Haemorrhagic Fever Overview

Viral infections causing a hemorrhagic syndrome, ranging in severity.

RNA genomic viruses, belonging to families like Flaviviridae, Bunyaviridae, Arenaviridae, and Filoviridae.

Includes viruses like yellow fever, dengue, Omsk, and Kyasanur.

Includes Nairovirus (Crimean-Congo HF), Phlebovirus (Rift Valley HF), and Hantaviruses.

Causes Hantavirus pulmonary syndrome (HPS) in some regions, and hemorrhagic fever with renal syndrome (HFRS) in others.

HFs are mostly found in warm, tropical/subtropical areas, but some cases occur in temperate climates like Europe.

Animals (rodents, bats, primates) or humans act as a source of infection.

Changes in climate can affect animal reservoirs of HF and their vectors (arthropods), potentially increasing disease incidence.

Time taken for symptoms to appear after infection.

Bleeding tendency, bruising, internal bleeding, etc.

Over-activation of immune system, leading to tissue damage.

Impaired liver function leads to clotting problems.

Low blood pressure due to adrenal gland damage.

First step in the cytokine storm, leading to vascular damage.

T lymphocytes are suppressed, limiting the ability to fight infection.

Vary from mild (flu-like) to severe (multiple organ failure).

Transmission of a disease from animals to humans, often through direct contact with infected animals or their bodily fluids, or indirectly through contaminated surfaces or vectors.

Transmission of a disease through physical contact with an infected individual or animal.

Transmission of a disease through contact with contaminated objects or surfaces.

Viruses that require an arthropod (e.g., mosquito, tick) vector for transmission.

A viral disease transmitted by mosquitoes, characterized by potential severe illness due to repeated infections causing hemorrhagic syndrome.

Viral disease transmitted by mosquitoes, often leading to long-lasting immunity.

The process by which a pathogen (disease-causing agent) causes disease.

Spread of disease between human individuals through various means like direct contact, bodily fluids exchange, sexual contact, or contaminated objects

HF often has two distinct phases: an initial phase with flu-like symptoms, followed by a toxic phase with worsening symptoms, liver failure, and potentially death.

Some HFs, like Rift Valley fever, have a biphasic course with two periods of fever separated by a brief improvement.

Complications associated with severe HF can include meningoencephalitis, retinopathy, liver damage, and bleeding.

Hantaviruses cause two syndromes: Hantavirus pulmonary syndrome (HPS), affecting the lungs, mainly in America, and hemorrhagic fever with renal syndrome (HFRS), affecting the kidneys, mainly in Europe and Asia.

The severity of HF varies based on host factors (age, sex, ethnicity) and virus characteristics.

Mortality rates for HFs vary greatly, ranging from 1-2% for Lassa fever to 40-90% for Ebola.

Suspicion of HF is raised by travel history, contact with animal or human reservoirs, or insect bites. Initial symptoms may be flu-like, but severe cases can involve shock and organ failure.

Laboratory diagnosis of HF involves detecting antibodies against the virus, viral antigens, or the virus itself in samples like blood.

Treatment for HF is primarily supportive and focuses on managing symptoms, vital functions, and restoring fluid balance. There is no specific antiviral treatment for most HFs.

Influenza, malaria, typhoid fever, leptospirosis, rickettsiosis, meningococcemia, and acute viral hepatitis (A-E) can be considered as initial possibilities because they share some early symptoms with HF.

Monoclonal antibodies like Inmazeb and Ebanga are effective against Ebola virus infection, but require early administration.

Non-specific prophylaxis, isolation, and use of personal protective equipment (PPE) are crucial for preventing the spread of HF, especially in healthcare settings.

To prevent transmission through vectors like mosquitoes, use insect repellents, mosquito nets, and avoid contact with animal reservoirs like rodents.

Antibiotics are only used in cases of bacterial superinfection that may complicate HF, but are not a primary treatment for the viral infection itself.

Specific antiviral agents are available and effective for only a minority of HF cases.

HF is a dangerous and potentially life-threatening illness, requiring prompt reporting to authorities to enable timely public health interventions.

A live attenuated virus vaccine that provides long-lasting immunity for most people, but not recommended for infants under 9 months, pregnant women, or those with weakened immune systems.

Recommended every 10 years for individuals with frequent exposure to yellow fever, such as those living in endemic areas or traveling there.

A vaccine that targets the four dengue virus serotypes, recommended for people living in or traveling to endemic areas who have already experienced dengue fever, as the second infection is usually more severe.

Two vaccines, Ervebo and Zabdeno-and-Mvabea, used to prevent Ebola infection.

Ervebo, a single-dose vaccine effective in adults, was used in the 2018-2020 Ebola outbreak in the Democratic Republic of Congo.

An Ebola vaccine for individuals over the age of 1, requiring two doses 8 weeks apart.

Boosters are recommended for individuals with frequent exposure to yellow fever, such as travelers to endemic areas, to maintain immunity levels.

A second dengue infection can be more severe than the first, leading to stronger immune reactions. The vaccine is intended to help protect against severe illness in those with known exposure.