pastrymama, I just got back from a trip to Santa Fe and I'm completely sickened by the tragedy you had to endure.
I am so sorry, it must have been horrible. The symptoms certainly sounded like infectious coryza, but I wonder that maybe something else might be the cause considering the measures you've taken with bringing in new chickens. Someone correct me if I'm wrong, but I think that infectious coryza is only carried by chickens (but maybe turkeys and pheasants? I can't remember)--but not wild birds. It could be possible that one of the chickens you got had it, but was otherwise healthy enough to keep any symptoms hidden. So, if it was IC, then it had to come in on one of the other chickens. There is another possibility, and that is
Trichomonas gallinae. This is a protozoan parasite of wild birds that causes symptoms that read remarkably like infectious coryza. Here's the rub--it seems that most doves (at least those inside Tucson) carry this parasite. It's suspected that city living contributes to the huge frequency of doves carrying this parasite. Doves outside the city limits rarely have it (
http://www.ncbi.nlm.nih.gov/pubmed/9706569). Tucson has the greatest density of Cooper's hawks in the world (I suspect Phoenix is a close second) precisely because of the huge density of doves that we have. But the costs are high, nestling Cooper's hawks suffer greatly because of this parasite, which they get when the parents feed them infected doves. At least 85% of all Cooper's hawk nestlings in the city have this parasite, but only 9% of those outside the city have it. Chickens, turkeys and pheasants can also get
Trichomonas gallinae. Here is a good, short and readable discussion of
Trichomonas:
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex4444.
Here's an excerpt from that link:
Avian trichomoniasis is principally a disease of young birds. The severity of the disease depends on the susceptibility of the bird and on the pathogenic potential of the strain of the parasite. Adult birds that recover from the infection may still carry the parasite, but are resistant to reinfection. These birds do not show obvious signs of infection.
In young birds, the early lesions appear as small white to yellowish areas in the mouth cavity, especially the soft palate (Figure 1). The lesions consist of inflammation and ulceration of the mucosal surface. The lesions increase in size and number and extend to the esophagus, crop and proventriculus (Figure 2). The lesions may develop into large, firm necrotic masses that may block the lumen. Occasionally, the disease may spread by penetrating the underlying tissues to involve the liver and other organs.
My guess is that a chicken with this infection would smell pretty bad too.
Here is what the Merck Vet. Manual (
http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/201400.htm) says about it (and when they say caseous, think "cheesy"):
The bird may be riddled with caseous, necrotic foci. The mouth and esophagus contain a mass of necrotic material that may extend into the skull and sometimes through the surrounding tissues of the neck to involve the skin. In the esophagus and crop, the lesions may be yellow, rounded, raised areas, with a central conical caseous spur, often referred to as yellow buttons. The crop may be covered by a yellowish, diphtheritic membrane that may extend to the proventriculus. The gizzard and intestine are not involved. Lesions of internal organs are most frequent in the liver; they vary from a few small, yellow areas of necrosis to almost complete replacement of liver tissue by caseous necrotic debris. Adhesions and involvement of other internal organs appear to be contact extensions of the liver lesions.
I don't have any experience with either of these diseases, only with what I've read. But, it sounds like one distinguishing feature is the age at which the birds are likely to exhibit the diseases; Trichomonas gallinae is more likely to be seen in younger birds and infectious coryza is more likely to be seen in older birds. Also, it sounds like it would be good to have a look at the liver. That might be the best distinguishing feature a BYC'er could use.
Given our urban environment, the large numbers of doves and sparrows (which also carry it) and the extremely high frequency of infection in the wild birds, I would have to wonder if they might be the culprits. Also, Trichomonas gallinae is typically transmitted to poultry from wild birds after sharing a water source. The parasite doesn't live long at all in a dry environment (I think it's measured in minutes), but can live quite well in a watering dish. Do you use poultry nipples? That might help limit transmission.
I don't know if any of this will help and I certainly hope I didn't muddle things for you. And please, if anyone else has something to correct or add here, please do. I'm not an expert by any means, just a guy that likes to read obscure crap and worry himself.
