vaccine-preventable diseases: why the Italian travelers are most affected? 's young, male, VFR (Visiting Friends and Relatives), directed in South-Central Asia, born or resident in Italy or in Japan: this hypothetical traveler, if it existed, would bring together all the factors that increase the risk of acquiring a vaccine-preventable disease as a result of an international journey.
It 's the picture that emerges from the GeoSentinel surveillance system, based on a network of 49 clinics spread of tropical diseases in six continents. We analyzed data on passenger care clinics in the network the decade 1997-2007. The findings are reported in an article published in the issue of Vaccine of 28 October.
What diseases?
The most frequent diagnosis was that of enteric fever: under that name were considered together with typhoid fever and paratyphoid, although for the latter there is no specific vaccine. The authors have included paratyphoid (which in the analysis accounted for 32% of cases of enteric fever) because there is some evidence that the live attenuated Ty21a oral typhoid vaccine provides partial protection against Salmonella paratyphi B. In second place we have hepatitis A. Following influenza, hepatitis B, varicella, measles, whooping cough, bacterial meningitis, rubella, mumps, tick-borne encephalitis, cholera, meningococcal sepsis, anger. There have been no diagnosed cases of yellow fever, Japanese encephalitis and poliomyelitis. There were three deaths, one for rabies, typhoid fever and pneumococcal meningitis.
What travelers?
have been identified, the independent risk factors: young age, male gender, VFR (Visiting Friends and Relatives), South-Central Asia destination. These data had already emerged in previous studies. In particular, VFR travelers, or immigrants in Western countries (and their children born in West) in the country of origin who return to visit relatives and friends, according to data in the literature are at increased risk of various diseases of the traveler, such as vaccine-preventable and malaria.
To be born or to be resident in Italy or Japan was a predictor of the acquisition of a vaccine-preventable disease. The authors offer no interpretation of the data and write broadly that it could be linked to national vaccination policies. Personally, the simplest explanation seems to me that the Italians are in sixth place in the world in terms of international travel but have not yet used to it, rather rooted in other Western countries, to go to a Travel Medicine clinic before leaving. In some parts of Italy, especially in small towns, a service of this type is not even provided by local health authorities, or is not valued in terms of resources, staff training and accessibility to the citizen. The lack of information produces insufficient access to important preventive measures like vaccination or chemoprophylaxis of malaria. As a result, the traveler is not prepared to get sick more often.
What areas of the world?
x-axis are the number of cases per 1000 passengers, on the y axis in the region of the world where the disease was contracted. The colors inside the columns refer to individual diseases.
The region with increased morbidity among travelers is the north-central Asia, mainly due to enteric fever.
In second place (who would have guessed?) Are Eastern Europe, which weighs mainly hepatitis A. Below are other areas of the world, the last place we the sub-Saharan Africa.
The authors do not comment on these results, which to me seem really interesting. One can venture a possible explanation for some unexpected differences in morbidity geographical area: the traveler direct sub-Saharan Africa is probably more inclined to inquire, and then to be vaccinated, compared to a traveler to Europe of 'east, perceived as a low risk area. In addition, malaria tablets Yellow fever vaccination, it must request to enter into certain African sub-Saharan Africa or in transit from one country to another, could serve as drivers for the other vaccinations.
Limitations of the study
Among the limitations of the study highlighted by the authors, the main I think the lack of information on the vaccination status of patients : the only 's previous medical history, the trip included in the surveillance system GeoSentinel, concerning the presence or absence of advice from a clinic of Travel Medicine. Of the reported cases, only 29% of the total and 5% of the VFR had carried out consultancy.
anamnesis In the absence of vaccination, it is not possible to calculate the rate of vaccine failure. Some of those who contracted enteric fever may have been vaccinated. Both the oral vaccine (Ty21a) and parenteral (Vi polysaccharide) are not extremely effective due S. typhi is the estimated efficacy of 63-71%, respectively, for the first and 55-74% for the second, while the oral vaccine may be only partially effective (49%) to S. B. paratyphi
Another limitation to note is that the cohort analyzed is represented only by those who went to one of the clinics in the network GeoSentinel, so that the conclusions of the study can not be automatically extended to the population of travelers in its entirety.
What this study tells us
is an analysis based on data from 580 patients who contracted a vaccine-preventable disease (a total of 37,542 passengers in ammalatisi result of a trip) in a span of ten years, this is the largest study reported to date on the subject. The study provides data that can have a significant relapse practice in consulting that we provide for passengers and can help set priorities for about the recommended vaccinations. As for our country , the results suggest the need to strengthen the activities of Travel Medicine and better information for Italian travelers.
to write this post I am based on the following article: Andrea K. Boggild, Francesco Castelli, Philippe Gautret, Joseph Torresi, Frank von Sonnenburg, Elizabeth D. Barnett, Christina A. Greenaway, Poh-Lian Lim, Eli Schwartz, Annelies Wilder-Smith, Mary E. Wilson and for the GeoSentinel Surveillance Network.
Vaccine preventable diseases in international returned travelers: Results from the GeoSentinel Surveillance Network. Vaccine 2010, 28:7389-7395
doi: 10.1016/j.vaccine.2010.09.009
To those who wish to learn more about the network GeoSentinel, reports the official site:
