The accumulation of dust mite allergens on mattresses made of different kinds of materials.

Background: Different mattress materials may affect the accumulation of allergens. Objective: To compare the amount of group 1 dust mite allergens (Der p1 + Der f1) on mattresses made of different kinds of materials before and after use. Methods: Sixty new mattresses made of kapok, synthetic fiber, coconut fiber and sponge-like polyurethane, were placed in the house officers’ dormitory at Siriraj hospital, Thailand. The dust samples were collected before (0), 1, 2, 3, 6, 9 and 12 months after the mattresses were used. Group 1 dust mite allergens were analyzed using two-site monoclonal antibody ELISA. Results: Der f1 made up 86.7 % of group 1 allergens found in the matress dust. After the 2nd month, only the mean level in sponge-like polyurethane mattress was under 2 µg/g dust (sensitized level). At the 6th month, the mean levels were 13.1 in coconut, 21.7 in kapok and 17.3 µg/g dust in synthetic fiber, all of which were more than 10 µg/g dust (symptomatic level). At the 9th month, the level in sponge-like polyurethane mattress was increased to 11.2 µg/g. At 12th month the level in coconut fiber, sponge-like polyurethane synthetic fiber and kapok mattresses were 20.2, 22.4, 28.9 and 32.2 µg/g dust respectively. Conclusions: The accumulation rate in kapok and synthetic mattresses was significantly higher than coconut and sponge-like polyurethane mattresses. The mean level of group 1 mite allergens exceeded 10 µg/g dust after the 6th month of use in coconut fiber, kapok and synthetic fiber and at the 9th month in sponge-like polyurethane mattress.

Effect of helminthic infections together with mite allergen exposure on the risk of wheeze in preschool children.

Although some studies have indicated that helminthic infections and house dust mite exposure may have an alleviating effect on wheeze, an interaction effect of both risk factors has not been examined in Thailand. The objective of this study was to investigate whether exposure to helminthic infections together with house dust mite allergen was associated with wheeze in children aged 18-36 months, living in an area of southern Thailand where helminthic infections are endemic. This study was undertaken as a part of The Prospective Cohort Study of Thai Children which recruited 1,076 children born between December 2000 and November 2001. A home dust sample was collected once when the infants were 12-18 months old to measure house dust mite allergen (Der p1). Questionnaire data on wheeze and a stool specimen for soil-transmitted helminth analysis were collected at age 18-36 months. Prevalence of exposure to house dust mite allergen (Der p1) > 10 μg/g dust was 31.8%. Soil-transmitted helminths were present in 25.0%, predominately Ascaris lumbricoides. Hookworm infection was asso-ciated with a physician’s diagnosis of wheeze (OR 4.20, 95% CI 1.45-12.10) and hospitalized wheeze (OR 5.40, 95% CI 1.26-23.01). Hospitalized wheeze was significantly higher in subjects exposed to Der p1 2-10 μg/g dust. Helminthic infections were not associated with a significant interaction effect with mite allergen against a risk of wheeze. Our survey confirms that hookworm infection and mite allergen exposure are independent risk factors for childhood wheeze and there is no evidence of important interaction between the two.

Levels of indoor allergens in public hospitals in Thailand.

Objective: To determine levels of indoor allergens in five public hospitals in Thailand. Methods: A total of 90 dust samples were collected from five public hospitals in Bangkok, Thailand, during March 2002 to October 2003. These hospitals provide both adult and pediatric care to over 500 patients daily. Each dust sample was collected at 12.00-13.00 pm during the years 2002-2003. The total amount of dust was weighed and one hundred milligram of fine dust from each sample was extracted. A commercialized two-site monoclonal antibody-based immunoassay (Indoor Biotechnologies, Ltd., Manchester, UK) was used to quantify the levels of Der p1, Der f1, Can f1 and Fel d1. Results: Fifty-one out of 90 dust samples were positive for indoor allergens. Four common groups of allergens were analyzed and detected; Der p 1 8/90 (8.89%), Der f 1 1/90 (1.11%), Fel d 1 39/90 (43.33%) and Can f 1 3/90 (3.33%)(of total samples). The arithmetic mean and standard deviation were 0.06 ug/g±0.26, 0.08 x 10-2 ug/g ± 0.001, 0.39 ug/g± 0.71 and 0.06 ug/g±0.30 for Der p 1, Der f 1, Fel d 1 and Can f 1, respectively (p =0.004). Fel d 1, the highest density allergen extracted from dust samples from hospital no. 5 and it showed a statistical difference compared with hospitals no.1,2,3,4 was observed; p < 0.05.* Conclusion: Our findings indicated that cat allergen can be found in a hospital setting where no cat is present.

The levels of cockroach allergen in relation to cockroach species and allergic diseases in Thai patients.

Recently, cockroaches have been established as the second most Important allergen, producing allergic diseases, especially in low socioeconomic populations. In Thailand, about 44-61% of atopic patients were positive to cockroach extract by a skin-prick test. This study examined cockroach allergen levels in relation to cockroach species and allergic diseases in the houses of cockroach-sensitive patients. Sixty households of allergic patients in the Bangkok metropolitan area were surveyed using open- and closed-ended questionnaires. Cockroaches were collected using commercial cockroach traps, while dust samples were obtained from the bedrooms, kitchens and living rooms of the houses using a vacuum cleaner. The cockroaches were counted and their species Identified. The levels of cockroach allergens were determined by specific monoclonal antibodies using a monoclonal antibody-polyclonal antibody based sandwich ELISA kit. Six cockroach species were Identified: Periplaneta americana (American cockroach, 72.15%), Supella longlpalpa (2.75%, found in only one house), Periplaneta brunnea (0.78%), Periplaneta australaslae (0.78%), Neostylopyga rhombifolla (0.78%), Blattella germanica (German cockroach, 0.39%) and nymphs (22.35%). Allergens of the predominant species, P. americana, were detectable in all homes studied, with the highest levels in the kitchen areas. The range of allergen levels in house dust varied from 0.40-162.00 microg per g of dust. The median and mean allergen levels in kitchen dust were 59.16 microg and 62.80 microg per g of dust, respectively, while the median allergen level in bedroom dust was only 15.90 microg per g of dust. The German cockroach allergen (Bla g 2) was undetectable in any of the houses. IN CONCLUSION: P. americana was the most common cockroach and may be the species causing allergic diseases, especially asthma, in Thailand, which differs from the USA and Europe

A comparative study of the major allergenic components in house dust extracts between siriraj and commercially prepared extracts.

The quantity and concentration of major allergens in mite allergenic extracts are crucial for skin testing, which is the recommended standard method for the diagnosis of house dust mite allergic disease. The purposes of this study were 1) To compare the constituents of major mite allergens in 3 types of mite extracts, i.e., extracts from mite reared in-house (Dermatophagoides pteronyssinus and Dermatophagoides farinae), extracts from commercial mite products and commercial ready-made mite extracts. These in-house extracts were prepared either with or without the preservative, glycerine. The concentrations of the major constituents of group 1 and 2 allergens of the extracts were determined by a two-site monoclonal based ELISA. 2 ) Biological assays were also carried out to determine the relative potency of the extracts in 120 allergic patients by skin prick test. It was found that the mean concentrations of Der p1, Der f1 and group 2 mite allergens in extracts from mites reared in-house were 102, 195 and 94 ตg/ml, respectively, compared to 169, 238 and 91 ตg/ml, respectively in commercial mite extracts. The commercial with product had the lowest concentrations of mite allergens (1 ตg/ml). Comparison of mite extracts with and without glycerine preservative showed no significant difference in concentrations of major allergens. Reduction of allergens concentration from 10,000 to 1,000 PNU/ml also reduced the concentration of mite allergen proportionately. Siriraj mite extracts were stable for at least 1 year at 4 oC without any significant change in composition or concentration. In conclusion, mite reared in-house can be used as raw material for preparation of mite allergenic vaccine.

Cockroach allergen detection and cockroach allergens of allergic Thai patients.

Hybridomas secreting monoclonal antibodies (MAb) specific to American cockroach (Periplaneta americana) were produced through a fusion of immune splenocytes of a BALB/c mouse immunized with crude cockroach (CR) extract and mouse myeloma cells. Two hybridomas namely 38G6 and 3C2 were established. These specific hybridomas secreted IgG1 monoclonal immunoglobulins with antigenic specificities to CR protein components of over 207 to 72 kDa and 45 to 40 kDa, respectively. The monoclonal antibodies were applied to select their specific epitopes out of the crude CR extract using affinity chromatography. A Prausnitz-Kustner test revealed that these epitopes were allergens which caused wheals and flares of the skin of a guinea-pig previously sensitized with a pool of serum samples from CR allergic patients. The monoclonal antibodies were also used in a capture ELISA to detect specific IgE in serum samples of allergic Thai patients. It was found that 72% and 76% of the patients had IgE antibodies to the epitopes of MAb 38G6 and MAb 3C2, respectively, indicating that the two epitopes are major CR allergens among the CR allergic Thai patients. An antibody-sandwich ELISA was developed for quantitative detection of CR allergens using the two monoclonal antibodies as a capture reagent and rabbit polyclonal antibodies to crude CR extract as a detection reagent. The assay could detect allergenic epitopes contained in as little as 122 pg of crude cockroach extract, and has high potential for direct measurement of the marker allergens in extracts of environmental samples.

Neurocysticercosis : Clinical manifestations and assessments.

Objective : In patients who have symptoms of epilepsy and other neurological deficits, one of the most common parasitic infections is neurocysticercosis (NCC) caused by Cysticercus cellulosae, the larval form of Taenia solium. In order to evaluate the characteristics of this illness which define the diagnosis, we assessed clinical manifestations, a positive ELISA for cysticercosis and neurological imaging in patients suspected of having NCC at a teaching hospital. Methods : This retrospective cohort study assessed 44 patients, who had laboratory results and clinical manifestations compatible with a diagnosis of NCC, between November 1998 and November 2001. The criteria for diagnosing this illness modified from these of Del Brutto and colleagues\\\' criteria. All patients were investigated with serum ELISA, 18 with CSF ELISA, if there was no contraindication. T. solium vesicular cyst soluble antigen was used for the detection of cysticercosis (T. solium) antibodies by solid-phase enzyme immunoassay. 35 patients were further investigated by a computerized tomography (CT) scan of central nervous system (CNS), if the results of other investigations were inconclusive. Using these criteria, we stratified all patients into three groups: possible NCC (19), probable NCC (10), and definite NCC (15). All definite patients were further examined with ELISA for Angiostrongylus cantonensis and Western blot for Gnathostoma spinigerum in order to look for cross-reactivity of the ELISA for cysticercosis. Results : In this study, a prevalence of NCC (34.1%) in the group of patients in whom there was clinical suspicion of NCC makes us concerned that Thailand is still an endemic area for this disease. The three most common clinical presentations were seizures, neurological deficit, and signs of increased intracranial pressure. Serum ELISA showed a sensitivity of 33.3% and a specificity of 93.1%. CSF ELISA showed a sensitivity of 40.0% and a specificity of 100%. CT scan brain showed a high sensitivity (92.9%) with a modest specificity (52.4%). Cross-reaction with other parasitic proteins was found with A. cantonensis (6.7%), but not with G. spinigerum. Conclusion : NCC is still endemic in Thailand. In the approach to this illness, we conclud that the diagnosis of NCC should be based on the patient's history and physical signs in conbination with radiological and serological investigations. Moreover, in areas where A. cantonensis and G. spinigerum were also prevalent, case should be taken in the interpretation of a positive ELISA for cystercercosis because of cross-reactivity with antibodies to A. cantonensis which should be checked individually.

Cerebral toxoplasmosis in AIDS patients: Clinical manifestations and laboratory diagnosis.

Objective : Patients with acquired immunodeficiency syndrome (AIDS) are susceptible to a variety of infections. Cerebral toxoplasmosis is one of the most common. The presumptive diagnosis is based on clinical manifestations, a positive Toxoplasma antibody test, characteristic neuroradiological abnormalities, and improvement after specific therapy. We evaluated not only the clinical manifestations and laboratory diagnosis but also its prevalence and the CD4 count in relationship to the development of cerebral toxoplasmosis in order to determine its place in the natural history of HIV infection. Methods : A retrospective cohort study was performed in 104 AIDS patients who were stratified into three levels: 35 with a definite diagnosis of cerebral toxoplasmosis and 41 with a probable diagnosis and 104 with a possible diagnosis. The criterion for diagnosing definite illness was a good response to specific treatment. Toxoplasma IgM were detected using solid-phase enzyme immunoassay and monoclonal captured ELISA methods respectively in all patients. 65 cases without a definitive diagnosis were further investigated with a CT scan of the brain. The patient data were followed up on day 7 and 14. Result : Toxoplasma IgG was present in 37 out of all case (35.6%) and Toxoplasma IgM was positive in only one case. The study showed that ELISA was a valuable method for diagnosis in addition of a CT scan of the brain. The ELISA detected antibodies in 24 out of 35 cases with a definite diagnosis (sensitivity 68.6%, 95% CI 5.7%-83.2%) and no antibody in 56 out of 69 cases with other diagnoses (specificty 81.2%, 95% CI 69.9%-89.6%). The CT scan showed positive features in 30 out of 33 cases with definite diagnosis (sensitivity 90.9%, 95% CI 75.7%-98.1%) but there were 4 (out of 32 cases) with a positive CT scan who were negative for the diagnosis, i.e., false positive, giving a specificity of 87.5%, 95% CI 71.0%-96.5%. The most common clinical presentations were headache and neurological deficit. Interestingly, neurological deficit was the only clinical manifestation that was associated with cerebral toxoplasmosis, when the group with a definite diagnosis was compared with the other diagnosis group (p-value 0.006). In HIV seropositive patients with previous Toxoplasma infection, cerebral toxoplasmosis was present in 24 out of 37 cases who were positive for Toxoplasma IgG (positive predictive value 64.9%), particularly in individuals with a CD4 count less than 100 cells/mm1. Conclusion : The two most common clinical manifestations were headache and neurological deficit. Detection of Toxoplasma gondii IgG and CT scan of the brain are valuable tools for the diagnosis of cerebral toxoplasmosis. Cerebral toxoplasmosis is mainly caused by reactivation, as Toxoplasma IgM antibodies were found in only one case.

Cloth can protect against house dust mite.

House dust mites and their faecal pellets are the most important indoor allergen causing allergic rhinitis and asthma. Reducing exposure to these allergens will result in relief to allergic persons. Encasement with mite-proof covers (pillow, mattress and quilt) is highly recommended for avoidance of dust mite allergens. The aim of this study is to assess the effectiveness of bed sheets and various mite-proof covers. Six materials were examined by the heat escape method, scanning electron microscope and two-site monoclonal antibody based-ELISA. The results demonstrated leakage of dust mite and its faecal pellets through bed sheets. This was due to such materials having pores larger than the dust mites. Plastic material provided the best protection against dust mite and their allergens but the material was not comfortable when used. Barrier that were made from impermeable cloth are recommended for dust mite allergen avoidance but the leakage of mite allergen through such materials need to be assessed in the laboratory.

Paragonimiasis: a case report from kanchnaburi province, Thailand.

A case report is detailed of paragonimiasis following segmentectomy of the posterior segment of the right upper lung in a 17-year-old female, from which two adult worms were recovered. The adult worms was stained and identified as Paragonimus heterotremus. Treatment was praziquantel (600 mg) two tablets three times a day for two days. The patient came from Lin Tin Village, Thong Pa Phum district, Kanchanaburi province and had no history of visiting endemic endemic Paragonimus areas. She was found of eating roasted freshwater crab.

The rapid detection of microsporidia in stool using a new trichrome-methylene blue stain: A preliminary report.

The increasing number of HIV-infected patients with intestinal microsporidiosis promt the physician to look for appropriate diagnostic techniques to identify microsporidia. The Weber’s modified trichrome stain has been established as a standard method for detection of microsporidia spores in fecal apecimens. This staninng is practical for routinely diagnosis. However, the original method requires approximately two hours to be completed. The new rapid trichrome-methylene blue technique was therefore developed to reduce the processing time from 120 to 15 minutes. Twenty-two formalinized stool samples known to be positive for microsporidia by transmission electron microscopy and 22 negative control specimens were stained by both original and new modified methods. With these two techniques, the parasitic morphology showed the same characteristic staining pattern, but the trichrome-methylene blue method provided a greater background contrast. The sensitivity and specificity of this modified technique were similar to the Weber’s method and the specificity was equal. This new less time-consuming procedure will be helpful in clinical management.