INVESTIGADORES
PICOLLO Maria Ines
congresos y reuniones científicas
Título:
Management of Pyrethroid Resistance in Head Louse Populations
Autor/es:
MARÍA INÉS PICOLLO
Lugar:
Urgup, Cappadocia
Reunión:
Congreso; 9. Fourth International Conference on Phthiraptera (ICP4); 2010
Institución organizadora:
International Society of Phthirapterists
Resumen:
In
Argentina,
the infestation with Pediculus humanus
capitis is an endemic sanitary problem affecting 30% of school-aged
children. Moreover, more than 90% of head louse populations have developed high
levels of resistance to permethrin (28.6-71.4) and other pyrethroids. As a
consequence, there had been a trend to the use of herbal remedies for the control of pyrethroid-resistant head lice. First
studies demonstrated that the essential oils from natural aromatic plants from Argentina produced differential fumigant toxicity against head
lice. Similarly, the terpenoid constituents of the effective essential oils, also demonstrated
differential activity. Additionally, some whole oils resulted more active than
any of its individual components. In order to improve the use of these natural
compounds as pediculicides, we investigated the physiochemical parameters
related with the activity of the monoterpenoids, as well as the toxic
interactions of the components that affect the activity of the mix.
A positive
relationship was found between the fumigant efficacy of the compounds and the corresponding
vapor pressures. The more volatile compounds were more effective fumigants against
lice and also against their eggs, indicating that these compounds could be incorporated into formulations as potential
pediculicides against both stages. Moreover, a clear correlation was established between the viscosity
and the contact toxic effect. It was a non-linear relationship which
demonstrated the highest pediculicide potency at a medium range of viscosities.
This means that the pediculicidal activity could be improve modifying the
viscosity of the formulation.
The individual components
of Argentinean plants varied in their activity when they were evaluated alone
or mixed (in the same natural ratio) with other components of the whole oil.
For example, a clear synergism was established by topical application between
pulegona and citral (the major components of Aloysia citriodora), and between citronelol, linalol and
citronellol from the geranium oil. These interactions were also found in
pediculicide formulations and lead the development of a commercial product
based on the synergized monoterpenes.
All this knowledge represents
important tools to design novel strategies to improve the overall management of head louse infestations.