Weight gain, hemoglobin uptake, and virus ingestion by Hyalomma truncatum (Acari: Ixodidae) ticks after engorgement on viremic guinea pigs.

The ability of guinea pigs to serve as a source of an arbovirus for feeding ticks was examined with Hyalomma truncatum Koch and Venezuelan equine encephalomyelitis virus. Ticks fed on guinea pigs to varying degrees, as indicated by both low and high weight gain and hemoglobin uptake. Pools of larval ticks measured at drop-off with undetectable or very low hemoglobin levels (mean hemoglobin content = 0.05 mg per pool) contained the same amount of virus (> 10(3.0) plaque-forming units [PFU] per pool) as pools of ticks with high hemoglobin levels (mean hemoglobin = 0.15 mg per pool). A group of nymphs that ingested a mean of 0.13 mg of hemoglobin contained the same amount of virus (mean viral titer approximately 10(2.5) PFU) as a group of nymphs that ingested 0.32 mg of hemoglobin. Some adult ticks that ingested < 0.35 mg of hemoglobin contained more virus than adults that ingested > 4.7 mg of hemoglobin.