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At least 127 records · Page 7Linked to original sources
PubMed2003

[Prevalence of pediculus humanus capitis infestation in schoolchildren at Despeñaderos, Córdoba Province].

BACKGROUND: Approximately 80% of Argentine children have pediculosis, making it imperious to detect the defects in the prevention and control actions for this parasitosis. OBJECTIVES: To study the infestation level by P. h. capitis, its temporal variation, and the association between infestation and host characteristics. MATERIALS AND METHODS: A monthly census in children of 6-8 years old from 2 primary schools (state and private) was carried out, recording the parasite stages found, children characteristics (sex, colour and length of hair), and infestation level. Data were analysed by means of contingency tables, difference of proportions, quotient of chances, and rank correlation coefficient. The independence of variables was analysed by c' test. RESULTS: The prevalence and chances of becoming infested were higher at the state school, where also all infestation levels were recorded, which did not occur at the private institute. The frequency of children infested was significantly lower when they had short hair. The correlation among infestation degree and hair length (short-long) was only significant for boys. Pediculosis cases were recorded at the beginning of the school year in both educative institutions, which demonstrated that infestation was acquired not only at school but also at home. CONCLUSIONS: Pediculosis is a social problems and the whole community must participate in preventive and control actions, for which sanitary education is essential, and the myth that the school is the only place of contagion must be eradicated.

Animals↗
PubMed2006

Experimentally infected human body lice (pediculus humanus humanus) as vectors of Rickettsia rickettsii and Rickettsia conorii in a rabbit model.

The human body louse, the natural vector of Rickettsia prowazekii, is able to experimentally transmit the normally flea-borne rickettsia R. typhi, suggesting that the relationships between the body louse and rickettsiae are not specific. We used our experimental infection model to test the ability of body lice to transmit two prevalent tick-borne rickettsiae. Each of two rabbits was made bacteremic by injecting intravenously 2 x 10(6) plaque-forming units of either R. rickettsii or R. conorii. Four hundred body lice were infected by feeding on the bacteremic rabbit and were compared with 400 uninfected lice. Each louse group was fed once a day on a separate seronegative rabbit. The survival of infected lice was not different from that of uninfected controls. Lice remained infected for their lifespan, excreted R. rickettsii and R. conorii in their feces, but did not transmit the infection to their progeny. The nurse rabbit of uninfected lice remained asymptomatic and seronegative. Those rabbits used to feed infected lice developed bacteremia and seroconverted. Although the body louse is not a known vector of spotted fevers, it was able in our study to acquire, maintain, and transmit both R. rickettsii and R. conorii.

Animals↗
PubMed1990

[The detection of Rickettsia prowazekii in the vectors of louse-born typhus Pediculus humanus by using monoclonal antibody-based preparations].

The results of this investigation indicate that preparations obtained on the basis of monoclonal antibodies have proved to be suitable for the detection of R. prowazekii antigens in the natural carrier of typhus when used in all types of the enzyme immunoassay; of these, the assay made by the capture method has been found to possess the highest sensitivity. The testing of the sensitivity limits has shown that this method known as ELISA-mu-capture, i.e. ELISA carried out with the use of antibodies to the mu chain of human immunoglobulin, is capable of detecting the antigen in a dose of 0.5-1 ng. Preparations based on monoclonal antibodies to species-specific R. prowazekii antigen permit the identification of the causative agent of typhus in its natural carrier within 24 hours.

Animals↗
PubMedDate not supplied

[Ultrastructural characteristics of the simple eyes of the louse Pediculus humanus corporis].

The simple eye of the human louse consists of two apparatuses: dioptric and light sensitive. The dioptric apparatus contains only a biconvex lens, which represents local thickening of the cuticle. The eye lacks the crystal cone (Semper cells) and special pigment cells. The light sensitive part of the eye contains about 130 photoreceptor cells. Each photoreceptor has rhabdomere which consists of numerous microvilli. The pigment granules are located only in the photoreceptor cells.

Animals↗
PubMed1984

Susceptibility to DDT and some other insecticides of head lice (Pediculus capitis De Geer) in Czechoslovakia.

For testing the susceptibility of the head louse to insecticides impregnated bunches of polyamide fibres, whose diameter resembled that of human hair (0.1 mm) were used. In this manner a low mortality of control lice collected from infected persons was obtained (2.9% after 16 hours of exposure). Even after 25 years of DDT use no apparent resistance could be demonstrated in 25 tested louse populations and cross resistance to permethrin in 7 tested populations. The diagnostic concentration for resistance to pp'-DDT was established at 1%. Of the tested insecticides the highest toxicity was shown by malathion (LC50 = 0.000 018%), pirimiphos-methyl had on average a twice lower toxicity, trichlorphon 104 times lower, tetramethrin 1220 times lower, permethrin 2.5 times lower and pp'-DDT 630 times lower toxicity.

Adolescent↗