Human Granulocytic Anaplasmosis presenting as Subacute Abdominal Pain and Hyponatremia

Human Granulocytic Anaplasmosis

Human granulocytic anaplasmosis (HGA) is a bacterial infection caused by Anaplasma phagocytophilum and transmitted by the bite of the black-legged (deer tick) in North America. Its incidence is increasing. HGA can be transmitted after 24 to 48 hours of tick attachment. The incubation period is 5 to 14 days after a tick bite. Symptoms include fever, chills, headache, and myalgia. Complications include shock, organ dysfunction, and death. Mortality is less than 1% with appropriate treatment. Doxycycline is first line treatment for all ages. Start it empirically if symptoms and risk factors suggest HGA. PCR is the confirmatory test of choice.

Human Granulocytic Anaplasmosis-A Systematic Review of Published Cases

Anaplasma phagocytophilum is an emerging, Gram-negative, obligate intracellular pathogen that is transmitted by a tick vector. Human infection ranges from asymptomatic to severe disease that can present with pancytopenia, multiorgan failure, and death. The aim of this systematic review is to analyze case reports and case series reported over the last two decades in peer-reviewed journals indexed in the Medline/PubMed database according to the PRISMA guidelines. We found 110 unique patients from 88 case reports and series. The most common mode of transmission was tick bite (60.9%), followed by blood transfusion (8.2%). Infection was acquired by blood transfusion in nearly half (42%) of the immunocompromised patients. Most patients reported fever (90%), followed by constitutional (59%) and gastrointestinal symptoms (56%). Rash was present in 17% of patients, much higher than in previous studies. Thrombocytopenia was the most common laboratory abnormality (76%) followed by elevated aspartate aminotransferase (AST) (46%). The diagnosis was most commonly established using whole-blood polymerase chain reaction (PCR) in 76% of patients. Coinfection rate was 9.1% and Borrelia burgdorferi was most commonly isolated in seven patients (6.4%). Doxycycline was used to treat 70% of patients but was only used as an empiric treatment in one-third of patients (33.6%). The overall mortality rate was 5.7%, and one patient died from trauma unrelated to HGA. The mortality rates among immunocompetent and immunocompromised patients were 4.2% (n = 4/95) and 18.2% (n = 2/11), respectively. Four of the six patients who died (66.6%) received appropriate antibiotic therapy. Among these, doxycycline was delayed by more than 48 h in two patients.