Study guide
4.10 Travel-Related Illness, Vector-Borne Disease & Outbreaks
ABIM Internal Medicine Exam
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1 Chapter 0: The ABIM Exam, Blueprint & Study Strategy
0.1 Exam Format, Question Types & the 2026 Blueprint 0.2 Eligibility, Registration, Fees & Exam-Day Logistics 0.3 Scoring, the Passing Standard & Score Reports 0.4 Building a Blueprint-Weighted Study Plan
2 Chapter 1: Cardiovascular Disease (14% of Exam)
1.1 Ischemic Heart Disease & Acute Coronary Syndromes 1.2 Antithrombotic Therapy, Secondary Prevention & Mechanical Complications of MI 1.3 Atrial Fibrillation, Atrial Flutter & Stroke Prevention 1.4 Supraventricular Tachycardias, Ventricular Arrhythmias & Bradycardias 1.5 Heart Failure: Classification, Staging & Guideline-Directed Medical Therapy 1.6 Device Therapy, HFpEF & the Cardiomyopathies 1.7 Valvular Heart Disease & Endocarditis Prophylaxis 1.8 Pericardial Disease & Acute Aortic Syndromes 1.9 Hypertension: Classification, Diagnosis & Secondary Causes 1.10 Hypertensive Crises & Dyslipidemia 1.11 Adult Congenital Heart Disease & Coarctation of the Aorta 1.12 Syncope: Reflex, Orthostatic & Cardiac Causes 1.13 Cardiac Physical Examination, Murmurs & Antithrombotic Selection
3 Chapter 2: Endocrinology, Diabetes & Metabolism (9% of Exam)
2.1 Diabetes Mellitus: Diagnosis, Glycemic Targets & Pharmacotherapy 2.2 Insulin Therapy, Hyperglycemic Emergencies & Chronic Complications 2.3 Thyroid Function Testing & Hypothyroidism 2.4 Thyrotoxicosis, Thyroid Storm & Thyroid Nodules 2.5 Adrenal & Pituitary Disorders 2.6 Hypercalcemia, Hypocalcemia & Disorders of Mineral Metabolism 2.7 Osteoporosis & Paget Disease of Bone 2.8 Ovarian, Testicular & Reproductive Endocrine Disorders 2.9 Hypoglycemia, Endocrine Tumors, Polyglandular Syndromes & Severe Hypertriglyceridemia
4 Chapter 3: Gastroenterology & Hepatology (9% of Exam)
3.1 Esophageal Disease 3.2 Stomach & Duodenal Disease and Gastrointestinal Hemorrhage 3.3 Inflammatory Bowel Disease 3.4 Celiac Disease & Irritable Bowel Syndrome 3.5 Diverticular Disease & Colorectal Cancer Screening 3.6 Viral Hepatitis, Steatotic & Alcohol-Associated Liver Disease 3.7 Cirrhosis & the Complications of Portal Hypertension 3.8 Acute Pancreatitis 3.9 Chronic Pancreatitis & Biliary Tract Disease 3.10 Inherited, Autoimmune & Drug-Induced Liver Disease 3.11 Small Intestinal Disease, Ischemia & Gastrointestinal Complications of HIV
5 Chapter 4: Infectious Disease (9% of Exam)
4.1 Lower Respiratory Tract Infections & Sepsis Syndromes 4.2 Viral Respiratory Pathogens & Tuberculosis 4.3 Central Nervous System Infections 4.4 Skin, Soft Tissue, Bone & Joint Infections 4.5 Infective Endocarditis & Cardiovascular Infection 4.6 Clostridioides difficile & Catheter-Related Bloodstream Infection 4.7 HIV Diagnosis, Antiretroviral Therapy & Prevention 4.8 Opportunistic Infections & Sexually Transmitted Infections 4.9 Fever of Unknown Origin, Neutropenic Fever & Toxic Shock 4.10 Travel-Related Illness, Vector-Borne Disease & Outbreaks 4.11 Infection Prevention, Nosocomial Infection & Postexposure Prophylaxis 4.12 Rheumatic Fever, Poststreptococcal Disease, Enteric & Hepatic Infections
6 Chapter 5: Pulmonary Disease (9% of Exam)
5.1 COPD: Diagnosis, GOLD Classification & Initial Pharmacotherapy 5.2 Interventions That Reduce COPD Mortality & Exacerbation Management 5.3 Asthma: Diagnosis, Stepwise Therapy & Status Asthmaticus 5.4 Interstitial Lung Disease & Idiopathic Pulmonary Fibrosis 5.5 Sarcoidosis, Hypersensitivity Pneumonitis & Occupational Lung Disease 5.6 Pulmonary Embolism: Diagnosis, Risk Stratification & Anticoagulation 5.7 Pulmonary Hypertension & Sleep-Disordered Breathing 5.8 Acute Respiratory Distress Syndrome & Mechanical Ventilation 5.9 Pleural Disease, Empyema & Pneumothorax 5.10 Bronchiectasis, Cystic Fibrosis & Restrictive Lung Disease 5.11 Evaluation of Cough, Dyspnea, Hemoptysis & the Solitary Pulmonary Nodule
7 Chapter 6: Rheumatology & Orthopedics (9% of Exam)
6.1 Rheumatoid Arthritis: Diagnosis & Systemic Manifestations 6.2 Antirheumatic Pharmacotherapy & the Spondyloarthropathies 6.3 Gout: Pathophysiology & Acute Management 6.4 Urate-Lowering Therapy & Calcium Pyrophosphate Deposition Disease 6.5 Osteoarthritis 6.6 Systemic Lupus Erythematosus 6.7 Systemic Sclerosis, Sjogren Syndrome & Inflammatory Myopathies 6.8 The Vasculitides 6.9 Regional Musculoskeletal Syndromes, Back Pain & Sports Injuries 6.10 Other Primary Rheumatic Disorders & Mixed Connective Tissue Disease 6.11 Osteonecrosis & Metabolic Bone Disease
8 Chapter 7: Hematology (6% of Exam)
7.1 Approach to Anemia & the Microcytic Anemias 7.2 Macrocytic, Normocytic & Hemolytic Anemias 7.3 Hemoglobinopathies, Thalassemias & Paroxysmal Nocturnal Hemoglobinuria 7.4 Platelet Disorders, Thrombocytopenia & the Bleeding Patient 7.5 Coagulation Factor Disorders, Thrombophilia & Anticoagulant Reversal 7.6 Acute Leukemias, Chronic Leukemias & Myeloproliferative Neoplasms 7.7 Lymphomas & Plasma Cell Disorders 7.8 Myelodysplastic Syndrome, Myeloproliferative Neoplasms & Porphyria 7.9 Transfusion Medicine & Late Complications of Transplantation
9 Chapter 8: Medical Oncology (6% of Exam)
8.1 Breast, Lung, Colorectal & Prostate Cancer 8.2 Oncologic Emergencies 8.3 Genitourinary & Gynecologic Malignancies 8.4 Head and Neck, Bone & Soft Tissue Cancer and Cancer of Unknown Primary 8.5 Complications of Cancer & Its Treatment 8.6 Cancer Prevention, Survivorship & Psychosocial Care
10 Chapter 9: Nephrology & Urology (6% of Exam)
9.1 Acute Kidney Injury: Staging, Etiology & Urine Microscopy 9.2 Glomerular Disorders & Nephrotic Syndrome 9.3 Nephritic Syndromes, RPGN & Indications for Renal Replacement Therapy 9.4 Chronic Kidney Disease: Staging & Progression Retardation 9.5 Complications of Chronic Kidney Disease: Anemia, CKD-MBD & Acidosis 9.6 Hyponatremia, Hypernatremia & Water Balance 9.7 Potassium Disorders & Systematic Acid-Base Analysis 9.8 Renal Tubular Acidosis & Nephrolithiasis 9.9 Prostate Disorders, Urinary Incontinence & Other Urologic Conditions 9.10 Cystic Kidney Disease, Obstructive Uropathy, Tubulointerstitial Disease & Hematuria
11 Chapter 10: Neurology (4% of Exam)
10.1 Acute Ischemic Stroke: Syndromes & Reperfusion 10.2 Transient Ischemic Attack, Secondary Prevention & Hemorrhagic Stroke 10.3 Headache & Facial Pain 10.4 Seizures, Epilepsy & Movement Disorders 10.5 Multiple Sclerosis & Neuromuscular Junction Disorders 10.6 Motor Neuron Disease & Acute Peripheral Neuropathy 10.7 Cranial Neuropathies & Neuro-Ophthalmology 10.8 Peripheral Neuropathies, CNS Tumors & Other Neurologic Disorders
12 Chapter 11: Psychiatry & Behavioral Health (4% of Exam)
11.1 Major Depressive Disorder & Medical Mimics 11.2 Antidepressant Pharmacotherapy & Treatment-Resistant Depression 11.3 Bipolar Disorder, Mood Stabilizers & Lithium Toxicity 11.4 Anxiety, Stress-Related & Obsessive-Compulsive Disorders 11.5 Alcohol Use Disorder & Withdrawal 11.6 Pharmacotherapy for Alcohol & Opioid Use Disorder 11.7 Toxidromes, Psychiatric Emergencies & Suicide Risk Assessment 11.8 Psychotic, Somatic Symptom, Factitious & Personality Disorders 11.9 Eating Disorders, Sleep Disorders & Sexual Health
13 Chapter 12: Dermatology (3% of Exam)
12.1 Dermatitis, Papulosquamous & Inflammatory Dermatoses 12.2 Acne, Rosacea & Cutaneous Infections 12.3 Herpes Zoster & Autoimmune Blistering Diseases 12.4 Nodules, Tumors & Cutaneous Oncology 12.5 Dermatologic Emergencies & Severe Cutaneous Adverse Reactions 12.6 Pigment Disorders, Alopecia, Nail Disease & Photosensitivity 12.7 Vascular Dermatoses, Environmental Injury & Cutaneous Signs of Systemic Disease
14 Chapter 13: Obstetrics & Gynecology / Women's Health (3% of Exam)
13.1 Contraception, Preconception Care & Teratogenicity 13.2 Hypertensive Disorders of Pregnancy & Gestational Diabetes 13.3 Thyroid Disease & Venous Thromboembolism in Pregnancy 13.4 Menopause & Menopausal Hormone Therapy 13.5 Abnormal Uterine Bleeding, Endometrial Disease & Gynecologic Cancer Screening 13.6 Breast Disorders & Diseases of the Vulva and Vagina 13.7 Menstrual Disorders, Fibroids, Endometriosis & Early Pregnancy Complications
15 Chapter 14: Geriatric Syndromes (3% of Exam)
14.1 Comprehensive Geriatric Assessment & Frailty 14.2 Falls, Gait Assessment & Polypharmacy 14.3 Urinary Incontinence & Pressure Injuries in Older Adults 14.4 Mild Cognitive Impairment, Dementia & Its Subtypes 14.5 Delirium & the Pharmacotherapy of Cognitive Disorders 14.6 Palliative Care, Hospice & Advance Care Planning 14.7 Chronic Wounds, Nutrition, Swallowing, Constipation & Hip Fracture 14.8 Sensory Impairment, Dizziness, Elder Mistreatment & Care Settings
16 Chapter 15: Allergy & Immunology (2% of Exam)
15.1 Anaphylaxis: Recognition & Emergency Management 15.2 Urticaria & Angioedema 15.3 Drug Allergy, Desensitization & Adult Immunodeficiency 15.4 Food Allergy, Insect Venom Hypersensitivity, Serum Sickness & Contrast Reactions 15.5 Rhinitis, Conjunctivitis, Eosinophilic & Mast Cell Disorders
17 Chapter 16: Preventive Medicine, Immunization & Clinical Epidemiology
16.1 The USPSTF Framework & Evidence-Based Cancer Screening 16.2 Cardiovascular & Metabolic Screening and Primary Prevention 16.3 Adult Immunization & Vaccines in Special Populations 16.4 Clinical Epidemiology, Biostatistics & Study Design
18 Chapter 17: Miscellaneous - Ethics, Patient Safety & Quality Improvement (2% of Exam)
17.1 Principles of Bioethics & Decisional Capacity 17.2 Informed Consent, Treatment Refusal & Special Scenarios 17.3 Surrogate Decision-Making, Advance Directives & Confidentiality 17.4 Patient Safety Science, Medical Error & Diagnostic Reasoning 17.5 Quality Improvement Methods, Health Disparities & Health Equity
19 Chapter 18: Perioperative Medicine & Medical Consultation
18.1 Preoperative Cardiovascular Risk Assessment 18.2 Preoperative Pulmonary Risk & Perioperative Medication Management 18.3 Perioperative Anticoagulation, Bridging & Postoperative Complications
20 Chapter 19: Ophthalmology (1% of Exam)
19.1 The Acute Red Eye & Ophthalmic Emergencies 19.2 Painless Vision Loss & Chronic Ophthalmic Disease 19.3 Uveitis, Scleritis & Orbital Disease
21 Chapter 20: Otolaryngology & Dental Medicine (1% of Exam)
20.1 Dizziness, Vertigo & Epistaxis 20.2 Ear Disorders, Hearing Loss & Upper Respiratory Infections 20.3 Oral Cavity, Salivary Gland, Laryngeal & Taste and Smell Disorders
4.10 Travel-Related Illness, Vector-Borne Disease & Outbreaks
Key Takeaways Explain This Topic AI
Travel-related illness, infectious disease outbreaks and specific causative organisms are separately enumerated blueprint subsections.
Fever in a traveler returning from a malaria-endemic region requires thick and thin blood smears repeated up to three times before malaria is excluded.
Plasmodium falciparum causes severe malaria and is treated as a medical emergency with parenteral artesunate when severity criteria are met.
Rocky Mountain spotted fever is treated empirically with doxycycline before confirmatory serology, because delay increases mortality and serology is negative early.
Doxycycline is the treatment of choice for rickettsial disease in all age groups, including children and pregnant patients when the alternative is untreated infection.
Last updated: August 2026
1. Fever in the Returning Traveler
The first task is triage: which febrile travelers have a potentially fatal, rapidly progressive illness, and which have a self-limited one?
Two questions dominate the history:
Where, exactly, and when? Match the incubation period to the exposure window. An illness beginning more than 21 days after return excludes dengue, chikungunya and most viral hemorrhagic fevers, but not malaria, typhoid, tuberculosis, viral hepatitis or leishmaniasis.
What exposures? Freshwater swimming (schistosomiasis, leptospirosis), unpasteurized dairy (brucellosis), undercooked meat, animal and arthropod bites, sexual contact, healthcare exposure, and whether malaria chemoprophylaxis was actually taken and completed.
Incubation periods that narrow the differential
Incubation Consider
Under 10 days Dengue, chikungunya, Zika, rickettsial infection, leptospirosis, enteric bacterial infection, viral hemorrhagic fever
10 to 21 days Malaria , typhoid, leptospirosis, African trypanosomiasis, Q fever
Over 21 days Malaria , tuberculosis, viral hepatitis, visceral leishmaniasis, amebic liver abscess, schistosomiasis
Malaria appears in every window. That is the point.
2. Malaria
Fever in anyone returning from an endemic area is malaria until excluded. Chemoprophylaxis reduces but does not eliminate risk, and non-adherence is common.
Diagnosis: thick and thin blood smears . The thick smear detects parasites; the thin smear speciates and quantifies parasitemia. A single negative smear does not exclude malaria — repeat every 12 to 24 hours for a total of three sets . Rapid antigen tests are useful adjuncts.
Species matters:
Plasmodium falciparum — causes nearly all severe disease and death. High parasitemia, cerebral malaria, acute kidney injury, acute respiratory distress syndrome, hypoglycemia, severe anemia and acidosis. Short incubation, usually within a month.
P. vivax and P. ovale — form dormant hepatic hypnozoites and relapse months later. Eradication requires primaquine or tafenoquine , which mandates G6PD testing first because these drugs cause severe hemolysis in deficient patients.
P. malariae — chronic low-grade parasitemia, associated with nephrotic syndrome.
P. knowlesi — Southeast Asia, can be rapidly severe.
Severe malaria — impaired consciousness, seizures, acidosis, hypoglycemia, renal failure, pulmonary edema, parasitemia above 5%, or jaundice with organ dysfunction — is treated with intravenous artesunate . Uncomplicated falciparum malaria is treated with an artemisinin-based combination or atovaquone-proguanil.
3. Enteric Fever (Typhoid)
Salmonella Typhi and Paratyphi, most often from South Asia. The classic picture is stepwise fever rising over days with relative bradycardia , abdominal pain, and constipation preceding diarrhea; rose spots are uncommon and evanescent. Leukopenia with a normal or low white count in a febrile patient is a useful clue. Blood cultures are positive in roughly half; bone marrow culture has higher yield. Fluoroquinolone resistance is now widespread in South Asia, so ceftriaxone or azithromycin is used empirically.
4. Dengue, Chikungunya and Zika
All three are Aedes -borne, overlap geographically, and present with fever and rash.
- Dengue Chikungunya Zika
- Dominant feature Severe myalgia, retro-orbital pain Severe, persistent polyarthralgia Mild; conjunctivitis
- Laboratory Thrombocytopenia, leukopenia , rising hematocrit Lymphopenia Often normal
Danger Plasma leakage and shock at defervescence Chronic arthritis Congenital malformation , Guillain-Barre syndrome
In dengue, deterioration occurs as the fever breaks , not at its peak — the critical phase is marked by plasma leakage, rising hematocrit and falling platelets. NSAIDs and aspirin should be avoided because of bleeding risk; supportive fluid management is the treatment.
5. Tick-Borne and Rickettsial Disease
The blueprint lists rickettsioses and ehrlichioses and vector-borne diseases under specific causative organisms.
Disease Organism Region / vector Distinguishing features
Rocky Mountain spotted fever Rickettsia rickettsii Southeastern and south-central US; dog tick Rash begins on wrists and ankles and spreads centrally, involving palms and soles ; hyponatremia, thrombocytopenia
Human monocytic ehrlichiosis Ehrlichia chaffeensis Southeastern US; lone star tick Usually rashless ; leukopenia, thrombocytopenia, elevated aminotransferases; morulae in monocytes
Human granulocytic anaplasmosis Anaplasma phagocytophilum Upper Midwest, Northeast; deer tick Rashless; morulae in neutrophils
Lyme disease Borrelia burgdorferi Northeast, upper Midwest; deer tick Erythema migrans ; later carditis with AV block, facial palsy, arthritis
Babesiosis Babesia microti Northeast, upper Midwest; deer tick Hemolytic anemia ; intraerythrocytic ring forms and tetrads; severe in asplenia
Tularemia Francisella tularensis Rabbits, ticks Ulcer with regional lymphadenopathy
The rule that generates the most exam points: treat empirically with doxycycline. Rocky Mountain spotted fever mortality rises steeply with each day of delayed therapy, and serology is negative during the first week — the window in which treatment matters most. Waiting for confirmation is the wrong answer. Doxycycline is recommended even in young children and is used in pregnancy when the alternative is untreated rickettsial disease.
Other points that discriminate: the absence of a rash does not exclude rickettsial illness (roughly 10% of Rocky Mountain spotted fever is spotless, and ehrlichiosis is usually rashless). Babesiosis coinfection should be considered in a Lyme patient with hemolysis, and is treated with atovaquone plus azithromycin rather than doxycycline.
6. Other Specific Organisms Named in the Blueprint
Prion disease — Creutzfeldt-Jakob disease presents with rapidly progressive dementia, myoclonus and ataxia ; MRI shows cortical ribboning and basal ganglia hyperintensity, EEG may show periodic sharp waves, and cerebrospinal fluid RT-QuIC is the most useful assay. There is no treatment.
Brucellosis — undulant fever, sacroiliitis, unpasteurized dairy exposure; treated with doxycycline plus rifampin or an aminoglycoside.
Leptospirosis — freshwater exposure; conjunctival suffusion without exudate is the classic sign; Weil disease adds jaundice and renal failure.
Q fever — Coxiella burnetii , from parturient livestock; causes pneumonia, hepatitis and culture-negative endocarditis.
Strongyloidiasis — chronic autoinfection can persist for decades; corticosteroids precipitate hyperinfection syndrome , so screening is required before immunosuppression in anyone with relevant exposure history.
7. Infectious Disease Outbreaks
A distinct blueprint subsection. The internist has three responsibilities in an outbreak:
Recognize the pattern. Clustering in place, time or exposure — several patients from one facility, event or food source.
Institute correct isolation immediately , before the pathogen is confirmed. Airborne precautions with a negative-pressure room for suspected tuberculosis, measles or varicella; droplet for influenza and meningococcus; contact for C. difficile and multidrug-resistant organisms. Standard precautions apply to every patient at all times.
Notify public health. Reporting is a legal obligation and is the mechanism by which contact tracing and source identification occur. Suspected bioterrorism agents — anthrax, plague, tularemia, botulism, smallpox, viral hemorrhagic fevers — require immediate notification.
Travel-related prevention is the counterpart: pre-travel counseling includes destination-specific vaccination, malaria chemoprophylaxis matched to regional resistance patterns, food and water precautions, insect-bite avoidance, and standby therapy for travelers diarrhea.