Tick, mosquito, flea, animal — geographic + exposure clues.
| Disease | Vector / region | Features | Diagnosis | Treatment |
|---|---|---|---|---|
| Lyme (Borrelia burgdorferi) | Ixodes; Northeast/Midwest US | Stage 1: erythema migrans (target). Stage 2: bilateral facial nerve palsy, carditis (AV block), aseptic meningitis. Stage 3: arthritis (knee), neuro | Clinical + serology (ELISA → Western blot) | Doxycycline (or amoxicillin/cefuroxime in pregnancy/peds <8); CNS/heart → IV ceftriaxone |
| RMSF (Rickettsia rickettsii) | Dermacentor; SE US (NC, OK) | Fever + headache + rash STARTING ON WRISTS/ANKLES → centripetal spread (palms/soles too); thrombocytopenia + hyponatremia | Clinical (don't wait for serology) | Doxycycline (even in pregnancy and kids) |
| Ehrlichiosis (Ehrlichia) | Lone Star tick; SE/SC US | Fever + headache + myalgia; LEUKOPENIA + thrombocytopenia + ↑LFTs. Morulae in monocytes | Smear + PCR | Doxycycline |
| Anaplasmosis | Ixodes; Upper Midwest/NE | Similar to ehrlichiosis but morulae in granulocytes (neutrophils) | Smear + PCR | Doxycycline |
| Babesiosis (Babesia) | Ixodes; New England, Midwest | Fever + hemolytic anemia + jaundice + asplenic patients severe; Maltese cross on smear | Smear or PCR | Atovaquone + azithromycin (severe: clindamycin + quinine) |
| Tularemia (Francisella) | Dermacentor / rabbit handling | Ulcer at bite site + regional LAD + fever (ulceroglandular) | Serology | Streptomycin or gentamicin |
| Disease | Vector / region | Features | Treatment |
|---|---|---|---|
| Malaria | Anopheles; tropics | Fever cycles, hemolytic anemia, splenomegaly. P. falciparum (severe, no relapse); vivax/ovale (hypnozoites → relapse) | Chloroquine if sensitive; artemisinin-based for resistant. Primaquine to clear hypnozoites in vivax/ovale (check G6PD first) |
| Dengue | Aedes; tropics | Saddleback fever + retro-orbital pain + thrombocytopenia + 'breakbone' myalgia; hemorrhagic/shock on second infection | Supportive (AVOID aspirin/NSAIDs — bleeding); IV fluids |
| Zika | Aedes; Latin America | Mild rash + conjunctivitis + arthralgias; Guillain-Barré association; congenital microcephaly | Supportive; avoid pregnancy ≥2 months after exposure |
| Chikungunya | Aedes | Severe arthralgia + fever + rash; arthritis persists months | Supportive (acetaminophen, NOT NSAIDs early to rule out dengue) |
| West Nile | Culex | Fever + headache; rare meningoencephalitis + flaccid paralysis | Supportive |
| Disease | Source | Features | Treatment |
|---|---|---|---|
| Cat scratch (Bartonella henselae) | Cat scratch/bite | Tender regional LAD + low-grade fever; HIV → bacillary angiomatosis | Azithromycin |
| Brucellosis | Unpasteurized dairy / livestock | Undulating fever + arthralgia + sweats | Doxycycline + rifampin |
| Leptospirosis | Animal urine / water exposure | Fever + conjunctival suffusion + myalgia; Weil disease = jaundice + AKI + hemorrhage | Doxycycline or penicillin |
| Q fever (Coxiella) | Livestock / aerosols | Atypical pneumonia + hepatitis | Doxycycline |
| Plague (Yersinia pestis) | Flea (prairie dogs SW US) | Bubonic: tender bubo + fever; pneumonic = bioterror form | Streptomycin or gentamicin |
| Hantavirus | Rodent excrement (SW US) | Pulmonary syndrome: fever → ARDS | Supportive ICU |
| Rabies | Bat/dog/raccoon bite | Hydrophobia, paresthesia at bite, encephalitis | Wound care + RIG + vaccine series; PEP per algorithm |
| Toxoplasmosis | Cat litter / undercooked meat | Pregnant → fetal hydrocephalus + intracranial calcifications; AIDS → ring-enhancing lesions | Pyrimethamine + sulfadiazine + leucovorin |
| Echinococcus (hydatid cyst) | Dog / sheep | Liver cysts with daughter cysts ('eggshell' calcifications) | Albendazole ± surgery |