American Hepatozoonosis

Todayโ€™s path rounds are on ๐€๐ฆ๐ž๐ซ๐ข๐œ๐š๐ง ๐ก๐ž๐ฉ๐š๐ญ๐จ๐ณ๐จ๐จ๐ง๐จ๐ฌ๐ข๐ฌ!

๐–๐ก๐š๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐‡๐ž๐ฉ๐š๐ญ๐จ๐ณ๐จ๐จ๐ง๐จ๐ฌ๐ข๐ฌ is infection by ๐‡๐ž๐ฉ๐š๐ญ๐จ๐ณ๐จ๐จ๐ง species, where are a genus of ๐€๐ฉ๐ข๐œ๐จ๐ฆ๐ฉ๐ฅ๐ž๐ฑ๐š๐ง๐ฌ. Apicomplexans are a type of parasite that must live within the cells of their hosts in order to survive.

๐–๐ก๐จ ๐ ๐ž๐ญ๐ฌ ๐ข๐ญ?
This disease affects dogs! This particular disease is most common in the southern United States.

๐–๐ก๐š๐ญ ๐œ๐š๐ฎ๐ฌ๐ž๐ฌ ๐ข๐ญ?
American hepatozoonosis is caused by ๐‡๐ž๐ฉ๐š๐ญ๐จ๐ณ๐จ๐จ๐ง ๐š๐ฆ๐ž๐ซ๐ข๐œ๐š๐ง๐ฎ๐ฆ. This parasite is spread by ๐ž๐š๐ญ๐ข๐ง๐  ticks, not being bit by the tick! Weird.

Within the tick, Hepatozoon undergoes reproduction to produce ๐ฌ๐ฉ๐จ๐ซ๐จ๐ณ๐จ๐ข๐ญ๐ž๐ฌ. An animal will eat the tick, and the sporozoites will be released into the intestines, migrate through the intestinal wall, and enter the bloodstream. Once in the bloodstream, the parasite makes a home for itself in ๐ฅ๐ž๐ฎ๐ค๐จ๐œ๐ฒ๐ญ๐ž๐ฌ (white blood cells), which allow it to be spread throughout the body. The parasites will then undergo further development in many tissues, including the liver and skeletal muscle.

๐–๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐š ๐ฉ๐ซ๐จ๐›๐ฅ๐ž๐ฆ?
When the parasites set up shop in the muscle or liver, they induce a strong immune response. This immune reaction causes fever, depression, anorexia, soreness, and stiffness for the animal. Often affected dogs have such severe muscle soreness they become unwilling to move at all, even to eat or drink! All because of a little friend hanging out in their muscle cells ๐Ÿ˜ข

๐‡๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐š๐ ๐ง๐จ๐ฌ๐ž๐?
The best method of diagnosis is a ๐ฆ๐ฎ๐ฌ๐œ๐ฅ๐ž ๐›๐ข๐จ๐ฉ๐ฌ๐ฒ, where a pathologist can look at the tissue under a microscope and see the little parasites hanging out in the cells. Often, these parasites can also be seen on a ๐›๐ฅ๐จ๐จ๐ ๐ฌ๐ฆ๐ž๐š๐ซ within the leukocytes, which can help make the diagnosis prior to sending off tissues.

๐‡๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐ž๐š๐ญ๐ž๐?
Unfortunately this infection is considered to be a lifelong condition, with no treatment methods causing complete clearance of the parasite. Patients are often given long-term pain medications and antiparasitic medications to help control the disease, but the efficacy is rather poor.

๐๐ก๐จ๐ญ๐จ๐ฌ
1-2) ๐๐ž๐ฎ๐ญ๐ซ๐จ๐ฉ๐ก๐ข๐ฅ๐ฌ, one of the main clean-up cells, containing Hepatozoon. They kinda look like a cartoon bacteria ๐Ÿ˜†
3-5) What a pathologist might see in a muscle biopsy under the microscope!

๐’๐จ๐ฎ๐ซ๐œ๐ž๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโ€™s Pathology of Domestic Animals, Volume 1. Sixth Edition.

Photos 1-5 ยฉ Noahโ€™s Arkive contributors Labranche, Harvey/Raskin, King licensed under CC BY-SA 4.0.

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