Lecture 15: Hemorrhagic Fever

What are hemorrhagic fevers known for?

Acute febrile illness with a propensity for bleeding.

How many different viruses cause hemorrhagic fevers?

25 different viruses from 4 families: Flaviviridae, Arenaviridae, Bunyaviridae, and Filoviridae.

What type of viruses are responsible for hemorrhagic fevers?

Single stranded RNA viruses with envelopes.

Which hemorrhagic fever virus is best known for its high case fatality rates?

Ebola virus (Filoviridae).

What was the number of deaths attributed to Ebola in the DRC in 2018?

2299 deaths.

What is the primary reservoir for Ebola virus?

Unknown, but some primates and certain species of bats are sero-positive.

What are the main transmission routes for Ebola?

Aerosol exposure to contaminated urine, direct exposure to blood/excreta, and human-to-human contact with body fluids.

What are the hallmark features of viral hemorrhagic fevers?

Microvascular instability and impaired hemostasis.

What is the typical incubation period for hemorrhagic fevers?

5-14 days.

What are the initial clinical signs of hemorrhagic fevers?

Non-descript signs resembling many diseases like malaria or typhoid.

What is the case fatality rate for hemorrhagic fevers?

90%.

What samples are needed for diagnosing hemorrhagic fevers?

Blood, throat washings, urine, and post-mortem tissue specimens.

What is the primary treatment approach for hemorrhagic fevers?

Mostly supportive care, including fluid therapy and monitoring.

What is a common complication in pregnant females infected with hemorrhagic fevers?

Miscarriage due to high virus concentration in the placenta.

What antiviral drug has shown some effectiveness against certain hemorrhagic fevers?

Ribavirin, but not extensively tested with Ebola.

What is the first approved vaccine for Ebola?

rVSV-ZEBOV, approved in December 2019.

What is a ring vaccination strategy?

Vaccinating an area and those near it to decrease the spread of disease.

What challenges exist in the development of vaccines and antivirals for hemorrhagic fevers?

Lack of financial incentives, remote areas, local traditions, and testing difficulties.

What is the Zika virus classified as?

An arbovirus of the Flaviviridae family.

How is Zika virus primarily transmitted?

By Aedes sp. mosquitos, mainly Aedes aegypti.

What are common symptoms of Zika virus infection?

Mild flu-like signs, maculopapular rash, and conjunctivitis.

What rare neurological issue is associated with Zika virus?

Guillain-Barre syndrome.

What increased risk is associated with Zika virus in pregnant females?

Increased incidence of congenital microcephaly.

What was the first major epidemic of Zika virus?

In Micronesia in 2007.

What is the incubation period for Zika virus?

2-3 days.