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At least 685 records · Page 38Linked to original sources
PubMed2004

Typhoid fever in travelers: who should be targeted for prevention?

To clarify indications for typhoid vaccination, we reviewed laboratory-confirmed cases of typhoid fever reported to the United States Centers for Disease Control and Prevention between 1994 and 1999. To estimate the risk of adverse events associated with typhoid vaccination, we reviewed reports to the Vaccine Adverse Event Reporting System for the same period. Acute Salmonella enterica serotype Typhi infection was reported for 1393 patients. Of these patients, recent travel was reported by 1027 (74%), only 36 (4%) of whom reported having received a vaccination. Six countries accounted for 76% of travel-associated cases (India [30%], Pakistan [13%], Mexico [12%], Bangladesh [8%], The Philippines [8%], and Haiti [5%]). For 626 travelers who traveled to a single country, the length of stay was <or=1 week for 31 (5%), <or=2 weeks for 100 (16%), <or=3 weeks for 169 (27%), <or=4 weeks for 232 (37%), <or=5 weeks for 338 (54%), and <or=6 weeks for 376 (60%). Reports of serious adverse events due to typhoid vaccination were very rare. Vaccination should be considered even for persons planning short-term travel to high-risk areas.

Adolescent↗
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

Real-time polymerase chain reaction assay for the rapid detection and characterization of chloroquine-resistant Plasmodium falciparum malaria in returned travelers.

BACKGROUND: Imported drug-resistant malaria is a growing problem in industrialized countries. Rapid and accurate diagnosis is essential to prevent malaria-associated mortality in returned travelers. However, outside of a limited number of specialized centers, the microscopic diagnosis of malaria is slow, unreliable, and provides little information about drug resistance. Molecular diagnostics have the potential to overcome these limitations. OBJECTIVE: We developed and evaluated a rapid, real-time polymerase chain reaction (PCR) assay to detect Plasmodium falciparum malaria and chloroquine (CQ)-resistance determinants in returned travelers who are febrile. METHODS: A real-time PCR assay based on detection of the K76T mutation in PfCRT (K76T) of P. falciparum was developed on a LightCycler platform (Roche). The performance characteristics of the real-time assay were compared with those of the nested PCR-restriction fragment-length polymorphism (RFLP) and the sequence analyses of samples obtained from 200 febrile returned travelers, who included 125 infected with P. falciparum (48 of whom were infected CQ-susceptible [K76] and 77 of whom were CQ-resistant [T76] P. falciparum), 22 infected with Plasmodium vivax, 10 infected with Plasmodium ovale, 3 infected with Plasmodium malariae malaria, and 40 infected with other febrile syndromes. All patient samples were coded, and all analyses were performed blindly. RESULTS: The real-time PCR assay detected multiple pfcrt haplotypes associated with CQ resistance in geographically diverse malaria isolates acquired by travelers. Compared with nested-PCR RFLP (the reference standard), the real-time assay was 100% sensitive and 96.2% specific for detection of the P. falciparum K76T mutation. CONCLUSION: This assay is rapid, sensitive, and specific for the detection and characterization of CQ-resistant P. falciparum malaria in returned travelers. This assay is automated, standardized, and suitable for routine use in clinical diagnostic laboratories.

Animals↗
PubMedDate not supplied

Epidemiology of travelers' diarrhea and relative importance of various pathogens.

Each year 12 million persons travel from an industrialized country to a developing country in the tropics or subtropics. These travelers experience a high rate of diarrhea caused by a wide variety of enteric pathogens acquired by ingestion of contaminated food or water. One or more pathogens can be found in the stool of a majority of ill individuals. Enterotoxigenic Escherichia coli generally are the most frequently identified pathogens, having been found in a median of 42% of travelers' diarrheal episodes in studies in Latin America, 36% in Africa, and 16% in Asia. Other pathogens that cause diarrhea in a smaller fraction of ill travelers include Shigella species, Salmonella species, Campylobacter jejuni, Vibrio, Aeromonas hydrophila, Entamoeba histolytica, Giardia lamblia, rotavirus, and 27-nm viruses, including Norwalk virus. Other organisms that may cause a fraction of the episodes of travelers' diarrhea include Plesiomonas shigelloides, enteroadherent E. coli, adenovirus or other viruses, and Cryptosporidium. Mixed infections of two or more of these pathogens also occur.

Developing Countries↗
PubMedDate not supplied

Epidemiologic studies of travelers' diarrhea, severe gastrointestinal infections, and cholera.

A retrospective survey, which is based on interviews conducted between 1975 and 1984 with 20,000 European tourists returning from 15 destinations in various climatic zones, demonstrates that travelers' diarrhea is the most frequent health problem encountered by travelers in the tropics. The incidence varied from 4% to 51%, depending on the destination. High-risk groups were persons younger than 30 years, adventurous travelers, and travelers with preexisting gastrointestinal illnesses. Illness acquired at various geographic regions showed only minor differences in chronology and symptomatology. The clinical course of travelers' diarrhea was usually short and mild. Additionally, by longitudinal and retrospective analyses, the incidence and prognosis of gastrointestinal infections of greater severity that were acquired after a short stay in a developing country, such as giardiasis, amebiasis, typhoid fever, and cholera, were evaluated; typhoid fever and cholera, in particular, were found to be quite rare.

Adult↗
PubMedDate not supplied

Pathogens that cause travelers' diarrhea in Latin America and Africa.

With the advent of rapid and convenient means of transportation, millions of persons travel each year from industrialized to developing countries in the tropics and subtropics. These travelers are at risk for a variety of infectious diseases that are endemic in these areas; the most frequently occurring of these is diarrhea. Studies of groups of travelers to Latin America and Africa have found that approximately one-half develop diarrhea during their stay abroad. Etiologic investigations of these illnesses have demonstrated that the important agents that cause travelers' diarrhea are similar to those that cause diarrhea in children in the developing countries. One-third of the cases are associated with enterotoxin-producing strains of Escherichia coli. Smaller proportions appear to be due to rotavirus, Norwalk virus, Shigella, Salmonella, Giardia lamblia, and Entamoeba histolytica. Although they have not been fully evaluated in travelers' illnesses in Latin America or Africa, Campylobacter jejuni, Aeromonas hydrophila, other viruses, and Cryptosporidium probably cause some of the currently unexplained cases of diarrhea.

Africa↗
PubMedDate not supplied

Chronic diarrhea in travelers: diagnostic and therapeutic considerations.

Although the epidemiology, and pathophysiology of travelers' diarrhea are well understood, the long-term consequences of this syndrome are poorly appreciated. Many people struck with travelers' diarrhea do not completely recover but rather develop one of several chronic diarrheal syndromes. In some patients an episode of travelers' diarrhea seems to unmask a preexistent, underlying gastrointestinal disorder. The frequency of these complications and the magnitude of this problem are unknown. The differential diagnosis, diagnostic workup, and treatment of such patients have been outlined; unfortunately, many patients with chronic diarrhea elude diagnosis, and treatment is problematic. Some of the questions that must be answered include the following: What is the magnitude of the problem of chronic diarrhea following travelers' diarrhea? What is the natural history of patients with this syndrome? Which individuals are most likely to develop a chronic diarrheal syndrome, and can they be identified in advance? Are new etiologic agents involved in these chronic diarrheal syndromes? Answers to these questions will require well-organized, multicenter studies of a large number of travelers to various locales.

Chronic Disease↗
PubMed1981

Travelers' diarrhea among American Peace Corps volunteers in rural Thailand.

Diarrheal disease was studied prospectively in 35 Peace Corps volunteers during their first five weeks in rural Thailand. Twenty (57%) developed the syndrome of travelers' diarrhea. Recognized bacterial enteric pathogens were isolated from stools during 47% of 39 episodes of travelers' diarrhea. Enterotoxigenic Escherichia coli was isolated during 26% and Shigella during 13% of the episodes. Of the 20 volunteers, 50% had bacteriologic and/or serologic evidence of infection with enterotoxigenic E. coli. Sixty-one percent of isolates of enterotoxigenic E. coli and 92% of isolates of Shigella were resistant to doxycycline. Other enteric pathogens, including Campylobacter jejuni/coli, Yersinia enterocolitica, Salmonella, rotavirus, Norwalk agent, and Entamoeba histolytica, were associated with episodes of travelers' diarrhea. Aeromonas hydrophila, isolated from 31% of 39 episodes of travelers' diarrhea, was of unknown pathogenic importance. Thus, episodes of travelers' diarrhea in Thailand were associated with a variety of organisms, among which antibiotic-resistant bacterial enteropathogens were common.

Adult↗
PubMed1985

A newly recognized cause of travelers' diarrhea: enteroadherent Escherichia coli.

Adherence to HEp-2 tissue culture cells has been proposed as a virulence characteristic of enteropathogenic Escherichia coli (EPEC). A preliminary study revealed that E. coli that adhered to HEp-2 cells, but did not produce conventional enterotoxins and did not belong to recognized EPEC serogroups, could be isolated from adults from the United States who acquired diarrhea in Mexico. The purpose of this study was to determine the prevalence of these enteroadherent E. coli (EAEC) in 188 travelers with diarrhea and in 92 well travelers. EAEC were found in 14.9% of patients with diarrhea and in 7.6% of well individuals. Compared with well travelers, patients with diarrhea in whom no recognized enteropathogen could be identified had a 30.4% prevalence of EAEC (P less than .0003). These results further support our finding that EAEC are associated with diarrhea in travelers to Mexico and may help to explain the effect of antibiotics in the prevention and therapy for travelers' diarrhea in patients with no recognized bacterial enteropathogens.

Adhesiveness↗
PubMed1990

Prevalence and clinical importance of Entamoeba histolytica in two high-risk groups: travelers returning from the tropics and male homosexuals.

This study was undertaken to learn the prevalence of amebiasis and to assess the clinical importance of Entamoeba histolytica in two high-risk groups: 2700 travelers returning from the tropics and 320 male homosexuals. Some 16.3% of the homosexual men and 4.0% of the travelers had E. histolytica infections. Only five travelers showed a pathogenic zymodeme of E. histolytica, which correlated closely with invasive amebiasis with positive amebic serology and clinical symptoms with diarrhea. The homosexual group had neither a pathogenic isoenzyme pattern nor positive amebic serology. Currently, travelers to the tropics have a risk of 0.3% (1:340) of acquiring invasive amebiasis; 92.5% of all E. histolytica infections in travelers remain asymptomatic and are confirmed by serology and zymodeme status. No homosexual presented with invasive amebiasis.

Adult↗
PubMed1990

Antimicrobial resistance of Shigella isolates in the USA: the importance of international travelers.

A nationwide sample of Shigella isolates was collected and tested for resistance to 12 antimicrobial agents to assess the prevalence and epidemiologic correlates of antimicrobial resistance in Shigella. Of the isolates, 32% were resistant to ampicillin, 7% to trimethoprim-sulfamethoxazole, and 0.4% to nalidixic acid. Fifty (20%) of 252 isolates were associated with foreign travel. The best predictor of clinically important resistance was a history of foreign travel: 20% of isolates from foreign travelers showed trimethoprim-sulfamethoxazole resistance, compared with only 4% of isolates from those without such a history. Quinolone resistance was not identified in travel-related isolates, and quinolones may be more appropriate for initial therapy of travel-related shigellosis than is trimethoprim-sulfamethoxazole.

Anti-Bacterial Agents↗
PubMed1991

Trichinella infection in travelers.

To define the incidence of trichinosis associated with foreign travel and characterize the epidemiologic and clinical features of cases acquired abroad, all case report forms submitted to the Centers for Disease Control through state health departments and the National Morbidity Reporting System from 1975 to 1989 were reviewed. Twenty-six cases of travel-associated trichinosis were identified during that period. Most reported cases (73%) occurred between 1982 and 1987. Affected patients were more likely to have traveled to Mexico and Asian countries (65%). Reported high-risk behaviors included consumption of undercooked pork products, use of unsanitary cooking practices, and importation of potentially contaminated meat products into the United States. Trichinosis should be considered in the differential diagnosis of eosinophilia in travelers returning from abroad. Pretravel counseling that includes information concerning the risk of eating improperly prepared meat products may help future travelers minimize the risk of acquiring this illness.

Adolescent↗
PubMed1996

High prevalence of antibodies against circumsporozoite antigen of Plasmodium falciparum without development of symptomatic malaria in travelers returning from sub-Saharan Africa.

Circumsporozoite (CS) antibodies, indicating that falciparum malaria infection has occurred, have been shown to be reliable indicators of transmission in malaria-endemic areas. In order to estimate the actual rate of malaria infection, the prevalence of CS antibodies in serum was investigated by ELISA in a selected population of travelers returning from sub-Saharan Africa without any clinical sign of malaria. Sera from 39 (48.8%) of 80 individual travelers were positive, while this was only true for 8 (5.6%) of 142 travelers who took package tours. The risk of malaria infection was therefore 8.7 times greater for individual tourists than for package-tour travelers. These data demonstrate the importance of adequate malaria chemoprophylaxis in nonimmune travelers to areas with highly endemic disease.

Adolescent↗
PubMed1987

Norfloxacin versus placebo for prophylaxis against travellers' diarrhoea.

In a randomized, double blind study, 127 subjects travelling to countries outside Northern Europe were given norfloxacin 200 mg or placebo bid as prophylaxis against diarrhoea. Fifty-six subjects randomized to norfloxacin and 59 to placebo fulfilled criteria for evaluation of efficacy and of those, respectively six and 20 (P = 0.0006) developed diarrhoea. The mean duration of symptoms in the placebo group was 3.6 days, while all subjects on norfloxacin had symptoms for one day only. In travellers to Mediterranean Europe or the Canary Islands, no significant differences were seen between norfloxacin and placebo. Among subjects going to Africa, Asia or Latin America, 4/32 subjects on norfloxacin and 16/30 on placebo developed diarrhoea (P = 0.0004). Adverse effects were few and mild. Faeces for aerobic cultures was obtained before travelling and three weeks and then three months post-treatment. Treatment with norfloxacin resulted in a significant reduction of samples yielding aerobic Gram-negative rods but did not affect enterococci. In the placebo group, Gram-negative organisms other than Escherichia coli were increased on return to Sweden and the subjects frequently acquired Gram-negative organisms resistant to antibiotics. In none of the groups was there a tendency towards increased norfloxacin resistance. Biotyping of E. coli showed that in both groups the subjects changed their E. coli strains frequently during and after travelling. This trial showed that norfloxacin is a safe and effective prophylactic agent with no adverse effect on bacterial flora, but that its use should be restricted to travellers to non-European countries.

Adult↗
PubMed2003

Is patient travel distance associated with survival on phase II clinical trials in oncology?

BACKGROUND: Prior research has suggested that patients who travel out of their neighborhood for elective care from specialized medical centers may have better outcomes than local patients with the same illnesses who are treated at the same centers. We hypothesized that this phenomenon, often called "referral bias" or "distance bias," may also be evident in curative-intent cancer trials at specialized cancer centers. METHODS: We evaluated associations between overall survival and progression-free survival and the distance from the patient residence to the treating institution for 110 patients treated on one of four phase II curative-intent chemoradiotherapy protocols for locoregionally advanced squamous cell cancer of the head and neck conducted at the University of Chicago over 7 years. RESULTS: Using Cox regression that adjusted for standard patient-level disease and demographic factors and neighborhood-level economic factors, we found a positive association between the distance patients traveled from their residence to the treatment center and survival. Patients who lived more than 15 miles from the treating institution had only one-third the hazard of death of those living closer (hazard ratio [HR] = 0.32, 95% confidence interval [CI] = 0.12 to 0.84). Moreover, with every 10 miles that a patient traveled for care, the hazard of death decreased by 3.2% (HR = 0.97, 95% CI = 0.94 to 0.99). Similar results were obtained for progression-free survival. CONCLUSION: Results of phase II curative-intent clinical trials in oncology that are conducted at specialized cancer centers may be confounded by patient travel distance, which captures prognostic significance beyond cancer stage, performance status, and wealth. More work is needed to determine what unmeasured factors travel distance is mediating.

Adult↗
PubMed1984

Prophylactic doxycycline for travelers' diarrhea in Thailand. Further supportive evidence of Aeromonas hydrophila as an enteric pathogen.

A randomized double-blind study to determine the efficacy of a three-week course of doxycycline (100 mg daily) in preventing travelers' diarrhea was performed in 1980 among 63 United States Peace Corps volunteers during their first five weeks in Thailand, an area where doxycycline-resistant enterotoxigenic Escherichia coli are known to be common. Eight (24%) of 33 volunteers taking placebo and 3 (10%) of 30 taking doxycycline developed travelers' diarrhea for a calculated protection of 59%, but this was not statistically significant (p = 0.12). Aeromonas hydrophila was isolated from 8 to 19 volunteers with either travelers' diarrhea or mild diarrhea in the placebo group, but from only 1 of 12 in the doxycycline group (p less than or equal to 0.05). Furthermore, doxycycline significantly prevented colonization of the gastrointestinal tract with A. hydrophila while it was being taken (p less than or equal to 0.01). Enterotoxigenic E. coli was isolated from only one volunteer with travelers' diarrhea in the placebo group and from none in the doxycycline group. Doxycycline prophylaxis of travelers' diarrhea in this geographic area, though not shown to be significantly protective, further supports the role of A. hydrophila as an enteric pathogen.

Adult↗
PubMed1985

Health precautions for travelers to Mexico.

After Canada, Mexico is the most popular destination for Americans traveling outside the United States. As a developing country, Mexico presents numerous health hazards to American visitors, including the prevalent travelers' diarrhea (turista), from which 40% will suffer, and the less common typhoid, dengue, rabies, malaria, taeniasis, cysticercosis, and trichinosis. Environmental hazards, including sun, heat, high altitude, motion sickness, and accidents, also threaten the unwary traveler. In the event of illness or injury, Americans may find medical facilities unfamiliar and less well equipped than those in the United States. Utilizing both an individualized risk assessment for each traveler and readily available references, physicians, in partnership with local public health agencies, can develop comprehensive preventive health plans for their patients traveling to Mexico.

Diarrhea↗
PubMed2004

Coagulation changes and edema formation during long-distance bus travel.

Long-distance travel in a cramped position by aircraft or by bus and car has been suggested to be associated with an increased risk for thromboembolic events. Recently, we demonstrated moderate activation of coagulation after a long-haul flight. At present the single contributing factors (i.e. hypoxia and low humidity on board an aircraft and prolonged sitting in an aircraft, car or bus inducing venous stasis) have not yet been investigated. Therefore we measured markers of coagulation and fibrinolysis as well as functional parameters of coagulation using activated thrombelastography in 19 healthy volunteers before, during and after a real 10-h bus journey. In addition, changes in leg volume were measured. Thrombelastography revealed moderate activation of coagulation in all travelers, which was accompanied by a significant increase in prothrombin fragment F1 + 2. Thrombin-antithrombin III complexes and D-dimer remained unchanged, and tissue-type plasminogen activator and plasminogen-activator inhibitor 1 decreased after travel. After the travel we found a significant increase in leg volume that was exclusively distributed in the calf. We conclude that beside long-haul flights also long-distance bus travel induces a certain activation of the coagulation system. Thus, it is questionable whether hypoxia is the crucial risk factor for thromboembolic events after long-haul flights.

Aircraft↗