What Are Viral Hemorrhagic Fevers

Viral hemorrhagic fevers are caused by specific types of viruses; they can cause dramatic internal and external bleeding in severe cases, and pose a great risk to public health in areas where they spread. In this article, you will learn about these diseases, where they spread, what causes them, how they are diagnosed and treated, and how to prevent contracting them when you travel to an endemic area.

Introduction

Viral Hemorrhagic Fevers (VHFs) are illnesses that are caused by four different virus families and can manifest, as the name hemorrhagic fever suggests, as a fever accompanied by failure of the cardiovascular system leading to excessive internal and external bleeding.¹

Epidemiology and transmission:

These viruses are transmitted either by:

• Close contact with specific types of animals like bats, rodents, and livestock (their stools, urine, or food are contaminated with their stools and urine)
• By a vector (animal) that can transmit them to humans, like specific types of mosquitoes and ticks
• Close contact with body fluids (e.g. blood, saliva, vomit) of infected people

Since all these diseases are zoonoses (infections that are transmitted from animals to humans), they mainly spread in areas where the animals and vectors that transmit them are present, which are largely in Africa, Asia, and South America, causing outbreaks from time to time.²

Between 2014 and 2016, the largest outbreak to date occurred. The Ebola virus caused the outbreak in West Africa that started in Guinea and then spread to Sierra Leone and Liberia. The outbreak killed over 11,000 people and cost billions of dollars, resulting in economic loss.³

Although VHFs are uncommon in the Western world, they pose a risk by potentially being used in biological terrorism attacks.⁴

Causes:

There are four families of viruses that can cause hemorrhagic fevers, and each family include many individual viruses:⁵

Arenaviridae family

Lassa virus is a virus of the arenaviridae family. The name Lassa comes from the Nigerian town where the virus was first found. This virus causes Lassa fever and is transmitted to humans by infected rats and from person to person following contact with the infected person’s secretions. Lassa fever is endemic in West Africa and is estimated to kill 5,000 people every year. According to the CDC, this virus is classified as posing a high risk for bioterrorism.

Flaviviridae family

Yellow fever virus is a virus of the flaviviridae family that causes yellow fever; it can cause jaundice (one sign of it is yellowing of the skin), hence the name. It spreads in Africa and South America and is transmitted by the bite of an infected mosquito. There is a vaccine against this virus that can be taken before travelling to countries with endemic viruses.

Filoviridae family

Ebola virus is a virus of the filoviridae family that causes Ebola disease and is named after the Ebola River in the Democratic Republic of Congo, where the first outbreak happened. It can be transmitted by infected fruit bats and non-human primates (e.g. apes and monkeys) and by contact with body fluids (e.g. blood, urine, vomit, sweat) of infected people. According to the CDC, this virus is classified as a virus posing a high risk for bioterrorism.

Bunyaviridae family:

Crimean-Congo hemorrhagic virus is a virus of the Bunyaviridae family that causes Crimean-Congo hemorrhagic fever; the virus was first found in Crimea and then in the Congo. It is transmitted by infected ticks and from an infected person by contact with body fluids. The virus spreads in Eastern and Southern Europe, parts of Asia, and Africa.

Signs and symptoms:

Signs and symptoms of viral hemorrhagic fevers vary between different viruses. However, most start abruptly with the following symptoms(CDC):

• Fever
• Headache
• Myalgias (muscle pain)

These can be followed by:

• Coagulopathy (the body’s ability to form clots to stop bleeding is impaired), which manifests as Petechiae (bleeding under the skin and mucous membranes that look like small purple dots), bruises, or excessive bleeding in severe cases
• Gastrointestinal symptoms are common: vomiting, diarrhoea, and abdominal pain.
• Shock (sudden decrease in the blood flow, and is a life-threatening condition)
• Lung and liver damage

Further manifestations that can be associated with specific viral hemorrhagic fevers include symptoms like hearing loss, abortion, birth defects, renal failure, and partial blindness.

Diagnosis

Since the viruses that cause hemorrhagic fevers are deadly and highly infectious, their diagnosis cannot be made in regular diagnostic laboratories but in specialised laboratories around Europe, the USA, and Africa. The following is done for their diagnosis:

• Travel history might be taken into consideration for patients presenting with fever, jaundice, and bleeding. Questions about the specific countries and regions they  visited, activities done during the visits, contact with animals and their excreta, etc., can help the doctor diagnose these illnesses
• The virus can be grown from patients’ samples and then be seen using special microscopes; these methods might take weeks to complete
• The virus could be isolated from patients’ samples, and its genetic material (that is, RNA in these viruses) can be detected, which is considered the best technique for their diagnosis.
• Other tests can detect parts of the virus called antigens, or the antibodies that our body produces to defend against these viruses.⁵

Treatment

There are no specific drugs available to treat these viruses, and the treatment relies mostly on supportive treatments and the management of the symptoms. The specific interventions vary according to the severity of the disease but in all cases the patients should be monitored, and psychological support should be provided.⁶

Symptoms can be managed as follows:

• Paracetamol can be given for fevers
• Whole blood transfusion can be necessary in cases of major bleeding or severe pallor (pale colour of the skin and mucous membrane that lines the nose and mouth)·Analgesics can be used to treat pain.
•  Oxygen can be given in cases of difficulty in breathing
• Oral rehydration solutions (ORS) might be given in cases of diarrhoea.
• Antiemetic drugs (e.g. ondansetron) can be used to combat nausea and vomiting
•  A sugar solution can be given to patients with hypoglycemia (low blood sugar)
• Anti-anxiety drugs (e.g. diazepam) can be used to manage the patients’ anxiety

FAQs

Will I be in danger if I travel to countries where these viruses spread?

Cases of travellers being infected with these viruses when travelling to countries where the infection is spread are rare, and travellers are more likely to contract Malaria than hemorrhagic fevers.⁷ However, some activities that might cause an interaction with animal hosts (e.g. rodents, bats, and livestock), and vectors (i.e. ticks and mosquitoes), might increase the risk of infection. 

These activities include:

• Hiking and camping in rural areas
• Fieldwork, cave exploration, and mining

What precautions can I take if I travel to a country where these viruses spread?

• Do not visit places where an outbreak is known to be happening, and avoid contact with known infected people.
• Avoid contact with animals that could be a source of infection, like bats, rodents, and livestock.
• Avoid ticks by using insect repellents, wearing clothes that cover your skin, and checking your clothes and skin for ticks at the end of the day and removing them immediately if found.
• Avoid mosquitoes by using insect repellents and mosquito nets and wearing clothes that cover your skin.
• Avoid eating food from unknown sources, such as meat from infected animals and food contaminated with urine or stools of infected animals, which can cause disease.

According to the NHS, if you have travelled to a country where these viruses spread and developed flu-like symptoms (e.g. fever, malaise, vomiting, diarrhoea) within 21 days of coming back, you should swiftly seek medical attention and detail your travel history to your healthcare provider. (To navigate the spread of some VHFs by country, you can visit HERE). 

Are there any vaccines available to take before travelling to a risky area?

Yellow fever, transmitted by infected mosquitoes, has a commercially available vaccine. A certificate of yellow fever vaccination might be required prior to travel to specific countries. In the UK, there are yellow fever vaccination centres that provide the vaccine. The only vaccine for yellow fever that is used in the UK is an attenuated (weakened) virus given in one dose to people over 9 months of age who are at risk. (For more information about the vaccine, read HERE).

In the United States, there is an Ebola vaccine that is approved to be used in people at high risk of being infected, like healthcare workers responding to outbreaks in endemic areas (CDC). 

Summary

Viral hemorrhagic fevers are caused by four families of viruses that spread where the animal or vector transmitting them is found. A person can be infected from direct contact with infected animals and people or by the bite of specific types of mosquitoes and ticks. These viruses cause illnesses that, in severe cases, lead to dramatic bleeding, coma, and death; that, coupled with the fact that there are no specific treatments or vaccines for most of these viruses and the difficulty of their containment when an outbreak starts, make them a major threat to people in endemic areas.