Hemorrhagic Fever

Viral hemorrhagic fevers (VHFs) are a group of illnesses caused by four families of viruses. These include the Ebola and Marburg, Lassa fever, and yellow fever viruses. VHFs have common features: they affect many organs, they damage the blood vessels, and they affect the body's ability to regulate itself. Some VHFs cause mild disease, but some, like Ebola or Marburg, cause severe disease and death.

VHFs are found around the world. Specific diseases are usually limited to areas where the animals that carry them live. The viruses that cause viral hemorrhagic fevers live naturally in a variety of animal and insect hosts — most commonly mosquitoes, ticks, rodents or bats. Each of these hosts typically lives in a specific geographic area, so each particular disease usually occurs only where that virus's host normally lives.

• The route of transmission varies by specific virus. Some viral hemorrhagic fevers are spread by mosquito or tick bites. Others are transmitted by contact with infected blood or semen. A few varieties can be inhaled from infected rat feces or urine or crushing an infected tick.
  • Viral hemorrhagic fevers are spread by contact with infected animals, people or insects. The risk for travelers is low, but you should avoid visiting areas where there are disease outbreaks. Because there are no effective treatments for some of these viral infections.

Viral hemorrhagic fever is a general term for a severe illness, sometimes associated with bleeding, that may be caused by a number of viruses. The term is usually applied to disease caused by Arenaviridae (Lassa fever, Junin and Machupo), Bunyaviridae (Crimean-Congo haemorrhagic fever, Rift Valley Fever, Hantaan haemorrhagic fevers), Filoviridae (Ebola and Marburg) and Flaviviridae (yellow fever, dengue, Omsk haemorrhagic fever, Kyasanur forest disease). (From: WHO - Haemorrhagic fevers, Viral)

• From: WHO – Dengue and severe dengue
  • Dengue fever is a mosquito-borne tropical disease caused by the dengue virus.[1] Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic skin rash. Recovery generally takes two to seven days. In a small proportion of cases, the disease develops into severe dengue, also known as dengue hemorrhagic fever, resulting in bleeding, low levels of blood platelets and blood plasma leakage, or into dengue shock syndrome, where dangerously low blood pressure occurs.
  • Dengue is spread by several species of female mosquitoes of the Aedes genus, principally Aedes aegypti.[1][2] The virus h.as five serotypes;[7][8] infection with one type usually gives lifelong immunity to that type, but only short-term immunity to the others. Subsequent infection with a different type increases the risk of severe complications. A number of tests are available to confirm the diagnosis including detecting antibodies to the virus or its RNA.
  • Dengue has become a global problem since the Second World War and is common in more than 120 countries, mainly in Southeast Asia, South Asia and South America. About 390 million people are infected a year and approximately 40,000 die. In 2019 a significant increase in the number of cases was seen. The earliest descriptions of an outbreak date from 1779. Its viral cause and spread were understood by the early 20th century. Apart from eliminating the mosquitos, work is ongoing for medication targeted directly at the virus. It is classified as a neglected tropical disease.

Signs and symptoms

• Signs and symptoms of VHFs include (by definition) fever and bleeding.
  • Severe cases of some types of viral hemorrhagic fevers may cause bleeding, but people rarely die of blood loss. Bleeding may occur:
    • Under the skin - flushing of the face and chest, small red or purple spots (petechiae), bleeding, swelling caused by [edema], low blood pressure [hypotension), and circulatory shock.
    • In internal organs
    • From the mouth, eyes or ears
  • Other signs and symptoms of severe infections can include:
    • Septic shock
    • Nervous system malfunctions
    • Coma
    • Delirium
    • Kidney failure
    • Respiratory failure
  • Malaise, [muscle pain], headache, vomiting, and diarrhea occur frequently.
  • The severity of symptoms varies with the type of virus. The “VHF syndrome” (capillary leak, bleeding diathesis, and circulatory compromise leading to shock) appears in a majority of people with [filovirus] hemorrhagic fevers (e.g., Ebola and Marburg virus), Crimean–Congo hemorrhagic fever (CCHF), and the South American hemorrhagic fevers caused by arenaviruses, but only in a small minority of patients with dengue, [[Rift Valley fever).

History:

From: (Wikipedia – Dengue fever)

• The first record of a case of probable dengue fever is in a Chinese medical encyclopedia from the Jin Dynasty (265–420 AD) which referred to a "water poison" associated with flying insects. The primary vector, A. aegypti, spread out of Africa in the 15th to 19th centuries due in part to increased globalization secondary to the slave trade. There have been descriptions of epidemics in the 17th century, but the most plausible early reports of dengue epidemics are from 1779 and 1780, when an epidemic swept across Southeast Asia, Africa and North America. From that time until 1940, epidemics were infrequent.
• In 1906, transmission by the Aedes mosquitos was confirmed, and in 1907 dengue was the second disease (after yellow fever) that was shown to be caused by a virus. Further investigations by John Burton Cleland and Joseph Franklin Siler completed the basic understanding of dengue transmission.
• The marked spread of dengue during and after the Second World War has been attributed to ecologic disruption. The same trends also led to the spread of different serotypes of the disease to new areas and the emergence of dengue hemorrhagic fever. This severe form of the disease was first reported in the Philippines in 1953; by the 1970s, it had become a major cause of child mortality and had emerged in the Pacific and the Americas. Dengue hemorrhagic fever and dengue shock syndrome were first noted in Central and South America in 1981, as DENV-2 was contracted by people who had previously been infected with DENV-1 several years earlier.

Epidemiology

• Cocoliztli in Mexico 1545 and 1576.
• The Great Yellow Fever Epidemic of 1793 in Philadelphia, PA, US. Nearly 10% of the population of 50,000 succumbed to the disease.
• Mékambo in Gabon is the site of several outbreaks of Ebola virus disease.
• Orientale Province, Democratic Republic of the Congo villages of Durba and Watsa were the epicenter of the 1998–2000 outbreak of Marburg virus disease.
• Uíge Province in Angola was the site of another outbreak of Marburg virus disease in 2005, the largest one to date of this disease.[9]
• A VHF outbreak in the village of Mweka, Democratic Republic of the Congo (DRC) that started in August 2007, and that has killed 103 people (100 adults and three children), has been shown to be caused (at least partially) by Ebola virus.
• A viral hemorrhagic fever is a possible cause of the Plague of Athens during the Peloponnesian War.[
• A viral hemorrhagic fever is an alternate theory of the cause of the Black Death and the Plague of Justinian
• The initial, and currently only, outbreak of Lujo virus in September–October 2008 left 4/5 patients dead.
• The 2014 West Africa Ebola outbreak, which was the biggest outbreak in history.

Resources & Additional Reading:

• Medline Plus – Hemorrhagic Fevers
• Wikipedia – Viral Hemorrhagic fever
• Wikipedia – Dengue Virus
• CDC - Viral Hemorrhagic Fevers (VHFs
• Mayo Clinic – Viral hemorrhagic fevers
• Johns Hopkins Medicine – Viral Hemorrhagic Fevers
• WHO – Haemorrhagic fevers.
• Top Health Fix – Viral Hemorrhagic Fever. By David Grant
• Features – Viral Hemorrhagic Fevers: Sensitive surveillance system required to prevent large outbreaks