Climate change and malaria in Canada: a systems approach.

This article examines the potential for changes in imported and autochthonous malaria incidence in Canada as a consequence of climate change. Drawing on a systems framework, we qualitatively characterize and assess the potential direct and indirect impact of climate change on malaria in Canada within the context of other concurrent ecological and social trends. Competent malaria vectors currently exist in southern Canada, including within this range several major urban centres, and conditions here have historically supported endemic malaria transmission. Climate change will increase the occurrence of temperature conditions suitable for malaria transmission in Canada, which, combined with trends in international travel, immigration, drug resistance, and inexperience in both clinical and laboratory diagnosis, may increase malaria incidence in Canada and permit sporadic autochthonous cases. This conclusion challenges the general assumption of negligible malaria risk in Canada with climate change.

Detection of pathogenic protozoa in the diagnostic laboratory: result reproducibility, specimen pooling, and competency assessment.

Stool microscopy as performed in clinical parasitology laboratories is a complex procedure with subjective interpretation. Quality assurance (QA) programs often emphasize proficiency testing as an assessment tool. We describe a result reproducibility assessment tool, which can form part of a broader QA program, and which is based on the blinded resubmission of selected clinical samples, using concordance between the reports of the initial and resubmitted specimen as an indicator. Specimens preserved in sodium acetate-acetic acid-formalin can be stored for several months for use in such a program. The presence of multiple protozoa in one specimen does not affect concordance. Some dilution of specimens occurs in this process, and this may explain poor concordance when specimens with low protozoal concentrations are resubmitted. Evaluation of this tool in a large parasitology laboratory revealed concordance rates for pathogenic protozoa (Entamoeba histolytica/Entamoeba dispar, Giardia lamblia, and Dientamoeba fragilis) of about 80%, which may be considered for use as a benchmark value. We also used this tool to demonstrate that when pairs of specimens from one patient are pooled to create a single specimen, concordance between the results of the individual and pooled specimens is high.

Tattooing and transfusion-transmitted diseases in Brazil: a hospital-based cross-sectional matched study.

BACKGROUND: Presence of tattoos has been a criterion for temporary deferral of blood donors. Scientific evidence remains equivocal regarding the association between tattooing and transfusion-transmitted diseases (TTDs). METHODS: A cross-sectional matched study was undertaken among adults attending a Brazilian hospital and blood bank. The exposure of interest was having at least one permanent tattoo, and the outcomes were the presence of serological markers for the following TTDs: hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections, syphilis, and Chagas' disease. Exposed and unexposed subjects were matched on age, sex, and main clinical complaint. Associations were assessed by odds ratios (ORs), adjusted for confounders by unconditional logistic regression. FINDINGS: The study recruited 345 subjects, 182 with tattoos. Having a tattoo was associated with HCV (OR: 6.41; 95% confidence interval (CI) 1.29, 31.84), and with having at least one positive test for any TTD (OR: 2.05, 95% CI: 1.11, 3.81). No statistically significant associations were found between tattooing and HBV or HIV infection, syphilis or Chagas' disease, but these results are inconclusive given the large CI obtained. INTERPRETATION: Having a tattoo is not an important indicator for testing positive for a TTD, except for HCV infection. Taking into consideration the increasing prevalence of tattooing in the general population, the absolute need of a safe and sustainable blood supply and optimization of the cost-effectiveness of screening blood donors, further research on tattoos is urgently required.

Tattoos and transfusion-transmitted disease risk: implications for the screening of blood donors in Brazil.

Having a tattoo has been associated with serological evidence of hepatitis B and C viruses, as well as human immunodeficiency virus infections and syphilis; all of these are known to be transmissible by blood transfusion. These associations are of higher magnitude for individuals with nonprofessionally-applied tattoos and with two or more tattoos. Tattoos are common among drug addicts and prisoners, conditions that are also associated with transfusion-transmitted diseases. We examined the implications of these associations for the screening of blood donors in Brazil. Numbers of individuals who would be correctly or unnecessarily deferred from blood donation on the basis of the presence of tattoos, and on their number and type, were calculated for different prevalence situations based on published odds ratios. If having a tattoo was made a deferral criterion, cost savings (due to a reduced need for laboratory testing and subsequent follow-up) would accrue at the expense of the deferral of appropriate donors. Restricting deferral to more at-risk sub-groups of tattooed individuals would correctly defer less individuals and would also reduce the numbers of potential donors unnecessarily deferred. Key factors in balancing cost savings and unnecessary deferrals include the magnitude of the pool of blood donors in the population, the prevalence of individuals with tattoos and the culture of tattoos in the population. Tattoos can therefore be an efficient criterion for the screening of blood donors in certain settings, a finding that requires corroboration from larger population-based studies.

Tattoos and transfusion-transmitted disease risk: implications for the screening of blood donors in Brazil

Having a tattoo has been associated with serological evidence of hepatitis B and C viruses, as well as human immunodeficiency virus infections and syphilis; all of these are known to be transmissible by blood transfusion. These associations are of higher magnitude for individuals with nonprofessionally-applied tattoos and with two or more tattoos. Tattoos are common among drug addicts and prisoners, conditions that are also associated with transfusion-transmitted diseases. We examined the implications of these associations for the screening of blood donors in Brazil. Numbers of individuals who would be correctly or unnecessarily deferred from blood donation on the basis of the presence of tattoos, and on their number and type, were calculated for different prevalence situations based on published odds ratios. If having a tattoo was made a deferral criterion, cost savings (due to a reduced need for laboratory testing and subsequent follow-up) would accrue at the expense of the deferral of appropriate donors. Restricting deferral to more at-risk sub-groups of tattooed individuals would correctly defer less individuals and would also reduce the numbers of potential donors unnecessarily deferred. Key factors in balancing cost savings and unnecessary deferrals include the magnitude of the pool of blood donors in the population, the prevalence of individuals with tattoos and the culture of tattoos in the population. Tattoos can therefore be an efficient criterion for the screening of blood donors in certain settings, a finding that requires corroboration from larger population-based studies.

Tattooing and risk for transfusion-transmitted diseases: the role of the type, number and design of the tattoos, and the conditions in which they were performed.

Tattoos have been shown to be associated with transfusion-transmitted diseases (TTDs), particularly hepatitis B virus (HBV) and hepatitis C virus (HCV) infections. Very little is known about the association between different categories of tattoos and TTDs. In a cross-sectional study in Brazil, we studied 182 individuals with tattoos and assessed the odds of testing positive for a TTD according to tattoo type, number, design and performance conditions. Major findings were significant associations between an increasing number of tattoos and HBV infection (odds ratio (OR) of 2.04 for two tattoos and 3.48 for > or = 3 tattoos), having a non-professional tattoo and testing positive for at least one TTD (OR = 3.25), and having > or = 3 tattoos and testing positive for at least one TTD (OR = 2.98). We suggest that non-professional tattoos and number of tattoos should be assessed as potential deferral criteria in screening blood donors.

Increasing referral of at-risk travelers to travel health clinics: evaluation of a health promotion intervention targeted to travel agents.

BACKGROUND: Increases in travel-related illness require new partnerships to ensure travelers are prepared for health risks abroad. The travel agent is one such partner and efforts to encourage travel agents to refer at-risk travelers to travel health clinics may help in reducing travel-attributable morbidity. METHODS: A health promotion intervention encouraging travel agents to refer at-risk travelers to travel health clinics was evaluated. Information on the knowledge, attitudes, and behaviors of travel agents before and after the intervention was compared using two self-administered questionnaires. The Wilcoxon signed rank test was used to compare the mean difference in overall scores to evaluate the overall impact of the intervention and also subscores for each of the behavioral construct groupings (attitudes, barriers, intent, and subjective norms). Multiple regression techniques were used to evaluate which travel agent characteristics were independently associated with a stronger effect of the intervention. RESULTS: A small improvement in travel agents overall attitudes and beliefs (p =.03) was found, in particular their intention to refer (p =.01). Sixty-five percent of travel agents self-reported an increase in referral behavior; owners or managers of the agency were significantly more likely to do so than other travel agents (OR = 7.25; 95% CI: 1.64 32.06). Older travel agents, those that worked longer hours and those with some past referral experience, had significantly higher post-intervention scores. CONCLUSIONS: Travel agents can be willing partners in referral, and agencies should be encouraged to develop specific referral policies. Future research may be directed toward investigating the role of health education in certification curricula, the effectiveness of different types of health promotion interventions, including Internet-facilitated interventions, and the direct impact that such interventions would have on travelers attending travel health clinics.

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.

Wheat germ supplement reduces cyst and trophozoite passage in people with giardiasis.

The protozoan parasite Giardia lamblia is a major cause of waterborne enteric disease worldwide. Lectins are proteins that bind to carbohydrate (sugar) moieties. Potential targets for lectins are found on the surface of most single-celled organisms. Modest concentrations of wheat germ agglutinin (WGA) have been shown to inhibit G. lamblia excystation and trophozoite growth in vitro and can reduce cyst passage in mice infected with the closely related protozoan parasite, G. muris. Commercial preparations of wheat germ (WG) contain 13-53 microg of WGA per gram. We performed a double-masked, placebo-controlled study of dietary supplementation with WG in 63 subjects with giardiasis in Montreal and Lima (25 asymptomatic patients passing cysts; 38 patients with symptoms). Asymptomatic subjects received WG (2 g, 3 times a day) or placebo (cornstarch, 2 g, 3 times a day) for 10 days, followed by metronidazole (250 mg 3 times a day) for 7 days. Symptomatic subjects received metronidazole (250 mg 3 times a day) plus either WG or placebo for 7 days. Stool specimens were collected every day (Montreal) or every other day (Lima) for 10 days and on Day 35 for microscopic examination and coproantigen determination. Subjects kept a diary of symptoms for 10 days after recruitment. In asymptomatic subjects, both cyst passage and coproantigen levels were reduced by approximately 50% in those taking WG compared with the placebo group (P < 0.01 and P = 0.06, respectively). In symptomatic subjects, cyst passage and coproantigen levels fell precipitously in response to metronidazole therapy, and there were no clinically important differences between those receiving supplemental WG or placebo. However, symptoms appear to have resolved more rapidly in the subjects taking WG in addition to metronidazole. The WG supplement was well tolerated in both symptomatic and asymptomatic subjects. These data suggest that components of WG, possibly WGA, either alone or in combination with antiprotozoal agents, can influence the course of human giardiasis.

Outbreak of cutaneous larva migrans in a group of travellers.

We describe an outbreak of cutaneous larva migrans (CLM) in a group of 140 holidaymakers to a resort in Barbados and the index case. methods A two-page questionnaire was mailed to holidaymakers and 90% responded. results 25.4% of respondents developed a rash consistent with CLM. Risk factors for developing the illness were younger age and less frequent use of protective footwear while walking to the beach. Patients had difficulty in obtaining a correct diagnosis during their initial medical consultation and in obtaining medication from pharmacies. Efficacious treatments were oral and topical thiabendazole. conclusions CLM can occur in a large proportion of people exposed to contaminated soil or sand. Protective footwear is effective in reducing infection. Thiabendazole is an efficacious treatment.

Trypanosoma cruzi infection of squirrel monkeys: comparison of blood smear examination, commercial enzyme-linked immunosorbent assay, and polymerase chain reaction analysis as screening tests for evaluation of monkey-related injuries.

BACKGROUND AND PURPOSE: Wild-caught New World monkeys (NWM) from Central or South America are often infected with Trypanosoma species, including T. cruzi. In humans, T. cruzi causes Chagas' disease. Even in closed monkey colonies, T. cruzi can be propagated by blood-to-blood exposure, sexual activity, and transplacental transmission. Animal handlers and laboratory staff who deal with blood and tissues from infected NWM are at riskfor acquiring Chagas' disease via accidental exposure. METHODS: We screened 162 blood samples from wild-caught Saimiri sp. monkeys for Trypanosoma species infections by use of blood smear examination, ELISA, and polymerase chain reaction (PCR) analysis. Blood samples from 19 employees with recent history of monkey-associated injuries also were tested. RESULTS: Six percent (10/162) of the monkey samples were T. cruzi positive on the basis of blood smear examination results, 10.4% (17/162) were positive by ELISA results, and 26.5% (43/162) were positive by PCR results. Other organisms identified by PCR analysis included T. rangeli in two animals, Plasmodium spp. in two animals (P. malariae confirmed by PCR results) and microfilariae in one animal (morphologically, Mansonella perstans). Evidence of trypanosome infection was not found in the 19 employee samples on the basis of results of any of the three aforementioned tests. CONCLUSIONS: Close attention must be paid to worker safety where wild-caught NWM are used. The PCR analysis has a clear advantage over conventional techniques (ELISA, blood smear) for screening NWM for trypanosome infections during quarantine and after employee injury.

Mycobacterium ulcerans infection (Buruli ulcer): first reported case in a traveler.

A chronic, painless sore developed over a 2-month period on the left calf of a Canadian man traveling for 8 months in Africa. A presumptive diagnosis of a Mycobacterium spp. infection was made despite initially negative biopsy and culture results, after failure of several courses of anti-bacterial antibiotics. Mycobacterium ulcerans was eventually isolated and the lesion progressed despite treatment with multiple anti-mycobacterial agents. The lesion finally responded to wide and repeated excision, aggressive treatment with anti-mycobacterial antibiotics, and split-thickness skin grafting. The isolation and treatment of this unusual organism are discussed.

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.

Screening returning travelers.

Posttravel screening is the clinical and laboratory assessment of an individual aimed at uncovering occult infections, pathology, or health risks, the treatment of which will yield a significant health benefit to the individual. Screening must be tailored to the different risk patterns associated with different travel categories (e.g., missionary, tourist). Screening, predominantly a secondary prevention strategy, is most cost-effective when integrated with primary prevention strategies aimed at preventing future travel related illness (Table 6). The screening process begins with a medical history that allows a definition of risks and a tailored approach to laboratory tests. The screening tests currently available for STDs, tuberculosis, and parasitic infections have been reviewed, and although cost-effectiveness data are not available for most post-travel screening tests, recommended approaches are proposed. Traditionally, screening has been directed at uncovering occult infectious disease (STDs, tuberculosis, and parasitic infections). Important benefits can be gained, however, by including screening questions and tests for those diseases that are the major causes of mortality, both in nontraveling and in traveling North Americans, that is, the atherosclerotic and neoplastic diseases and trauma, especially vehicular.