Kala-azar in a high transmission focus: an ethnic and geographic dimension.
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In 1994-1996, we studied a group of 58 game wardens stationed in an area known to be highly endemic for visceral leishmaniasis (kala-azar) for evidence of infection with Leishmania donovani. Leishmania DNA was detected by the polymerase chain reaction in the peripheral blood of cases of active kala-azar, former patients with visceral leishmaniasis, patients, and asymptomatic subjects. Using the cloned antigen rk39, antibodies were detected in 44.2% of the game wardens while leishmanin skin test result was positive in 77% of our sample. It was shown that certain tribes from northern Sudan were more likely to develop subclinical infections, while those of the Baria tribe from southern Sudan and those of the Nuba tribe from western Sudan were more likely to develop visceral leishmaniasis. Whether this is due to genetic factors or previous exposure to Leishmania parasites remains to be elucidated. (+info)
Epidemiologic aspects of American visceral leishmaniasis in an endemic focus in Eastern Venezuela.
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An endemic focus of American visceral leishmaniasis (AVL) in eastern Venezuela has been evaluated in terms of patients (n = 48), immunologic reactivity to Leishmania in household contacts (n = 187) and neighborhood controls (n = 170), detection of Leishmania (L. donovani complex) in dogs and wild animals by the polymerase chain reaction (PCR) and characteristics of the sandfly population. The male:female ratio of patients was 1.18:1; 89.6% were < or =12 years old. Serologic reactivity was significantly higher in household contacts than in controls (P = 0.0008), as was the size of leishmanin reactions in contacts < or =10 years of age (P = 0.0141). Leishmania donovani complex-specific PCRs were positive in dogs, an opossum (Didelphis marsupialis), and a black rat (Rattus rattus). Lutzomyia longipalpis and Lu. evansi, both implicated in the transmission of AVL, were identified among the 386 sand flies examined. These observations provide the bases for an active control program as well as further studies of reservoirs and vector-host relationships in this area. (+info)
Experimental phycomycosis in mice; examination of the role of acquired immunity in resistance to Absidia ramosa.
(59/2169)
Attempts were made to stimulate acquired immunity to experimental Absidia ramosa infection in mice. Unprotected animals inoculated with large doses of A. ramosa spores frequently developed acute phycomycosis of the central nervous system. Mice previously exposed to sub-lethal doses of spores showed a high resistance to subsequent challenge with A. ramosa. No consistent increase in resistance was observed in mice vaccinated with killed A. ramosa spores, hyphal walls, intracellular mycelial antigens or various combinations of these, with Freund's incomplete adjuvant. Antibodies to soluble mycelial antigens were inconsistently present in the sera of mice vaccinated with sub-lethal doses of viable spores. They were generally present in the sera of animals vaccinated with mycelial extracts of hyphal walls but not killed spores. Delayed hypersensitivity reactions to A. ramosa mycelial antigens could usually be elicited by intradermal tests in mice exposed to viable spores but irregularly in those vaccinated with non-viable preparations. Positive reactions were also frequently given by older mice not deliberately exposed to A. ramosa. Although mice previously exposed to viable A. ramosa spores were highly resistant to intravenous or intracerebral challenge with this fungus, they were more likely to develop persistent local granulomata on subcutaneous injection of spores than were unvaccinated animals. (+info)
Healthy adults demonstrate less skin reactivity to commercial extracts of commonly ingested food than to D. farinae.
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The aim of this study is to determine the skin reactivity of healthy Oriental adults to commercial extracts of commonly ingested food and the house dust mite D. farinae, a common local aeroallergen. D. farinae and 18 food extracts were skin prick tested on adults without any personal history of atopic diseases and food allergy. The extracts of food not consumed by any subject on religious or personal grounds were not tested for that individual. A total of 103 healthy adults who fulfilled the selection criteria were skin prick tested. There were 35 males and 68 females. Their mean age was 29 years (SD +/- 7.5) with a range of 19 to 49 years. Sixty-eight percent were Chinese, 12.6% Malay, 12.6% Indian and 6.8% other Oriental races. Fifty-four (52.4%) were positive for D. farinae while only 12 (11.7%) were positive for at least one food extract The food extract that gave the most number of positive reactions was shellfish mix (5/102, 4.9%). A family history of atopy did not have any significant correlation with the results of skin test. It was concluded that healthy adults demonstrate less skin reactivity to extracts of commonly ingested food than to D. farinae. (+info)
Sensitization to Blomia tropicalis and dermatophagoides pteronyssinus-a comparative study between Singapore and Taiwan.
(61/2169)
Blomia tropicalis (Bt) and Dermatophagoides pteronyssinus (Dp) are the predominant domestic mites species in Singapore and Taiwan. This study aims to characterize and compare the mite sensitization profiles in both countries. Skin prick tests were performed on 203 Singaporeans with Dp and Bt crude extracts. In vitro IgE and IgG4 reactivity to extracts and specific allergens (Der p 1, Der p 2 Der p 5 and Blo t 5) were determined by immunoassays. Approximately 91% of the tested Singaporeans were skin test positive for both Bt and Dp. Both populations share similar frequencies of in vitro IgE reactivity to all the allergens tested, but they differ in the pattern and magnitude of allergen sensitization. Although Der p 1, Der p 2 and Blo t5 are major sensitizing allergens in both countries, Blo t 5 is a more potent one in Singapore, probably reflecting the high level of exposure to Bt. The unique major Bt and Dp allergens should be included for precise diagnosis and effective immuno-therapeutic treatment of mite allergy in both countries. (+info)
Prospective study of work related respiratory symptoms in trainee bakers.
(62/2169)
OBJECTIVES: To investigate the occurrence of work related respiratory symptoms and to assess the effect of atopy in a group of trainee bakers. METHODS: A prospective study of work related respiratory symptoms among 125 trainee bakers who were investigated with a questionnaire plus skin prick test with wheat flour and alpha-amylase allergens at baseline and then after 6, 18, and 30 months. RESULTS: At the baseline examination, four students (3.2%) complained of respiratory symptoms (cough and rhinitis) when working with flours and four were skin positive to wheat flour or alpha-amylase. The incidence of work related respiratory symptoms was 3.4% at 6 months, and the cumulative incidence was 4.8% and 9.0% at 18 and 30 months, respectively. The incidence of skin sensitisation to occupational allergens was 4.6% at 6 months and the cumulative incidence was 4.6% at 18 months and 10.1% at 30 months. The generalised estimating equation approach to longitudinal data showed that work related respiratory symptoms in the study population was significantly associated with a personal history of allergic disease (odds ratio (OR) 5.8, 95% confidence interval (95% CI) 1.8 to 18.2) and skin sensitisation to wheat flour or alpha-amylase (OR 4.3, 95% CI 1.2 to 14.9). Atopy based on prick test was not related to the occurrence of work related respiratory symptoms over time (OR 1.1, 95% CI 0.3 to 3.8). CONCLUSIONS: Personal history of allergic disease is a predisposing factor for the development of symptoms caused by exposure to wheat flour and may be a criterion of unsuitability for starting a career as a baker. Atopy based on the skin prick test is useful for identifying subjects with allergic disease, but should not be used to exclude non-symptomatic atopic people from bakery work. (+info)
Risk of enzyme allergy in the detergent industry.
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OBJECTIVES: To assess the prevalence of enzyme sensitisation in the detergent industry. METHODS: A cross sectional study was conducted in a detergent factory. Sensitisation to enzymes was examined by skin prick and radioallergosorbent (RAST) tests. 76 Workers were tested; 40 in manufacturing, packing, and maintenance, and 36 non-exposed people in management and sales departments. The workers were interviewed for work related respiratory and skin symptoms. Total dust concentrations were measured by a gravimetric method, and the concentration of protease in air by a catalytic method. RESULTS: Nine workers (22%) were sensitised to enzymes in the exposed group of 40, whereas none were sensitised in the non-exposed group. All the sensitised people had symptoms at work; all had rhinitis and one had asthma. Protease concentrations were generally < 20 ng/m3, but occasional peak values up to 80 ng/m3 were detected in the packing and maintenance tasks, and high values of > 1 microgram/m3 in the mixing area. CONCLUSION: Despite the use of encapsulated enzyme preparations, high enzyme concentrations in workplace air are possible, resulting in a higher risk of sensitisation than expected. (+info)
Acquired cell-mediated immunodepression in acute Chagas' disease.
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In this study two groups of patients with acute Chagas' disease were identified. Group one consisted of five patients with apparent acute Chagas' disease. These patients showed symptoms and signals of an acute illness, such as high fever and enlarged spleen. One of these patients developed severe myocarditis and heart failure. Group two consisted of seven patients with inapparent acute Chagas' disease. This was a nonclinical entity, not perceived by the patient who did not seek medical care. The diagnosis was made by the shift of a serologic test which indicates the presence of immunoglobulin M antibodies to Trypanosoma cruzi. The patients with apparent acute Chagas' disease showed positive delayed-type skin response to T. cruzi antigen. Also, their leukocytes showed significant inhibition of migration in the presence of this antigen. By contrast, the patients with the inapparent acute Chagas' disease did not show positive delayed-type skin response to T. cruzi antigen and no significant inhibition was observed when their cells migrated in the presence of this antigen. Of interest, none of these patients was capable of developing contact sensitivity to 2,4-dinitrochlorobenzene. However, three out of five patients with the apparent acute disease and all the normal control subjects showed positive contact reaction after sensitization to this drug. The results of these experiments would suggest that the thymus-derived (T)-lymphocyte function is depressed in patients with the clinically inapparent acute Chagas' disease. This immunodepression seems to be acquired in the course of the T. cruzi infection because all patients showed positive delayed-type skin response to at least one ubiquitous microbial extract, thus indicating previously normal T-cell function. We hypothesize that T. cruzi antigens may directly stimulate T cells with the concomitant release of factors that might become supressive for T-cell responses. Furthermore, the suppressive effect might interfere with the T-cell response to other antigens, such as to 2,4-dinitrochlorobenzene. (+info)