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Biomedical subjects

T W Gyorkos

Publications and source records attributed to T W Gyorkos.

At least 19 recordsLinked to original sources
PubMed1996

Common-source outbreak of acute infection due to the North American liver fluke Metorchis conjunctus.

BACKGROUND: We investigated an outbreak of acute clinical illness among 19 people who ate raw fish (sashimi) prepared from the white sucker, Catostomus commersoni, caught in a river north of Montreal, Canada. METHODS: We collected epidemiological, clinical, laboratory, and serological data on 19 individuals who ate the sashimi and six who did not. Because of the suggestive clinical picture, we set out to recover helminth parasites from uneaten fish. FINDINGS: The illness consisted of persistent upper abdominal pain, low grade fever, high blood eosinophil concentrations, and raised liver enzymes. After 10 days, opisthorchild-like eggs were found in stools. Symptoms persisted for 3 days to 4 weeks without treatment, but responded rapidly to praziquantel therapy. Necropsy of golden hamsters infected with metacercariae from uneaten fish revealed adult flukes identified as Metorchis conjunctus. INTERPRETATION: We describe an acute illness caused by the North American liver fluke M conjunctus. This is a new human disease and is the first report of a common-source outbreak of an acute illness caused by liver flukes of the family Opisthorchiidae.

Adult↗
PubMed1996

Randomized controlled trial of artesunate plus tetracycline versus standard treatment (quinine plus tetracycline) for uncomplicated Plasmodium falciparum malaria in Brazil.

A triple-blind, randomized, clinical trial was undertaken in a Brazilian Amazon region to compare the effectiveness of oral artesunate (seven days, total dose = 0.75 g) plus tetracycline (seven days, total dose = 10.5 g) (AT) and oral quinine (three days, total dose = 6 g) plus tetracycline (seven days, total dose = 10.5 g) (QT) against uncomplicated Plasmodium falciparum malaria. Effectiveness was assessed by cure rates (World Health Organization [WHO]) and parasite clearance at day 2. Patients were randomized, 88 to each group. The groups had similar baseline clinical characteristics. The incidence of side effects was much higher in the QT group (82%) than in the AT group (50%) (P < 0.001). Cure rates were similar: 80% in the AT group and 77% in the QT group (P = 0.68). Parasitemia (by day 2) cleared faster in the AT group than in the QT group (98.5% versus 47.6%, respectively; P < 0.001). These results indicate that the combination of artesunate plus tetracycline is effective in the treatment of uncomplicated falciparum malaria and may provide a useful alternative to other treatment regimens.

Adolescent↗
PubMed1995

Imported malaria. Clinical presentation and examination of symptomatic travelers.

BACKGROUND: The diagnosis of malaria in nonendemic countries presents a continuing challenge. Increasing physician awareness of the variability in its clinical presentation will improve clinical management and health outcomes. METHODS: Charts of patients in whom malaria was diagnosed at two hospital-based tropical disease centers between September 1, 1980, and December 31, 1991, were reviewed. RESULTS: Of a total of 482 cases, 182 were caused by Plasmodium falciparum and 246 by Plasmodium vivax. Fifty-two patients with P falciparum malaria were hospitalized; 13 were classified as having severe falciparum malaria. Nineteen patients with P vivax malaria required hospitalization. The only death was caused by P vivax. Chemoprophylaxis was used by, or prescribed for, 46% of patients; however, of these, only half were compliant in taking their medication. Eighty-seven percent of patients with falciparum malaria presented within 6 weeks of return from travel to an endemic area. One third of patients with P vivax malaria presented more than 6 months after travel. The average time between onset of symptoms and physician contact was 6.7 days. Diagnosis was often delayed in those who sought care outside the referral center. Almost all patients had a history of fever, but only half were febrile at presentation. Presenting symptoms and signs were non-specific. Fifty percent of patients were thrombocytopenic. Other laboratory abnormalities were mild. CONCLUSIONS: Since the presentation of malaria is vague and nonspecific, the diagnosis should be considered in any appropriately symptomatic patient with a history of travel to a malaria-endemic area, and appropriate testing should be done. Up-to-date information on chemoprophylaxis should be provided to all travelers to malaria-endemic regions.

Adult↗
PubMed1995

Bayesian estimation of disease prevalence and the parameters of diagnostic tests in the absence of a gold standard.

It is common in population screening surveys or in the investigation of new diagnostic tests to have results from one or more tests investigating the same condition or disease, none of which can be considered a gold standard. For example, two methods often used in population-based surveys for estimating the prevalence of a parasitic or other infection are stool examinations and serologic testing. However, it is known that results from stool examinations generally underestimate the prevalence, while serology generally results in overestimation. Using a Bayesian approach, simultaneous inferences about the population prevalence and the sensitivity, specificity, and positive and negative predictive values of each diagnostic test are possible. The methods presented here can be applied to each test separately or to two or more tests combined. Marginal posterior densities of all parameters are estimated using the Gibbs sampler. The techniques are applied to the estimation of the prevalence of Strongyloides infection and to the investigation of the diagnostic test properties of stool examinations and serologic testing, using data from a survey of all Cambodian refugees who arrived in Montreal, Canada, during an 8-month period.

Bayes Theorem↗
PubMed1995

Compliance with antimalarial chemoprophylaxis and the subsequent development of malaria: a matched case-control study.

To determine if there is a difference in compliance with antimalarial chemoprophylaxis between febrile travelers with and without malaria, 157 patients with malaria, a history of fever, and recent travel to a malaria-endemic area were compared with 157 matched controls. Antimalarial prophylaxis had been taken by 48% of all patients. Chemoprophylaxis use was correlated with region and purpose of travel. Cases were less likely to have taken prophylaxis (53%) than controls (76%) (odds ratio = 0.35, confidence interval = 0.27, 0.73), even after controlling for region of travel, purpose of travel, and previous exposure to malaria. Chemoprophylaxis was effective in reducing malaria risk. Travel agents and health practitioners should provide all travelers to malaria-endemic areas with adequate information about chemoprophylaxis and its importance.

Adult↗
PubMed1995

Diagnosis of malaria in the febrile traveler.

To determine if clinical presentation can be used for predicting malaria infection in febrile patients with recent travel to a malaria-endemic area, 157 patients with malaria, a history of fever, and recent travel to a malaria-endemic area were compared with 157 matched controls in case-control study. Fever pattern, symptom duration, temperature, splenomegaly, and platelet count were correlated with malaria infection. These criteria, however, either singly or in combination, had low sensitivity for accurately identifying patients with malaria. Because no criterion could accurately predict the presence of malaria, it is concluded that microscopic examinations of blood for malaria parasites should be done in all symptomatic patients with a history of travel to a malaria-endemic area.

Case-Control Studies↗
PubMed1994

Modified technique for efficient detection of microsporidia.

Changes in temperature (from room temperature to 50 degrees C) and staining time (from 90 to 10 min) were evaluated as a means of improving the detection of microsporidia from stool specimens. A blinded and independent comparison of 50 known positive matched-specimen pairs by three technologists resulted in consistently easier microscopic detection. The background is clearer, and spores stain more intensely. Staining time is reduced by 80 min.

AIDS-Related Opportunistic Infections↗
PubMed1993

Screening for schistosomiasis, filariasis, and strongyloidiasis among expatriates returning from the tropics.

The clinical utility of eosinophil determinations, stool examinations, and serological studies for detection of parasitic infection was examined in an asymptomatic expatriate population by retrospective chart review. The screened population consisted of 1,605 patients attending a tropical medicine clinic. The sensitivity of eosinophil counts as a screening test for infection with filaria, schistosomes, or Strongyloides stercoralis was 38%, and its positive predictive value was 9%. A cost-efficacy analysis of the use of three diagnostic tests in screening for infection with filaria (n = 23), schistosomes (n = 34), or Strongyloides (n = 7) was performed. The use of stool examination and serological screening together had a sensitivity of 89%, at a total cost similar to that of a conventional strategy involving a stool examination and an eosinophil count, which would have picked up only 61% of our cases. In this population, eosinophil counts contribute little to the diagnostic accuracy obtained with stool examination and serological screening, and the low specificity of eosinophil counts generates high costs.

Adolescent↗
PubMed1993

Antimalarial drug utilization by women in Ethiopia: a knowledge-attitudes-practice study.

A survey was undertaken between December 1991 and February 1992 to assess the knowledge, attitudes, and practices with respect to malaria of 300 women from six randomly selected rural communities in central Ethiopia. A total of 85% were able to recognize one or more of the common symptoms of the disease; however, the modes of transmission were generally misunderstood and only 23% believed that transmission could be prevented. More women preferred to obtain antimalarials from government clinics rather than from private drug shops, mission clinics, unofficial suppliers of injections, open markets, or from leftover sources. Under-5-year-olds were identified as the most malaria-vulnerable group and given priority for treatment; severity of illness was the principal determinant in seeking treatment. Decisions about treatment were generally made jointly by both parents. Knowledge about the transmissibility of malaria decreased with increasing distance from a health unit (odds ratio: 0.48; 95% confidence interval: 0.27, 0.86). A logistic regression analysis indicated that literacy and village were the most important variables associated with knowledge about preventing malaria.

Adolescent↗
PubMed1992

Epidemiologic and serologic definition of primary and secondary trichinosis in the Arctic.

A large outbreak of trichinosis acquired from walrus in Salluit in 1987 provided the immunologic and epidemiologic data from which two distinct clinical syndromes were identified. The first syndrome is the classic myopathic form with edema, fever, myalgia, and rash. The second is a persistent diarrheal illness with little edema or myalgia. The clinical presentations are paralleled by distinct differences in type and development of antibody response. The clinical and serologic profiles of the two syndromes support the hypothesis that the myopathic form represents a primary infection of Trichinella nativa, while the second represents a secondary infection in previously sensitized individuals.

Adolescent↗
PubMed1992

Intestinal parasite infection in the Kampuchean refugee population 6 years after resettlement in Canada.

A follow-up prevalence study was done in 1989 of the same Kampuchean refugee population (247 subjects) that had been screened and treated for intestinal parasite infection 6 years earlier. A control group (102 subjects) included Kampuchean refugees who had arrived in Montreal at about the same time. These groups did not differ in age, sex, family size, or number of months spent in refugee camps. Statistically significant prevalence differences were observed in the rescreened group between 1982-1983 (63.7%) and 1989 (21.9%) and between the rescreened group and the control group (39.2%). These differences are largely attributable to the elimination of Ascaris infection and decreases in Giardia and hookworm infections. However, Strongyloides infection decreased only slightly (from 15% to 11%) in the rescreened group, while 12% of the control group was infected. Despite an early screening and treatment program, there remain important health risks in this immigrant population due to long-lived potentially pathogenic parasites.

Adult↗
PubMed1990

An outbreak of toxoplasmosis in pregnant women in northern Québec.

An ongoing screening program for toxoplasmosis identified a cluster of four women from northern Québec who, over a 4-month period, seroconverted during their pregnancy. An epidemiologic investigation was carried out in an attempt to identify the source of this infection. All potential risk factors were assessed by a questionnaire administered to 22 Inuit women who had delivered babies in the previous year. Seroconversion was significantly associated with skinning of animals for fur (P = .015) and frequent consumption of caribou meat (P = .034). Compared to seronegative women, women who were seropositive were more than four times more likely to have eaten dried seal meat (P = .067), more than six times more likely to have eaten seal liver (P = .064), and more than eight times more likely to have consumed raw caribou meat more than once per week (P = .054). These observations have contributed to the development of guidelines for the prevention of toxoplasmosis in seronegative pregnant women in this arctic region.

Adolescent↗
PubMed1990

Seroepidemiology of Strongyloides infection in the Southeast Asian refugee population in Canada.

As part of a screening and treatment program for intestinal parasite infections offered to newly arrived Southeast Asian refugees in Canada between July 1982 and February 1983, a total of 232 sera were tested for Strongyloides infection using an enzyme-linked immunosorbent assay (immunoglobulin G). These results were compared with coprologic results and eosinophil counts. The seroprevalence was 76.6% (131 of 171) among Kampucheans, 55.6% (15 of 27) among Laotians, and 11.8% (4 of 34) among Vietnamese. A statistically significant relation (p less than 0.001) was found between Strongyloides serology and Strongyloides infection on stool examination (prevalence, 24.7%) among Kampucheans. Eosinophilia (greater than or equal to 10%) was found to be significantly associated with both infection measures. Using coprologic results as the "gold standard," the properties of the serologic test were estimated to be: sensitivity (95%), specificity (29%), positive predictive value (30%), and negative predictive value (95%). These estimates should be regarded as minimal values, as stool examination for Strongyloides infection can be an unreliable diagnostic reference. Further evaluation of the discrepancies observed between coprologic and serologic testing is required to determine the usefulness of these tests in epidemiologic studies.

Adolescent↗
PubMed1989

Effect of screening and treatment on imported intestinal parasite infections: results from a randomized, controlled trial.

A randomized, controlled trial was undertaken to evaluate the effects of a screening program for intestinal parasite infection in newly arrived Southeast Asian refugees to Montréal, Québec, Canada, during 1982-1983. Families assigned to the screened groups were examined, infected persons were treated and followed until they were infection-free, and all screened families were reexamined at six months. Families assigned to the control groups were examined at six months only. Statistically significant prevalence differences in unadjusted and adjusted estimates over the six-month study period were found between screened persons and controls for each of three groups of refugees from Kampuchea, Laos, and Vietnam, respectively. In general, the greatest prevalence differences ascribed to the screening program were observed in hookworm and Ascaris lumbricoides infections. Continued high levels of Giardia lamblia and Strongyloides stercoralis infection were observed at six months; this raises concerns over the effective therapeutic management of infected persons, the risk of local transmission, and the relevance of screening for intestinal parasites in new arrivals from endemic areas.

Asia, Southeastern↗
PubMed1989

Absence of significant differences in intestinal parasite prevalence estimates after examination of either one or two stool specimens.

The authors undertook a retrospective search of intestinal parasite laboratory records obtained from 200 consecutive-day pairs of stool specimens to compare prevalence estimates from the first and second stool examinations. The laboratory results had previously been recorded as part of a screening program offered to Southeast Asian refugees arriving in Montréal, Québec, Canada, between July 1982 and February 1983. No statistically significant differences in either overall prevalences or parasite-specific prevalences were observed. This suggests that, at least in some population-based situations, single stool examinations provide estimates of intestinal parasite prevalence which are as valid as those from the routine examination of two consecutive-day specimens. Blinded studies must be undertaken to accurately assess the true value of multiple specimen submission in epidemiologic studies.

Asia, Southeastern↗