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Biomedical subjects

Robert Steffen

Publications and source records attributed to Robert Steffen.

35 records · Page 2Linked to original sources
PubMed2002

Markers of inflammation in bacterial diarrhea among travelers, with a focus on enteroaggregative Escherichia coli pathogenicity.

The intestinal inflammatory response of traveler's diarrhea acquired in Goa, India, and Guadalajara, Mexico, was studied. Fecal lactoferrin was found in stool samples in which enteroaggregative Escherichia coli (EAEC), enterotoxigenic E. coli, or Salmonella or Shigella species were isolated, with Shigella-positive cases showing the highest level. Samples from cases of Shigella-associated diarrhea had the highest concentrations of fecal cytokines. Travelers to India who had EAEC-associated diarrhea showed elevated levels of interleukin (IL)-8 (median, 341.15 pg/mL) and IL-1beta (median, 749.90 pg/mL). Although 15 travelers to Mexico who had EAEC-associated diarrhea had a median concentration of 0 pg/mL for both IL-8 and IL-1beta, 2 had high levels of IL-8 (1853 and 11,786 pg/mL), and 5 showed elevated levels of IL-1beta (1-1240 pg/mL). Samples from patients in India who had pathogen-negative diarrhea or from patients in Mexico who had asymptomatic EAEC infection were negative for cytokines. Bacterial pathogens causing traveler's diarrhea commonly produce intestinal inflammation, although a subset of patients with EAEC-associated diarrhea fail to develop an inflammatory response.

Biomarkers↗
PubMed2002

Prevalence of enteric pathogens among international travelers with diarrhea acquired in Kenya (Mombasa), India (Goa), or Jamaica (Montego Bay).

Stools from tourists from Europe and North America who acquired diarrhea in Mombasa (Kenya), Goa (India), or Montego Bay (Jamaica) were examined for enteric pathogens. Enterotoxigenic Escherichia coli (ETEC) was the most common pathogen (25%) identified in the 3 locations. Isolation of Shigella species was more frequent in Goa and Mombasa than in Montego Bay (10%, 9%, and 0.3%, respectively; P <.005). Viruses (rotaviruses and enteric adenoviruses) were found in 9% of travelers to the 3 areas. Of 275 ETEC isolates in this study, 158 (57%) produced a defined colonization factor antigen (CFA). Coli surface 6 (CS6) was the most frequent and was found in 41%-52% of CFA/CS-positive ETEC isolates. The frequency of resistance among bacterial enteropathogens to traditional antimicrobial agents was particularly high throughout the study period in all 3 regions. Quinolones were active against the bacterial enteropathogens in the 3 sites.

Bacteria↗
PubMed2002

Rate of occurrence and pathogenic effect of enteroaggregative Escherichia coli virulence factors in international travelers.

One or more putative enteroaggregative Escherichia coli (EAEC) virulence factors (aggA, aggR, aspU, or aafA) were identified in 60 (70%) of 86 EAEC isolates from travelers with diarrhea compared with a rate of 7 (8%) of 90 in patients with diarrhea who were infected with nonadherent E. coli (odds ratio, 27.36; 95% confidence interval, 11.30 to 65.91). The presence of aggR or one or more virulence factors in EAEC from patients with diarrhea was associated with a statistically increased concentration of interleukin-8 (IL-8) in feces compared with that in EAEC negative for these factors: for aggR positive (9 of 12 [75%]; median, 800 pg/ml) versus aggR negative (5 of 18 [28%]; median, 0), P < 0.05; and for isolates positive for > or =1 virulence factor (13 of 21 [62%]; median, 360 pg/ml) versus those negative for > or =1 virulence factor (1 of 9 [11%]; median, 0), P < 0.05. Other fecal cytokines (IL-1beta and IL-1ra) were found in increased concentrations (P < 0.05 when at least one EAEC virulence factor was present compared with the concentrations when EAEC negative for multiple virulence factors was found in patients with diarrhea. Putative virulence factors were commonly found in EAEC from patients with diarrhea, and the pathogenicity of many strains was suggested by showing an association between the presence of plasmid-borne virulence factors and the presence of fecal cytokines. The different patterns of virulence factors of EAEC revealed several clusters demonstrating diversity among the isolates from the various regions.

Bacterial Adhesion↗
PubMed2002

Effectiveness of a repellent containing DEET and EBAAP for preventing tick bites.

OBJECTIVE: Topical repellents can provide effective personal protection from tick-borne diseases by preventing the attachment of ticks. The goal of this study was to assess the effectiveness of a commercially available repellent spray containing both N,N-diethyl-3-methylbenzamide, previously known as N,N-diethyl-m-toluamide (DEET), and ethyl-butylacetylaminopropionate (EBAAP) against tick bites in a population at risk in Switzerland under real-life conditions. METHODS: The effectiveness of an insect repellent spray containing both DEET and EBAAP was evaluated in a randomized, double-blind, placebo-controlled field study. The study, requiring simple application of the repellent to exposed skin, was carried out on 276 forestry workers and orienteers under everyday conditions in Switzerland from May to September 1999. We measured total effectiveness of the repellent by the following formula: percentage effectiveness = 100 x (T(P) - T(R))/T(P), where T(P) and T(R) were the average number of ticks per hour spent in wooded areas for the repellent and placebo groups, respectively. RESULTS: The average number of tick bites per hour of exposure to wooded areas differed significantly between the placebo (n = 138) and repellent (n = 138) groups, 0.17 vs 0.10 (P < .05). Total repellent effectiveness against tick attachment was 41.1% (95% CI, 2.5-79.6). On the arms, an effectiveness of 66% (95% CI, 17.3-114.7) was observed. No significant difference in the average number of unattached ticks could be found. CONCLUSIONS: This study found that an easily applied repellent is moderately effective in reducing the risk of tick bites.

Administration, Cutaneous↗
PubMed2002

Traveler's diarrhea: epidemiology and impact on visitors to Fortaleza, Brazil.

OBJECTIVE: To assess the epidemiology and impact of traveler's diarrhea (TD) among visitors to the city of Fortaleza, Ceará, Brazil, as part of a global study on TD carried out in four countries. METHODS: Within a cross-sectional survey, questionnaires were completed by departing travelers at the Fortaleza airport between March 1997 and February 1998. The questions inquired about demographics, duration of stay, reason for their visit, pretravel health advice they had received, risky food and beverage consumption while in Fortaleza, and quality of life during the visit to Fortaleza in relation to having or not having contracted TD. RESULTS: A total of 12,499 questionnaires were analyzed. The most common reason that the visitors gave for their travel to Fortaleza was a holiday (60.3%). The total diarrhea attack rate was 13.4%. Younger people (< 36 years) had significantly higher TD attack rates than did older persons. Using a logistic regression model, we investigated the visitors' risk factors, including age, gender, length of stay, and trip's purpose. According to that analysis, characteristics that are slightly predictive of TD are gender, length of stay, and visiting as a tourist rather than for some other purpose. Characteristics that protect against contracting TD include being older and traveling for business rather than for some other reason. Of those who were incapacitated by TD, the mean duration of the impairment was 42 hours. CONCLUSIONS: TD affected the travel plans and activities of many of the visitors to Fortaleza. Further, although aware of the health risks, the majority of those travelers did not avoid all potentially contaminated food or beverage items. Given this pattern of behavior, future efforts to combat TD may have to depend on such other alternative strategies as new vaccines.

Adolescent↗
PubMed2002

Light visor treatment for jet lag after westward travel across six time zones.

INTRODUCTION: The aim of this field study was to evaluate the efficacy of a light treatment for jet lag, using a head-mounted light visor, following a westward flight across six time zones. METHODS: There were 20 subjects who were exposed to bright white light (3000 lux) or dim red light (10 lux) for 3 h on the first two evenings after a flight from Zurich to New York. Salivary dim light melatonin onset (DLMO), assessed 2 d before and 2 d after the flight, provided a measure of circadian phase. Sleep was recorded by actigraphy, while post-flight performance testing and subjective scales provided additional indices of jet lag severity. RESULTS: The DLMO measurements showed a larger phase delay in the bright light than in the dim light group (2.59 h vs. 1.58 h, p < 0.02). There was no overall difference in sleep efficiency (SE) between the two groups, but a significant Group x Night interaction reflected a small increase across the first two post-flight nights in the bright light group, and a small decrease in the dim light group. Reaction time on one of two performance tests was consistently faster in the dim light group, but was unrelated to circadian phase or to prior sleep. There were no major group differences in subjective sleep quality, daytime sleepiness, jet lag severity, or mood. DISCUSSION: This is the first full-scale study to show that bright light treatment can accelerate circadian reentrainment following transmeridian travel. However, the effect on reentrainment rate was modest, and was not accompanied by any improvement in sleep, performance, or subjective assessments of jet lag symptoms.

Adult↗
PubMedDate not supplied

Travelers' knowledge, attitudes, and practices on prevention of infectious diseases: results from a pilot study.

BACKGROUND: The European Travel Health Advisory Board conducted a cross-sectional pilot survey to evaluate current travel health knowledge, attitudes, and practice (KAP) and to determine where travelers going to developing countries obtain travel health information, what information they receive, and what preventive travel health measures they employ. METHOD: Trained interviewers invited passengers at the departure gates of three international airports: London Heathrow, Paris Charles de Gaulle, and Munich to respond to a self-completion questionnaire. A total of 609 responses were collected. RESULTS: The study showed that more than one-third of travelers questioned had not sought pretravel health advice and of those who did, over 20% sought advice 14 days or less prior to travel. One-third of the respondents were aged 50 or more, and 20% had planned their trip less than 2 weeks before leaving. Only a minority were able to demonstrate that they had been immunised as per the World Health Organization or national recommendations. Respondents often misperceived both the risk of malaria at the destination and recommended preventive measures. CONCLUSIONS: The results of this pilot survey provided a valuable insight into the KAP of travelers and highlighted an important educational need among those traveling to risk destinations. Strategies are needed for raising awareness of preventable travel health issues and for raising compliance with existing recommendations.

Adolescent↗
PubMedDate not supplied

Knowledge, attitudes and practices of business travelers regarding malaria risk and prevention.

BACKGROUND: This study aimed to determine the knowledge, attitudes and practices of Swiss business travelers with regard to malaria. METHODS: Questionnaires printed in three languages were distributed by employers, travel agencies and tropical medicine specialists to business travelers with destinations in malaria endemic countries. RESULTS: In total, 401 questionnaires were evaluated. Thirty-three percent visited high-risk areas, 27% visited low-risk areas, and 40% visited only malaria-free areas within endemic countries. Among the investigated business travelers, 6% had experienced malaria infection, and 29% had previously had blood smears tested for malaria at least once. Almost all business travelers, 95%, knew that mosquitoes are the main vectors of malaria. The infection risk between dusk and dawn was known to 71%, and the incubation time to 36%. Apart from fever (99%) and headache (63%), other malaria symptoms were known to only 13% to 36% of the travelers. If signs of illness such as fever and headache occurred, 63% would react adequately and seek medical advice within 24 h. Only 16% of the travelers to African high-risk areas followed the recommended behavior concerning anti-mosquito and antimalarial strategies; 31% of those on trips to low-risk areas used an adequate protective strategy. Of the business travelers using chemoprophylaxis during travel, just 50% continued intake post travel, as requested, after leaving the endemic area. CONCLUSIONS: Business travelers are well informed regarding the mode of transmission and the risk of malaria at specific destinations but tend to comply poorly with anti-mosquito and chemoprophylactic strategies. The knowledge, attitudes and practices of business travelers with regard to malaria prevention need to be improved.

Adult↗
PubMedDate not supplied

Knowledge, attitudes and practices in travel-related infectious diseases: the European airport survey.

BACKGROUND: The European Travel Health Advisory Board conducted a cross-sectional pilot survey to evaluate current travel health knowledge, attitudes and practices (KAP) and to determine where travelers going to developing countries obtain travel health information, what information they receive, and what preventive travel health measures they employ. Subsequently, the questionnaire used was improved and a cross-sectional, multicenter study was undertaken in airports in Europe, Asia, South Africa and the United States. This paper describes the methods used everywhere, and results from the European airports. METHOD: Between September 2002 and September 2003, 5,465 passengers residing in Europe and boarding an intercontinental flight to a developing country were surveyed at the departure gates of nine major airports in Europe. Questionnaires were self-administered, and checked for completeness and validated by trained interviewers. RESULTS: Although the majority of travelers (73.3%) had sought general information about their destination prior to departure, only just over half of the responders (52.1%) had sought travel health advice. Tourists and people traveling for religious reasons had sought travel health advice more often, whereas travelers visiting friends and relatives were less likely to do so. Hepatitis A was perceived as the most probable among the infectious diseases investigated, followed by HIV and hepatitis B. In spite of a generally positive attitude towards vaccines, 58.4% and 68.7% of travelers could not report any protection against hepatitis A or hepatitis B, respectively. Only one in three travelers to a destination country with at least some malaria endemicity were carrying antimalarial drugs. Almost one in four travelers visiting a high-risk area had an inaccurate risk perception and even one in two going to a no-risk destination were unnecessarily concerned about malaria. CONCLUSIONS: The large variation in destinations, age of the travelers and reasons for traveling illustrates that traveling to a developing country has become common practice. The results of this large-scale airport survey clearly demonstrate an important educational need among those traveling to risk destinations. Initiatives to improve such education should target all groups of travelers, including business travelers, those visiting friends and relatives, and the elderly. Additionally, travel health advice providers should continue their efforts to make travelers comply with the recommended travel health advice. Our common objective is to help travelers stay healthy while abroad, and consequently to also reduce the potential importation of infectious diseases and the consequent public health and other implications.

Adolescent↗
PubMedDate not supplied

Immunogenicity of booster vaccination with a virosomal hepatitis A vaccine after primary immunization with an aluminum-adsorbed hepatitis A vaccine.

BACKGROUND: Increasing numbers of individuals are traveling to areas of high hepatitis A endemicity and require immunization against the hepatitis A virus (HAV). The option of using a virosomal, aluminum-free, HAV vaccine (Epaxal) for booster immunization following primary vaccination with an aluminum-adsorbed vaccine has been assessed. METHODS: In total, 142 healthy subjects, 79 men and 63 women, aged 12 to 72 years, were injected intramuscularly with a booster dose of Epaxal (0.5 mL containing < or =500 RIA units of HAV antigen) 6 to 24 months after primary vaccination with Havrix (0.5 or 1.0 mL containing 720 or 1440 ELISA units of HAV antigen, respectively, adsorbed onto aluminum hydroxide). Anti-HAV antibody titers were measured on days 0 and 28 by an enzyme immunoassay. Adverse events were recorded for 1 month postinjection. RESULTS: Overall, 98/118 subjects (83%) with no serologic evidence of past HAV infection were still seroprotected at enrolment (anti-HAV antibody titer < or = 20 mIU/mL). The seroprotection rate was 87% in those primed with Havrix 1440 6 to 12 months earlier (n=93) and 60% in those primed < or =12 months before enrolment (n=20, mean 16 months). The geometric mean anti-HAV antibody titer increased from 65 mIU/mL at day 0 to 1,722 mIU/mL at day 28 after a single booster dose with Epaxal in evaluable subjects who were primarily vaccinated with either a single dose of Havrix 1440 (n=111) or two separate doses of Havrix 720 (n=4). All subjects were seroprotected at day 28, and 98% showed at least a four-fold increase in anti-HAV antibody titer. Epaxal was well tolerated and no serious adverse events were reported. At day 28, the tolerability of the vaccination was judged as either "very good" or "good" by 96% of vaccinees and by all investigators. CONCLUSION: Epaxal can be successfully used to boost immunization following primary vaccination with an aluminum-adsorbed vaccine, and is well tolerated.

Adolescent↗
PubMedDate not supplied

Epidemiology of travelers' diarrhea: details of a global survey.

BACKGROUND: Recent epidemiologic data on travelers' diarrhea (TD) are essential for the evaluation of conventional and future prophylactic and therapeutic measures. METHODS: To determine the epidemiology, including risk factors, impact and quality-of-life evaluation of TD, a cross-sectional survey was conducted over 12 months at the airports of Mombasa (Kenya), Goa (India), Montego Bay (Jamaica) and Fortaleza (Brazil) by distributing questionnaires to visitors just prior to their flying home. The study period was March 1996 to July 1998. RESULTS: Overall, 73,630 short-term visitors completed a questionnaire. The total diarrhea attack rate varied between a high of 54.6% in Mombasa and a low of 13.6% in Fortaleza, but only between 31.5% and 5.4% of all travelers had classic TD. The 14-day incidence rates varied between 19.5% and 65.7%. Few travelers meticulously avoided potentially dangerous food items, although in India and Kenya most travelers avoided those considered most dangerous. Risk factors were stays exceeding 1 week, age between 15 and 30 years, and residence in the UK. The impact, measured as incapacity or quality-of-life scores, was very considerable. CONCLUSIONS: TD continues to affect vacationers and business travelers as frequently as it did some 20 years ago. Compliance with recommendations to reduce exposure to pathogens by avoiding dangerous food items is poor among travelers from all countries. Implementation of food safety education programs may be difficult to achieve.

Adolescent↗