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Ehrlichiosis (Template:Pron-en; also known as canine rickettsiosis, canine hemorrhagic fever, canine typhus, tracker dog disease, and tropical canine pancytopenia) is a tick-borne disease of dogs usually caused by the organism Ehrlichia canis. Ehrlichia canis is the pathogen of animals. Humans can become infected by E. canis and other species after tick exposure. German Shepherd dogs are thought to be particularly affected by the disease, other breeds generally have milder clinical signs. Cats can also be infected.

Ehrlichia

Ehrlichia is a rickettsial bacteria belonging to the family Ehrlichiaceae. There are several species of Ehrlichia, but the one that most commonly affects dogs and causes the most severe clinical signs is Ehrlichia canis. This species infects monocytes in the peripheral blood. The brown dog tick, or Rhipicephalus sanguineous, that passes the organism to the dog is prevalent throughout most of the United States, but most cases tend to occur in the Southwest and Gulf Coast regions where there is a high concentration of the tick. Ehrlichia is found in many parts of the world and was first recognized in Algeria in 1935. During the Vietnam War ehrlichiosis became well known as a dog disease due to the infection and death of many military working dogs. Two types of human ehrlichiosis have been identified in the United States: human monocytic ehrlichiosis and human granulocytic ehrlichiosis.

Disease overview

Dogs get ehrlichiosis from the brown dog tick, which passes an ehrlichia organism into the bloodstream when it bites. It is also possible for dogs to become infected through a blood transfusion from an infected dog. There are three stages of ehrlichiosis, each varying in severity. The acute stage, occurring several weeks after infection and lasting for up to a month, can lead to fever and lowered peripheral blood cell counts due to bone marrow suppression. The second stage, called the subclinical phase, has no outward signs and can last for the remainder of the dog's life, during which the dog remains infected with the organism. Some dogs are able to successfully eliminate the disease during this time. In some dogs the third and most serious stage of infection, the chronic phase, will commence. Very low blood cell counts (pancytopenia), bleeding, bacterial infection, lameness, neurological and ophthalmic disorders, and kidney disease, can result. Chronic ehrlichiosis can be fatal.

Signs and symptoms

The acute stage of the disease, occurring most often in the spring and summer, begins one to three weeks after infection and lasts for two to four weeks. Clinical signs include a fever, petechiae, bleeding disorders, vasculitis, lymphadenopathy, discharge from the nose and eyes, and edema of the legs and scrotum. There are no outward signs of the subclinical phase. Clinical signs of the chronic phase include weight loss, pale gums due to anemia, bleeding due to thrombocytopenia, vasculitis, lymphadenopathy, dyspnea, coughing, polyuria, polydipsia, lameness, ophthalmic diseases such as retinal hemorrhage and anterior uveitis, and neurological disease. Dogs that are severely affected can die from this disease.

Although people can get ehrlichiosis, dogs do not transmit the bacteria to humans; rather, ticks pass on the ehrlichia organism. Clinical signs of human ehrlichiosis include fever, headache, eye pain, and gastrointestinal upset. It is quite similar to Rocky Mountain spotted fever, but rash is not seen in patients.

Diagnosis

Diagnosis is achieved most commonly by serologic testing of the blood for the presence of antibodies against the ehrlichia organism. Many veterinarians routinely test for the disease, especially in enzootic areas. It should be noted, however, that during the acute phase of infection, the test can be falsely negative because the body will not have had time to make antibodies to the infection. As such, the test should be repeated. In addition, blood tests may show abnormalities in the numbers of red blood cells, white blood cells, and most commonly platelets, if the disease is present. Uncommonly, a diagnosis can be made by looking under a microscope at a blood smear for the presence of the ehrlichia morulae, which sometimes can be seen as intracytoplasmic inclusion bodies within a white blood cell.Cite error: The <ref> tag has too many names (see the help page).

Humans

• CDC - Human Ehrlichiosis in the United States basic Q&A
• NIH basic facts
• Tick-Borne Diseases, Ehrlichiosis detailed medical treatment
• Directors of Health Promotion and Education basic facts and advice

External links

• Ehrlichia Infection in Dogs from The Pet Health Library

1. ^ Ettinger, Stephen J.;Feldman, Edward C. (1995). Textbook of Veterinary Internal Medicine(4th ed.). W.B. Saunders Company. ISBN 0-7216-6795-3.{{cite book}}: CS1 maint: multiple names: authors list (link)

• Dog diseases
• Bacterial diseases