Blackhead Disease Dissection

So I've started losing turkey poults to disease. I noticed a week or so ago some strange turkey poops - tannish yellow and really bubbly. I would notice a turkey start to act differently - no flight distance, droopy feathers. Instantly, I suspected blackhead (Histomonas meleagridis). This is bad, very bad, as this disease can easily cause +90% mortality in turkeys.

Blackhead is a devestating disease in turkeys, and it's usually a problem attributed with having ground that was exposed to chickens. The protozoan that causes blackhead is a pretty wimpy critter, but it's got a great survival strategy. Blackhead will set up shop inside of a chicken and "hide" in cecal worms (found in all chickens), hitching a ride out of a chicken's intestinal tract when the cecal worm sends it's eggs out. The cecal worm eggs can stay dormant in the soil for up to 4 years, and the blackhead in the egg hangs out waiting. Other birds can pick up the cecal worm eggs (and the blackhead) either through ingesting soil or eating earthworms which have eaten soil with cecal worm eggs in it. Once in the intestinal tract, the blackhead emerges, and if your a turkey, well, you're in a heap of trouble. The blackhead builds up, destroying the caecal pouch in the digestive tract, where it then gets into the blood and destroys the liver.

So when suspected, blackhead is really easy to check for in turkeys.

1. Take poult in question and get some tools - utility knife and tin snips were used.

2. Open up the abdominal cavity. If you've never done this before, just cut above the anus and with shallow cuts work your way up to the breast. Once you're there, use tin snips to open up the chest cavity so you can get a good look at the liver. 3. Check the liver and caecum. Here you can see the bullseye decay spots (necrosis) indicative of blackhead, sorry about the glare. Click to enlarge to get a better view. It was really obvious in real life. to the left, you can see the gas that cases the foamy poop.

The finger thing in the guts is the caecal pouch. Normally, it would be like the other intestines (there's some right above it), but it's got a characteristicly caeseous (cheese like) substance that's packed it full. This is another blackhead give away. I didn't cut it open because it absolutely reeks.


Above is another liver view. So cecal & earthworms can lead to an outbreak in a turkey flock, but the rapid transmission in the flock is due to cloacal (ie butthole) drinking. This is a relatively new understanding of blackhead transmission, and I found it going through recent poultry science journals.

So human babies, puppies, kittens, etc chew and slobber over everything to inoculate thier systems. Turkeys also do this, but they do it in a slightly different way. It's weird, but a turkey/chicken/etc actually lets bacteria into its system by opening up the other end. This works great, unless of course your laying on top of some infected poo. Counterintuitvely, ingesting the protozoan (not in cecal eggs) doesn't seem to infect the turkey, as the acidity in the proventriculus and stomach easily knocks out the protozoan.

There's no cure for blackhead, but understanding how it works, has caused me to start moving my turkeys a lot. Hopefully this will keep other cloacal transmissions from occurring.