DURATION OF TICK ATTACHMENT REQUIRED FOR TRANSMISSION OF GRANULOCYTICEHRLICHIOSIS

Deer tick-transmitted pathogens such as Lyme disease spirochetes and b abesiae appear to require a period of reactivation and replication dur ing the tick's blood meal before it is able to infect a host. The dura tion of nymphal tick attachment that is required for transmission of t he agent of human granulocytic ehrlichiosis (HGE) was determined by re moving feeding ticks from mice at various time points. As with spiroch etes and babesiae, ehrlichiae infected few mice when ticks were remove d prior to 36 h of tick attachment. This ''grace period'' may serve as a modifying factor in the epidemiology of this newly emergent zoonosi s and help physicians make informed decisions concerning management of tick bites in HGE-endemic areas.