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Viral hemorrhagic fevers

Definition


Disease: Viral hemorrhagic fevers Viral hemorrhagic fevers
Category: Infectious diseases

Disease Definition:

Caused by viruses from four distinct families, viral hemorrhagic fevers (VHFs) range from relatively mild to life-threatening. While all start with fever and muscle aches, some viral hemorrhagic fevers develop to more serious problems including severe internal and external bleeding (hemorrhage), widespread tissue death (necrosis), and shock. Viral hemorrhagic fevers presently can’t be cured by any treatment. Only two of the many viral hemorrhagic fevers have immunizations. The best approach is prevention until additional vaccines are developed.
 

Work Group:


Symptoms, Causes

Symptoms:

A broad range of diseases are included in the VHF designation. The signs and symptoms of VHF could differ widely, even between members of the same viral family. But VHFs have some common characteristics, particularly in their effects on the vascular system, the network of arteries, vein and capillaries circulating blood throughout the body. Hemorrhagic fevers make blood vessels more likely to leak; resulting in bleeding that could range from relatively minor to massive. The bleeding may occur from the eyes, mouth, ears, rectum, under the skin and in internal organs.  Potentially lethal signs and symptoms such as shock and coma may be experienced by people with severe bleeding, but they rarely die of blood loss. VHFs start with fever and muscle aches; many cause diarrhea and vomiting; and all create problems in a number of organ systems, especially the liver, lymphatic system, lungs and sometimes the kidneys. Signs and symptoms of most VHFs usually start two days to two weeks after the person has been exposed to the virus. Problems more specific to diseases within each of the four families of viruses causing viral hemorrhagic fevers are listed below.

 

ARENAVIRUSES:

Lassa fever, Argentine hemorrhagic fever, Bolivian hemorrhagic fever, Brazilian hemorrhagic fever and Venezuelan hemorrhagic fever are included in this viral family. In case a person has been exposed to one of these diseases, he/she will probably have some of the following signs and symptoms:

  • Pain behind the chest wall and in the back
  • Cough
  • Abdominal pain
  • Diarrhea
  • Vomiting
  • Facial swelling
  • A life-threatening inflammation of the brain called encephalitis
  • Fluid around the lungs (pleural effusion)
  • Temporary or permanent hearing loss
  • A sore and inflamed throat with white patches on the tonsils
  • Fever that might be constant or intermittent
  • Bleeding from the gums or in the stomach, small intestine and other internal organs
  • Inflammation of the transparent membrane (conjunctiva) covering the eyelids and part of the eyeballs, a condition called conjunctivitis.

 

 

BUNYAVIRUSES:

Crimean-Congo hemorrhagic fever, Rift Valley fever, hantavirus pulmonary syndrome and hemorrhagic fever with renal syndrome are included in this group of VHFs. Signs and symptoms of bunyaviruses, depending on the type of virus involved, may include the following:

  • Sore throat
  • Headache
  • Fever
  • Severe muscle aches
  • Cough
  • Encephalitis
  • Diarrhea
  • Respiratory failure may potentially result from shortness of breath and difficulty breathing in the case of hantavirus pulmonary syndrome.
  • Sore eyes and sensitivity to light (photophobia); mood swings and agitation; bleeding into the skin and from the gums, rectum and kidneys; and finally pulmonary failure is seen in the cases of Crimean-Congo hemorrhagic fever.

 

FILOVIRUSES:

Ebola virus and Marburg viruses are included in this viral family that are among the most virulent of all known diseases. Signs and symptoms start within two days to two weeks of the infection and initially include those common to other VHFs, such as intense weakness, muscle pain, fever, diarrhea and vomiting. Some people develop the following in case the disease progresses:

  • Seizures
  • Delirium
  • Coma
  • A distinctive, hemorrhagic rash, usually occuring around the fifth day
  • Bleeding from the nose, eyes, ears, mouth and rectum

 

Ebola and Marburg viruses depending on the strain are fatal in 50 to 90 % of infected people and in pregnant women, they are almost always fatal.

 

FLAVIVIRUSES:

Yellow fever, dengue fever, dengue hemorrhagic fever, Omsk hemorrhagic fever and Kyasanur Forest disease are included in this group. Dengue and yellow fevers are probably the most well known VHFs. Dengue is a major public health concern, with 50 million cases a year taking place worldwide, including major epidemics at popular tourist destinations.

 

Yellow fever:

The hallmark sign of yellow fever is the yellowing of the skin and eyes (jaundice). Fever, muscle aches, facial flushing, sensitivity to light and headache are some of the other common signs and symptoms of yellow fever.

 

Dengue fever:

While older children and adults might experience a high fever, severe headache, muscle aches, rash and eye pain; babies and young children may develop a rash and severe, flu-like symptoms. This means that the signs and symptoms of dengue fever differ with age. An extremely high fever might occur with bleeding, convulsions and circulatory failure in the hemorrhagic form.

 

Kyasanur Forest disease and Omsk hemorrhagic fever:

The initial signs and symptoms are followed by a short period of recovery preceding their reappearance, that is; both conditions are biphasic diseases. Signs and symptoms of these two diseases regardless of the period they occur in usually include:

  • Headache
  • Diarrhea
  • Nosebleeds
  • Bleeding in the gastrointestinal tract
  • Vomiting
  • Pain in the arms and legs
  • Pain behind the eyes
  • Fever that might be constant or intermittent
  • A rash on the soft palate of the mouth
  • Swollen glands in the neck
  • Bleeding in the eyes

 

Before traveling to a developing country, it’s best to see a doctor to make sure to receive any available vaccinations and pre-travel advice for staying healthy. The person should immediately consult a doctor in case he/she is suspecting of a VHF virus exposure in travels.
Once the person comes back home and finds out that they carry out signs and symptoms, a doctor should be consulted who focuses on international medicine or infectious diseases. A specialist might be able to recognize and treat the disease faster. The person should make sure to let the doctor know which areas he/she has visited.
 

Causes:

Most of the viruses related to VHFs are zoonotic, meaning that their survival depends on the insect or animal that they are residing in. Humans generally acquire the virus when coming into contact with an infected host, but sometimes, after the initial infection, person-to-person transmission could occur. Usually because of a combination of climatic, social and ecological factors, human epidemics occur sporadically.

 

ARENAVIRUSES:

A common arenavirus, Lassa fever is endemic in West Africa, where each year as many as 500,000 cases occur. It might spread in the ways listed below:

 

Person-to-person contact:

When a person comes in contact with the urine, blood, or throat secretions of an infected person, particularly during the acute fever stage of the disease, the person may contract the virus.

 

Contaminated needles and syringes:

During an accidental needle stick or in a hospital where equipment might be reused, this form of transmission is most likely to occur.

 

Sexual contact:

Men who have recovered from Lassa fever are recommended to refrain from sexual activity for at least three months because the virus could be transmitted in semen long after the infection. 

 

Wild rodents:

The main source of Lassa virus infection is the multimammate rat. The person might acquire the virus from direct contact with infected rat urine or droppings, from touching surfaces or objects or eating food contaminated with these excretions, or potentially by inhaling airborne particles containing the virus (airborne or aerosol transmission). There are particular arenavirus diseases that are carried by rodents, such as Argentine, Bolivian, Brazilian and Venezuelan hemorrhagic fevers. They occur only in South America and are less pervasive arenavirus illnesses.

 

BUNYAVIRUSES:

Contact with an infected insect or animal spread the diseases in this group:

 

Mosquitoes: 

Humans contract the virus by a mosquito bite or through contact with blood, organs, body fluids and probably the raw milk of infected animals. Rift Valley fever initially affects animals, specifically sheep, cattle, camels and goats, but it could also result in severe disease in humans. Several mosquito species spread the disease, some of which transmit the virus to their offspring. Mosquitoes that aren’t infected acquire the virus when they feed on sick animals and later on pass it on to their next victim, preserving the cycle of infection.

 

Ticks:

In several countries in Asia, Africa and Europe, Crimean-Congo hemorrhagic fever, which is a severe type of VHF that’s usually fatal, is endemic. It’s spread by ticks, some of which transmit the virus to their offspring through their eggs. More often, ticks acquire the virus when they feed on infected animals, specifically cattle, goats and sheep. Especially during the first week after the animal has been exposed to the virus, humans may get infected from direct contact with the blood or tissues of sick livestock, or from a tick bite.

 

Rodents:

Occurring in Canada, United States and South America, hantavirus pulmonary syndrome, which is caused by hantaviruses, is spread by rodents. People mostly contract the virus when they breathe the aerosolized droppings of infected rodents. Farm workers, campers and other people spending time outdoors in endemic areas are at an increased risk, but a person might also be exposed to the virus in case rodents nest near their home or invade their home throughout cold weather.  

 

FILOVIRUSES:

Once a person has been infected, the virus could be transmitted in many ways, though the natural source of these diseases is unknown, some of the ways of transmission are:

 

Contaminated needles and syringes:

This form of transmission most likely takes place during an accidental needle stick or in a hospital where equipment is used on more than one person.

 

Person-to-person contact:

A person might get infected via exposure to the blood, body fluids or organs of a severely infected person with Ebola or Marburg virus. Health care workers and family members taking care of sick relatives are at high risk.

 

Contact with nonhuman primates:

After handling monkeys infected with the Marburg virus, some researchers have contracted the infection.

 

Sexual Contact:

Since the virus could be transmitted in semen long after infection, experts suggest that men who have recovered from Lassa fever to refrain sexual activity for at least three months.

 

FLAVIVIRUSES:

Insects are mostly responsible for the spread of this family of viruses:

 

Mosquitoes:

Virulent forms of flaviviruses include yellow fever and dengue hemorrhagic fever that spread by a specific efficient species of mosquito; called Aedes aegypti. The mosquitoes flourish in and near human dwellings where they multiply in even the cleanest water. Mostly yellow fever and dengue fever occur in South America, Asia and parts of Africa. Nowadays, the risk of having epidemics in a large part of the United States and some Caribbean and European countries is increased because the Aedes aegypti is found in those areas.

 

Ticks:

Kyasanur Forest disease and Omsk hemorrhagic fever are far more obscure and isolated diseases, for instance, only in portions of western Siberia does Omsk hemorrhagic fever occur, where it primarily affects muskrat trappers. A person might contract Omsk hemorrhagic fever by touching infected muskrats or by drinking water that contains the virus. Additionally, both diseases are spread by ticks.

 

People have a low chance of contracting most VHFs. Some are held to isolated pockets in distant areas where the risk of transmission is slight. And since each virus is often related to a specific host species, it’s normally restricted to the area where that species lives.

The viruses causing VHFs are found over most of the world. Some VHFs, specifically Lassa, yellow and dengue hemorrhagic fevers lay a real threat to people traveling to or living in regions where these diseases are widespread, mainly South America and sub-Saharan Africa. The risk of contracting any disease abroad depends on the route and activities, the length of the person’s stay and the rate of transmission of a specific disease at the time. In the case of a short visit to a region, the person’s at higher risk when traveling for months and living in a tent. Yet, the person’s at risk of epidemic diseases like dengue fever even in the best of situations, although that chance is lower if there aren’t any outbreaks of the disease throughout the visit. Someone is more likely to contract a hantavirus in case the region inhabited by the person has a large rodent population known to carry the virus. The risk is higher if the person lives in the country or suburbs, work outdoors, or spend time in rodent-infested buildings. Other people who are at an increased risk of infection include hospital workers treating people with VHFs as well as researchers and laboratory personnel dealing with the viruses. Health care workers frequently contract Ebola from patients in Africa, and several cases of laboratory-acquired infection have been reported worldwide.
 

Complications

Complications:

There are some problems that occur with many of the viruses, despite the fact that complications of VHFs differ. Those complications include:

 

Blindness:

About one in five cases of Rift valley fever infections result in blindness.

 

Uveitis:

Uveitis results in redness, pain and sensitivity to light, but when treated quickly and appropriately, it usually doesn’t cause long-term complications. This serious eye inflammation affects the uvea, the layer just beneath the white of the eye (sclera).

 

Hair loss:

Temporary or permanent hair loss is experienced by several people who have recovered from VHFs.

 

Pericarditis:

This condition is the swelling and irritation of the pericardium, the thin, membranous sac surrounding the heart. Pericarditis often causes shortness of breath, an overall feeling of weakness or fatigue and sharp, stabbing chest pain. Severe pericarditis could lead to life-threatening conditions like cardiac tamponade that puts pressure on the heart and intervenes with its ability to pump blood efficiently, while mild cases may disappear on their own.

 

Spontaneous abortion:

Losing the unborn child is a common complication of VHFs in pregnant women.

 

Encephalitis:

VHFs may possibly cause this severe and potentially life-threatening brain inflammation. Respiratory arrest, marked mental impairment, coma and death may be caused by severe encephalitis.

 

Hearing problems:

Difficulty hearing and potentially, deafness will be experienced in as many as one-third of those who recover from Lassa fever.

 

Orchitis:

A viral infection may cause this acute inflammation of the testicles that results in swelling and pain. Infertility may result from orchitis.
 

Treatments:

Most VHFs have no particular treatment, although the antiviral drug ribavirin might help shorten the course of the infection and stop complications in certain arenaviruses and bunyaviruses. A dispute is done for whether bleeding complications should be treated with therapies such as platelets, heparin and clotting factors or not.
Supportive care is important for each person with VHF, whichever type of the virus is involved. It is likely to include measures to:

  • Aid breathing with a mechanical ventilator when necessary
  • Provide adequate fluids and maintain the balance of electrolytes, substances such as sodium, potassium, chloride and calcium that control the movement of nutrients into cells
  • Provide therapy for secondary infections and other complications
  • If required, provide kidney dialysis, an artificial way of removing excess fluids and wastes from the body when the kidneys stop working.
     

Prognosis:

Not available

Expert's opinion

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