Epidemiology and surveillance of travel-related diseases
From being handled as a mere interest of practitioners, go back and forth medication has developed into a major clinical self-discipline. Counselling on this container can draw on a rising wealth of proof. Research on more than a few shuttle well being dangers have accelerated previously few years: whereas PubMed listing handiest 447 entries for ‘Trip medication’ within the years 1980-89, 961 are listed fori990-ninety nine, and three,588 for the time from 2000 to November 2009 , It used to be regarded relatively early on that native illness knowledge from shuttle locations was once no longer adequate for assessing commute-related well being dangers. Go back and forthlers behave another way to inhabitants of travelled areas and accordingly are likely to produce other well being dangers. An growing sequence of research aimed instantly on the quite a lot of populations of travelers are being carried out and are yielding data that has already modified go back and forth drugs follow profoundly. As a substitute of assessing well being dangers via deducting from data received from different populations, well being experts can now draw on outcomes from research which might be involved right away with the traveller.
They’re assisted more and more by means of networks that acquire and supply up to date data. In the UK, the Nationwide Trip Well being Community and Centre (NaTHNaC) has been namely created by means of the federal government to advertise scientific requirements in shuttle medication with the intention of‘defending the well being of the British traveller’ , Whereas surveillance of infectious illnesses has a protracted historical past, surveillance of imported illnesses in travelers has began comparatively lately. Most techniques are in line with nationwide notification schemes which might be prognosis-oriented. These standard surveillance programmes mostly rely on reporting to after which with the aid of public well being departments and laboratories. Direct contact with the traveller by using the particular person doing the reporting is an exception. Nationwide methods of infectious illnesses surveillance normally focal point on full protection. The prospective benefit of this way is that no circumstances are overpassed. In fact, on the other hand, compliance with notification rules could be very restricted. Estimated protection charges at or beneath 50% are the norm moderately than the exception. The shortage of motivation amongst these requested via legislation to record is without doubt one of the main stumbling factors for conventional surveillance techniques.
Along with methods aiming at full protection, more and more nationwide and global sentinel networks are being centered. Using sentinel web sites has the downside that full protection can’t be carried out. Then again, a prudent collection of individuals can be sure that a sentinel community produces consultant knowledge. On the whole, sentinel networks encompass voluntary individuals who’re extra serious about surveillance. Hence, data glide is steadily sooner than in methods which are aiming at complete protection. Examples for this are multinational networks comparable to FluNet, the WHO world influenza community  and the European Legionellosis Surveillance Scheme (ELSS) ,
Elevated consciousness of rising infectious ailments has fostered the introduction of syndrome-primarily based surveillance webworks. They work nearly solely in sentinel settings. Not like conventional notification techniques, their goal is to not acquire data on pre-outlined analysis. This sort of community moderately tries to assemble open, presumably even nonstandardised data with the intention to observe new outbreaks and rising pathogens inside a short while. Presumably probably the most formidable challenge of this kind is the United States Division of Defence World Rising Infections gadget (DoD-GEIS)  . Medical sentinel networks signify every other broadening of typical surveillance programmes. The pricey advantage of those techniques is that the individuals reporting the requested knowledge have viewed the visitors themselves and may relay first-hand knowledge. A couple of supplier-primarily based sentinel networks had been carried out throughout up to date years, specifically in the United States, as a part of a nationwide response plan towards rising infectious illnesses [6,7]. The primary sentinel surveillance effort focusing explicitly on guests was once Geosentinel, with the aid of design a worldwide community that makes an attempt to seize rising infectious ailments .
The dearth of surveillance information for imported infectious diseases in Europe brought about the inspiration of the European Community on Imported Infectious Illness Surveillance (Trop- NetEurop), which specializes in the surveillance of imported ailments in guests . This can be a clinician-primarily based sentinel community The community is designed to successfully discover emerging infections of attainable regional, nationwide or world impression at their level of entry into the home inhabitants. Sentinel surveillance reporting is conducted by means of taking part websites the use of a standardised and computerised reporting machine. Fast transmission of anonymised traveller and laboratory information to the critical database assures well timed detection of sentinel situations. Membership is voluntary and self-chosen by using taking part centres and monitored via the guidance committee of the community. Despite the fact that the service provider of the community does now not assure a consultant information assortment for Europe, most main referral centres of the continent are represented. Inside an extraordinarily quick time, it has grown to fifty eight individuals in 17 international locations, which signify nearly all of centres of excellence for imported infections on the continent. Community participants oversee roughly fifty seven,000 travellers yearly, making it the biggest infectious illness sentinel community international. Even though specializing in analysis- based totally reporting on the forefront, TropNetEurop is actively encouraging reporting of sudden occasions and syndromes. As shall be mentioned, the community has been very a hit in detecting outbreaks of rising ailments previously and has therefore confirmed its price as an extra surveillance device ,
As a minimum for giant referral centres, reporting of all guests viewed through a sentinel web page is obviously an awesome activity if no longer supported financially. As a result, TropNetEurop setded on common reporting of best three illness entities: malaria, dengue fever and schistosomiasis. Focusing on this very restricted quantity of stories eased the hassle for all member web sites whereas nonetheless protecting a gradual waft of experiences that offer precious data in month-to-month bulletins which might be mailed to all contributors and, in abbreviated kind, to different well being experts outdoor the community .
Outcomes following the gathering of studies of malaria confirmed that, relying on the regional influence of immigrants and the quantity of commute within the native inhabitants, information from nationwide sources in Europe can also be closely skewed in opposition to one or the opposite staff [ 10]. Judging from the info supplied by way of nationwide programs of illness notification, TropNetEurop covers roughly 10% of all malaria travelers viewed in Europe [10, 11]. Assessment of the said information on falciparum malaria confirmed that West Africa contributed with the aid of a ways essentially the most malaria guests to TropNetEurop websites: sixty eight.2% of all immiprovides and fifty eight.eight% of Europeans had been contaminated there . Fairly fewer immigrants and extra vacationers have been contaminated in East and Southern Africa. Studies from the World Tourism Company express that simplest zero.6-2.four% of European triplers to doubtlessly malarious areas selected West Africa as a vacation spot [ 12,13]. This implies a relatively excessive relative chance of buying falciparum malaria in West Africa. When compared, WTO stories that sixteen-21% of guests from the identical collective visited Southeast Asia. As simplest only a few travelers with falciparum malaria have been suggested from this house, the relative possibility seems to be very low. These findings are similar to earlier research from more than a few nonendemic international locations [14—16]. Most effective a minority of visitors with falciparum malaria took prophylaxis or mixture prophylaxis acceptable to the drug resistance state of affairs of malaria on the respective vacation spot . It’s possible that a excessive share of the malaria circumstances mentioned may have been evaded through taking the suitable malaria prophylaxis routine. Data like this will also be utilized when giving well being recommendation to guests.
The direction of sickness with falciparum malaria tends to be milder in immigrants when put next with Caucasians, even though on hand information aren’t enough to indicate expensive variations. Numerous visitors of the previous staff had been semi-immune inhabitants of malarious areas, whereas European guests had been all non-immune. It’s striking, then again, that three.7% of immigrants developed problems all the way through their medical sickness. Whereas this share is decrease than in European travelers (6.three%), some immigrants had been significantly unwell when providing on the reporting centres. Immisupplies who plan to seek advice from their house us of a after a couple of years could have handiest a restricted notion of the trip well being dangers and essential prophylactic measures as a way to deal with their trip well being wants. It is a staff that’s underrepresented in go back and forth clinics and must be sought actively. Most likely shocking in the beginning, a gaggle that seems to have the next- than-moderate chance for problems with falciparum malaria are industry visitors. Judging from the reviews to TropNe- tEurop, this crew are likely to are trying to find pre-trip counselling much less regularly, to practice recommendation much less reliably and, if symptomatic, to are seeking for scientific lend a hand later than different travelers.
|Table 1 Indicators and signs in Europeans and Immigrants with falciparum malaria , used with permission from Oxford College Press|
|Symptom||(n = 790)||(n = 869)|
|Fever||603 (seventy six.three%)||
704 (eighty one%)
|Headache||388 (forty nine.1%)||
432 (forty nine.7%)
|Myalgia, arthralgia||136 (17.2%)||
seventy seven (9.7%)
ninety six (12.2%)
|Pores and skin affections||
fifty six (7.1%)
|Different||157 (19.9%)||153 (17.6%)|
forty nine (6.2%)
|More than one entries imaginable.|
Whereas analysing falciparum malaria in visitors, it used to be proven conclusively that growing age is a chance issue for extreme falciparum malaria in non-immune guests . Altogether, 1,181 non-immune travelers with falciparum malaria met the learn about’s inclusion standards. Outcomes from adjusted analyses, controlling for possible confounding, confirmed that the danger of demise from falciparum malaria (OR 1.eighty five, CL95% 1.30-2.sixty two), experiencing cerebral malaria (OR 1.sixty six, CL95% 1.31-2.12) or extreme illness on the whole (OR 32, CL95% 1.14—1.fifty three) or being hospitalised (OR 1.21, CL95% 1.06-1.39) elevated considerably per decade of existence. Evaluating aged (60 years and older) travelers with youthful travelers confirmed that case fatality was once nearly 6 occasions larger amongst aged guests (OR 5.seventy four, CL95% seventy eight-18.forty seven). Cerebral issues came about thrice extra incessantly (OR three.29, CL95% 1.20-9.01). Antimalarial chemoprophylaxis used to be considerably related to decrease case fatality (OR zero.17, CL95% zero.04—zero.seventy four) and not more generic cerebral problems (OR zero.forty four, CL95% zero.20-zero.ninety six). The learn about supplied proof that falciparum malaria is extra critical in older travelers, and proven that medical surveillance networks are in a position to offering high quality information for investigating uncommon occasions or ailments.
Prognosis of the information on dengue fever in guests confirmed that almost all had been Europeans who travelled for vacationer causes , Asia contributed essentially the most dengue visitors to TropNetEurop web sites: 23.three% visited Southeast Asia, 22.9% the Indian subcontinent and 6.5% Indonesia. Numbers have been quite decrease for the Americas, which contributed a complete of 38.2% of all visitors. One case used to be stated in a traveller who had lower back from Hawaii in 2000, heralding the later outbreak of dengue fever on Maui . Stories from the World Tourism Group exhibit that sixteen-21% of European guests travelled to Southeast Asia and simplest 6-eight% to India [12,13]. This means a excessive relative possibility of buying dengue fever within the latter area, whereas numbers from Southeast Asia seem to mirror the excessive collection of vacationers to that space. The low selection of infections that have been bought in Africa is in line with all earlier epidemiological information [21-29], Importation of dengue fever into Europe presentations a seasonal sample that in all probability displays the go back and forth habits of European vacationers quite than genuine diversifications in illness job.
The early years of reporting to TropNetEurop noticed a gentle annual raise within the complete collection of said instances of dengue per 12 months. This reached a height in 2005 and a moderate decline has been seen considering then. Modifications within the native
task of dengue had been really extensive: the percentage of instances in visitors arriving from Southeast Asia elevated from 29% in 1999 to sixty six.1% in 2002 and reduced once more to forty three.2% in 2008. A identical tendency used to be seen in case experiences from India (14.5% in 1999 to 21.1% in 2001 and 9% in 2008), whereas case reviews from the Americas reduced. This may increasingly mirror adjustments in go back and forth patterns, however stories from the World Tourism Group don’t indicate main shifts within the commute actions of Europeans far from the Americas and against Asia [12, 13]. Extra possible, these numbers replicate the task of dengue within the areas which are visited by means of European visitors. To that end, a rise of case experiences in visitors who’ve again from a pandemic house can function an early indicator for elevated illness process. Signs usually related to dengue, similar to fever, myalgia, arthralgia and exanthema, can also be useful in making the analysis when existing, however lacking standard signs does no longer exclude an infection. Most dengue instances on this workforce have been symptomatic they usually presented with fever and headache in addition to different signs together with myalgias, fatigue, pores and skin issues (exanthema) and diarrhoea.
|Table 2 Age-particular frequency of results of extreme falciparum malaria , used with permission from Oxford College Press|
|Age workforce||Choice of visitors||Deadly circumstances||Cerebral issues (B50.zero)||Different problems (B50.eight)||Clinic admissions*|
|forty-forty nine years||
|50-fifty nine years||
|60-sixty nine years||
|70-seventy nine years||
|*Lacking values in 39 instances.|
As proven above, sentinel surveillance in travelers is hampered by way of the shortage of authentic denominator knowledge. It is vitally difficult, if no longer unattainable, to acquire dependable estimates relating to the go back and forth actions of the inhabitants contributing to this information. This downside is elevated through the contribution of asylum seekers and refugees coming from different international locations into the realm the place surveillance is being based. To that end, a lot of guests returning with falciparum malaria from West Africa may just most effective mirror elevated go back and forth job to that house and no longer an elevated chance for an infection. Medical sentinels are in a position to realize illness importation from international locations the place this regularly does no longer happen. Then again, their potential to realize elevated dangers of an infection in endemic international locations may be very restricted. It’s because importation of tropical ailments just isn’t a familiar experience and the collection of attainable nations with an infection is big, in order that even massive scientific devices regularly examine too few instances of illness importation from single international locations to be alerted to a rise in an infection. For instance, if a unit on the root of a month-to-month moderate observes one case of malaria importation from a virulent disease united states of america, even a doubling of infections from that u . s . won’t lift suspicion, as a result of small numbers are topic to huge probability version. Detection of not likely notification will increase from single endemic international locations requires a minimal choice of circumstances. For tropical ailments, that is simplest possible when combining surveillance knowledge from a few sentinel devices.
As a community of scientific web sites which might be additionally liable for pre-trip counselling, TropNetEurop has a powerful pastime in detecting elevated dangers of an infection in vacationer nations immediately. Due to this fact pooled TropNetEurop surveillance information are screened for sudden notification will increase at month-to-month intervals. As knowledge from imported illness surveillance lack a real denominator, surprising notification will increase is also because of elevated transmission charges, modifications in trip or migration patterns, or altered notification behaviour, e.g. induced via outbreak rumours. For that reason, surprising will increase are no doubt no proof of an elevated chance of an infection in vacationer international locations, however quite will have to be interpreted as a warning sign to center of attention consideration on any vital observations that must set off additional investigation. Seeing that additional investigations are time-ingesting, a priori exclusion of non-vital alerts saves instruments and improves vigilance. That is particularly necessary when illness importation from a couple of dozen possible international locations of an infection is being monitored, and when consideration must be centered to be able to forestall the related findings being drowned with the aid of the multitude of knowledge.
To monitor TropNetEurop information for sudden notification will increase, a instrument software used to be developed for watching latest case numbers and evaluating these with numbers from previous reference sessions. Poisson possibilities, expressing the chance of detecting as many because the just lately noticed instances or extra when put next with the anticipated choice of instances from the previous, are calculated for every usa and introduced in tables and maps. On the maps, ranges of significance are indicated via totally different coloration. To account for the more than one-checking out state of affairs, observations are thought to be not going if the Poisson chance is decrease than zero.001.
An instance of the described screening method given in Determine 6.1 evidently demonstrates the screening outcomes from spring 2002 that brought on the detection of a scourge of dengue fever amongst vacationers in Thailand. Altogether, 37.5% of the dengue infections noticed inside a length of 6 months have been imported from Thailand. When compared with the identical length the earlier yr when the united states accounted for most effective 1% of the circumstances, the up to date statement was once not likely and subsequently could have heralded a real elevate in possibility. Additional indicators have been bought from the Cote d’Ivoire and a few Imperative American and Caribbean international locations. Alternatively, these indicators had been resulting from single case observations that might no longer be thought to be since the nations had no longer contributed circumstances to the database within the earlier reference length.
Detection of sentinel situations
TropNetEurop has tested on a number of events that delicate detection of sentinel occasions in visitors can result in outbreak detection.
Falciparum malaria within the Dominican Republic 
Like most nations within the Caribbean, huge components of the Dominican Republic are regarded as as low-possibility areas for falciparum malaria [31 ]. Generally, best border areas with Haiti and provinces within the north-west of the u . s . a . had been related to endemicity. This sample used to be reversed a couple of years in the past: beginning with an index case in June 1999,12 further European visitors introduced with falciparum malaria got within the Dominican Republic all through the length from November 1999 to February 2000. The visitors have been recognized and mentioned inside TropNetEurop. The guests have been all on package deal excursions to the Dominican Republic; two had been Spanish, one used to be Austrian and the remaining had been German nationals. All guests had travelled to Punta Cana, a city positioned on the japanese tip of the Dominican Republic, or local seashore hotels. This space had no longer been recognized as being malarious, and according to virtually all European suggestions at the moment, not one of the guests took malaria chemoprophylaxis. In a similar way, malaria publish-publicity prophylaxis was once now not adminsitered. Inside 1-2 weeks of coming back from their trip, visitors offered to their common practitioner or at emergency departments with fever, and had been admitted after prognosis of falciparum malaria was oncedependent. Drug therapy proved a hit in all guests and the medicalpathwas once uneventful.
The clustering of instances right through a relatively quick time seemed to point out a metamorphosis within the epidemiological situation and would possibly herald additional outbreaks amongst vacationers all the way through future commute seasons. In line with knowledge from the Malaria Division within the Dominican Republic, there had been a rise in malaria in 1999 following storm George with three,003 instances mentioned as much as 20 November, a rise over the two,000 circumstances for the entire of 1998. Within the east of the u . s ., a scourge of falciparum malaria among the many native inhabitants was once stated and traced again to constructing actions on behalf of the vacationer business. Right here, Haitian builders have been introduced in and a few of them imported P. falciparum lines. With anopheline vectors existing and plentiful breeding web sites in that space, transmission of falciparum malaria was once technically straightforward , No reviews had been bought of infections amongst vacationers from different international locations, particularly america, Canada and the UK. This will likely mirror a distinct use of malaria chemoprophylaxis or publicity prophylaxis for shuttle to the Dominican Republic. The dialogue of the index case among the many member web sites of TropNetEurop brought on elevated consciousness throughout the community and ended in the reporting of different circumstances inside days of presentation in visitors who may in any other case have long past overlooked seeing that they introduced at completely different hospitals far and wide Europe.
African trypanosomiasis from Tanzania 
African trypanosomiasis (napping illness) is a extreme professionaltozoan an infection (Trypanosoma brucei), on a regular basis unfold from contaminated animals and people via the tsetse fly. Even though the World Well being Group is reporting a rise in its incidence in Africa, African trypanosomiasis has remained a uncommon, however smartly-documented result in of fever in guests returning from endemic areas. Steered, acceptable remedy has resulted in beneficial effects for a lot of guests in Europe. Sport parks in Tanzania have lengthy been thought to be to be low-possibility areas for African trypanosomiasis , Alternatively, in February 2001, two index instances, adopted by means of a further six European instances and one South African, presented with trypanosomiasis . The guests had been identified and suggested inside TropNetEurop. All of the visitors had travelled to the Tarangire and Serengeti Nationwide Parks. This space has been recognized as being endemic for African trypanosomiasis; on the other hand, case incidence amongst Tanzanian and overseas nationals has been quite low up to now few many years.
All through their experience or in brief after their return, guests introduced with fever at their basic practitioner or emergency departments. Prognosis was once dependent by way of skinny and thick blood movie and even supposing explicit medicine was once difficult to acquire, drug therapy proved a hit in all however one traveller, even if three travelers introduced with multi-organ failure. The temporal clustering of imported circumstances steered a metamorphosis within the native epidemiology and may have heralded future instances in vacationers right through the commute season. The response of the Tanzanian authorities upon being knowledgeable, concerned strengthening of the set up of insecticide impregnated pursuits in Serengeti round roads, inns, workforce quarters and campsites. The impact of this preliminary programme was once a dramatic decline in tsetse flies within the Serengeti all over the 2d half of of 2001. Medication for remedy of African trypanosomiasis have been extraordinarily tough to acquire, and in one of the most European visitors remedy with suramin was once most effective that you can imagine after casual lend a hand from member web sites of the community
Falciparum malaria in unlawful Chinese language immigrants 
Between November 2002 and March 2003, 17 instances of malaria amongst unlawful Chinese language immigrants had been noticed in seven hospitals in important and northerly Italy (15 circumstances of Plasmodium falciparum, one case of P. malariae and one combined an infection P. faldparum/P. malariae); one traveller died. Previous to 2000, P. falciparum malaria had now not been suggested in Chinese language immigrants, regardless of many heaps dwelling in Italy and different elements of Europe . Even though malaria remains to be endemic in elements of China, principally at a low degree of transmission , the key species is the benign pressure of malaria, P. vivax. P. falciparum transmission is confined to provinces bordering Lao PDR and Vietnam. All travellers mentioned a keep various from some days to a couple of months (three to 9) in an African u . s . a . all over their trip to Europe. Some had already fallen sick whereas in Africa. Others had reportedly died from ‘fever’ earlier than achieving Europe. Malaria in Chinese language immigrants highlighted a brand new route being utilized by merchants of‘human cargo’, which bypassed the standard route thru Important Asia and Jap Europe. A single u . s ., Cote d’Ivoire, was once the transit united states for just about all travelers. The clustering of circumstances, regardless of variable time in transit, means that the unlawful immigrants arrive in Europe in teams when the entry prerequisites are extra beneficial. Even if Italy was once the ultimate vacation spot, as a minimum some entered thru France, which additionally stated circumstances of P. falciparum in Chinese language immigrants (Legros F, Centre Nationwide de Reference de PEpid£miologie du Paludisme, France, Non-public verbal exchange).
Falciparum malaria in travelers to Gambia
Right through summer time and autumn 2008, inns in Gambia have been overtly marketed in a number of European nations as malaria- free locations. All over the comparatively brief period of time of two and a 1/2 months between September and November 2008, TropNetEurop member web sites mentioned fifty six guests arriving from Gambia with falciparum malaria. Thirty-two of them have been male and 24 feminine. The age vary was once 15 to seventy one years. Whereas the explanations for shuttle had been rather numerous, a putting lack of efficient prophylactic measures used to be obvious in all. Forty-5 guests had now not used any malaria chemoprohylaxis. All seven travelers who indicated that they’d taken prophylactic medicine used insufficient or people who have been completely mistaken; two took homeopathic prophylaxis, three used chloroquine most effective, one used paludrine best, and one stopped taking atovaquone/proguanil too early. For that reason, regardless of the documented chance of difficult an infection with falciparum malaria happening in travelers arriving from the Gambia, just about all visitors selected to make use of no or insufficient prophylaxis. Knowledge on these instances used to be printed in no time  and in consequence the tips insurance policies of trip companies promoting vacations in Ghana have been challenged and sooner or later reversed.
When the usage of all its advantages of scientific vigilance, direct verbal exchange and quick remarks, a medical surveillance community will also be remarkably efficient in detecting sentinel situations and in translating the brand new data into modifications of medical observe. Travelers may also be very helpful when ‘serving’ as surveillance instruments for imported ailments. They trip broadly and doubtlessly expose themselves to all forms of infectious ailments, they’re very cellular, and so they return throughout the incubation length of most ailments to a clinical device that’s in a position to reaching quick and definitive diagnosis. Clustering of infections in returning travelers can be utilized right away to warn outbound guests of a specific possibility and to extend their safety. As well as, guests might also function ‘canary birds’ for illness outbreaks in developing international locations that would possibly now not have the ability to present services for fast analysis. For that reason, data derived from returning visitors will also be valuable for the host us of a if channelled again to the clinical authorities. TropNetEurop screening for will increase in surprising notifications has proved to be a delicate early warning instrument for the detection of elevated transmission charges in endemic nations.
One day, it’s hoped that conventional surveillance programs and just lately presented networks will be capable of cooperate extra totally. All programs have strengths and vulnerablenesses and may acquire from data supplied by means of every different. Therefore, linkage of present networks that might keep away from duplication of labor and absolutely make the most the tips potential of all mixed programs must be inspired.
1. PubMed (2009) http://www.ncbi.nlm.nih.gov/entrez/ (accessed 29 November 2009).
2. NaTHNac (2009) http://www.nathnac.org/ (accessed 29 November 2009).
3. FluNet (2009) http://gamapserver.who.int/GlobalAtlas/home.asp (accessed 29 November 2009).
4. EWGLI (2009) http://www.ewgli.oig/ (accessed 29 November 2009).
5. DoDGeis (2009) http://www.geis.fhp.osd.mil/aboutGEIS.asp (accessed 29 November 2009).
6. Talan D et al. (1998) EMERGEncy ID NET: an emergency department-based emerging infections sentinel network. Ann Emerg Med 32: 703-711.
7. Freedmann D etal. (1999) GeoSentinel: the global emerging infec¬tions sentinel network of the international society of travel medi¬cine. J Travel Med 6: 94-98.
8. TropNetEurop (2009) http://www.tropnet.eu (accessed 29 Novem¬ber 2009).
9. Jelinek T et al. (2000) European network on imported infectious disease surveillance (TropNetEurop). Eur Qual Assur News 11: 170-172.
10. Jelinek T et al. (2002) Clinical and epidemiological characteristics among travellers and immigrants with imported falciparum malaria in Europe: sentinel surveillance data from TropNetEurop. Clin Infect Dis 34: 572-576.
11. Anonymous (1998) Surveillance of malaria in European Union countries. Eurosurveillance 3: 45-47.
12. Anonymous (1999) Yearbook of Tourism Statistics: World Tourism Organization. World Health Organization, Madrid.
13. World Tourism Barometer (2009), http://www.unwto.org/facts/ eng/barometer.htm (accessed 19 September 2012).
14. Jelinek T etal. (1994) Malaria in non-immune travelers: a synopsis of history, symptoms and treatment in 160 patient. J Travel Med 1: 199-202.
15. Matteelli A etal. (1999) Epidemiological features and case manage¬ment practices of imported malaria in northern Italy 1991-1995. Trop Med Int Health 4: 653-657.
16. Nuesch R et al. (2000) Hospital admissions for malaria in Basel, Switzerland: an epidemiological review of 150 cases. J Travel Med 7: 95-97.
17. Anonymous (2003) International Travel and Health Geneva: World Health Organization. World Health Organization, Madrid.
18. Muhlberger N etal. (2003) Age as a risk factor for severe manifesta¬tions of falciparum malaria in non-immune patients – observa¬tions from TropNetEurop- and SIMPID-surveillance data. Clin Infect Dis 36: 990-995.
19. Jelinek T et al. (2002) Imported dengue fever in Europe: sentinel surveillance data from TropNetEurop. Clin Infect Dis 35: 1047¬1052.
20. Anonymous (2001) Dengue – USA (Hawaii), http://www. promedmail.org/20010922.2296 (accessed 29 November 2009). ed: ProMED-mail.
21. Lange WR et al. (1992) Dengue fever: a resurgent risk for the inter-national traveler. Am Fam Physician 45: 1161-1168.
22. Melissant CF and Kauffinann RH (1992) Infection with Dengue virus. Neth J Med 41: 272-274.
23. Wittesjo B et al. (1993) Dengue fever among Swedish tourists. Scand J Infect Dis 25: 699-704.
24. Chippaux A and Poveda JD (1993) Imported dengue in France (1989-1993). Conditions to be met for assuring an accurate etio¬logical diagnosis. Bull Soc Pathol Exot 86: 402-405.
25. Hasler C etal. (1993) Imported dengue fever following a stay in the tropics. Schweiz Med Wochenschr 123: 120-124.
26. Pick N and Potasman I (1995) Dengue fever. Harefuah 129: 30-32.
27. Anonymous (1994) Imported dengue – United States, 1992. MMWR Morb Mortal Wkly Rep 43: 97-99.
28. Anonymous (1992) Imported dengue – United States, 1991. MMWR Morb Mortal Wkly Rep 41: 731-732.
29. Anonymous (1995) Imported dengue – United States, 1993-1994. MMWR Morb Mortal Wkly Rep 44: 353-356.
30. Jelinek T et al. (2000) Emergence of Falciparum malaria among European tourists to the Dominican Republic. Emerg Infect Dis 6: 537-538.
31. Anonymous (1997) Malaria in the Americas, 1996. Epidemiol Bull 18: 1-8.
32. Castellanos P (1999) Malaria, imported – Europe ex Dominican Rep.(03): ProMED.
33. Jelinek T et al. (2002) Cluster of African trypanosomiasis among travellers to the Serengeti. Emerg Infect Dis 8: 634-635.
34. Ponce de Leon S et al. (1996) Trypanosoma brucei rhodesiense infection imported to Mexico from a tourist in Kenya. Clin Infect Dis 23: 847-848.
35. Ripamonti D et al. (2002) African sleeping sickness in tourists returning from Tanzania: the first 2 Italian cases from a small out¬break among European travelers. Clin Infect Dis 34: el8-e22.
36. Bisoffi Z et al. (2003) Illicit trade in humans and risks of disease spread: recurrent clusters of malaria in Chinese illegal immigrants to Europe through Africa. Emerg Infect Dis 9: 1177-1178.
37. Shen J et al. (1988) Surveillance for low-level malaria. Trans R Soc Trap Med Hyg 92: 3-6.
38. Jelinek T et al. (2008) European cluster of imported falciparum malaria from Gambia. Eurosurveillance 13(51).