The sero-prevalence of antibodies to trypanosoma cruzi in Latin American refugees and immigrants to Canada.

BACKGROUND: Chagas' disease is caused by infection with the protozoan agent Trypanosoma cruzi. An estimated sixteen to eighteen million people are infected in Latin America. Outside of endemic regions, Chagas' disease may be transmitted through the transfusion of infected blood components, congenital infection and organ transplantation. We sought to determine the sero-prevalence of antibodies to T. cruzi in a community sample of Latin American refugees and immigrants to Canada. METHODS: This was a sero-prevalence study in Latin American refugees and immigrants living in Canada. Eligible subjects were born in South America, Central America or in Mexico. Participants were recruited from a variety of community settings, as well as from medical clinics. Serum was tested by enzyme-linked immunoassay for antibodies to T. cruzi. RESULTS: A total of 102 participants were enrolled. One sample tested positive for antibodies for T. cruzi. The seroprevalence in our sample was 1.0% (95% CI: 0.2%- 5.3%). INTERPRETATION: We found a low sero-prevalence of Chagas' disease in a community sample of Latin American immigrants and refugees. Physicians who treat Latin American immigrants should consider the risk profile and clinical status of the individual in their decision to screen for Chagas' disease.

Malaria chemoprophylaxis in the age of drug resistance. II. Drugs that may be available in the future.

All current regimens of malaria chemoprophylaxis have serious drawbacks as a result of either suboptimal efficacy, difficulty with medication compliance, or adverse events. Two 8-aminoquinolines may be approaching registration, with primaquine having completed its prophylactic field testing and tafenoquine having begun advanced field testing at the end of 2000. Primaquine has long been used for management of relapses of malaria, but in the past decade, it has been reexamined for use in malaria prevention in order to stop infection in the liver. In field trials performed in Indonesia and Colombia, the efficacy of primaquine for malaria prevention was approximately 90%, compared with that of placebo. Because of its short half-life, primaquine requires daily administration. For adults, the prevention regimen is 30 mg base daily (0.5 mg base/kg/day), and it can probably be discontinued soon after departure from an area where malaria is endemic. To kill parasites that already exist in the liver, terminal prophylaxis is given after exposure to relapses of malaria infection; for adults, such prophylaxis usually consists of 15 mg base (0.3 mg base/kg/day) given daily for 2 weeks. Primaquine-induced gastrointestinal disturbances can be minimized if the drug is taken with food. Neither primaquine nor tafenoquine should be given to persons with glucose-6-phosphate dehydrogenase deficiency, to avoid the development of potentially severe drug-induced hemolysis. Tafenoquine is an analogue of primaquine that is more potent than the parent drug. Field trials in Kenya, Ghana, Gabon, and Southeast Asia have demonstrated an efficacy rate of approximately 90% for tafenoquine. Its long half-life allows for infrequent dosing (currently tested at 200 mg base/week), and its effect on parasites at the liver stage may allow for drug discontinuation at the time of departure from the area of endemicity.

Malaria chemoprophylaxis in the age of drug resistance. I. Currently recommended drug regimens.

As international travel becomes increasingly common and resistance to antimalarial drugs escalates, a growing number of travelers are at risk for contracting malaria. Parasite resistance to chloroquine and proguanil and real or perceived intolerance among patients to standard prophylactic agents such as mefloquine have highlighted the need for new antimalarial drugs. Promising new regimens include atovaquone and proguanil, in combination; primaquine; and a related 8-aminoquinoline, tafenoquine. These agents are active against the liver stage of the malaria parasite and therefore can be discontinued shortly after the traveler leaves an area where malaria is endemic, which encourages adherence to the treatment regimen. Part 1 of this series reviews currently recommended chemoprophylactic drug regimens, and part 2 will focus on 8-aminoquinoline drugs.

Malaria deaths in visitors to Canada and in Canadian travellers: a case series.

Over the last decade there has been a marked increase in case of drug-resistant and severe malaria in Canadian travellers. We report 7 deaths due to falciparum malaria that occurred in Canada or in Canadian travellers. Risks for malaria infection include inappropriate recommendations for malaria prevention by health care providers and lack of knowledge about or adherence to appropriate recommendations by the travelling public. Risks for death include delays in seeking medical attention, delays in diagnosis and inadequate care by Canadian physicians and hospitals, and lack of access to parenteral therapy for severe malaria. Malaria infections and deaths are preventable. Better education of health care providers and travellers about the risks of malaria and appropriate prevention and treatment measures may decrease this unnecessary burden on the Canadian health care system.

Internet and computer-based resources for travel medicine practitioners.

The field of travel medicine is concerned primarily with ways to maintain the health of international travelers. Remaining current in this area requires up-to-date knowledge of global infectious diseases, patterns of drug resistance, advances in preventive measures, and public health regulations pertaining to the crossing of international borders. This review of off-line commercial databases and Internet sources will assist infectious disease consultants in accessing current reliable travel health information. Of the North American pretravel off-line databases, TRAVAX (United States) and The Medical Letter are the most comprehensive, whereas the Global Infectious Disease and Epidemiology Network is extraordinary in its provision of global infectious disease epidemiology for posttravel assessment. A total of 65 Web sites are listed within 9 categories, covering such areas as authoritative government travel health recommendations, commercially-oriented sites, and travel medicine listserv discussion groups. Even among reputable Web sites, contradictory information may be found that demands careful consideration by the clinician and by the traveling public.

An outbreak of cyclosporiasis in 1996 associated with consumption of fresh berries- Ontario.

BACKGROUND: A large foodborne outbreak of cyclosporiasis occurred in North America in 1996. An index cluster of cases associated with a catered event on May 11, 1996, in Ontario sparked the recognition of this outbreak in Canada. OBJECTIVES: To describe the Ontario experience with the North American outbreak of cyclosporiasis in 1996. PATIENTS AND METHODS: Public health units investigated the index and subsequent event-associated clusters. Investigations included retrospective cohort studies of clusters, traceback of suspect foods and a case-control study of sporadic cases. These activities, coordinated with those in the United States, were part of an international investigation. RESULTS: In Ontario, 232 cases of cyclosporiasis (20 laboratory-confirmed and 72 clinically defined cases associated with seven events plus 140 additional laboratory-confirmed sporadic cases) were identified between May 1 and July 30, 1996. For the index cluster, a strawberry flan with raspberries and blueberries was the only significant exposure (relative risk 2.16, P=0.02). Fresh berries were served at all seven events associated with clusters of cases. Raspberries were definitely served at three events, possibly served at three events, and not served at one event. Only imported berries were available in Ontario in May 1996, when initial clusters and sporadic cases were identified. The raspberries served at the two events with well documented traceback data came from Guatemala. Univariate analyses of the matched case-control study demonstrated that illness was associated with consumption of raspberries (matched odds ratio 21.0, 95% CI 3.48 to 448) and strawberries (matched odds ratio 28.5, 95% CI 4.02 to 478). Further evidence amassed by the international investigation compellingly implicated Guatemalan raspberries as the vehicle of the outbreak. CONCLUSION: Cyclosporiasis may be acquired domestically from the consumption of contaminated produce. The scope and vehicle of this international foodborne outbreak were recognized through a coordinated public health response.

Entamoeba histolytica and Entamoeba dispar: epidemiology and comparison of diagnostic methods in a setting of nonendemicity.

Recent studies suggest that stool antigen assays are more sensitive and specific than microscopy for the diagnosis of Entamoeba histolytica infection. One hundred twelve patients presenting at 3 centers with symptoms or risk factors of E. histolytica infection were prospectively enrolled in this study to evaluate new diagnostic tests for infections with E. histolytica and Entamoeba dispar. Four ELISA-based stool antigen kits for detecting E. histolytica or E. dispar were blindly compared with stool microscopy. Amebic serology was assessed by indirect hemagglutination. When antigen assays were used as the reference standard, microscopy performed at referral centers was more specific (68.4% vs. 9.5%) but less sensitive (70.4% vs. 92.1%) than microscopy performed in community laboratories. Diagnosis with the E. histolytica test and Merlin Optimun S ELISA indicated that only 3 (4.2%) of 72 coproantigen-positive stools were positive for E. histolytica. Indirect hemagglutination was a good predictor of E. histolytica infection when titers of antibody to ameba were >/=1:512.

Evaluation of fever in the returned traveler.

The differential diagnosis of a febrile illness in the returned traveler is extensive. The most commonly encountered tropical infections are malaria, dysentery, hepatitis, and dengue fever; a substantial number of febrile illnesses are never diagnosed. Malaria is by far the most important infection to consider in the returned traveler who presents with fever. As international travel continues to increase in popularity, the ongoing need for clinicians to broaden their knowledge of travel-related diseases is evident. The ability to recognize and manage tropical diseases in travelers is essential because the morbidity and mortality of these infections are often preventable with prompt therapy. When expertise in this area is lacking, febrile returned travelers should be referred to a tropical disease unit or an infectious disease consultant for urgent assessment.

The role of corticosteroids in the treatment of cerebral schistosomiasis caused by Schistosoma mansoni: case report and discussion.

A 26-year-old Brazilian man was admitted to The Toronto Hospital with a headache and visual scintillation. His last travel to Brazil was five years previously. A computed tomography (CT) scan of the head showed an occipital mass with surrounding vasogenic edema. Occipital brain biopsy revealed Schistosoma mansoni eggs. The patient was treated with two doses of praziquantel (20 mg/kg) and dexamethasone (10 mg). His symptoms and occipital mass resolved. Cerebral schistosomiasis is, in part, caused by the host's inflammatory response to Schistosoma. Modes of treatment have included surgical resection, the antiparasitic drugs oxamniquine or praziquantel, and corticosteroids. Corticosteroids may diminish granulomatous inflammation, thereby preventing further tissue destruction, and there is evidence that they also reduce ova deposition. Our review of the literature supports prompt medical therapy in patients with cerebral schistosomiasis. While the minimally or asymptomatic individual may be treated with praziquantel alone, clinicians should consider adjunctive therapy with corticosteroids for patients with prominent neurologic signs or symptoms or mass lesions with evidence of surrounding edema on a CT scan or by magnetic resonance imaging.

Vaccination of travelers against hepatitis A and B.

Despite the fact that effective preventive measures have become available, there has been no decline in the incidences of both hepatitis A and hepatitis B in most industrialized countries to date. This is, in part, due to the rapid increase in the number of travelers to areas of medium and high endemicity for both diseases, primarily developing countries. Targeting of travelers at risk of contracting these diseases for vaccination offers a chance of significantly reducing their incidence. Hepatitis A, an acute disease associated with poor food hygiene, is the most common vaccine-preventable infection in travelers. Hepatitis A immunity should, therefore, be considered essential for anyone visiting an area of high endemicity. In contrast, hepatitis B is a blood-borne virus which was thought, until recently, to pose a relatively low risk to the majority of travelers. However, the 1990s has seen international tourism and business travel grow faster in Europe than anywhere else in the world, with travel to areas of high endemicity for hepatitis B (Africa, Asia and South America) being commonplace. Thus the number of reported hepatitis B cases is increasing in many countries. Furthermore, there is considerable overlap of high-endemicity areas of hepatitis A and hepatitis B so that travelers are often considered to be at risk from both viruses. As well as separate hepatitis A and B vaccine preparations, a combined hepatitis A and B vaccine is now available which may offer improvements in vaccination schedule, enhanced patient compliance, and reduced cost.

Reactivation of neurocysticercosis: case report.

A 37-year-old woman with a known history of longstanding neurocysticercosis presented with a three-day history of new onset headache. Several years prior to her current presentation, she had undergone cysticidal treatment and was assumed to be cured of active disease. Computed tomography and magnetic resonance imaging studies done three months prior to presentation showed multiple intracerebral calcified lesions consistent with resolved neurocysticercosis. Physical and laboratory findings were noncontributory. Imaging studies showed the same previously calcified lesions, but they were now surrounded by large amounts of edema. This case represents a unique report of reactivation of neurocysticercosis and raises interesting questions about the natural history of this infection.

Cultural sensitivity training among foreign medical graduates.

OBJECTIVES: To examine the effectiveness of culture sensitivity training for foreign-trained medical graduates licensed to practice in Ontario, Canada. DESIGN: A study of pretest-post-test design was conducted to determine the effect of cultural sensitivity training on newly immigrated physicians licensed in Canada. Twenty-four physicians, those who had passed the medical licensing exam in 1996 and had not yet started their residency program, were given 15 hours of cultural sensitivity training and were considered the experimental group. This group was compared with a control group of 24 physicians who had passed the licensing exam and were in the process of completing residency. SETTING: University of Toronto. SUBJECTS: Foreign-trained medical graduates. RESULTS: Both groups completed the Cross-Cultural Adaptability Inventory both before and after the training of the experimental group. Statistical significance in three subscales of the Open-Mindedness/Flexibility, Emotional Resilience and Perceptual Acuity dimensions were demonstrated in the experimental group as compared with the control group. CONCLUSIONS: In order for Canada to mould professional and effective physicians great care must be taken in the design and process of cultural sensitivity programmes to enhance both knowledge and skills. Follow-up should be undertaken to compare their effectiveness with the control group.

Survey of use of malaria prevention measures by Canadians visiting India.

BACKGROUND: Imported malaria is an increasing problem, particularly among new immigrant populations. The objective of this study was to determine the malaria prevention measures used by Canadians originating from a malaria-endemic area when returning to visit their country of origin. METHODS: A 35-item English-language questionnaire was administered by interview to travellers at a departure lounge at Pearson International Airport, Toronto, between January and June 1995. Information was collected on subject characteristics, travel itinerary, perceptions about malaria, and pretravel health advice and malaria chemoprophylaxis and barriers to their use. RESULTS: A total of 324 travellers departing on flights to India were approached, of whom 307 (95%) agreed to participate in the study. Participants were Canadian residents of south Asian origin with a mean duration of residence in Canada of 12.8 years. Most of the respondents were returning to visit relatives for a mean visit duration of 6.8 weeks. Although 69% of the respondents thought malaria was a moderate to severe illness and 54% had sought advice before travelling, only 31% intended to use any chemoprophylaxis, and less than 10% were using measures to prevent mosquito bites. Only 7% had been prescribed a recommended drug regimen. Family practitioners were the primary source of information for travellers and were more likely to prescribe an inappropriate chemoprophylactic regimen than were travel clinics or public health centres (76% v. 36%) (p = 0.003). Respondents who had lived in Canada longest and those with a family history of malaria were more likely to use chemoprophylaxis (p < 0.01). INTERPRETATION: Few travellers were using appropriate chemoprophylaxis and mosquito prevention measures. Misconceptions about malaria risk and appropriate prevention measures were the main barriers identified.