Scavenging dogs and the spread of tick infestation in Nigeria.

A dog, on whose body ticks were found early in January, 1977, was kept in the household during the night but allowed to scavenge during the day without the ticks being removed throughout the year. Weekly counts of the number of different stages of ticks found on the body were made and the behaviour of the engorged dropped ones was studied. The preoviposition, oviposition and preeclosion periods of replete ticks were also studied. Rhipicephalus sanguineus and Haemaphysalis leachi leachi were the only ticks found on the body; the former was more abundant but both occurred throughout the year with greater abundance during the rains. Completion of the life cycle was faster in both species during the dry season than the rainy season. Each stage of the life cycle was very prolonged during the harmattan. On dropping, adults showed an initial phase of inactivity, the length of which was influenced by the climatic season. While engorged larvae and nymphs could overcome impediments by waking round them, the adults appeared to be contended with ovipositing there. Some adult R. sanguineus were caught while attempting to bit a human bait. The public health significance of this fact as well as the role of scavenging dogs in aiding the dissemination and maintaining the population of ticks of dogs in Nigeria are discussed.