Biomedical subjects

K Pålsson

Publications and source records attributed to K Pålsson.

9 recordsLinked to original sources

PubMed2006

Repellency of MyggA Natural spray (para-menthane-3,8-diol) and RB86 (neem oil) against the tick Ixodes ricinus (Acari: Ixodidae) in the field in east-central Sweden.

In the field in south-central Sweden, we tested by randomised, standardised methodology the potential anti-tick repellent activity of two concentrations of MyggA Natural spray (containing PMD) (4.2 and 3.2 g/m2) and one of RB86 (with 70% neem oil containing azadirachtin) (3 g/m2) to host seeking nymphs of Ixodes ricinus. Each substance was applied separately to 1 m2 cotton flannel cloths. Nymphal ticks on the cloths, pulled over the vegetation, were recorded at 10-m stops. Nymphal numbers recorded differed significantly between treated cloths [4.2 or 3.2 g MyggA Natural spray/m2 and 3 g RB86/m2] and the untreated control (df = 3, chi2 = 112.74, P < 0.0001). Nymphal numbers also differed significantly among collectors (df = 3, chi2 = 15.80, P < 0.001). Repellency of treated cloths, i.e., 4.2 or 3.2 g MyggA Natural spray/m2 and 3 g RB 86/m2 declined from day 0 (i.e. the day of impregnation) to day 3 after impregnation from 77 to 24%, 58 to 16% and 47 to 0.5%, respectively. This study suggests that all three treatments have significant repellent activities against I. ricinus nymphs.

Animals↗

PubMed2005

Evaluation of extracts and oils of tick-repellent plants from Sweden.

Abstract. Leaves of Myrica gale Linnaeus (Myricaceae), Rhododendron tomentosum (Stokes) H. Harmaja (formerly Ledum palustre Linnaeus: Ericaceae) and Artemisia absinthium Linnaeus (Asteraceae) were extracted with organic solvents of different polarities and the essential oils of leaves were obtained by steam distillation. The extracts or oils were tested in the laboratory for repellency against host-seeking nymphs of Ixodes ricinus Linnaeus (Acari: Ixodidae). Rhododendron tomentosum oil, 10%, diluted in acetone, exhibited 95% repellency; R. tomentosum and A. absinthium extracts in ethyl acetate, > 70% repellency; A. absinthium extract in hexane, approximately 62% repellency; and M. gale oil, 10%, approximately 50% repellency on I. ricinus nymphs. Compounds in the leaf extracts or in the oils were collected by solid phase microextraction (SPME) and identified by gas chromatography-mass spectrometry (GC-MS) and/or MS. Characteristic volatiles detected from oil or extract of M. gale were the monoterpenes 1,8-cineole, alpha-terpineol, 4-terpineol and thujenol; and of R. tomentosum myrcene and palustrol. Characteristic volatiles from leaf extracts of A. absinthium were sabinene, oxygenated monoterpenes, e.g. thujenol and linalool, and geranyl acetate. Each plant species synthesized numerous volatiles known to exhibit acaricidal, insecticidal, 'pesticidal' and/or arthropod repellent properties. These plants may be useful sources of chemicals for the control of arthropods of medical, veterinary or agricultural importance.

Animals↗

PubMed1999

Plant products used as mosquito repellents in Guinea Bissau, West Africa.

By standardized interviews of people in 23 rural villages, in the Oio region of Guinea Bissau, we collected data on which plant species and plant derived products or methods people use to reduce mosquito biting activity. The following plants were used to reduce numbers of mosquitoes indoors at night: fresh or smouldering Hyptis suaveolens Poit. (Lamiaceae), smoke of the bark of Daniellia oliveri Rolfe (Caesalpiniaceae), smoke of the infructescence of Elaeis guineensis Jacq. (Arecaceae), smoke of the seed capsules of Parkia biglobosa (Jacq.) Benth. (Mimosaceae), smoke of the leaves of Azadirachta indica A.Juss. (Meliaceae) and Eucalyptus sp. (Myrtaceae), fresh Ocimum canum Sims (Lamiaceae), and fresh Senna occidentalis (L.) Link (Caesalpiniaceae). In two field experiments we estimated the 'repellent activity' of certain of these plants and compared their efficacies with those of two commercially available mosquito repellents, i.e. 'positive' controls. In the first experiment we tested: smouldering H. suaveolens (85.4% repellency); fresh H. suaveolens (73.2%); burning of the bark of D. oliveri (74.7%); and smoke of the leaves of Eucalyptus (72.2%). In the second experiment we tested: smouldering H. suaveolens (83.6% repellency); fresh H. suaveolens (66.5%); burning of the bark of D. oliveri (77.9%); smoke of the leaves of A. indica (76.0%); smoke of the infructescence of E. guineensis (69.0%); fresh O. canum (63.6%); and fresh S. occidentalis; (29.4%). All the products tested, except S. occidentalis were significantly more effective than the negative control.

Animals↗

PubMed1999

Comparison of plant products and pyrethroid-treated bed nets for protection against mosquitoes (Diptera: Culicidae) in Guinea Bissau, West Africa.

In Guinea Bissau, West Africa, the shrub Hyptis suaveolens Poit. (Lamiaceae) and smoke of the bark of the tree Daniellia oliveri Rolfe (Caesalpiniaceae) traditionally are used to reduce numbers of mosquitoes indoors at night. We recorded the numbers of mosquitoes in the bedrooms of 30 households in a rural village, Mandinka-Rá in central Guinea Bissau. Each household was provided with bed nets and allocated randomly to 1 of 6 treatments as follows: (1) lambda-cyhalothrin-treated bed nets (10 mg/m2), (2) permethrin-treated bed nets (500 mg/m2), (3) burning of H. suaveolens, (4) burning of the bark of D. oliveri, (5) fresh H. suaveolens, and (6) control group using untreated bed nets and no plant products. In treatment groups 1-4, the mean number of mosquitoes was significantly less than the mean of the control. These results indicated that the use of burning H. suaveolens or D. oliveri indoors at night repelled endophagic mosquitoes and may contribute significantly to reducing the prevalence of diseases caused by pathogens transmitted by house-frequenting, nocturnally blood-feeding arthropods.

Africa, Western↗

PubMed1998

The palpal ratio method compared with PCR to distinguish between Anopheles gambiae s.s. and A. melas from Guinea Bissau, West Africa.

We compared the palpal ratio method with the polymerase chain reaction (PCR) to distinguish between Anopheles gambiae s.s. and A. melas. At the end of the rainy season of 1995, female mosquitoes were collected indoors in the Antula area of Bissau, Guinea Bissau. A subsample of 354 mosquitoes were identified first with PCR and then with the palpal ratio method (study A). Subsequently, another 195 mosquitoes were identified first with the palpal ratio method and then with PCR (study B). The highest percentage (100%, n = 16) of correctly identified A. melas was obtained at the palpal ratio cut-off point of 0.83. However, at this point 4.0% (14/347) and 11.3% (21/186) of the A. gambiae were erroneously identified as A. melas in study A and B, respectively. This suggests that the palpal ratio method is not sufficiently reliable to distinguish between A. gambiae and A. melas from the Bissau area.

Animals↗

PubMed1992

High HIV seroprevalence and increased HIV-associated mortality among hospitalized patients with deep bacterial infections in Dar es Salaam, Tanzania.

OBJECTIVES: To correlate deep bacterial infections with HIV infection and evaluate the influence of HIV on clinical picture and outcome in patients with meningitis, pneumonia or pyomyositis. DESIGN: Case-control comparison of HIV seroprevalence between patients and an age- and sex-matched control group in a prospective cross-sectional study of hospitalized patients. PARTICIPANTS: One hundred and sixty-five patients admitted to hospital with either purulent meningitis, pneumonia or pyomyositis and 165 age- and sex-matched controls from orthopaedic/trauma wards. SETTING: University Hospital, Dar es Salaam, Tanzania. OUTCOME MEASURES: Differences in HIV seroprevalence and mortality. RESULTS: Of 78 patients with purulent meningitis, 19 (24%) were HIV-seropositive, compared with 13 (17%) in the control group (P = 0.345). Of 36 patients with meningitis seen before a meningococcal epidemic affected Dar es Salaam, there was a statistically significant association with HIV infection (P = 0.013). Ten out of 19 (53%) HIV-seropositives died, compared with nine out of 59 (15%) seronegatives (P = 0.028). Of patients with pneumococcal meningitis, five out of six (83%) seropositives died, compared with two out of 12 (17%) seronegatives (P = 0.013). Fifteen out of 45 (33%) patients with pneumonia were HIV-seropositive, compared with four (9%) in the control group (P = 0.001). There was no difference in mortality between seropositive and seronegative patients with pneumonia. HIV seroprevalence was 62% among 42 patients with pyomyositis and 12% among 42 controls (P less than 0.0001). Eighteen out of 25 (72%) seropositive patients with pyomyositis fulfilled the World Health Organization (WHO) clinical case definition for AIDS. Response to recommended antibiotic treatment was satisfactory among patients with pneumonia and pyomyositis. CONCLUSIONS: These results show a strong association between pyomyositis, pneumonia and HIV infection. They also indicate an increased mortality associated with HIV infection in patients with pyogenic meningitis, especially pneumococcal meningitis. Pyomyositis should be considered an indicator of stage III HIV disease in the proposed WHO clinical staging system.

AIDS-Related Opportunistic Infections↗

PubMed1992

Alternative confirmatory strategies in HIV-1 antibody testing.

Alternatives to confirmation of human immunodeficiency virus (HIV)-1 seropositivity by Western blot analysis were evaluated retrospectively using combinations of six anti-HIV-1 screening assays, including four enzyme-linked immunosorbent assays (ELISA) and two simple tests (a rapid dot immunoassay and an agglutination assay), according to an algorithm where sera are first screened by one assay and those repeatedly reactive on this assay are tested repeatedly by a second assay. Two panels of sera collected in Dar es Salaam, Tanzania, were used. Panel 1 was composed of 1,465 consecutive blood donor sera of which 99 (6.8%) were confirmed HIV-1 antibody positive, and panel 2 was composed of sera from 396 consecutively admitted patients at two medical wards of which 116 (29.3%) were confirmed HIV-1 antibody positive. Sera reactive on any of the six screening assays were also tested by a confirmatory Western blot assay. The sensitivity of the assays at the initial valid testing were as follows: Abbott 99.5%, Behring 99.5%, Organon 97.7%, Wellcozyme 100%, HIV CHEK-1 95.8%, and Serodia 95.8%. After repeat testing of sera that initially gave false-negative results all assays showed 100% sensitivity except HIV CHEK-1 (98.6%). The specificities after repeat testing were between 99.6 and 99.9% for all assays except for the Behring ELISA (98.1%). Several combinations of screening assays were found to give the same diagnostic accuracy as the screening assay followed by Western blot analysis. We conclude that an alternative confirmatory strategy can be fully satisfactory for some testing purposes.

Agglutination Tests↗

PubMed1988

An amplification technology for improving sensitivity when measuring components in biological samples.

A new technology for improving the sensitivity in measuring components in biological samples is described. The method is based on the use of spherical microbeads (detection beads) which contain a large amount of immobilized enzyme and a reagent with biospecific affinity for the component to be detected. These microbeads have been used in a 'sandwich reaction' for visualization of P-fimbriated Escherichia coli which has a known receptor structure (Gal(alpha 1-4)Gal(beta)). In the initial step the bacteria were enriched on a solid support (e.g., a plastic film or beads (greater than 150 microns)) to which the receptor structure had been covalently bound. In the next step detection beads coupled with enzyme and receptor structure were added and finally a chromogenic substrate for the enzyme was used for visualization. A sensitivity of 10(5) bacteria/ml was reached. The detection beads are of general utility and might be useful for the detection of lectins on other pathogens.

Agglutination Tests↗

PubMedDate not supplied

Traditional use of mosquito-repellent plants in western Kenya and their evaluation in semi-field experimental huts against Anopheles gambiae: ethnobotanical studies and application by thermal expulsion and direct burning.

Ethnobotanical survey in 2 communities in western Kenya revealed that the most commonly known repellent plants were Ocimum americanum L. (64.1%), Lantana camara L. (17.9%), Tagetes minuta L. (11.3%) and Azadirachta indica A. Juss (8.7%) on Rusinga Island, and Hyptis suaveolens Poit. (49.2%), L. camara (30.9%) and O. basilicum L. (30.4%) in Rambira. Direct burning of plants is the most common method of application for O. americanum (68.8%), L. camara (100%) and O. basilicum (58.8%). Placing branches or whole plants inside houses is most common for H. suaveolens (33.3 and 57.8% for the respective locations), A. indica (66.7 and 100%), and T. minuta (54.8 and 56.0%). The repellency of plants suggested by the ethnobotanical survey and other empirical information was evaluated against the malaria vector Anopheles gambiae s.s. Giles in experimental huts within a screenwalled greenhouse. Thermal expulsion and direct burning were tested as alternative application methods for the selected plants O. americanum, O. kilimandscharicum Guerke, O. suave Willd., L. camara, A. indica, H. suaveolens, Lippia uckambensis Spreng and Corymbia citriodora Hook. When thermally expelled, only H. suaveolens failed to repel mosquitoes, whereas the leaves of C. citriodora (74.5%, P < 0.0001), leaves and seeds of O. suave (53.1%, P < 0.0001) and O. kilimandscharicum (52.0%, P < 0.0001) were the most effective. Leaves of C. citriodora also exhibited the highest repellency (51.3%, P < 0.0001) by direct burning, followed by leaves of L. uckambensis (33.4%, P = 0.0004) and leaves and seeds of O. suave (28.0%, P = 0.0255). The combination of O. kilimandscharicum with L. uckambensis repelled 54.8% of mosquitoes (P < 0.0001) by thermal expulsion. No combination of plants increased repellency by either method. The semi-field system described appears a promising alternative to full-field trials for screening large numbers of candidate repellents without risk of malaria exposure.

Animals↗