Some quantitative aspects of natural babesial infection in the haemolymph of Boophilus microplus engorged female ticks

Quantitative aspects of the natural babesial (Babesia bovis and Babesia bigemina) infection in Boophilus microplus engorged female ticks obtained from two herds of Holstein heifers positive by the immunofluorescent antibody test to both protozoan were evaluated. The number of kinetes/ microscope fie...

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Veröffentlicht in:Parasite (Paris) 1997-12, Vol.4 (4), p.337-341
Hauptverfasser: Guglielmone, A.A., Gaido, A.B., Aguirre, D.H., Cafrune, M.M.
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Sprache:eng
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Zusammenfassung:Quantitative aspects of the natural babesial (Babesia bovis and Babesia bigemina) infection in Boophilus microplus engorged female ticks obtained from two herds of Holstein heifers positive by the immunofluorescent antibody test to both protozoan were evaluated. The number of kinetes/ microscope field of haemolymph was determined for each tick from day 5 to 10 post-collection. A close relationship between daily and cumulative babesial infection was detected. Correlation and determination coefficients between days post-collection and the daily and cumulative infection rates, including heavily infected ticks (those ticks carrying at least 3.0 kinetes/ microscope field of haemolymph), were always higher than 0.9 (P< 0.01) in ticks of both herds. The median was found to be a more representative measure than the mean to define the distribution of kinetes number amongst infected ticks since this is a negative binomial distribution. The analysis of the sequential order of days of infection more accurately showed the amplification of the babesial infection in the tick haemolymph than the evolution of kinetes number in relation to days post-collection. Sampling ticks on days 8, 9 and 10 post-collection would have detected all ticks infected with Babesia spp. from both herds. A categorization of infected or non infected ticks would be of greater epidemiological importance than the haemolymph infection level, based upon previous laboratory studies that showed a poor relationship between haemolymph infection in the female ticks and the infection rate in their eggs. However, further studies in natural infected ticks and better techniques to differentiate B. bovis and B. bigemina kinetes are needed before these laboratory results can be applied to field conditions. On a étudié les aspects quantitatifs de l'infection babésienne naturelle (Babesia bovis et Babesia bigemina) chez des femelles gorgées de Boophilus microplus récoltées dans deux troupeaux de génisses Holstein présentant des anticorps spécifiques aux deux espèces de Babesia, selon le test d'immunofluorescence. Le nombre de kinètes/champ microscopique d'hémolymphe est établi pour chaque tique entre le 5e et le 10e jour après sa récolte. On a trouvé une corrélation étroite entre les infections journalières et les infections cumulées par Babesia. Les coefficients de corrélation et de détermination entre les jours post-récolte et les taux d'infection journalière et cumulée, y compris pour les tiques très infectées
ISSN:1252-607X
1776-1042
DOI:10.1051/parasite/1997044337