CISTM 11: Updates and Abstracts
CISTM 11: Updates and Abstracts
By Lin H. Chen, MD
Dr. Chen is Assistant Clinical Professor, Harvard Medical School, Director, Travel Medicine Center, Mt. Auburn Hospital, Cambridge, MA.
Dr. Chen reports no financial relationships relevant to this field of study.
Synopsis: Conference Report from Budapest
During the 11th Conference of the International Society of Travel Medicine held in Budapest, Hungary, from May 24-28, 2009, the symposium titled "Update: WHO, CDC & Yellow Fever Issues," included a session from Dr. David Hill from National Travel Health Network and Centre (NaTHNaC) titled "Defining Yellow Fever (YF) Risk in Endemic Areas." Dr. Hill described the data that were used, which included historic human serological surveys, YF cases in humans and nonhuman primates, vector distribution, and geographical parameters of vegetation and altitude. Areas are designated endemic, transitional, low risk, and no risk. (See Table.)
These newly defined risk levels should improve risk determination and communication as well as targeted YF vaccination.
The following abstracts were judged by a panel of referees to have the most impact and relevance in the practice of travel medicine. They consist of 3 oral presentations (free communications, described first below) and 3 posters.
First prize: FC06.01
Low Quality of Routine Microscopy for Malaria in Dar es Salaam, Tanzania: Implications for the Sick Traveler. V. D'Acremont,1,2 J. Kahama-Maro,2 D. Mtasiwa,3 C. Langeler,1 B. Genton1,4,5
1Swiss Tropical Institute, Public Health and Epidemiology, Basel, Switzerland, 2City Medical Office of Health, Dar es Salaam, United Republic of Tanzania, 3Ministry of Health and Welfare, Dar es Salaam, United Republic of Tanzania, 4Department of Ambulatory Care and Community Medicine, University of Lausanne, Travel Clinic, Lausanne, Switzerland, 5Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.
The investigators evaluated the quality of routine microscopy for malaria in hospitals, health centers, and dispensaries in Dar es Salaam, Tanzania. They compared the positivity rate using routine microscopy with that of rapid diagnostic tests (RDT) and also measured the sensitivity and specificity of routine blood slides against expert microscopy as reference. Over a 15-month period, they found the mean positivity rates for microscopy to be 41% (hospitals), 49% (health centers), and 65% (dispensaries), range 13-90%. Over the following 18 months, the respective mean PR using routine RDTs were 7%, 10%, and 9% (6-12%). The healthcare facility laboratories reported 178/335 blood slides (53%) as positive, while expert microscopy actually found only 7 of these (2%) were positive. Sensitivity of routine microscopy versus that of expert microscopy was only 71%, and specificity 47%. When positive, the median parasitemia was 3 per 200 white blood cells (WBC) by routine microscopy and 1193 per 200 WBC by expert microscopy.
Conclusions. The investigators found poor quality of routine microscopy at all levels, with low specificity and sensitivity even in the largest city of Tanzania. The researchers note that, while overdiagnosis and overtreatment of malaria are not considered to be deleterious, false-positive cases might lead to fatality from another undiagnosed cause of fever. Furthermore, the low sensitivity can leave nearly 30% of the malaria cases untreated. The use of RDTs as a first-line diagnostic tool for malaria can improve the management of febrile travelers as well as local residents. Travel medicine practitioners should alert travelers to the poor malaria microscopy in healthcare facilities of endemic areas.
Second prize: FC04.05
What Does the Pre-travel Consultation Look Like? Using Innovative Methodology to Understand Consultation Dynamics. A. Willcox, J. Dale, A. Adams, University of Warwick, Medical School, Warwick, United Kingdom.
The investigators performed video-recordings of 32 pre-travel consultations and analyzed the dynamics of the consultation using the Roter Interaction Analysis System (RIAS) and a bar-coding technique. The study found that bar coding allowed for a visual assessment of the phases of a consultation and distinguished the pre-travel consultation from traditional models of a consultation. RIAS allowed for scoring of patient-centeredness and for comparing pre-travel consultations with other types of consultation.
Conclusions. The investigators concluded that pre-travel consultations require a model of practice tailored to the needs of the traveler. Video recording can aid travel medicine clinicians by giving a visual perspective to assess the strengths and weaknesses of their consultation.
Third prize: FC03.01
Irritable Bowel Syndrome among a Cohort of European Travelers to Low Income Destinations. R. Pitzurra, A. Tschopp, C. Hatz, R. Steffen, M. Mutsch, University of Zurich, Institute of Social and Preventive Medicine (ISPM), Zurich, Switzerland.
The investigators conducted a 3-stage survey of European travelers to high-risk destinations between July 2006 and June 2008 to detect irritable bowel syndrome (IBS). The questionnaires elicited symptoms of IBS based on Rome III criteria before travel, immediately post-travel, and 6 months post-travel. Among 3100 travelers enrolled in the study, 2800 (90.3%) concluded the survey immediately post-travel, and 2440 (78.7%) completed the study and were analyzed. Classic traveler's diarrhea (TD) was reported by 34.3%, with rates more than 35% for travelers to Central and West Africa and South Asia. At 6 months post-travel, 31 travelers (1.3%) had symptoms consistent with IBS, resulting in an estimated incidence of 0.9% for a 2-week stay. The preliminary multivariate analysis found classic TD was an independent risk factor for IBS (RR 4.8, 95% CI 2.2 - 10.4). Additional risk factors for IBS include age, newcomers to the tropics and subtropics, and reported consumption of potentially contaminated food and beverages. No significant difference was found for gender, trip duration, travel destination, or education.
Conclusions. IBS appears to occur at a lower rate in Europeans than other travelers (e.g., North Americans), and TD appears to be a risk factor for IBS.
First prize: PO07.07
Are Incidences of Fecal-orally Transmitted Diseases among Travelers Changing due to Better Hygienic Standards in the (Sub) Tropics or to Pre-travel Vaccination? G. Baaten,1,2,3 G. Sonder,1,2,3 R. Coutinho,1,2,4 A. van den Hoek1,3
1Public Health Service (GGD) Amsterdam, Department of Infectious Diseases, Amsterdam, Netherlands, 2Academic Medical Centre Amsterdam, Department of Internal Medicine, Division of Infectious Diseases, Tropical Medicine and AIDS, Amsterdam, Netherlands, 3National Coordination Centre for Traveller's Health Advice (LCR), Amsterdam, Netherlands, 4National Institute for Public Health and the Environment, Centre for Infectious Disease Control, Bilthoven, Netherlands.
The objective of this study was to determine whether the declining incidence of fecal-orally transmitted infections among travelers to the tropics could be attributed to pre-travel vaccinations, improved hygiene standards at destinations, or both. The investigators analyzed national surveillance data on laboratory-confirmed, travel-related hepatitis A and shigellosis in the Netherlands from 1995 through 2006. They calculated region-specific annual attack rates based on the numbers of Dutch travelers to the tropics as a denominator. They also used the Human Development Indices (HDI) from the United Nations Development Program to evaluate region-specific trends in hygienic standards.
From 1995 through 2006, overall annual attack rates per 100,000 travelers from the Netherlands declined from 22 to 6 for hepatitis A, and from 27 to 8 for shigellosis. For Latin America, rates declined from 6 to 1, and from 20 to 9, respectively; for North Africa and the Middle East from 62 to 7 and from 31 to 7. For Asia, hepatitis A rates remained stable (6 per 100,000), whereas shigellosis rates declined (from 22 to 7). For Sub-Saharan Africa, the rates did not decline; the median hepatitis A rate was 10, and the shigellosis rate was 39. Sub-analysis for popular tourist destinations showed low and stable rates for the Caribbean, dramatic decline for Turkey and Egypt, and lower rates for East Africa than for West Africa. Median rates for the Indian subcontinent were highest: 34 per 100,000 for hepatitis A and 84 for shigellosis. Rates for Thailand and Malaysia were stable and the lowest: 1 per 100,000 for hepatitis A, and 5 for shigellosis.
Trends in these incidences correlated with HDI baseline level and degree of increase. All regions showed an HDI increase (median 2.4% per 5 years). Baseline HDIs for Latin America, Turkey, and Thailand and Malaysia were the highest. HDI increase was highest for Egypt (+4.8%). The HDI for Sub-Saharan Africa was the lowest, and the HDI increase the smallest (+1.2 %). HDI for the Indian subcontinent was the second lowest.
Conclusions. The study illustrates that the incidence of illness in travelers from fecal-oral transmission is associated with hygienic standards at travel destinations. The findings support the use of travelers' health to estimate local disease epidemiology.
Second prize: PO02.12
Serologic Response to Rabies Pre-exposure Vaccination in Persons with Potential Occupational Exposure in Singapore: Implications for Travelers. P.L. Lim,1 T.M. Barkham2
1Tan Tock Seng Hospital, Infectious Diseases, Singapore, Singapore, 2Tan Tock Seng Hospital, Laboratory Medicine, Singapore, Singapore.
The investigators set out to examine when the first rabies serology and booster should be performed following primary immunization. They measured rabies antibody levels in 80 animal workers one year after primary or booster rabies vaccinations and compared demographic data and previous vaccine history. Among the cohort, 66 completed primary rabies series in 2006, one missed the third dose, and 13 received one booster (had prior primary series). Twenty-six (39%) of the 66 who had only primary vaccination had titers below recommended minimum (0.5 IU/mL) and were given boosters. All 13 who received a booster (100%) had rabies antibody levels above 0.5 IU/mL, with a median time from primary vaccination to most recent booster of 9 years (range 3-20 years).
Conclusions. The authors concluded: A substantial percentage of those vaccinated had antibody levels below the minimum recommended level one year post primary rabies series; serological surveillance to determine the need for a booster may be justified in those with an ongoing need for protection, both animal workers and travelers with extensive animal exposures; and individuals who received a booster even after a long interval from primary vaccination had adequate rabies antibody levels, suggesting that long-lasting immunity that can be boosted is present after primary rabies vaccination. These findings support the use of serological testing for travelers with ongoing potential animal exposure.
Third prize: PO03.07
Molecular Mechanisms of Resistance to Rifaximin in in vitro Selected Enterotoxigenic and Enteroaggregative Escherichia Coli Mutants. J. Gascon,1 M.-J. Pons,2 L. Mensa,2 L. Vila,2 J. Ruiz2
1Centre de Recerca en Salud Internacional (CRESIB), Tropical Medicine, International Health, Barcelone, Spain, 2Centre de Recerca en Salud Internacional (CRESIB), Molecular Biology, Barcelone, Spain
The objective of this study was to analyze the role of efflux pump and point mutations in the rpoB gene in the development of rifaximin resistance in Escherichia coli. The investigators isolated E. coli (2 enterotoxigenic and 2 enteroaggregative) from the blood of patients with traveler's diarrhea, grew the isolates in rifaximin-containing media, and selected 15 rifaximin-resistant mutants. Efflux pump-susceptibility to rifaximin was determined by agar dilution method, both in absence and presence of Phe-Arg-β-naphthylamide (PAβN), an efflux pump inhibitor. Mutations in the rpoB gene were identified by PCR amplification.
The results obtained show that two mechanisms are implicated in the rifaximin resistance. The most frequent causes were amino acid substitutions at positions 516 and 526 of the subunit of RNA polymerases, previously described in rifampicin resistance. The efflux pump accounted for the resistance in 6 mutants. Mutations in the rpoB gene accounted for 4 mutants, and the remaining mutants contained both mechanisms of resistance.
Conclusions. All mutant strains demonstrated at least one mechanism of rifaximin resistance. Both mutations studied in the rpoB gene and PAβN-inhibited efflux pump contributed to rifaximin resistance.
During the 11th Conference of the International Society of Travel Medicine held in Budapest, Hungary, from May 24-28, 2009, the symposium titled "Update: WHO, CDC & Yellow Fever Issues," included a session from Dr. David Hill from National Travel Health Network and Centre (NaTHNaC) titled "Defining Yellow Fever (YF) Risk in Endemic Areas."Subscribe Now for Access
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