Experimental transmission of African swine fever virus by the soft tick Ornithodoros (Pavlovskyella) marocanus (Acari: Ixodoidea: Argasidae).

A total of 1,600 Ornithodoros (Pavlovskyella) marcocanus larvae were fed on a pig with a viremia of 10(7.4) HAd50/ml of African swine fever virus (ASFV). Infected larvae were sampled daily for 15 d, and nymphs were sampled at least once per instar until they became adults. Initial titers of 10(4.48) HAd50 per larva declined to 10(4.04) within 2 d. Larval titers reached a maximum of 10(6.0) HAd50 per larva 10 d after the infective blood meal. Nymphs of each instar were fed on a susceptible pig and in each case transmitted ASFV by bite. Virus titers for first to fourth instars ranged from 10(4.61) to 10(3.34) HAd50 per nymph. Transstadial survival occurred in subsequent first, second, third, and fourth instars with an 89% survival rate over 250 d. Approximately 30% of adult ticks that were infected as larvae remained infected and transmitted ASFV to susceptible pigs 588 d later. In addition, ASFV was recovered from the same adult ticks 655 d after the infective blood meal.