Parasitic and infectious diseases of the biliary tract in migrants and international travelers

Introduction: In recent years, global and regional crises have led to extraordinary worldwide migration, accompanied by an increase in long-distance travel from Western countries. Both are linked to a rising incidence of rare parasitic and infectious diseases in first world countries, including in the biliary tract.

Areas covered: A selective literature research in PubMed was performed to review the most important parasitic and infectious biliary diseases, which are caused by a wide variety of pathogens and may be latent over long periods, with chronic courses leading to cholangitis, hepatic failure or development of cholangiocarcinoma. Parasites such as Ascaris, Fasciola and Clonorchis/Opisthorchis are particularly important and may trigger biliary diseases or predisposition for bacterial superinfections. Viral or protozoal cholangitis is mainly a problem of impaired immunity.

Expert commentary: Currently, these entities are still rare in migrants and long-distance travelers. However, a significant increase in Western countries has to be expected. Incidences are most likely underestimated because of protracted clinical latency. Diagnosis depends on the relevant pathogens, the host’s immune status and the extent or distribution of biliary obstruction. Modern tomographic methods, ERCP and specific microbiological/parasitological/virological tests are of crucial diagnostic importance. Antimicrobial/antiparasitic/antiviral therapy along with ERCP and interventional sonography/radiology provide effective treatment options.     

Parasitic nematode modulation of allergic disease

Incidence of allergic diseases such as asthma has increased at an alarming rate in Western countries in the past few decades. However, in parts of the world in which parasitic nematode infections are highly prevalent, allergy remains uncommon. Hence, it has been postulated that nematodes offer humans protection against this type of disease. This article reviews the evidence to support this idea, considering data from human studies and results from investigations into the protective effects of nematodes in animal models of allergic disease. The evidence strongly favors a protective role for nematodes; thus, the search is on to find the molecules involved, with a view toward using them for therapeutic purposes. The article also describes the nature and mode of action of recently characterized nematode-derived molecules with antiallergic properties and highlights their therapeutic efficacy in allergy models.     

Risk assessment and disease prevention in travelers visiting friends and relatives

Although VFR travelers are at risk for acquiring infections and experiencing illness while traveling, many of these diseases are preventable. A comprehensive approach to decreasing their travel-related morbidity requires continued surveillance, data collection, systematic analysis, and action. A review of the literature provides few examples of interventions designed specifically to address VFR travel needs. Given the geographic and cultural diversity of these populations, models grounded in health behavior theory provide the best potential for clinically relevant replication. Outreach aimed at improving knowledge and care-seeking behaviors among VFR travelers may be facilitated through community-based campaigns in areas with large foreign-born populations. In developed countries, policies must be reviewed to ensure that travel-related services are accessible, affordable, and appropriate for these diverse populations. In the clinical setting, providers must develop culturally appropriate methods of communicating with traveling populations to influence behavior. In particular, primary care providers should take an active approach through screening for high-risk travel, and increasing their competency in travel medicine. Special attention should be given to illness that is prevented by routine childhood immunization (eg, varicella, measles, and hepatitis B); by disease prevented by travel vaccines (eg, typhoid fever and hepatitis A); and disease that can be prevented by careful avoidance measures or compliance with preventive medication (eg, malaria and tuberculosis).With increased immigration from developing to developed regions and widely affordable travel, the number of VFR travelers is expected to increase. As such, increased efforts to prevent VFR traveler morbidity serve the individual while also contributing to global public health.     

Vaccination in travelers

Vaccination of populations throughout the world has led to dramatic decreases in morbidity and mortality from many infectious diseases, including poliomyelitis and measles. In the United States, for example, morbidity and mortality from invasive disease from Haemophilus influenzae type b has decreased more than 99%. International travelers should ensure that they are up-to-date on their routine immunizations and then consider vaccination against other diseases based on risk. This article reviews new vaccines such as those against rotavirus, Lyme disease, and enterotoxigenic Escherichia coli and provides updated information on the risk of typhoid fever and the efficacy of vaccination against it. The use of hepatitis A vaccine in outbreak control, the safety of yellow fever vaccine, and the importance of protecting travelers against rabies exposure are also discussed. Vaccination is an important way for travelers to maintain their health before, during, and after travel.     

Inflammatory bowel disease in travelers: choosing the right vaccines and check-ups

The majority of patients with inflammatory bowel disease (IBD) achieve good control of the inflammatory activity using available therapies. When remission is achieved and quality of life recovered, a considerable proportion of IBD patients express their desire to travel abroad, be it for business, academic or leisure purposes. Their physicians should help and encourage them whenever possible. However, preventive measures are warranted to minimize the risk, since IBD patients are exposed to the same infectio...     

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.     

Malaria prevention in travelers

A common approach to malaria prevention is to follow the "A, B, C, D" rule: Awareness of risk, Bite avoidance, Compliance with chemoprophylaxis, and prompt Diagnosis in case of fever. The risk of acquiring malaria depends on the length and intensity of exposure; the risk of developing severe disease is primarily determined by the health status of the traveler. These parameters need to be assessed before recommending chemoprophylaxis and/or stand-by emergency treatment. This review discusses the different strategies and drug options available for the prevention of malaria during and post travel.     

Meningococcal vaccine in travelers

PURPOSE OF REVIEW: New vaccines to prevent meningococcal disease have been licensed in recent years. It is therefore timely to discuss current vaccine strategies pertinent to international travelers in relation to the changing epidemiology. RECENT FINDINGS: Serogroup W135 achieved epidemic status in Africa in 2002, and then largely disappeared over a short time period. The year 2006 saw a marked epidemic rise in meningitis attack rates across the meningitis belt in Africa. This rise was mainly due to a new serogroup A strain, indicating that a new meningitis epidemic wave is beginning in Africa. Epidemics are also spreading south of the meningitis belt, including the Greater Lakes Area (Burundi, Rwanda, Republic of Tanzania). The new quadrivalent conjugate meningococcal vaccine is now licensed in North America but not elsewhere. In most other industrialized countries, the serogroup C conjugate vaccine is licensed. Plain polysaccharide quadrivalent vaccines are available almost worldwide. SUMMARY: Quadrivalent meningococcal vaccination is a visa requirement for Hajj and Umrah pilgrims to Saudi Arabia. Travelers to the meningitis belt during the dry season should be advised to receive meningococcal vaccine that covers all four serogroups. This recommendation should be extended to the Greater Lake Area, because of recent epidemics. Vaccine choices depend on availability.     

Rickettsial diseases in travelers

Often undiagnosed in travelers with acute nonspecific febrile illness, gastrointestinal, abdominal, pulmonary, neurologic, or cutaneous signs and symptoms, rickettsial diseases are transmitted in particular geographic and ecologic settings by ticks, fleas, chiggers, and lice. Recognition of an eschar at the vector inoculation site can be a key diagnostic clue for scrub typhus, African tick bite fever, and other tick-borne spotted fevers. Although laboratory confirmation is necessary, usually during convalescence, for an accurate diagnosis, a clinical diagnosis and empiric treatment with doxycycline are the standard practical approach. Knowledge of potential exposure, the natural history of the infection, and incubation periods of each rickettsiosis assist in considering particular rickettsioses.     

Simultaneous vaccination in Japanese travelers

BACKGROUND: Simultaneous vaccination is not common in Japan because there is little information available on its effects. Some people are quite concerned about the possibility of adverse reactions due to simultaneous vaccination. The objective of this study was to evaluate whether the frequency and severity of adverse effects are increased by simultaneous vaccination in comparison to single vaccination. METHOD: A retrospective observational study was conducted in 399 asymptomatic travelers who visited the travel clinic during the period January-July 2005. One hundred forty-two participants were given a single vaccination, 257 participants were given simultaneous vaccination. Travel-specific vaccinations were for hepatitis A, hepatitis B, tetanus, rabies and Japanese encephalitis, and routine vaccines were for diphtheria+tetanus, measles, mumps and oral polio vaccine. To evaluate adverse effects, travelers were asked to complete a prepared questionnaire after vaccination. RESULTS: Adverse effects were reported by 26.3% of travelers, with 21.8% reporting local reactions and 4.5% reporting systemic reactions. The simultaneous vaccination group reported significantly more frequent adverse effects than those reported by the single vaccination group. Particularly, tetanus vaccination was shown to significantly raise the risk of adverse effects (P<0.001). However, no serious adverse effects were reported. CONCLUSIONS: Simultaneous vaccination was feasible for Japanese travelers because most problems were generally minor and related to local reactions at the sites of injections. Provision of a simultaneous vaccination schedule should motivate more Japanese travelers to obtain immunizations and thereby reduce the risk of vaccine-preventable diseases.