Viral Haemorrhagic Fevers Overview

Study Notes

VHFs are zoonotic diseases caused by various viruses, including Lassa fever, Ebola fever, Marburg fever, Yellow fever, Dengue, and more.
Common types of VHFs: Crimean-Congo hemorrhagic fever (CCHF), Rift Valley fever, Kyasanur fever, and Haemorrhagic fever with renal syndrome (Hantaan fever).

In 2022, Iraq documented over 200 CCHF cases in the first half of the year.
CCHF transmission is most active from May to September, peaking in June and July.
Viral reservoirs primarily include domestic livestock: sheep, goats, cattle, and pigs.
Ticks can remain attached to hosts for 2 to 13 days, during which the virus multiplies within 36 hours of attachment.
Virus does not survive outside the host but can persist in infected body fluids (blood, stool, vomit).

Via ticks, direct contact with infected animal fluids, nosocomial routes, and vertical transmission.
Low risk of community transmission among close contacts.
Relatives and caregivers must avoid contact with infected individuals and use personal protective equipment.
Nosocomial transmission heightened during late disease stages due to higher viral loads.
Risk of transmission is increased in healthcare settings, especially with aerosol-generating procedures.
Breastfeeding is not associated with CCHF virus transmission.

Primarily affects agricultural workers, veterinarians, and individuals in endemic areas (e.g., abattoirs, leather factories).
Higher risk for campers, hikers, hunters, soldiers, healthcare workers, and travelers to affected regions.

CCHF virus (CCHFV) belongs to the Nairovirus family, with negative-stranded, enveloped RNA viruses.

Most cases are subclinical (88%).
Acute infections can lead to hemorrhage and multiorgan failure with an incubation period of 1 to 13 days.
Common symptoms:
- Sudden fever
- Headache, malaise, myalgia
- Sore throat, dizziness, conjunctivitis, photophobia
- Abdominal pain, nausea, vomiting
- Hepatomegaly, lymphadenopathy, confusion
Initial nonspecific symptoms may last up to seven days before recovery or severe progression.

Hemorrhagic signs may include petechiae, ecchymoses, epistaxis, gum bleeding, pulmonary hemorrhage, and intra-abdominal bleeding.
Severe cases often result from a "cytokine storm," leading to:
- Hypotension, shock, multiple organ failure, and potential death.
Laboratory findings may show thrombocytopenia, leukopenia, hyperbilirubinemia, elevated transaminases, and prolonged clotting times.