Sorry, my sentence was awkward. I just meant that the two Osps were regulated in the tick, before transfer to the host.
I said I was going to ignore early transmission, but of course once I started thinking about it, I couldn't. It's like "don't think of an elephant."
Did you notice the relevant thread that Cobwebby resurrected?
http://www.lymeneteurope.org/forum/view ... &t=94#p225
There's a good eye-witness story from the late Joe Hamm, about partially fed ticks, abandoning a dead deer in favor of its killer.
Claudia provided an abstract to a 1993 ( watershed year in Lyme history) paper by Shih and Spielman describing experiments with partially fed ticks (see below). They don't think they're extremely rare, and they see the importance of that with regard to both prevention and, I presume, diagnosis. After 1993 (when Steere's influential paper on "the overdiagnosis of Lyme disease" persuaded the mainstream to work on preventing diagnosis rather than improving it) this observation of early transmission would have been out of favor, and followups might have been difficult politically.
http://www.ncbi.nlm.nih.gov/pmc/article ... 3-0052.pdf
J Clin Microbiol. 1993 Nov;31(11):2878-81.
Accelerated transmission of Lyme disease spirochetes by partially fed vector ticks.
Shih CM, Spielman A.
Department of Tropical Public Health, Harvard School of Public Health, Boston, Massachusetts 02115.
To determine how rapidly Lyme disease spirochetes (Borrelia burgdorferi) can be transmitted by partially fed vector ticks (Ixodes dammini), attached nymphs were removed from their hosts at various intervals post-attachment and subsequently permitted to re-feed to repletion on noninfected mice. We confirm previous reports that ticks deposit Lyme disease spirochetes in the skin of their hosts mainly after 2 days of attachment. Those that have been removed from a host within this interval can reattach and commence feeding. Spirochete-infected nymphs that have previously been attached to a host for 1 day become infectious to other hosts within another day. Noninfected nymphs acquire infection from spirochete-infected hosts within a day of attachment and become infectious to other hosts 3 to 5 days later. Virtually all ticks transmitted infection when reattaching after first feeding for 2 days. We conclude that partially fed nymphal ticks transmit spirochetal infection more rapidly than do ticks that have never been attached to a host and that infected ticks become infectious before they molt.
PMID: 8263171 [PubMed - indexed for MEDLINE] PMCID: PMC266148 Free PMC Article
edited: Claudia provided this reference, not cave76 as I said before. I fixed it.Transmission of spirochetal infection from partially fed nymphs to their hosts depends on the capacity of a tick to acquire spirochetes early in the feeding process as well as its ability to reattach to another host. We found that spirochetal infection is efficiently acquired within the first day of feeding and that ticks can reinfest new hosts. We found that nymphs do detach spontaneously from free-ranging mice in thelaboratory, perhaps as frequently as 15% of the time. Indeed, about a tenth of questing nymphs in nature seem to be distended (24), and reattachment by partially fed subadult ticks commonly occurs (1, 9, 12).
Our observation of accelerated transmission by ticks that fed transiently on infected hosts suggests certain unexpected events in the life cycle of these spirochetes. We believe that this acceleration is not due to contaminative transmission because reattachment was delayed for several days. The previously observed phase of rapid multiplication (17) may be accompanied by spirochetal dissemination. Such disseminated infection normally is followed by a period of spirochete destruction that eliminates all but those spirochetes that survive in the lumen of the gut. Indeed, disseminated infections in nonfeeding ticks have occasionally been encountered during the course of fine-structural studies (6, 27).Such hemocelic spirochetes may become nonviable by the time that the tick has molted, and this persistence may reflect some failure of clearance by the inflammatory system of the tick. Lyme disease spirochetes, then, transiently disseminate soon after they are ingested by vector ticks.
Exposure to vector ticks infected by the agent of Lyme disease generally occurs during outdoor activities associated with recreation or employment (19, 22). In one study at a site at which Lyme disease was endemic, vector deer ticks were found on or near the well-maintained lawns of the home of a patient with Lyme disease (8). Spirochetal infection was detected in 33% of the nymphs and 55% of the adults. Indeed, vector ticks feeding on infected hosts may detach prematurely because of grooming or host-derived antitick immunity (4, 5, 25, 26). These partially fed ticks may already have acquired spirochetal infection and avidly seek other hosts. Pet ownership appears to be a risk factor for human Lyme disease (10, 23), and this may reflect contact with ticks that have detached from a cat or dog within the household, Although the natural frequency of such partially fed nymphs has not been determined, they may present a particularly great risk of transmission of spirochetes.