Arthropod-Borne Diseases

🕷️ Arthropod-Borne Diseases: Tiny Bites, Big Problems

🧿 Lyme Disease

Case:
A 12-year-old girl returns from summer camp in Connecticut with flu-like symptoms... and a new bullseye-shaped rash on her arm!

🛠️ Management:
- If rash present: Immediate doxycycline!
- No rash: Confirm with ELISA and Western blot.
- Advanced cases: (CNS or arthritis) Treat with ceftriaxone.

⚠️ Complications:
- Early: Meningitis, Bell’s palsy, heart block, migratory arthritis.
- Late: Arthritis, encephalitis.

🔎 High-Yield Fact:
Caused by Borrelia burgdorferi, spread by Ixodes scapularis (Northeast, Midwest, West Coast US).

⛰️ Rocky Mountain Spotted Fever (RMSF)

Case:
A 40-year-old woman develops fever, headache, petechial rash after hiking in Missouri. Labs: Low platelets!

🛠️ Management:
- Confirm diagnosis: titer, PCR, or lesion biopsy.
- Immediate treatment: doxycycline.

⚠️ Complications:
- Mental status changes, DIC (dangerous blood clotting disorder).

🔎 High-Yield Fact:
Caused by Rickettsia rickettsii, via American dog ticks (Central/Southern US).

⭐ Ehrlichiosis

Case:
A 30-year-old woman in Texas presents with fever, altered mental status, but no neck rigidity.
Labs: Leukopenia, high LFTs, CSF shows lymphocytes.

🛠️ Management:
- Confirm with PCR or titer.
- Treat with doxycycline.

⚠️ Complications:
- Seizures, coma, respiratory failure.

🔎 High-Yield Fact:
Caused by bacteria via lone star tick (Texas, Southeast US).

🧬 Babesiosis

Case:
A 65-year-old man returns from hunting in Michigan with fever, jaundice, and hemolytic anemia!

🛠️ Management:
- Diagnose: PCR or blood smear (Look for Maltese cross in RBCs!).
- Treat with azithromycin + atovaquone.

⚠️ Complications:
- Hemolysis, anemia, jaundice.

🔎 High-Yield Fact:
Protozoa transmitted by Ixodes scapularis (same as Lyme!).

🌲 Anaplasmosis

Case:
A 24-year-old man camping in Oregon finds a tick bite, then develops flu-like illness.
Labs: Neutropenia!

🛠️ Management:
- Confirm: PCR or titer.
- Treat with doxycycline.

⚠️ Complications:
- Seizures, coma, renal and respiratory failure.
- Risk of opportunistic infections (HSV esophagitis, fungal infections).

🔎 High-Yield Fact:
Spread by Ixodes scapularis. Blood smear shows morulae inside granulocytes.

✨ Golden Rule

"If it's a tick-borne disease — treat first with doxycycline, test later!"