Human (Granulocytic) Anaplasmosis (HGA ... - Allina Health

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In 2010, there were 720 reported confirmed or probable cases of HGA in Minnesota (16.9 cases per 100,000 population), more than twice the number reported in 2009. 59% were in males, the median age was 57 years, and the majority of cases were reported in May-July, with a peak in June. 27% of patients were hospitalized (1-42 days) and there was one reported death. 5% of HGA cases also had Lyme disease, and 1% also had confirmed or probable babesiosis. The frequency of co-infection may be underestimated. A disease related to HGA, called Human Monocytic Ehrlichiosis, is caused by Ehrlichia chaffeensis. It is uncommon in Minnesota. It is found throughout much of the southeastern and southcentral United States and is carried mainly by the Lone Star tick. However, a few cases of Ehrlichia muris-like agent-related disease, carried by I. scapularis, have been reported in Minnesota and Wisconsin since 2009. Ehrlichia ewingii, the agent of canine granulocytic ehrlichiosis, may occasionally cause an ehrlichia-like illness in humans. Anaplasma phagocytophilum (formerly known as Ehrlichia phagocytophilum) is the agent of HGA. It has tropism for neutrophils (whereas E. chaffeensis has tropism for monocytes). The incubation period is typically 7-10 days before development of overt symptoms, although onset of illness may be 5-21 days after exposure. Disease transmission is usually from tick bite, although other reported routes include blood inhalation/percutaneous blood exposure following butchering of white-tailed deer, blood transfusion, and transplacental infection. Many infections go undiagnosed because of the mild nonspecific symptomatology associated with the majority of infections. Symptoms typically include chills, fever, headache, myalgias and arthralgias. Less common symptoms include nausea/anorexia and vomiting, weight loss, abdominal pain, cough, diarrhea, and mental status changes. Rare patients will develop encephalitis, acute respiratory distress syndrome, or shock-like illness with multiorgan involvement. Disease tends to be most severe in elderly or immunocompromised individuals. The fatality rate is usually less than 1%, although some sources state a 2-3% fatality rate, and may be associated with opportunistic superimposed fungal or viral infection. Laboratory Findings: The majority of patients will have thrombocytopenia. Approximately 50% will have leukopenia. Liver function tests (LFTs) may be elevated due to hepatocellular injury. Pathology: Intravacuolar bacterial microcolonies reside in neutrophils and may be seen by microscopic evaluation when peripheral blood is smeared on a slide and stained by the Wright-Giemsa method. These microcolonies resemble a mulberry and are therefore called morules or morulae because the Latin word for mulberry is “morula.” 2
Morules in neutrophils indicated by arrows Other pathologic findings include infiltrates of foamy macrophages in reticuloendothelial organs, multiorgan perivascular lymphohistiocytic infiltrates, and focal hepatocellular apoptosis (reflecting the hepatocellular injury manifesting as elevated liver function tests (LFTs)). Treatment: The first-line treatment for adults and children of all ages, as recommended by the CDC, is doxycycline. Treatment should be initiated immediately whenever HGA is suspected. For patients who are allergic to doxycycline or have other contraindications, alternative antibiotic treatment should be considered (see CDC for recommendations and doses). However, prophylactic antibiotic treatment following a tick bite in an individual who has not developed disease is not recommended, since there is no evidence that this is effective. 3
Page 1: July 2012 Human (Granulocytic) Anap
Page 5 and 6: BABESIOSIS Babesiosis (originally c
Page 7 and 8: Infected individuals may be asympto
Page 9 and 10: TRANSFUSION-TRANSMITTED DISEASE Cas
Page 11: REFERENCES K. Annen, D.O., et al. T

Human (Granulocytic) Anaplasmosis (HGA ... - Allina Health

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