There has been a greater emphasis lately on abortive infections when characterising host range of avian haemosporidians (see recent articles by Valkiunas and Palinauskas). I was under the impression that abortive infections generally never reach the tissue stage of development. However I read in the recent paper by Valkiunas et al. that abortive infections can still develop to the tissue stage, but of course gametocytes will not develop in the blood. This could lead to a very similar parasite DNA distribution within the host to latent infections.
So I am wondering if there is any particular way to accurately tell the difference between an abortive infection and a latent infection where (1) parasite DNA exists in muscle and organ tissues and (2) gametocytes are absent from the blood. What do you think about this issue? Would you basically have to identify abortive stages in the blood to confirm (could be very difficult I imagine). Thanks again, I appreciate the help.
I would say that the answer is "No". It seems highly unlikely you would be able to definitively distinguish between the two (interpretational problem). As an aside, there is currently no way at all of determining the presence of hypnozoites in the liver in human malarial infections. This is only partly a valid analogy with the avian situation (cf. the question asked), however. It is merely illustrative of potential and actual haemosporidian-associated difficulties as regards detection of organisms in latent infections; inter alia when not many parasites are present in the body.
Do you think that if a small liver fragment was removed and histological exams performed would be possible to determine the stage of infection? I complet understand the difficults of performing this procedure, specially in field conditions.
You mention liver, so if you are referring to histological detection of hypnozoites in primates (rather than to avian haemosporidian infections), the answer is "No". It would be like looking for a needle in a haystack. Hypnozoites are directly sporozoite-derived and relatively few sporozoites are inoculated by mosquitoes. It is difficult enough to find hypnozoites in the liver (a primate liver is large) after injection of massive numbers of sporozoites experimentally. As for avian infections, finding schizonts in whatever tissue(s) histologically would not reveal for certain whether or not an abortive infection is involved (see the original question).
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