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Tick transmission of Anaplasma centrale
Abstract:
Anaplasma centrale was isolated from a field collection of Rhipicephalus simus. Transstadial transmission of A. centrale with adult ticks was demonstrated, but the infection was not carried transovarially. Ticks from this collection were subsequently reared as a non-infected, laboratory strain. It was proved that the Onderstepoort live blood vaccine strain of A. centrale, isolated by Theiler in 1911, is still tick transmissible after more than 75 years of needle passage through cattle in the laboratory. Attempts to demonstrate transstadial transmission of the vaccine strain with Boophilus decoloratus and Boophilus microplus failed.
Insights
Anaplasma centrale can be transmitted by adult Rhipicephalus simus ticks, but not through eggs. The vaccine strain remains tick-transmissible after decades of lab passage.
Area of Science:
- Veterinary Entomology
- Parasitology
- Infectious Diseases
Background:
- Anaplasma centrale is an important cattle pathogen.
- Tick-borne transmission is crucial for Anaplasma epidemiology.
- The Onderstepoort vaccine strain has undergone extensive laboratory passage.
Purpose of the Study:
- To investigate the tick transmission of Anaplasma centrale.
- To determine if field-isolated Anaplasma centrale is transstadially and transovarially transmitted.
- To assess the tick transmissibility of the long-passaged Onderstepoort vaccine strain.
Main Methods:
- Isolation of Anaplasma centrale from Rhipicephalus simus ticks.
- Experimental transmission studies using different tick species (Rhipicephalus simus, Boophilus decoloratus, Boophilus microplus).
- Assessment of transstadial and transovarial transmission in ticks.
Main Results:
- Transstadial transmission of Anaplasma centrale was demonstrated with adult Rhipicephalus simus ticks.
- Transovarial transmission of Anaplasma centrale was not observed in Rhipicephalus simus.
- The Onderstepoort vaccine strain of Anaplasma centrale remained tick-transmissible after over 75 years of needle passage.
- Attempts to transmit the vaccine strain using Boophilus decoloratus and Boophilus microplus failed.
Conclusions:
- Adult Rhipicephalus simus ticks can transmit Anaplasma centrale, but not transovarially.
- The Onderstepoort vaccine strain retains its tick transmissibility despite prolonged laboratory passage.
- Boophilus species may not be competent vectors for the Onderstepoort vaccine strain.