Clinical approach to the infectious disease patient

Mobile Tropical Medicine, February 2014Slide deck developed by LTC(P) Stephen Thomas, WRAIR VDB

Richard Ruck, MDLTC, MC, USA

Pediatric Infectious DiseasesViral Diseases Branch, WRAIR

Richard.c.ruck.mil@mail.mil 301-319-9904

Outline

• BLUF

• Soliciting a detailed medical history

• Infectious diseases of returning travelers

• Geographic disease distribution

• Infectious Disease Emergencies

• Medical history and clinical syndromes making the diagnosis

BLUF: Caring for the ID Patient

• A comprehensive, in-depth medical history is your best diagnostic tool

• Geographic and ID threat situational awareness

• Know your ID emergencies

• Know what you don’t know, seek assistance when needed

Common Things are Common

Usually this…

Not this…

Soliciting a Detailed Medical History

Chief Complaint

• Localizing– Focal lesion (cellulitis)– Bite (arthropod, animal, human)– Post-traumatic (altercation, vegetation)– Anatomical (CNS, GU, GI, etc.)

• Generalized and systemic– Fever, chills, rigors– Muscle and / or joint pain– Fatigue

Cat bites causing skin /soft tissue infections

History of Present Illness

• Key information– Detailed chronology of illness

• Patient was well until…DATE…when…X…happened• Appearance / disappearance of signs / symptoms

– Non-specific illnesses may declare themselves

• Identify patterns if they exist– Example: patterns of fever (every 3 days)

– Incorporate important medical background of patient• Age (impacts presentation, fever curves, etc.)• Immunodeficient (HIV, medications, malignancy)

History of Present Illness

• Key information– Incorporate activities / exposures

• Animals, arthropods, people, vegetation• Urban, rural environment exposure• Indoor or outdoor activities

– Incorporate relevant active (recent) medications• Prophylaxis, immunomodulators, OTC medications

– Incorporate relevant associated travel history

Review of Systems

• Pertinent positives and negatives – Specifically mention if no fever– CNS: evidence of meningitis, encephalitis, any neuro– Respiratory: tracheobronchitis, pneumonia– Oropharynx: pharyngitis, bleeding gums, dentition– GI: diarrhea with blood, mucus, rice water appearance– GU: discharge, dysuria, abnormal menses– Skin: rash, location, itching, character– Extremities: localized pain, joint versus bone pain

Past Medical/Surgical History

• Drill down on relevant pre-existing medical conditions– Immunosuppressive conditions

• Drill down on chronic or re-occurring conditions– Examples: frequent respiratory infections, meningitis

• Presence or absence of organs– Appendix, gallbladder, spleen, thymus

• Previous surgical interventions– Heart surgery (valve)– Implant of any hardware or foreign material

• Known lab / radiologic abnormalities– Examples: lung nodule/Ca++, heart block, etc.

Medications / Immunizations

• Rx and OTC (previous antibiotics)• Immunosuppressives

– Examples – prednisone

• Anti-pyretics (ASA, NSAIDS, acetaminophen)– Manipulate fever curve

• Prophylaxis (detailed account)– Test understanding (especially malaria prophylaxis)

• Anything which could impact absorption or metabolism of chronic or prophylactic medications impacting their performance.

• All routine and travel specific vaccinations!

Social History

• Activities, hobbies, occupation (defines potential exposures)– Examples: hunter, gardener, fishing

• Sexual practices– Examples: monogamous, MSM, high risk behaviors

• Drugs and alcohol– Needle based drugs, potential for cirrhosis, etc.

• Tobacco– American or foreign

• Food– OCONUS (“on economy”),

Family History

• First degree relatives– Immunosuppressive conditions– Recurrent infections

• Individuals sharing household– Recent medical events (including vaccinations)

• “Sick contacts”

– Immunosuppressive conditions– Recent or current illness

• If yes, explore diagnosis if known • Hospitalized?

Travel

• Where (geographic specific infections)

• When (rainy season = vectors)

• Activities during travel (urban, rural)

• Accommodations (hotel with A/C, outdoors)

• Food (hot, cold, water, hotel, street, etc.)– Raw or uncooked meat, raw vegetables– Unpasteurized milk products

• Precautions (any PPM?)

Differential diagnosisTravel history- activities

• Sex - common during travel• Medical encounters

– Medical/dental/tattoos

• Recreational exposures– Fresh water– Soil contact

• Insect exposures• Animal exposures

– Bites– Direct contact with dogs, primates, etc.

College student not feeling well with fever, develops MS changes, hypotension, respiratory failure, the rash below

WF with RUQ pain, intermittent fever, expat. In Switzerland, owns dog, frequent walks in countryside, CT scan below.

Diagnosis: Echinococcus multilocularis

Service member wading in African stream, near Lake Victoria about four weeks ago. Now with right upper quadrant pain, fever, malaise, non-productive cough

Schistosomiasis: Geographic Distribution

• Trematode

• Widely distributed in tropical and subtropical regions

• 207 million people infected worldwide

• Over 800 million at risk of infection

• 280,000 deaths annually

• Amongst parasite infections, second only to malaria

in its global impact

Infectious Diseases of Returning TravelersClues in Evaluation

Top 5 Illnesses in returning travelers

Differential DiagnosisIncubation Period

• Sex/body fluids– HAV, HBV, HCV, CMV– HIV– Syphilis

• Freshwater– Leptospirosis– Schistosomiasis

• Rodents– Hantaviruses– Lassa fever

• Ingestions– Brucellosis

• Animal exposure– Q fever– Rabies– Anthrax

• Soil– Melioidosis– Dimorphic fungi

Differential diagnosis Exposures and associated infections

• Ticks/mites– Rickettsial– TBE– CCHF– Scrub typhus

• Sandflies– Leishmaniasis

• Lice– Relapsing fever– Epidemic typhus

• Mosquitoes– Malaria– Yellow fever– Dengue– Chickungunya– Japanese encephalitis– Rift Valley fever

• Fleas– Endemic typhus

Differential diagnosis Exposures and associated infections

Clinical syndromes

Differential DiagnosisClinical syndrome- undifferentiated fever

• Malaria• Leptospirosis• Typhoid• Dengue• Chikungunya

• Q fever• Acute schistosomiasis• Brucellosis• Amebic liver abscess• HIV

Viral• Yellow fever• Dengue• Hantaviruses• Lassa fever• Ebola• Marburg• CCHR• Rift Valley fever

Bacterial• Meningococcal• Leptospirosis• Rickettsial• Vibrio vulnificus

Differential diagnosisClinical syndrome- fever and hemorrhage

• Malaria• Meningococcal• Japanese encephalitis• Dengue• West Nile Virus• Rabies• African trypanosomiasis

– T. b. rhodesiense

• Q fever• Rickettsial• Brucellosis• Leptospirosis• Plague• Anthrax• Angiostrongyliasis

Differential diagnosisClinical syndrome- fever and CNS findings

• CAP• Influenza• SARS• Malaria• Hantaviruses• Plague• Anthrax• Tularemia

• Q fever• Legionella• Cocci/Histo• Melioidosis• Tuberculosis• Acute schistosomiasis• Hookworm/ascariasis• Pulmonary embolism

Differential diagnosisClinical syndrome- fever and respiratory symptoms

• Hepatitis A• Hepatitis B• Hepatitis D• Hepatitis E• Yellow Fever• EBV• CMV

• Q fever• Leptospirosis• Rickettsial• Brucellosis

Differential diagnosisClinical syndrome- fever and hepatitis

Localized• Tularemia• Leishmaniasis• Plague• Bartonella• HSV• LGV• Syphilis

Generalized• Mononucleosis• Acute HIV• Rickettsial• Leptospirosis• Brucellosis• Relapsing fever• Trypanosomiasis• Toxoplasmosis

Differential diagnosisClinical syndrome- fever and lymphadenopathy

Geographic Disease Distribution

CONUS / OCONUS

Typhoid fever

• People often shed bacteria for months after infection• GI/abdominal symptoms, fever, headache, splenomegaly, elevated LFTs,

furry tongue • -invades lymphatic tissues• -spread to any organ• Complications include intestinal hemorrhage or perforation, meningitis,

myocarditis, cholecystitis, pneumonia, osteomyelitis• Rate of complications increased in individuals co-infected with

Schistosomiasis and/or malaria.

Hepatitis A

Hepatitis E

HIV

Japanese Encephalitis

Malaria – E hemisphere

Malaria– W Hemisphere Mefloquine Resistant

Melioidosis

Meningitis

Schistosomiasis

Tuberculosis

Rock Mountain Spotted Fever / Tularemia

Anaplasmosis / Babesiosis / Lyme Disease

Rock Mountain Spotted Fever

Rickettsia parki rickettsiosis

Ehrlichiosis / STARI / Tularemia

Rock Mountain Spotted Fever / Tularemia

Anaplasmosis / Lyme Disease

Infectious Disease Emergencies

Infectious Disease Emergencies

• Acute bacterial meningitis• Meningococcemia• Intracranial subdural empyema• Necrotizing soft tissue infections• Toxic shock syndrome• Neutropenic fever• Sepsis in patients with splenectomy (actual/functional)• Plasmodium falciparum malaria• Cholera• Rocky Mountain Spotted Fever• Babesiosis

Evaluation of the febrile patient

Evaluation of the febrile patientGeneral approach

• Careful history and serial physical examination• Appropriate/directed laboratory tests

– Malaria• Serial thick and thin smears• Rapid diagnostic tests (e.g., BinaxNOW- P. falciparum Sensitivity/Specificity– 99.7% /

94.2%)

– CBC with diff – Liver associated enzymes

• Appropriate/directed radiographic studies• Speed of evaluation contingent upon

– Tempo of illness– Differential diagnosis– Immune status of patient

Evaluation of the febrile patientGeneral approach

• Develop a management plan– Differential diagnosis– Clinical data

• Consider empirical therapies– Malaria- must not miss malaria!– Meningococcal– Rickettsial/leptospirosis– Lassa fever

• Must recognize diseases that require special precautions– Hemorrhagic fevers (S, D, C, +/- Airborne)– Meningococcal (Droplet)– Tuberculosis (Airborne)

Outbreak of falciparum malaria among JTF Liberia QRF Marineson “DOT ppx;” prominent GI sx dx delayed

FeverResource limited setting

• Febrile illness is common – High mortality rates

• Diagnostic challenges– Clinical history/PE not diagnostic– Lack of laboratory services– Expensive lab services– Unreliable lab services

• Forced to treat empirically based on febrile syndrome

BMJ 2011; 343:1

FeverResource limited setting

• Fever<7d without focus– Malaria– Bacteremia– Meningococcal disease– Typhoid– Rickettisia– Dengue– Influenza– Leptospirosis– HIV- primary– Acute schisto

• Fever>7d without focus– TB– Typhoid– Malaria– Osteomyelitis– Endocarditis– Liver abscess– Brucellosis– Visceral leishmaniasis– Fungi (crypto, cocci, histo)

BMJ 2011; 343:1

FeverResource limited setting

• Rapidly assess patient– Physical exam– Malaria risk

• Fever from life-threatening cause– Neck stiffness– Unconsciousness, lethargy, seizure– Severe abdominal pain– Respiratory distress

• Immediate management– IV fluids, antimalarial, antibiotics, glucose

• MEDEVAC, hospital admission

http://www.who.int/hiv/pub/imai/acute_care.pdf

Medical History Informing Diagnosis

Mandell et al. PPID 7th ed.

Mandell et al. PPID 7th ed.