The Febrile Returned The Febrile Returned Traveler and Dengue FeverTraveler and Dengue Fever

AM ReportAM Report

Sept. 25, 2009Sept. 25, 2009

The TravelerThe Traveler

• Health problems are common in the traveler – Self-reported rate of 22-64% of people who

travel to developing countries

• The major categories are:– Systemic febrile illness w/o localizing findings– Diarrhea– Dermatologic disorders– Non-diarrheal GI disorders

GeoSentinalGeoSentinal

• Surveillance effort made up of the CDC and International Society of Travel Medicine

• Stretches out over six continents and collects data on ill travelers

• Large study of almost 25,000 ill travelers between 1997-2006 (all-comers)– Non-specific fever was the chief complaint in

28%

Febrile IllnessFebrile Illness• For returned travelers presenting with an acute

fever Malaria was the #1 cause, Dengue Fever #2– 21%, 6% respectively, although it is thought that

Dengue is widely underrecognized and underdiagnosed secondary to lack of knowledge on the part of health care providers

– In travelers to SouthEast Asia, Dengue is the #1 cause of febrile illness

– In the Caribbean and South/Central America, they are roughly even

• Numbers 3-5 are mononucleosis (EBV or CMV), Rickettsial infection, and typhoid/paratyphoid fever

Dengue Fever – What is it?Dengue Fever – What is it?

• Mosquito-born virus – Four, actually. DENV-1 through DENV-4– Flavivirus genus– Single strand RNA viruses– Exposure to one serotype provides almost no

cross-protection to re-infection from other 3 types

• 50 million infections occur yearly throughout the world

SymptomsSymptoms

• Typically start 4-7 days after the bite– Incubation period of 3-14 days

• Spectrum, from asx infection to self-limited fever to hemorrhagic fever

• Age is a big predictor for response – children under the age of 15 tend to have more asx infections (>50%)

Classic PresentationClassic Presentation“Break-Bone Fever”“Break-Bone Fever”

• Acute febrile illness– Typically lasts 5-7 days– Once fever disappears, prolonged fatigue (days to week)

is common• Muscle/joint pain• Headache/retroorbital pain• Varied rashes common in primary infection

– Macular of maculopapular• GI sx common in secondary infection• Rarely (<10%), can have hematologic sx

– Purpura, spontaneous bleed, melena, metorrhagia, epistaxis

Lab FindingsLab Findings

• Thrombocytopenia (<100K)

• Leukopenia

• Elevated AST (2-5x upper limit of nl)

More serious presentation – More serious presentation – Dengue Hemorrhagic FeverDengue Hemorrhagic Fever

• Four cardinal features, per the WHO

– “Plasma Leakage Syndrome”

• Increased vascular permeability defined by either hemoconcentration (>20% rise above baseline crit), presence of pleural effusion or ascites

– Thrombocytopenia (<100K)

– Fever lasting 2-7 days

– Spontaneous bleeding or a “hemorrhagic tendency” (ie positive tourniquet test)

• Inflate BP cuff on arm to midway between systolic and diastolic pressure, wait five minutes

• If >20 petechiae/sq inch on skin below the cuff, test is positive

** If all four of these signs/sx plus shock Dengue Shock Syndrome (DSS)

EpiEpi• Dengue was the cause of about 10.4% of

post-travel systemic febrile illnesses among travelers returning from Southeast Asia– Second only to malaria

• Most frequently identified cause of systemic febrile illness among travelers returning from Southeast Asia (32%), Caribbean (24%), South Central Asia (14%), South America (14%). Second to malaria in Central America (12%)

DiagnosisDiagnosis• Other than specific WHO criteria for Dengue

Hemorrhagic Fever, classic DF has no clear criteria

• Mostly clinical, based on signs/sx• Epidemiological studies define it differently -

has been a problem for research efforts• Hemagglutination Inhibition Assay is the gold

standard• In developed countries, can do PCR, Ag

testing, or IgM/IgG immunoassay

PreventionPrevention

• Tx is pretty much all supportive, so focus on prevention– Particularly those traveling to Asia, Central and South

America, and the Caribbean

• Tetravalent vaccines in development (animal testing phase)

Mosquito Control (Aedes Aegypti)Mosquito Control (Aedes Aegypti)

– Insecticides not very effective, as they breed inside houses

– Community education to reduce breeding site (tires, other containers with standing water)

– Standard methods to prevent mosquito bites (long sleeves, DEET, etc)

– Place a water bug, Mesocyclops, in containers

ReferencesReferences

• Freedman, DO, Weld, LH, Kozarsky, PE, et al. Spectrum of disease and relation to place of exposure among ill returned travelers. N Engl J Med 2006; 354:119.

• Up-To-Date. Clinical presentation and diagnosis of dengue virus infections. Updated January, 2009

• Steffen, R, deBernardis, C, Banos, A. Travel epidemiology--a global perspective. Int J Antimicrob Agents 2003; 21:89.

• World Health Organization Public Website – “Dengue and Dengue Haemorrhagic Fever” http://www.who.int/mediacentre/factsheets/fs117/en/

• Wilson, ME, Weld, LH, Boggild, A, et al. Fever in returned travelers: Results from the GeoSentinel Surveillance Network. Clin Infect Dis 2007; 44:1560.