $7 to $22). Many innovative vector control efforts are affordable and could decrease future costs of dengue illness in the Maldives.

Status of imported malaria on Réunion Island in 2016

BACKGROUND

Autochthonous malaria has been eliminated from Réunion in 1979. To prevent secondary transmission and re-emergence of autochthonous malaria, permanent epidemiologic and entomological surveillance and vector control measures are conducted around imported malaria cases. Results of local malaria surveillance (clinical data and results of epidemiological and entomological investigations around cases) were collected for 2013-2016 and were analysed according to historical data and to the exchanges with malaria-affected areas (estimated by airport data).

RESULTS

Form 2013 to 2016, 95 imported malaria cases have been detected in Reunion Island: 42% of cases occurred in the area of repartition of Anopheles arabiensis, but Anopheles mosquitoes were present only around seven cases including one gametocyte carrier. No autochthonous or introduced case has occurred during this period. The lack of chemoprophylaxis or poor adherence was found in the majority (96%) of malaria cases between 2013 and 2016, regardless of trip type. Affinity tourism in Madagascar and Comoros was the cause of 65% of imported malaria cases.

DISCUSSION

The incidence of imported malaria and the incidence rate per 100,000 travellers has continuously decreased since 2001. Now with the drastic decrease of malaria transmission in the Comoros archipelago, most of imported malaria cases in Reunion Island have been contaminated in Madagascar. Immigrants regularly resident in Reunion Island, which travel to malaria endemic countries (mainly Madagascar) to visit their friends and relatives (VFRs) represent a high-risk group of contracting malaria. VFRs, low adherence to pre-travel recommendations, in particular, the compliance on the use of chemoprophylaxis are the main drivers of imported malaria in Reunion Island. Furthermore as previously described, some general practitioners in Reunion Island are always not sufficiently aware of the official recommendations for prescriptions of prophylactic treatments.

CONCLUSION

Social mobilization targeted on the Malagasy community in Reunion Island could help to decrease the burden of imported malaria in Reunion Island. Because of the low number of gametocyte carriers and the absence of an Anopheles mosquito population when most malaria cases were imported those last 4 years, the risk of the appearance of introduced malaria cases and indigenous malaria cases appears low in Reunion Island.

Surveillance of travel-associated diseases at two referral centres in Marseille, France: a 12-year survey

Background

With increasing international travel and historically high numbers of residents visiting friends and relatives overseas, travel-associated illnesses are frequent in Marseille, France. We report the changing epidemiology of travel-related illnesses over a 12-year period.

Methods

A single site GeoSentinel surveillance analysis was undertaken for 3460 ill returned travellers presenting to two public hospitals in Marseille, France from March 2003 to October 2015, with travel-related illnesses. Demographic characteristics, travel history, presenting symptoms and information on pre-travel consultations were collected.

Results

There was a predominance of travel to sub-Saharan Africa, in particular to Comoros archipelago. Tourism was the main reason for travel (1591/3460, 46%), followed by visiting friends or relatives (VFR) (895/3460, 26%), with a mean duration of 29 days; 35% (1212/3460) of travellers reported a pre-travel health consultation. The most common syndromic diagnoses were febrile systemic illness (1343, 39%), dermatologic (716, 21%), gastrointestinal (340, 10%) and respiratory/ear-nose-throat (331, ENT) (10%). Hospitalization rates were highest amongst travellers from sub-Saharan Africa (858/ 1632, 53%), and VFR (573/ 895, 64%, P < 0.001). Frequent diagnoses included malaria (797, 23%), dengue (96, 2.77%) and chikungunya (75, 2.17%), reflecting global trends. Comparison of two periods (2003-10 to 2011-15) demonstrated an increase in chikungunya and decrease in malaria and influenza-like illness. We report an increase in ill travellers from the Caribbean, Middle East and South-East Asia.

Conclusion

Surveillance of travellers provides relevant sentinel information on the changing epidemiology of infectious diseases across the globe, most notably for malaria, dengue and chikungunya. We demonstrate the use of travel surveillance in improving pre-travel consultation needs and to address autochthonous vector-borne viral risks.

Chikungunya Infection: a Global Public Health Menace

Chikungunya virus (CHIKV) has been involved in epidemics in African and Asian subcontinents and, of late, has transcended to affect the Americas. Aedes aegypti and Aedes albopictus are the major vectors for CHIKV infection, which results in dissemination of virus to various vital organs. Entry of virus into these tissues causes infiltration of innate immune cells, monocytes, macrophages, neutrophils, natural killer cells, and adaptive immune cells. Macrophages bearing the replicating virus, in turn, secrete pro-inflammatory cytokines IL-1β, TNF-α, and IL-17. Together, this pro-inflammatory milieu induces osteoclastogenesis, bone loss, and erosion. CHIKV is characterized by fever, headache, myalgia, rash, and symmetric polyarthritis, which is generally self-limiting. In a subset of cases, however, musculoskeletal symptoms may persist for up to 3-5 years. Viral culture and isolation from blood cells of infected patients are the gold standards for diagnosis of CHIKV. In routine practice, however, assays for anti-CHIKV IgM antibodies are used for diagnosis, as elevated levels in blood of infected patients are noted from 10 days following infection for up to 3-6 months. Early diagnosis of CHIKV is possible by nucleic acid detection techniques. Treatment of acute CHIKV is mainly symptomatic, with analgesics, non-steroidal anti-inflammatory agents (NSAIDs), and low-dose steroids. No vaccines or anti-viral medicines have been approved for clinical therapy in CHIKV as yet. Hydroxychloroquine and methotrexate have been used in chronic CHIKV infection with variable success.

Four years into the Indian ocean field epidemiology training programme

INTRODUCTION

Following the 2005-6 chikungunya outbreak, a project to strengthen regional Public Health preparedness in the Indian Ocean was implemented. It includes the Comoros, Madagascar, Mauritius, Reunion (France) and Seychelles. A Field Epidemiology Training Programme (FETP-OI) was started in 2011 to develop a pool of well-trained intervention epidemiologists.

METHODS

The FETP-OI consists of two years of supervised, learning-by-doing, on-the-job training at national sites involved in disease surveillance and response. It includes work placements at the Madagascar Pasteur Institute and the French regional epidemiology unit in Reunion and up to three training courses per year. Training objectives include epidemiological surveillance, outbreak investigations, research studies, scientific communication and transfer of competencies.

RESULTS

In four years, two cohorts of in total 15 fellows originating from four countries followed the FETP-OI. They led 42 surveillance projects (71% routine management, 14% evaluations, 12% setup, 3% other) and investigated 36 outbreak alerts, 58% of them in Madagascar; most investigations (72%) concerned foodborne pathogens, plague or malaria. Fellows performed 18 studies (44% descriptive analyses, 22% disease risk factors, and 34% on other subjects), and presented results during regional and international conferences through 26 oral and 15 poster presentations. Four articles were published in regional Public Health bulletins and several scientific manuscripts are in process.

CONCLUSION

The FETP-OI has created a regional force of intervention consisting of field epidemiologists and trained supervisors using the same technical language and epidemiological methods. The third cohort is now ongoing. Technically and financially sustainable FETP-OI projects help addressing public health priorities of the Indian Ocean.

Travelers' health problems and behavior: prospective study with post-travel follow-up

Background

The annual number of international tourist arrivals has recently exceeded one billion, yet surprisingly few studies have characterized travelers’ behavior, illness, and risk factors in a prospective setting. Particularly scarce are surveys of data spanning travel, return, and follow-up of the same cohort.

This study examines behavior and illness among travelers while abroad, after return home, and at follow-up. Patterns of behavior connected to type of travel and illness are characterized so as to identify risk factors and provide background data for pre-travel advice.

Methods

Volunteers to this prospective cohort study were recruited at visits to a travel clinic prior to departure. Data on the subjects’ health and behavior were collected by questionnaires before and after journeys and over a three-week follow-up. In addition, the subjects were asked to fill in health diaries while traveling.

Results

The final study population consisted of 460 subjects, 79 % of whom reported illness during travel or on arrival: 69 % had travelers’ diarrhea (TD), 17 % skin problems, 17 % fever, 12 % vomiting, 8 % respiratory tract infection, 4 % urinary tract infection, 2 % ear infection, 4 % gastrointestinal complaints other than TD or vomiting, and 4 % other symptoms. Of all subjects, 10 % consulted a doctor and 0.7 % were hospitalized; 18 % took antimicrobials, with TD as the most common indication (64 %). Ongoing symptoms were reported by 25 % of all travelers upon return home.

During the three-week follow-up (return rate 51 %), 32 % of respondents developed new-onset symptoms, 20 % visited a doctor and 1.7 % were hospitalized.

Factors predisposing to health problems were identified by multivariable analysis: certain regions (Southern Asia, South-Eastern Asia, and Eastern Africa), female gender, young age, and long travel duration.

Conclusions

Despite proper preventive measures like vaccinations, malaria prophylaxis, and travel advice, the majority of our subjects fell ill during or after travel. As the symptoms mostly remained mild, health care services were seldom needed. Typical traveler profiles were identified, thereby providing a tool for pre-travel advice. The finding that one third reported new-onset illness during follow-up attests to the importance of advising clients on potential post-travel health problems already during pre-travel visits.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1682-0) contains supplementary material, which is available to authorized users.

Epidemiology of 62 patients admitted to the intensive care unit after returning from Madagascar

BACKGROUND

To our knowledge, there is no data on the epidemiology of patients hospitalized in intensive care unit (ICU) after a stay in Madagascar or other low-income countries. It is possible that such data may improve transfer delays and care quality for these patients.

METHODS

In a retrospective study, we reviewed the charts of all patients admitted to ICU of the Reunion Island Felix Guyon University Hospital from January 2011 through July 2013. We identified all patients who had stayed in Madagascar during the 6 months prior to ICU admission.

RESULTS

Of 1842 ICU patients, 62 (3.4%) had stayed in Madagascar during the 6 months prior to ICU admission. Patients were 76% male and the median age was 60.5 (48.25-64.75) years; patients were more frequently residents of Madagascar than travellers (56.5%). In most cases, patients were not hospitalized or given antibiotics in Madagascar. The most frequent causes of hospitalization were infections including malaria (21%) and lower respiratory infection (11%). Carriage and infection with multidrug resistant (MDR) bacteria on ICU admission were frequent (37% and 9.7%, respectively). The mortality rate in ICU was 21%, and severity acute physiological Score II was 53.5 (37-68).

CONCLUSIONS

Patients admitted to ICU after a stay to Madagascar are mainly elderly patients with chronic illnesses, and often foreign residents. The admission causes are specific of the country like malaria, or specific to the population concerned such as cardiovascular accidents that could be prevented.

An update on travelers' diarrhea

PURPOSE OF REVIEW

Travelers' diarrhea, affecting millions of travelers every year globally, continues to be a leading cause of morbidity despite advances in vaccination, prevention, and treatment. Complications of travelers' diarrhea often present to gastroenterologists and some patients followed by gastroenterologists are at higher risk of developing travelers' diarrhea. This review will provide an update on recent progress made in the epidemiology, pathogenesis, diagnosis, prevention, and treatment of travelers' diarrhea.

RECENT FINDINGS

Most causes of travelers' diarrhea remain bacterial, but newly recognized pathogens are emerging. Patient-related and travel-related factors affect disease development risk and should guide prophylaxis and treatment. Although specific vaccines are being developed, they have not yet had a major impact on travelers' diarrhea, and understanding their roles and limitations is especially important. Prophylaxis and treatment of populations at risk (children, chronically ill patients, and those on immunosuppressive medications) remain challenging and require a tailored approach.

SUMMARY

Travelers' diarrhea will continue to challenge patients and physicians despite the use of sanitation advice, prophylactic vaccines, and treatment with antibiotics. Effects may extend beyond the time of travel, such as postinfectious complications and exacerbation of preexisting disease. Future research should focus on novel strategies for reducing exposure to pathogens, vaccine development, early detection, and targeted treatments.

Single-Stranded RNA Viruses

In this chapter, we describe 73 zoonotic viruses that were isolated in Northern Eurasia and that belong to the different families of viruses with a single-stranded RNA (ssRNA) genome. The family includes viruses with a segmented negative-sense ssRNA genome (families Bunyaviridae and Orthomyxoviridae) and viruses with a positive-sense ssRNA genome (families Togaviridae and Flaviviridae). Among them are viruses associated with sporadic cases or outbreaks of human disease, such as hemorrhagic fever with renal syndrome (viruses of the genus Hantavirus), Crimean–Congo hemorrhagic fever (CCHFV, Nairovirus), California encephalitis (INKV, TAHV, and KHATV; Orthobunyavirus), sandfly fever (SFCV and SFNV, Phlebovirus), Tick-borne encephalitis (TBEV, Flavivirus), Omsk hemorrhagic fever (OHFV, Flavivirus), West Nile fever (WNV, Flavivirus), Sindbis fever (SINV, Alphavirus) Chikungunya fever (CHIKV, Alphavirus) and others. Other viruses described in the chapter can cause epizootics in wild or domestic animals: Geta virus (GETV, Alphavirus), Influenza A virus (Influenzavirus A), Bhanja virus (BHAV, Phlebovirus) and more. The chapter also discusses both ecological peculiarities that promote the circulation of these viruses in natural foci and factors influencing the occurrence of epidemic and epizootic outbreaks