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Biomedical subjects

Robert Steffen

Publications and source records attributed to Robert Steffen.

At least 19 recordsLinked to original sources
PubMed2006

Hepatitis A virus infections in travelers, 1988-2004.

BACKGROUND: Uncertainty exists about the current risk of hepatitis A virus infection in nonimmune travelers to destinations with high or intermediate risk of transmission. We analyzed recent epidemiological data on imported hepatitis A to determine region-specific attack rates and incidences. METHODS: Surveillance data on hepatitis A virus infections diagnosed during 1988-2004 were evaluated on the basis of notification by laboratories, additional reports of physicians, and traveler's statistics. This study focuses on international travelers with hepatitis A virus infection detected after their return to Switzerland. RESULTS: The rate of imported hepatitis A virus infections decreased 75% from 1988 to 2004 and accounted overall for 42% of all hepatitis A cases reported in Switzerland. The actual incidence of hepatitis A in travelers to countries of high or intermediate risk of transmission was 3.0-11.0 per 100,000 person-months abroad for all travelers and 6.0-28.0 per 100,000 for those presumed to be nonimmune. The actual proportion of those visiting friends and relatives among patients with hepatitis A has increased to 28.2%, with children aged 0-14 years predominating. Reductions in the incidence by hepatitis A vaccination were estimated to vary between 35.0% and 61.8% for different destinations. CONCLUSIONS: The risk of hepatitis A virus infections has decreased by a factor of 10-50-fold over time, compared with findings from older studies. The risk, however, remains very considerable at many destinations, including frequently visited places, such as Mexico. Children of immigrants are a high-risk population. Strategies are needed to reach those at highest risk.

Adolescent↗
PubMed2006

Prevention of travel-related infectious diseases: knowledge, practices and attitudes of Swedish travellers.

More Swedish residents travel to countries where they are at risk for contracting malaria, hepatitis, and other serious travel-related diseases. To safeguard the public's health, it is important to determine if travellers accurately perceive health risks and take appropriate preventative measures before and during their trips. This study examined travel health knowledge, attitudes and practices among Swedish residents traveling to destinations with risk of malaria and hepatitis. Self-administered anonymous questionnaires were distributed to Swedish residents (n=957) waiting to board intercontinental flights at the Stockholm-Arlanda International Airport. A majority of travellers sought general information (74%) and travel health advice (59%) prior to departure. Most perceived vaccination as safe and effective, but only 40% and 3% of travellers reported adequate vaccine coverage against hepatitis A or hepatitis B, respectively. Although most did not know the actual malaria risk at the destination, 97% of persons flying to high-risk areas were carrying malaria medication. The study results were in line with those found in surveys conducted in other countries, and demonstrate need for further health education among travellers to risk destinations. Efforts should focus on reaching more travellers, providing clear information and improving compliance with recommended travel health advice.

Adolescent↗
PubMed2006

A randomized, double-blind, multicenter study of rifaximin compared with placebo and with ciprofloxacin in the treatment of travelers' diarrhea.

Rifaximin was compared with placebo and ciprofloxacin for treatment of travelers' diarrhea in a randomized, double-blind clinical trial. Adult travelers (N = 399) consulting travel clinics in Mexico, Guatemala, and India were randomized to receive rifaximin 200 mg three times a day, ciprofloxacin (500 mg two times a day and placebo once a day), or placebo three times a day for 3 days. Patients recorded in daily diaries the time and consistency of each stool and documented symptoms for 5 days after treatment. Stool samples were collected for microbiologic evaluations before and after treatment. The median time to last unformed stool (TLUS) in the rifaximin group (32.0 hours) was less than one half that in the placebo group (65.5 hours; P = 0.001; risk ratio 1.6; 95% confidence interval 1.2, 2.2; primary efficacy endpoint). The median TLUS in the ciprofloxacin group was 28.8 hours (P = 0.0003 versus placebo; P = 0.35 versus rifaximin). Rifaximin was less effective than ciprofloxacin for invasive intestinal bacterial pathogens. Oral rifaximin is a safe and effective treatment of travelers' diarrhea caused by noninvasive pathogens.

Adolescent↗
PubMed2006

Deaths caused by malaria in Switzerland 1988-2002.

Despite sophisticated intensive medicine, between one and three malaria-associated deaths occur annually in Switzerland. In this retrospective study, 33 deaths (25 men and 8 women) caused by falciparum malaria reported in Switzerland from 1988 to 2002 were analyzed. The case fatality ratio (CFR) for the falciparum infections for the 15-year period was 1.2%, with a peak of 2.2% in 1991. Sub-Saharan Africa was the source of all the imported fatal infections. Non-immune Europeans had a significantly higher case fatality ratio than the non-Europeans (1.7% versus 0.2%; P < 0.001). Careless use or non-use of prophylaxis, sometimes because of physicians giving unsatisfactory pre-travel advice, and initially missed diagnosis post-travel were factors that contributed to the development of severe infections leading to death. Travelers should be sensitized to the risk of malaria by well-informed general practitioners. Updated information is readily available (www.safetravel.ch). Regarding diagnosis and treatment, greater physician awareness of the disease is needed, and expert advice should be sought without hesitation. Rapid malaria tests may be a useful diagnostic adjunct in centers where microscopic expertise is lacking. Falciparum malaria in a non-immune patient is an emergency requiring immediate treatment.

Adult↗
PubMed2005

Epidemiology of traveler's diarrhea.

Among travelers from developed countries who visit developing countries, >60% may experience traveler's diarrhea, accounting for 40,000 travelers daily or >15 million travelers annually. Traveler's diarrhea is often accompanied by other symptoms, most often abdominal cramps. Although the spontaneous cure occurs after a mean of 4 days, a few patients have symptoms for weeks, and it is increasingly noted that some patients may later develop irritable bowel syndrome. Traveler's diarrhea is life threatening only exceptionally, but it frequently it leads to incapacitation. Both host factors (e.g., age, behavior, nationality, and genetic factors) and environmental factors (primarily the selected destination and hotel) play an important role in risk for traveler's diarrhea.

Developed Countries↗
PubMed2005

Influenza virus infection in travelers to tropical and subtropical countries.

BACKGROUND: Influenza outbreaks have been reported among travelers, but attack rates and incidence are unknown. METHODS: A cohort study was conducted. Travelers to subtropical and tropical countries recruited at the University of Zurich Travel Clinic (Switzerland), January 1998 to March 2000, were investigated with pre- and posttravel assessment of hemagglutination inhibition and by questionnaire. RESULTS: Among 1450 travelers recruited who completed questionnaires and provided serum samples before departure, 289 (19.9%) reported febrile illness during or after traveling abroad; of these, 211 (73.0%) provided paired serum samples. Additionally, paired serum samples were collected from 321 frequency-matched afebrile control subjects among the remaining 1161 subjects of the study population. Seroconversion for influenza virus infection was demonstrated in 40 (2.8%) of all travelers; 18 participants (1.2%) had a > or = 4-fold increase in antibody titers. This corresponds to an incidence of 1.0 influenza-associated events per 100 person-months abroad. Among the 211 febrile participants, 27 (12.8%) had seroconversion, 13 (6.2%) with a > or = 4-fold increase; among the 321 afebrile control subjects, 13 (4.0%) had seroconversion, 5 (1.6%) with a > or = 4-fold increase. Twenty-five seroconverters (62.5%; P = .747) acquired influenza outside of the European epidemic season. Sixteen patients (40.0%) sought medical attention either abroad or at home, and 32 (80.0%) were asymptomatic at the time of completion of the survey. CONCLUSIONS: This survey indicates that influenza is the most frequent vaccine-preventable infection among travelers to subtropical and tropical countries. Infections occur mainly outside the domestic epidemic season, and they have a considerable impact. Pretravel vaccination should be considered for travelers to subtropical and tropical countries.

Adolescent↗
PubMed2005

Changing travel-related global epidemiology of hepatitis A.

Hepatitis A is highly endemic in many emerging cultures. Despite the availability of safe and effective vaccines and some improvements in sanitation in developing countries, hepatitis A remains a significant cause of morbidity for nonimmune travelers visiting such destinations. All are at risk, including short-term vacationers or business travelers who stay in deluxe accommodations. This may have considerable implications on public health. Hepatitis A vaccination programs for travelers have not proven to be effective, since many visitors to destinations at risk (e.g., Mexico) fail to consult health professionals prior to departure. Because 50% of the US population has an anticipated lifetime risk for exposure, universal immunization against hepatitis A should be considered.

Endemic Diseases↗
PubMed2004

Use of the inactivated intranasal influenza vaccine and the risk of Bell's palsy in Switzerland.

BACKGROUND: After the introduction of an inactivated intranasal influenza vaccine that was used only in Switzerland, 46 cases of Bell's palsy were reported. METHODS: We conducted a matched case-control study and a case-series analysis. All primary care physicians, ear, nose, and throat specialists, and neurologists in German-speaking regions of Switzerland were requested to identify cases of Bell's palsy diagnosed in adults between October 1, 2000, and April 30, 2001. Each physician was invited to select three control patients for each patient with Bell's palsy, with matching according to age, date of the clinic visit, and physician. Vaccination information was provided by the physicians. RESULTS: A total of 773 patients with Bell's palsy were identified. Of the 412 (53.3 percent) who could be evaluated, 250 (60.7 percent) were enrolled and matched with 722 control patients; the other 162 patients had no controls. In the case-control study, we found that 68 patients with Bell's palsy (27.2 percent) and 8 controls (1.1 percent) had received the intranasal vaccine (P<0.001). In contrast to parenteral vaccines, the intranasal vaccine significantly increased the risk of Bell's palsy (adjusted odds ratio, 84.0; 95 percent confidence interval, 20.1 to 351.9). Even according to conservative assumptions, the relative risk of Bell's palsy was estimated to be 19 times the risk in the controls, corresponding to 13 excess cases per 10,000 vaccinees within 1 to 91 days after vaccination. In the case-series analysis, the period of highest risk was 31 to 60 days after vaccination. CONCLUSIONS: This study suggests a strong association between the inactivated intranasal influenza vaccine used in Switzerland and Bell's palsy. This vaccine is no longer in clinical use.

Administration, Intranasal↗
PubMed2004

Enteroaggregative Escherichia coli diarrhea in travelers: response to rifaximin therapy.

BACKGROUND AND AIMS: We have recently shown that enteroaggregative Escherichia coli (EAEC) strains commonly cause travelers' diarrhea. The study was designed to determine whether U.S. travelers with EAEC diarrhea responded to rifaximin therapy. METHODS: In a multicenter placebo-controlled clinical trial of travelers' diarrhea without non-EAEC pathogens we evaluated 2 doses of rifaximin. EAEC was sought in stool samples in enrolled subjects by HEp-2 cell assay. Response to rifaximin (both groups combined) and placebo were evaluated in EAEC-positive and EAEC-negative patient groups. RESULTS: Compared with placebo, rifaximin shortened the postenrollment illness in travelers with EAEC diarrhea (median, 22 vs. 72 hours; P = 0.03). In subjects with EAEC-negative diarrhea, the median duration of post-treatment diarrhea was shorter with rifaximin (33 hours) than with placebo (52 hours), but this difference was not significantly different (P = 0.14). CONCLUSIONS: Improvement of EAEC-mediated diarrhea with antibiotic treatment supports the pathogenicity of this organism in travelers to developing countries. The study provides information on the value of the poorly absorbed drug rifaximin in therapy of travelers' diarrhea.

Anti-Infective Agents↗
PubMed2003

Tolerability of malaria chemoprophylaxis in non-immune travellers to sub-Saharan Africa: multicentre, randomised, double blind, four arm study.

OBJECTIVE: To compare the tolerability of malaria chemoprophylaxis regimens in non-immune travellers. DESIGN: Randomised, double blind, study with placebo run-in phase. SETTING: Travel clinics in Switzerland, Germany, and Israel. MAIN OUTCOME MEASURE: Proportion of participants in each treatment arm with subjectively moderate or severe adverse events. PARTICIPANTS: 623 non-immune travellers to sub-Saharan Africa: 153 each received either doxycycline, mefloquine, or the fixed combination chloroquine and proguanil, and 164 received the fixed combination atovaquone and proguanil. RESULTS: A high proportion of patients reported adverse events, even in the initial placebo group. No events were serious. The chloroquine and proguanil arm had the highest proportion of mild to moderate adverse events (69/153; 45%, 95% confidence interval 37% to 53%), followed by mefloquine (64/153; 42%, 34% to 50%), doxycycline (51/153; 33%, 26% to 41%), and atovaquone and proguanil (53/164; 32%, 25% to 40%) (P = 0.048 for all). The mefloquine and combined chloroquine and proguanil arms had the highest proportion of more severe events (n = 19; 12%, 7% to 18% and n = 16; 11%, 6% to 15%, respectively), whereas the combined atovaquone and proguanil and doxycycline arms had the lowest (n = 11; 7%, 2% to 11% and n = 9; 6%, 2% to 10%, respectively: P = 0.137 for all). The mefloquine arm had the highest proportion of moderate to severe neuropsychological adverse events, particularly in women (n = 56; 37%, 29% to 44% versus chloroquine and proguanil, n = 46; 30%, 23% to 37%; doxycycline, n = 36; 24%, 17% to 30%; and atovaquone and proguanil, n = 32; 20%, 13% to 26%: P = 0.003 for all). The highest proportion of moderate or severe skin problems were reported in the chloroquine and proguanil arm (n = 12; 8%, 4% to 13% versus doxycycline, n = 5; 3%, 1% to 6%; atovaquone and proguanil, n = 4; 2%, 0% to 5%; mefloquine, n = 2; 1%, 0% to 3%: P = 0.013). CONCLUSIONS: Combined atovaquone and proguanil and doxycyline are well tolerated antimalarial drugs. Broader experience with both agents is needed to accumulate reports of rare adverse events.

Adolescent↗
PubMed2003

Vaccination priorities.

Selection of immunizations should be based on requirements and on risk of infection. According to the International Health Regulations, many countries require yellow fever vaccination and proof thereof as the International Certificate of vaccination. Additionally selected countries require proof of vaccination against cholera and meningococcal disease. A consultation for travel health advice is always an opportunity to ascertain that routine immunizations have been performed. Recommended immunizations often are more important for traveller's health than the required or routine ones. The most frequent vaccine preventable infection in non-immune travellers to developing countries is hepatitis A with an average incidence rate of 0.3% per month; in high risk backpackers or foreign-aid-volunteers this rate is 2.0%. Many immunizations are recommended for special risk groups only: there is a growing tendency in many countries to immunize all young travellers to developing countries against hepatitis B, as it is uncertain who will voluntarily or involuntarily get exposed. The attack rate of influenza in intercontinental travel is estimated to be 1%. Immunity against poliomyelitis remains essential for travel to Africa and parts of Asia. Many of the 0.2-0.4% who experience an animal bite are at risk of rabies. Typhoid fever is diagnosed with an incidence rate of 0.03% per month among travellers to the Indian subcontinent, North and West Africa (except Tunisia), and Peru, elsewhere this rate is 10-fold lower. Meningococcal disease, Japanese encephalitis, cholera and tuberculosis have been reported in travellers, but these infections are rare in this population. Although no travel health vaccine is cost beneficial, most professionals will offer protection against the frequent risks, while most would find it ridiculous to use all available vaccines in every traveller. It is essentially an arbitrary decision made on the risk level one wishes to recommend protection--but the priorities need to be set correctly.

Epidemiologic Factors↗
PubMed2003

Travel epidemiology--a global perspective.

In order to have a rational approach to necessary preventive measures it is essential to know the health risks. The 80 million travellers each year with destinations in Africa, Asia, Latin America, Pacific Islands and remote areas in Eastern Europe are exposed to a broad range of pathogens that are rarely encountered at home. The risk depends on the degree of endemicity in the area visited, the duration of stay, the individual behaviour and the preventive measures taken. Travellers' diarrhoea (TD) is the most frequent ailment of visitors to countries with poor hygiene. The incidence rate is 25-90% in the first 2 weeks abroad. The risk of TD is far less in travellers originating in a high risk country, as some immunity develops. Malaria is an important risk for travellers going to endemic areas. Without chemoprophylaxis, the monthly incidence is high in some destinations, among them frequently visited tropical Africa where 80-95% of the infections are due to Plasmodium falciparum. The incidence rates are lower in most endemic areas of Asia and Latin America where Plasmodium vivax predominates. The risk is nil in all capital cities of South America and SE Asia, as well as in many frequently visited tourist destinations. The diseases preventable by immunization will be discussed in a separate paper (Vaccination priorities; page 175). Sexually transmitted diseases occur frequently, as some travellers (5% of Europeans) engage in casual sex, approximately half of them without being protected by a condom. The prevalence for HIV-infection, syphilis, gonorrhoea, etc. often exceeds 50% in prostitutes. In some European countries, a major proportion of heterosexuals with newly acquired HIV-infection have acquired it while abroad.

Accidents↗
PubMed2003

Phenotypic diversity of enterotoxigenic Escherichia coli (ETEC) isolated from cases of travelers' diarrhea in Kenya.

BACKGROUND: The aim of this study was to characterize phenotypically enterotoxins, colonization factors (CFs) and the antibiotic susceptibility of enterotoxigenic Escherichia coli (ETEC) strains isolated from cases of acute diarrhea that occurred in Europeans traveling to resorts in Mombasa, Kenya; this information is critical for the development of vaccines and empirical treatment. METHODS: Over a 1-year period from 1996 to 1997, five E. coli-like colonies were obtained from each of 463 cases with acute diarrhea. These strains were characterized for enterotoxins using GM-1 ELISA, for CFs using a dot-blot assay, and for antibiotic susceptibility using antibiotic disks. RESULTS: Of 164 strains characterized for ETEC phenotype, 30 (18%) expressed heat-labile toxin (LT) only, 83 (51%) heat-stable toxin (ST) only, and 51 (31%) both LT and ST. Analysis for CF expression demonstrated that 107 (65%) of the strains were positive for CFs, including CFA/IV (46%), CFA/II (35%), and CFA/I (5%), while less than 4% expressed less common CFs. All ETEC strains tested were resistant to erythromycin and sensitive to ceftriaxone. Over one-third of the strains were resistant to sulfamethoxazole-trimethoprim or tetracycline. Six strains were resistant to nalidixic acid; none of these were resistant to ciprofloxacin. CONCLUSIONS: Cumulatively, our findings indicate that ETEC in this region comprises a highly diverse group of bacterial enteropathogens, and that the development of prophylactic agents against ETEC faces major challenges because of this diversity.

Anti-Bacterial Agents↗
PubMed2003

Tuberculosis infection notification in Swiss medical students during their clinical electives.

OBJECTIVE: The aim of this study was to assess the tuberculin skin test conversion incidence in Swiss medical students. METHODS: This was a prospective cohort study of medical students at the University of Zurich, using a standardized tuberculin skin test before and after clinical electives. RESULTS: Two hundred and sixty-two students accepted the invitation to the pre-clerkship test, and 155 (59.2%) subjects were retested after an average period of 2.25 years. An increase of more than 10 mm in the transverse diameter of the induration in the retest compared to the baseline test was observed in 12 (7.7%) students. The annual conversion rate was 3.4% (95% CI 1.8-6.0%). CONCLUSIONS: Even in an industrialized country, the risk of tuberculosis infection--as estimated by the tuberculin skin test--is substantial for health care professionals. Possible explanations for the high incidence and possible bias are discussed.

Adult↗
PubMed2003

Therapy of travelers' diarrhea with rifaximin on various continents.

OBJECTIVE: Our aim was to compare the efficacy and safety of rifaximin, a virtually nonabsorbed antibiotic, 600 and 1200 mg per day, with placebo in patients with travelers' diarrhea. METHODS: This was a multicenter, 1:1:1 randomized, parallel-group, double-blind study, conducted in Antigua, Guatemala; Guadalajara and Morelia, Mexico; and the coast of Kenya north and south of Mombasa. Adult patients with acute travelers' diarrhea were recruited; exclusion criteria included primarily medication that could influence the outcome. Subjects were treated for 3 days, three times daily; follow-up lasted 5 days. For each 24-h period, the subjects completed a diary card. Pre- and posttreatment stool, blood, and urine samples were assessed. RESULTS: Among the 380 volunteers, median time to the last unformed stool was 32.5 and 32.9 h in both rifaximin groups, compared with 60.0 h with placebo (p = 0.0001). Also, secondary clinical outcome measures were favorably influenced by the active agent. No relevant side effects were reported. CONCLUSION: Rifaximin is efficacious and safe for treatment of travelers' diarrhea at daily doses of 600 mg or higher.

Adolescent↗