Tick-Borrelia interaction during reproduction of Ornithodoros erraticus, a vector of relapsing fever in Egypt

Abstract

The argasid tick Ornithodoros erraticus is widely distributed in Egypt and was found to harbor and transmit Borrelia crocidurae, the etiologic agent of the North African relapsing fever. Ticks become infected by feeding upon spirochaetemic animals, then the spirochaetes migrate from the digestive tract to the hemocoele and invade almost all tissues including the reproductive system where they multiply and may be transmitted transovarially to the offspring. The study of structural and physiological peculiarities of the tick reproduction and interaction between pathogen and vector tick is necessary to understand the basis underlying its success as a vector of diseases. In the present study a laboratory reared female O. erraticus with high infection rate were used to study the effect of borrelial infection on reproduction and proteins involved in egg production. Also, histological localization of the spirochaetes in the infected ovary was investigated. 1 Basic interrelationships of B. crocidurae with female O. erraticus: • The follow-up and inspection of the level of infection rate in the infected laboratory colony detected the presence of B. crocidurae in 95 – 100% of the examined mated fed females O. erraticus during the period of study. • Feeding of uninfected female O. erraticus on B. crocidurae infected hamster was associated with the ingestion of the spirochaete in the midgut immediately, then its entry in the haemolymph and salivary gland on the 1st day after feeding (d.a.f) and in the ovary on the 3rd d.a.f. Borrelial infection