A new malaria vector in Africa: Predicting the expansion range of Anopheles stephensi and identifying the urban populations at risk.

In 2012, an unusual outbreak of urban malaria was reported from Djibouti City in the Horn of Africa and increasingly severe outbreaks have been reported annually ever since. Subsequent investigations discovered the presence of an Asian mosquito species; Anopheles stephensi, a species known to thrive in urban environments. Since that first report, An. stephensi has been identified in Ethiopia and Sudan, and this worrying development has prompted the World Health Organization (WHO) to publish a vector alert calling for active mosquito surveillance in the region. Using an up-to-date database of published locational records for An. stephensi across its full range (Asia, Arabian Peninsula, Horn of Africa) and a set of spatial models that identify the environmental conditions that characterize a species' preferred habitat, we provide evidence-based maps predicting the possible locations across Africa where An. stephensi could establish if allowed to spread unchecked. Unsurprisingly, due to this species' close association with man-made habitats, our maps predict a high probability of presence within many urban cities across Africa where our estimates suggest that over 126 million people reside. Our results strongly support the WHO's call for surveillance and targeted vector control and provide a basis for the prioritization of surveillance.

Crossed radio-immunoisoelectric focusing as a method of identifying isoallergens: identification of isoallergens in rat urine extracts.

A method of 2-dimensional radio-immunoelectrophoresis to detect directly the presence of 'isoallergens' in complex allergenic (skin test) extracts is described. This procedure, in which the components are separated by isoelectric focusing in agarose gel in the first dimension is therefore basically similar to that of crossed radio-immunoelectrophoresis, and hence has been termed crossed radio-immunoisoelectric focusing. The method has been applied to the allergens present in rat urine and has verified the presence of the cross-reacting alpha 2-euglobulin and prealbumin components in (at least) 3 and 2 isoallergenic forms respectively.

Complex microphthalmos.

Forty patients were diagnosed as having complex microphthalmos on the basis of a malformed globe with a total axial length measurement at least 2 SDs below the mean for age-similar controls. Three had anterior segment dysgenesis; 4, congenital lens abnormalities; 14, chorioretinal colobomas; 12, persistent hyperplastic primary vitreous; 4, retinal dysplasia; and 3, complex malformations due to ipsilateral facial malformations. Measurements of total axial length indicated that complex microphthalmos was congenital and that postnatal growth of the malformed eye was similar to that of normal eyes. In most patients the anterior segment length was normal, while in all patients the posterior segment length was at least 2 SDs below the mean. Corneal diameter correlated significantly with total axial length (r2 = .57) and decreased linearly as total axial length decreased. In most patients in whom measurements were obtained, the lens and corneal power were increased, thereby compensating for decreased total axial length. We propose that inadequate production of secondary vitreous is the cause of the microphthalmos, given that the posterior segment was disproportionately reduced in size and the secondary vitreous is its predominant component. Evidence that each of the various ocular malformations can influence the production of secondary vitreous is presented.

Simple microphthalmos.

Simple microphthalmos was diagnosed in 22 patients on the basis of a normal-appearing eye and a total axial length at least 2 SDs below the mean for age. Anterior segment length was normal in most patients while posterior segment length was at least 2 SDs below the mean in all patients, indicating that disproportionate reduction in posterior segment length accounted for the microphthalmos. The normal values for total axial length, anterior segment length, and posterior segment length were determined from the analysis of axial length measurements obtained from age-similar controls. Ten patients had isolated microphthalmos. One of them was diagnosed as having nanophthalmos on the basis of microcornea, total axial length less than 18 mm, and absence of systemic disease. Twelve patients had associated systemic disorders, such as fetal alcohol syndrome, myotonic dystrophy, and achondroplasia, which implicated decreased size of the optic cup, altered vitreous proteoglycans, low intraocular pressure, and abnormal release of growth factors in the pathogenesis of microphthalmos.

Determination of inorganic anions in water by ion chromatography: a collaborative study.

The U.S. Environmental Protection Agency (U.S. EPA) and the American Society for Testing and Materials (ASTM) conducted a joint collaborative study validating an ion chromatographic method for determination fo inorganic anions (U.S. EPA method 300.0A and the equivalent proposed revision to ASTM method D4327). This study was conducted to determine the mean recovery and precision of analyses for bromide, chloride, fluoride, nitrate, nitrite, orthophosphate, and sulfate in reagent water, drinking water, and wastewater. The study design was based on Youden's nonreplicate plan for collaborative tests of analytical methods. The test waters were spiked with the anions at 6 concentration levels, prepared as 3 Youden pairs. The 22 volunteer laboratories were instructed to dilute 10 mL sample concentrate to 100 mL test water. A measured volume of sample (20-200 microL) was injected into an ion chromatograph equipped with a guard column, anion exchange column, and a chemical micromembrane suppression device. The anions were then separated using 1.7 mM sodium bicarbonate and 1.8 mM sodium carbonate, and measured by a conductivity detector. Submitted data were evaluated using U.S. EPA's IMVS computer program, which follows ASTM D2777-86 statistical guidance. U.S. EPA method 300.0A and ASTM method D4327 were judged acceptable for measurement of the above anions (except sulfate) at concentrations ranging from 0.3 to 25 mg/L and sulfate concentrations from 2.9 to 95 mg/L. Mean recoveries for the 7 anions from all matrixes, as estimated from the linear regression equations, ranged from 95 to 104%. At concentrations above 2-6 mg/L for bromide, fluoride, nitrate, nitrite, and orthophosphate, and above 24 mg/L for sulfate, the overall and single-analyst relative standard deviations were less than 10 and 6%, respectively. As concentrations decreased, precision became more variable. The relative standard deviations of results for chloride were slightly higher than the other anions, especially in matrixes with high chloride background. Analysis of Variance (ANOVA) tests at the 95% confidence interval indicated a statistically significant matrix effect for chloride, nitrite, and nitrate analyses in drinking water compared to analyses in reagent water. Because these matrix effects were caused by the spiking process and not the drinking water itself, the ANOVA determination was not considered to be of practical significance.

Gas chromatographic/electron capture detection method for determination of chlorinated acids in water: collaborative study.

A U.S. Environmental Protection Agency (USEPA) interlaboratory method validation study was conducted on USEPA Method 515.1, "Determination of Chlorinated Acids in Water by Gas Chromatography with an Electron Capture Detector." This method is one of the 6 pesticide methods developed for the USEPA National Pesticide Survey (NPS). Method recovery and precision for analyses of sub-ppb to low-ppb concentrations of chlorinated acids were determined in reagent water and finished drinking waters. The analytes evaluated in the study included the 12 pesticides that were quantitatively measured in the National Pesticide Survey (bentazon, 2,4-D, 2,4-DB, 3,5-dichlorobenzoic acid, DCPA-diacid, dicamba, dichlorprop. 5-hydroxydicamba, pentachlorophenol, picloram, 2,4,5-T, and 2,4,5-TP) and 5 pesticides (acifluorfen, chloramben, dalapon, dinoseb, and 4-nitrophenol) that were only qualitatively assessed in the National Pesticide Survey because of recognized method imprecision. The study design was based on Youden's nonreplicate plan for collaborative tests of analytical methods. The waters were spiked with 17 chlorinated acids, each at 6 concentration levels, prepared as 3 Youden pairs. Eight laboratories extracted the spiked test waters at pH < 2 with ethyl ether, performed a solvent exchange with methyl tert-butyl ether, prepared methyl esters of the extracted acids using diazomethane, and analyzed an aliquot of each derivatized extract by gas chromatography with electron capture detection. The submitted data were analyzed using a USEPA computer program, which measured recovery and precision for each of the 17 compounds and compared the performance of the method between water types. Method 515.1 was judged acceptable for the 12 NPS analytes recovered quantitatively; mean percent recoveries at 10-15 times the method detection limits ranged from 79 to 105% in reagent water and from 75 to 123% in finished drinking water. In reagent water, overall precision (reproducibility relative standard deviation, RSDR) ranged from 9.6 to 34.2% and in finished drinking water, the RSDR ranged from 11.9 to 37.0%. Single-analyst precision (RSD for repeatability, RSDr) ranged from 5.8 to 17.7% in reagent water and from 4.6 to 27.9% in drinking water. Results for the 5 other NPS analytes were too inaccurate or imprecise and, for these compounds, supported use of the method for qualitative measurements only; the 5 compounds are not included in the adopted method. The method has been adopted first action by AOAC INTERNATIONAL for determination of residues of 12 chlorinated acids in finished drinking water.

Gas chromatographic/nitrogen-phosphorus detection method for determination of ethylene thiourea in finished drinking waters: collaborative study.

A joint U.S. Environmental Protection Agency (USEPA)-AOAC interlaboratory method validation study was conducted on USEPA National Pesticide Survey (NPS) Method 6, "Determination of Ethylene Thiourea (ETU) in Finished Drinking Water by Gas Chromatography with a Nitrogen-Phosphorus Detector." The purpose of the study was to determine and compare the mean recoveries and precision for determination of ETU in reagent water and finished drinking waters. The study design was based on Youden's nonreplicate plan for collaborative tests of analytical methods. The waters were spiked with ETU at 6 concentrations levels, prepared as 3 Youden pairs. In the method, the test water is extracted by passing the sample through an absorbent matrix type tube. ETU is recovered from the tube with methylene chloride, the extract is solvent-exchanged to ethyl acetate, and an aliquot of each extract is analyzed by gas chromatography using a nitrogen-phosphorus detector. Twelve laboratories participated in the study. Data were analyzed using a USEPA computer program, which measured recovery and precision for ETU and compared the performance of the method between the 2 water types. Over the concentration range tested, the mean percent recoveries of ETU were 82-92% in reagent water and 85-98% in finished drinking water. The range of the between-laboratory relative standard deviations (RSDR) for the 6 concentrations was 5-24% in reagent water, but was only 4-9% in finished drinking water. The range of the within-laboratory relative standard deviations (RSDr) was 6-14% for reagent water and 6-10% for finished drinking water. Results for the 2 water matrixes showed no statistically significant differences.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergic bronchopulmonary aspergillosis: reactivity of IgE and IgG antibodies with antigenic components of Aspergillus fumigatus (IgE/IgG antigen complexes).

Sera of patients with ABPA were tested by XRIE tests incorporating their own serum (self-XRIE) to detect the presence of IgG/IgE antigen complexes to a "reference" Aspergillus fumigatus preparation. Of the 32 sera studied, 29 (90%) had visible precipitin (IgG) peaks, and 27 of these 29 as well as the three apparently precipitin-negative sera, i.e., 30 (94%), showed binding of specific IgE by autoradiography. The two precipitin-positive sera that did not show IgE binding were also skin test negative and RAST negative to this A. fumigatus antigen. Specific IgG as determined in ELISA correlated well with the grading of the XIE precipitin peaks (p less than 0.05). There was also a highly significant correlation between specific IgE by RAST and grading the radioactive uptake seen in the autoradiograph (p less than 0.001) indicating, for each serum, the presence of IgG antibodies to most of the components to which there was specific IgE. In the self-XRIE tests there was considerable variation of reactivity from serum to serum, in numbers of antigen/antibody peaks observed, in relative peak heights, and in the intensity of the respective staining. By comparing each test to a "reference" pattern developed with the use of an ABPA serum pool, the antigenic components of A. fumigatus were found to be of two main types: (1) antigens that appeared to be poorly precipitating (possibly low-molecular-weight components) but showed strong IgE binding (these were apparently major allergenic components and with one exception proved to be the faster migrating components) and (2) antigens that produced the strongest precipitin reactions with only weak binding of specific IgE and therefore minor allergenic components.

Antigens and allergens of Aspergillus fumigatus. II. Their further identification and partial characterization of a major allergen (Ag 3).

These further studies demonstrated that most antigens and allergens detected by allergic bronchopulmonary aspergillosis (ABPA) sera were recognized by rabbit antiserum, and a major allergenic component, Ag 3, as previously demonstrated by self-crossed radioimmunoelectrophoresis, was identified in the conventional system. Affinocrossed immunoelectrophoresis with concanavalin A indicated that for the patients with ABPA, although the major antigens contained alpha-D-manno- or alpha-D-glucopyranoside terminal residues, the major allergenic components did not. Fractionation of the salt-precipitated, protein-enriched fraction by gel filtration on Sephacryl S-200, monitored by fused-rocket immunoelectrophoresis/fused-rocket radioimmunoelectrophoresis with both the ABPA serum pool and specific rabbit antisera, revealed that most of the antigens were in a molecular weight range greater than 43 kd, whereas the allergens spread from as low as 10 to greater than 100 kd. The major allergen, Ag 3, was identified and demonstrated to have a molecular weight of approximately 24 kd. This component does not bind to concanavalin A and is also very heat labile.

Allergens of Aspergillus fumigatus: identification and characterization of components combining with specific IgE antibody.

Aspergillus fumigatus-specific IgE antibodies, mediating immediate type hypersensitivity reactions are found in a proportion (16-26%) of patients with asthma and their presence is a criterion for diagnosis of allergic bronchopulmonary aspergillosis (ABPA). Sensitive radiolabelled or enzyme-linked immunoassays are required for detection/quantification of these antibodies in patient's serum, and the fungal components, allergens, to which they combine, may be identified in crossed radio-immunoelectrophoresis tests. Of the 40 or more components antigenic for rabbits, as many as 18 have been identified as allergenic, two as major allergens. One major allergen with a molecular weight of approximately 24,000 daltons, pI 4.5, has been partially characterized. Further, in ABPA patients whose sera also contain IgG antibodies, both classes of antibody can combine with the same components forming IgE/IgG antigen complexes in vitro.

Pigeon breeders' disease: quantitative immunoelectrophoretic studies of pigeon bloom antigen.

This study employed quantitative immunoelectrophoretic techniques, on sera from confirmed cases of pigeon breeders' disease (PBD), to investigate the antigenicity of a pigeon bloom extract, implicated as a sensitizing agent in this disease. On crossed immunoelectrophoresis the maximum number of antigenic components identified was 29 for the bloom compared to 10 for pigeon serum. A major component was shown to be closely related to pigeon IgA, and demonstrated partial crossreactivity to the pigeon IgG. This component also showed identity with the major component of a pigeon droppings extract, considered to be derived from intestinal IgA. Only trace amounts of serum albumin were detected and most other bloom components were not serum-related. Although greater overall antigenic similarity was found to pigeon droppings extract, at least three of the bloom components appeared to be specific. The bloom extract also contained a low amount of an alpha-techoic acid-like component, causing some non-specific reactivity. Pigeon feather dust or 'bloom', like pigeon droppings, is therefore a potent source of antigens associated with PDB--pigeon IgA being a major component of both antigens.

Antigens/allergens of Aspergillus fumigatus. Identification of antigenic components reacting with both IgG and IgE antibodies of patients with allergic bronchopulmonary aspergillosis.

Evidence that both IgE and IgG antibodies present in the sera of allergic bronchopulmonary aspergillosis patients (ABPA) combine with several of the antigenic components of Aspergillus fumigatus has been obtained using a self-crossed radioimmunoelectrophoresis test. In this test, patient's serum was used to develop its own crossed immunoprecipitation pattern to a reference antigen before proceeding to autoradiography with 125I-anti-human IgE in the usual way. Comparison of autoradiograph with immunoprecipitate showed a varied pattern of reactivity, i.e. precipitin peaks with and without associated radioactivity, as well as some peaks appearing only in the autoradiograph. Control sera, including sera from A. fumigatus skin test positive patients and a skin test negative aspergilloma patient with multiple precipitins showed no such combined activity. The specificity of the test was further demonstrated using an ABPA serum pool, both by absorbing the IgE from the serum before incorporation in the gel and also by heat inactivation (56 degrees C, 4 h) of the serum to destroy the heat labile determinants on IgE molecules, thus preventing the uptake of the anti-IgE specific for these determinants.

Allergy to rabbits. I. Specificity and non-specificity of RAST and crossed-radioimmunoelectrophoresis due to the presence of light chains in rabbit allergenic extracts.

Investigations have been carried out into the presence of antibody light chains in rabbit allergenic extracts and the interference in RAST and crossed-radioimmunoelectrophoresis (XRIE) caused by antibodies directed against them. A "non-specific" uptake of radioactivity in XRIE has been demonstrated to be caused by direct cross-linking of the 125I rabbit anti-human IgE by the sheep antibodies in the immunoprecipitate of rabbit light chains. Preincubation with normal rabbit serum blocked this direct uptake of the labelled antibody and enabled specific IgE uptake on the light chains to be demonstrated for rabbit allergic sera. Verification of the allergenicity of the light chains was obtained from a specific light chain RAST. Elution from a Sephacryl S-200 gel filtration column indicated a MW of approx. 50 Kd and confirmation of the component as light chain dimers, not Fab fragments, was obtained by allotyping for loci present on heavy chains and light chains in the Fab region. Light chains were detected in urine from rabbits of all ages and in an extract of dust collected in a rabbit housing area. No background staining was observed in XRIE using rabbit antisera, either with rabbit allergic sera with specific IgE or with a human serum containing specific IgG antibodies to rabbit IgG. This latter serum also showed no evidence of uptake on all immunoprecipitates in systems using rabbit antisera, and did not give false positive RAST results when the labelled rabbit anti-human IgE contained unlabelled rabbit IgG. Those sera with specific IgE to light chains showed no uptake in XRIE using rabbit antisera, indicating that the IgE was possibly specific for epitopes revealed by the dissociation of the whole IgG molecule.

Quantitative immunoelectrophoretic analysis of rat allergen extracts. II. Fur, urine and saliva studied by crossed radio-immunoelectrophoresis.

Many constituents of rat fur, urine and saliva were identified as being allergenic using crossed radio-immunoelectrophoresis with sera from 14 patients who had asthma and rhinitis on exposure to rats. Three was considerable diversity in the spectra of components recognized by individual patients, though the majority reacted with immunoprecipitate 4. In all three extracts this represents a similar component, which was originally characterised as a urinary prealbumin. Most of the allergenic components of urine and saliva have also been detected in the fur extract. Some of the minor allergens are those antigens which appear to be unique to urine, saliva or the skin, suggesting that sensitisation to rats can result from exposure to allergenic material from all three of these sources.

Comparison of rat fur, urine, saliva, and other rat allergen extracts by skin testing, RAST, and RAST inhibition.

Extracts of a wide range of materials associated with exposure to rats were prepared and their relative allergenic activities were measured by skin-prick testing of rat-sensitive patients, RAST for serum IgE, and RAST inhibition of dust collected from a rat room. Most potent on a dry weight basis were preparations of fur, urine, epithelia, and saliva (all irrespective of the sex of the rat) and of the dust. Extracts of shaved pelt, whole pelt, feces, and serum proved less effective, whereas those of sawdust or diet had negligible activity. The presence of similar allergens in the more potent extracts was suggested by multiple skin sensitivity to different source materials, by close correlation between RAST results, and by the extent of RAST inhibition for individual extracts. The allergenicity of fur and epithelia probably results largely from contamination with saliva and urine.

Allergy to laboratory animals: characterization and source of two major mouse allergens, Ag 1 and Ag 3.

Using quantitative immunoelectrophoretic methods, two major allergenic components, Ag 1 and Ag 3, have been identified in extracts of mouse dust. Both antigens were of similar electrophoretic mobility and molecular weight (20-25 kilodaltons). However, Ag 1 proved to be antigenically identical to mouse urinary prealbumin, whilst Ag 3 was shown immunohistochemically to be present within the hair follicle and on the stratum corneum.

Allergy to rats: quantitative immunoelectrophoretic studies of rat dust as a source of inhalant allergen.

The antigenic composition of an extract of rat dust, as a source of aeroallergens for rat-sensitive individuals, has been investigated and compared to the antigenic composition of rat saliva and urine. Of four main antigenic peaks identified by crossed immunoelectrophoresis, one antigenic peak (Ag 4) was demonstrated to be antigenically closely related to and with similar molecular weight (approximately 22 kd) and isoelectric point values as urinary prealbumin, already recognized as a major rat allergen. Ag 4 was present in all dusts studied and was also identified as a minor component of saliva. However, no component with the same electrophoretic mobility or physicochemical characteristics of the alpha 2-euglobulin of male rat urine that shares partial identity with the prealbumin was detected, even in dust collected from a male rat room. A second high molecular weight (greater than 200 kd) component, Ag 1, present in most of the dust extracts, could not be detected in either urine or saliva. Crossed immunoelectrophoresis and skin prick tests confirmed the allergenicity of both these antigens. Analysis of an air filter sample taken within a male rat room revealed significant amounts of the "prealbumin" component, and a monospecific antiserum to this component was used to quantitate levels in dusts collected from various locations. These findings suggest that a major inhalant allergen present in rat dust is closely related to urinary prealbumin but that this and other allergenic components may not be derived predominantly from rat urine or saliva but possibly from secretions originating from the skin of the animals and present in the fur.

Allergy to mice. I. Identification of two major mouse allergens (Ag 1 and Ag 3) and investigation of their possible origin.

An extract of dust from the outlet filters of a mouse isolator was used as a basis for determining the source of inhalant allergens for subjects sensitive to this species. The antigenic components, identified by crossed immunoelectrophoresis (XIE), were compared to those found in extracts of other mouse-derived source materials, i.e. urine, fur, dander and saliva. Of the eight dust components, one (Ag 1) was identified as antigenically identical to the major urinary pre-albumin whilst the others were detected in fur, and to a lesser extent dander and saliva. None of the dust antigens was detected as a component of food or bedding. Crossed radio-immunoelectrophoresis (XRIE), performed using sera from a group of fifteen mouse-allergic subjects (positive by RAST to mouse extracts), identified seven of the dust antigens as IgE-binding components. Antigens 1 and 3 were reactive with all the sera tested and have, therefore, been termed the 'major' allergens. Varied responses were obtained to the other 'minor' antigens. Ag 1 (urinary pre-albumin) and Ag 3 were detected in all samples of mouse dust studied. RAST and RAST inhibition also indicated the presence of urinary pre-albumin. These findings suggest that the major mouse inhalant allergens may be derived predominantly from urine and secretions originating in the skin and present on the fur.

Allergy to rabbits. II. Identification and characterization of a major rabbit allergen.

Quantitative immunoelectrophoretic techniques have been used to study the antigenic components found in extracts of dust collected from rabbit housing areas. To determine the possible source of these antigens, comparisons have been made to rabbit saliva, urine, fur and dander. Specific antisera for the rabbit extracts were raised in guinea pigs. One major component of the dust (Ag Rl) was also found in large amounts in saliva, slightly less in fur and in only minimal amounts in urine and dander. Crossed radioimmunoelectrophoresis (XRIE) of the dust, performed with sera from 14 rabbit allergic individuals who were RAST positive to rabbit saliva, urine and dust identified four IgE-binding constituents. Individual responses varied but all sera reacted with Ag Rl, identifying this as a major rabbit allergen. Dust RAST inhibition studies with rabbit dust, saliva and urine indicated saliva to be closely related to the dust. Ag Rl is a glycoprotein which appears to be very heterogeneous in nature. It produced a broad biphasic precipitin peak on immunoelectrophoresis and eluted from Sephacryl S-200 gel filtration over the molecular weight range 30-50 Kd, although a molecular weight of 17 Kd was indicated by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and gradient gel electrophoresis. The RAST inhibition results and the antigenic similarity of saliva to the dust suggest this to be the most likely source of the major rabbit allergen, Ag Rl.