More than 20 RNA viruses within the families Flaviviridae, Arenaviridae, Filoviridae, and the order Bunyavirales (previously family Bunyaviridae) cause hemorrhagic fevers (HFs).
The prevalent viral HFs (VHFs) are dengue, yellow fever (YF), Lassa fever (LF), Rift Valley fever (RVF), and hemorrhagic fever with renal syndrome (HFRS).
Ebola virus (EBOV) caused a major outbreak in West Africa during 2014-2016 that led to >11,000 deaths. Because of the unusually large size and longer duration of this epidemic, our understanding of the spectrum of Ebola virus disease has improved.
The major factors in Ebola transmission are infection of household contacts of symptomatic infected individuals and exposure to infection during traditional burial practices.
Hantaviruses cause HFRS in the Old World and hantavirus cardiopulmonary syndrome (HCPS) in the New World. HCPS manifests as low-pressure pulmonary edema, pleural effusions, and cardiogenic shock, but not HF.
Mosquitoes are the vector of dengue, YF, and RVF.
Ticks are the vector of Crimean-Congo HF (CCHF), Omsk HF (OHF), Kyasanur forest disease (KFD), Alkhurma HF, and severe fever with thrombocytopenia syndrome (SFTS).
Arenaviruses and hantaviruses are rodent-borne zoonoses.
Marburg virus reservoir is a cave-dwelling, fruit-eating bat, Rousettus aegyptiacus; Ebola virus reservoir is not confirmed, although tree-roosting, fruit-eating bats are suspected.
Exposure to domestic animals is a major mode of infection in RVF and CCHF.
RVF causes simultaneous epizootics in animals and large epidemics in humans. A small minority of infected persons develop HF, encephalitis, or retinitis.
Dengue and Seoul hantavirus are urban infections. YF is endemic in jungles and African savannas, but also causes urban epidemics. Ebola is usually a rural infection but has the potential to spread to urban centers. The other VHFs are mostly rural infections.
Health care–associated infections are a feature of CCHF, filoviruses, arenaviruses, Andes hantavirus, and SFTS virus.
Air travel can transport infected persons with VHF to nonendemic areas, including Europe and North America. Especially with Ebola, Marburg, and Lassa, there is a risk of health care–associated outbreaks even in a modern hospital with good adherence to standard infection control practices. Special precautions are required for patients with suspected HF.
The incubation period is shorter than 2 weeks in most infections. The incubation of Ebola ranges from 2 to 21 days. The incubation is longer with hantaviruses (10 days to 5 weeks). The onset of illness usually is sudden but is insidious with arenaviruses.
Clues to dengue fever are urban acquisition, break-bone fever, rash, hemoconcentration, and thrombocytopenia. Danger signs for severe dengue include abdominal pain, persistent vomiting, effusions, mucosal bleed, lethargy, restlessness, liver enlargement, hemoconcentration, and severe thrombocytopenia.
YF vaccine–associated viscerotropic disease (YEL-AVD) may rarely occur in persons who are older or have abnormal thymus function. YF vaccine is contraindicated in immunocompromised persons.
Clues to LF are insidious onset, sore throat, chest pain, cervicofacial edema, high maternal mortality and fetal loss during pregnancy, and irreversible sensorineural deafness.
Clues to filoviruses are fever, diarrhea, severe bleeding, jaundice, rash, person-to-person transmission in ...