Understanding Your Anaplasma Test Results
Your lab results show you had a past infection with Anaplasma phagocytophilum (the bacteria that causes Human Granulocytic Anaplasmosis), but you do not have an active infection now and do not need treatment. 1
What These Numbers Mean
Your test measured two types of antibodies (proteins your immune system makes to fight infections):
IgG antibody level of 1:64: This is a low level of the "memory" antibody that stays in your blood after an infection has cleared. The level is below the threshold (1:128) that would suggest active disease. 1
IgM antibody level of <1:20: This is negative. IgM antibodies appear early during active infections, so the absence of IgM confirms you don't have a current infection. 2, 1
Interpretation: "Past Infection": Your body encountered this bacteria at some point in the past (possibly months or even years ago), fought it off, and retained some antibodies as a "memory" of that infection. 1
What This Bacteria Does
Anaplasma phagocytophilum is spread through tick bites and infects white blood cells called granulocytes. 2 When people get sick from it, they typically develop:
- High fever (92-100% of cases)
- Severe headache (82% of cases)
- Muscle aches (77% of cases)
- Chills and feeling generally unwell (97% of cases)
- Symptoms usually appear 5-14 days after a tick bite 2
Blood tests during active infection typically show low white blood cell counts, low platelet counts, and mildly elevated liver enzymes. 2
Do You Need Treatment?
No treatment is necessary for past infection. 2, 1 Here's why:
- This bacteria does not cause chronic infection in humans - once your immune system clears it, it's gone. 2
- Antibodies can persist for years after the infection has resolved (studies show antibodies can remain detectable for 2+ years). 1
- Treatment is only needed if you have active symptoms of infection. 2, 1
When Treatment Would Be Needed
Treatment with the antibiotic doxycycline (100 mg twice daily for 7-14 days) would only be necessary if you developed: 2, 1
- Fever, chills, severe headache, and muscle aches within 5-21 days of a tick bite
- Blood test abnormalities like low white blood cells or platelets
- Clinical suspicion of active anaplasmosis
If treated, patients typically feel better within 24-48 hours. 2, 1
Important Points to Remember
- You are not contagious - this infection spreads only through tick bites, not person-to-person. 2
- Past infection does not provide immunity - you could potentially get infected again from another tick bite. 1
- The mortality rate is very low (<1%) in healthy people but can be higher (up to 18%) in those with weakened immune systems. 1
- Most cases are mild or even asymptomatic - many people clear the infection without ever knowing they had it. 2, 3
What to Watch For
If you develop fever, severe headache, and muscle aches after spending time outdoors in tick-prone areas (especially between late spring and fall), seek medical attention promptly and mention your past Anaplasma exposure. 2 Early treatment prevents complications, though serious complications are uncommon. 2