Anaplasma phagocytophilum: Difference between revisions

Latest revision as of 16:23, 8 July 2023

Background

Causes human granulocytotropic anaplasmosis

Microbiology

Small, obligate intracellular Gram-negative bacterium
Related to Ehrlichia and Rickettsiae
Tropism for neutrophils

Epidemiology

Transmitted by Ixodes scapularis and Ixodes pacificus ticks
Rare case reports in Ontario
Transmission may take as little as 24 hours of tick attachment

Clinical Manifestations

Incubation period of 1 to 2 weeks
Usually an acute undifferentiated fever
Can be mild or severe
Fever, headache, malaise, and myalgias are common
Can also cause nausea, vomiting, diarrhea, cough, arthralgias, nuchal rigidity, and confusion
Less than 10% have rash, most of which is concurrent Lyme disease
36% of cases require hospitalization, and it is severe in 3 to 7%
Severe complications include respiratory failure, septic shock, rhabdomyolysis, hemorrhage, and opportunistic infections
- Rare meningoencephalitis
Higher case-fatality rate in Shandong Province in China, for no clear reason (16% versus 2.6%)
Thrombocytopenia, leukopenia, and mild anemia are common
- Return to normal range within 14 days, but with persistent left shift
Abnormal liver enzymes are common in the first 7 days

Diagnosis

20-80% of patients will have circulating neutrophils with detectable morulae on blood film (in neutrophils/granulocytes)
Serology used to diagnose, by measuring IgG levels ≥1:64 or a fourfold rise
- IgM testing less sensitive and specific
Culture not done routinely
PCR possible

Management

Doxycycline 100 mg po bid until at least 72 days after defervescence
- Possibly 10 days if risk of concurrent Lyme disease

@@ Line 1: / Line 1: @@
+==Background==
-= Microbiology =
+* Causes '''human granulocytotropic anaplasmosis'''
-* Small, obligate intracellular Gram-negative bacterium
-* Related to Ehrlichia and Rickettsiae
-* Tropism for neutrophils
+===Microbiology===
-= Clinical Presentation =
+*Small, obligate intracellular Gram-negative bacterium
-* Incubation period of 1 to 2 weeks
+*Related to ''[[Ehrlichia]]'' and ''[[Rickettsiae]]''
-* Usually an acute undifferentiated fever
+*Tropism for neutrophils
-* Can be mild or severe
-* Fever, headache, malaise, and myalgias are common
-* Can also cause nausea, vomiting, diarrhea, cough, arthralgias, nuchal rigidity, and confusion
-* Less than 10% have rash, most of which is concurrent Lyme disease
-* 36% of cases require hospitalization, and it is severe in 3 to 7%
-* Severe complications include respiratory failure, septic shock, rhabdomyolysis, hemorrhage, and opportunistic infections
-** Rare meningoencephalitis
-* Higher case-fatality rate in Shandong Province in China, for no clear reason (16% versus 2.6%)
-* Thrombocytopenia, lerkopenia, and mild anemia are common
-** Return to normal range within 14 days, but with persistent left shift
-* Abnormal liver enzymes are common in the first 7 days
+===Epidemiology===
-= Diagnosis =
+*Transmitted by [[Vector::Ixodes scapularis]] and [[Vector::Ixodes pacificus]] ticks
-* 20-80% of patients will have circulating neutrophils with detectable '''morulae''' on blood film (in neutrophils/granulocytes)
+*Rare case reports in Ontario
-* Serology used to diagnose, by measuring IgG levels ≥1:64 or a fourfold rise
+*Transmission may take as little as 24 hours of tick attachment
-** IgM testing less sensitive and specific
-* Culture not done routinely
-* PCR possible
+==Clinical Manifestations==
-= Management =
+*Incubation period of [[Usual incubation period::1 to 2 weeks]]
-* Doxycycline 100 mg po bid
+*Usually an acute undifferentiated fever
+*Can be mild or severe
+*Fever, headache, malaise, and myalgias are common
+*Can also cause nausea, vomiting, diarrhea, cough, arthralgias, nuchal rigidity, and confusion
+*Less than 10% have rash, most of which is concurrent Lyme disease
+*36% of cases require hospitalization, and it is severe in 3 to 7%
+*Severe complications include respiratory failure, septic shock, rhabdomyolysis, hemorrhage, and opportunistic infections
+**Rare meningoencephalitis
+*Higher case-fatality rate in Shandong Province in China, for no clear reason (16% versus 2.6%)
+*Thrombocytopenia, leukopenia, and mild anemia are common
+**Return to normal range within 14 days, but with persistent left shift
+*Abnormal liver enzymes are common in the first 7 days
+==Diagnosis==
+*20-80% of patients will have circulating neutrophils with detectable '''morulae''' on blood film (in neutrophils/granulocytes)
+*Serology used to diagnose, by measuring IgG levels ≥1:64 or a fourfold rise
+**IgM testing less sensitive and specific
+*Culture not done routinely
+*PCR possible
+==Management==
+*[[Doxycycline]] 100 mg po bid until at least 72 days after defervescence
+**Possibly 10 days if risk of concurrent [[Lyme disease]]
-[[Category:Parasites]]
 {{DISPLAYTITLE:''Anaplasma phagocytophilum''}}
+[[Category:Rickettsioses]]