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Viral Hemorrhagic Fever
Dengue fever facts
- Dengue fever is a disease caused by a family of viruses that are transmitted by mosquitoes.
- Symptoms of dengue feverinclude severe joint and muscle pain, swollen lymph nodes, headache, fever, exhaustion, and rash. The presence of fever, rash, and headache (the "dengue triad") is characteristic of dengue fever.
- Dengue is prevalent throughout the tropics and subtropics.
- Dengue fever is caused by a virus, and there is no specific medicine or antibiotic to treat it. For typical dengue fever, the treatment is directed toward relief of the symptoms (symptomatic treatment).
- Papaya leaf extract can be used to treat dengue fever.
- The acute phase of the illness with fever and muscle pain lasts about one to two weeks.
- Dengue hemorrhagic fever (DHF) is a specific syndrome that tends to affect children under 10 years of age. This complication of dengue causes abdominal pain, hemorrhage (bleeding), and circulatory collapse (shock).
- The prevention of dengue fever requires control or eradication of the mosquitoes carrying the virus that causes dengue.
- A vaccine for dengue fever was approved in April 2016 for use in dengue-endemic areas.
Dengue Symptoms and Signs
Primary symptoms of dengue appear three to 15 days after the mosquito bite and include the following:
- high fever and severe headache,
- with severe pain behind the eyes that is apparent when trying to move the eyes.
Other associated symptoms are:
- joint pain,
- muscle and bone pain,
- rash,
- and mild bleeding.
Many affected people complain of low back pain.
What is dengue fever? What causes dengue fever?
Dengue fever is a disease caused by a family of viruses transmitted by mosquitoes. It is an acute illness of sudden onset that usually follows a benign course with symptoms such as headache, fever, exhaustion, severe muscle and joint pain, swollen lymph nodes (lymphadenopathy), and rash. The presence of fever, itchy rash, and headache (the "dengue triad") is characteristic of dengue. Other signs of dengue fever include bleeding gums, severe pain behind the eyes, and red palms and soles.
Dengue (pronounced DENG-gay) can affect anyone but tends to be more severe in people with compromised immune systems. Because it is caused by one of five serotypes of the dengue virus, it is possible to get dengue fever multiple times. However, an attack of dengue produces immunity for a lifetime to that particular viral serotype to which the patient was exposed.
Dengue goes by other names, including "breakbone fever" or "dandy fever." Victims of dengue often have contortions due to the intense pain in the joints, muscles, and bones, hence the name breakbone fever. Slaves in the West Indies who contracted dengue were said to have dandy fever because of their postures and gait.
Dengue hemorrhagic fever is a more severe form of the viral illness. Symptoms include headache, fever, rash, and evidence of bleeding (hemorrhage) in the body. Petechiae (small red spots or purple splotches or blisters under the skin), bleeding in the nose or gums, black stools, or easy bruising are all possible signs of hemorrhage. This form of dengue fever can be life-threatening and can progress to the most severe form of the illness, dengue shock syndrome.
What geographic areas are at high risk for contracting dengue fever?
Dengue is prevalent throughout the tropics and subtropics. Outbreaks have occurred recently in the Caribbean, including Puerto Rico, the U.S. Virgin Islands, Cuba, and Central America. Cases have also been imported via tourists returning from areas with widespread dengue, including Tahiti, Singapore, the South Pacific, including the Philippines, Southeast Asia, the West Indies, India, and the Middle East (similar in distribution to the areas of the world that harbor malaria and yellow fever). Dengue is now the leading cause of acute febrile illness in U.S. travelers returning from the Caribbean, South America, and Asia.
- From January to July 2017, Sri Lanka reported 80,732 cases of dengue fever, with 215 deaths.
- New Delhi, India, reported an outbreak of dengue fever, with 1,872 testing positive for the illness in September 2015.
- In American Samoa, there were 370 cases of dengue reported from May 2015 to September 2, 2015, and 133 were hospitalized.
- Thailand reported the worst dengue outbreak in 20 years, with 126 deaths and 135,344 people infected with the virus, in October 2013.
- In 2011, Bolivia, Brazil, Columbia, Costa Rica, El Salvador, Honduras, Mexico, Peru, Puerto Rico, and Venezuela reported a large number of dengue cases. Paraguay reported a dengue fever outbreak in 2011, the worst since 2007. Hospitals were overcrowded, and patients had elective surgeries canceled due to the outbreak.
What geographic areas are at high risk for contracting dengue fever? (continued)
The U.S. Centers for Disease Control and Prevention (CDC) reports that from 1946 to 1980, no cases of dengue acquired in the continental United States were reported. Since 1980, a few locally acquired U.S. cases have been confirmed along the Texas-Mexico border, temporally associated with large outbreaks in neighboring Mexican cities.
A 2009 outbreak of dengue fever in the Florida town of Key West involved three patients who did not travel outside of the U.S. and contracted the virus. Subsequent testing of the population of Key West has shown that up to 5% of the people living in the area have antibodies to dengue. In total, 28 people were diagnosed with dengue fever in this outbreak. In 2015, 210 people were diagnosed with dengue on the Big Island of Hawaii. This is the largest outbreak in Hawaii since 2001, when 122 people were diagnosed with dengue.
Dengue fever is common in at least 100 countries in Asia, the Pacific, the Americas, Africa, and the Caribbean. Thailand, Vietnam, Singapore, and Malaysia have all reported an increase in cases.
According to the World Health Organization (WHO), there are about 390 million cases of dengue fever worldwide, and 96 million require medical treatment. Five hundred thousand cases of dengue hemorrhagic fever, the most severe form of dengue, require hospitalization each year. Nearly 40% of the world's population lives in an area endemic with dengue. The World Health Organization (WHO) estimates 22,000 deaths occur yearly, mostly among children.
How is dengue fever contracted? Is dengue fever contagious?
The virus is contracted from the bite of a striped Aedes aegypti mosquito that has previously bitten an infected person. The mosquito flourishes during rainy seasons but can breed in water-filled flower pots, plastic bags, and cans year-round. One mosquito bite can cause the disease.
The virus is not contagious and cannot be spread directly from person to person. It is mosquito-borne, so there must be a person-to-mosquito-to-another-person pathway. The full life cycle of the virus involves the mosquito as the vector (transmitter) and the human as the source of infection.
What is the incubation period for dengue fever?
After being bitten by a mosquito carrying the virus, the incubation period for dengue fever ranges from three to 15 (usually five to eight) days before the signs and symptoms of dengue appear in stages.
What are dengue fever symptoms and signs?
Dengue fever starts with symptoms of chills, headache, pain in the back of the eyes that may worsen upon moving the eyes, appetite loss, feeling unwell (malaise), and low backache. Painful aching in the legs and joints occurs during the first hours of illness. The temperature rises quickly as high as 104 F (40 C), with relatively low heart rate (bradycardia) and low blood pressure (hypotension). The eyes become reddened. A flushing or pale pink rash comes over the face and then disappears. The lymph nodes in the neck and groin are often swollen.
High fever and other signs of dengue last for two to four days, followed by a rapid drop in body temperature (defervescence) with profuse sweating. This precedes a period with normal temperature and a sense of well-being that lasts about a day. A second rapid rise in temperature follows. A characteristic itchy rash (small red spots, called petechiae) appears along with the fever and spreads from the extremities to cover the entire body except the face. The palms and soles may be bright red and swollen.
What tests do health care providers use to diagnose dengue fever?
The diagnosis of dengue fever is usually made when a patient exhibits the typical clinical symptoms of headache, high fever, eye pain, severe muscle aches, and petechial rash and has a history of being in an area where dengue fever is endemic. Dengue fever can be difficult to diagnose because its symptoms overlap with those of many other viral illnesses, such as West Nile virus and chikungunya fever.
Health care professionals may use a blood test called the DENV Detect IgM Capture ELISA to diagnose people with dengue fever. The FDA notes that the test may also give a positive result when a person has a closely related virus, such West Nile disease.
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What is the treatmentfor dengue fever?
Because dengue fever is caused by a virus, there are no specific antibiotics to treat it. Antiviral medications are also not indicated for dengue fever. For typical dengue, the treatment is concerned with relief of the symptoms and signs. Home remedies such as rest and fluid intake (oral rehydration) are important. Pain relievers such as aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) should only be taken under a doctor's supervision because of the possibility of worsening bleeding complications. Acetaminophen (Tylenol) and codeine may be given for severe headache and for joint and muscle pain (myalgia).
Patients hospitalized for dengue may receive IV fluids.
Carica papaya leaf extract (papaya leaf) has been shown in several clinical studies to be an effective treatment for dengue fever.
What types of doctors treat dengue fever?
If you have symptoms of dengue fever, you may first be seen by your primary care provider (PCP) such as your family practitioner or internist, and children may be seen by a pediatrician. If symptoms are severe, you may see an emergency medicine doctor in a hospital emergency department.
If your doctor is not familiar with treating dengue fever or your symptoms are severe, you may see an infectious disease specialist or a travel medicine physician.
What is the prognosis for typical dengue fever?
The prognosis for dengue is usually good. The worst symptoms of the illness typically last one to two weeks, and most patients will fully recover within several additional weeks.
Typical dengue is fatal in less than 1% of cases; however, dengue hemorrhagic fever is fatal in 2.5% of cases. If dengue hemorrhagic fever is not treated, mortality (death) rates can be as high as 20%-50%.
From 
What is dengue hemorrhagic fever?
Dengue hemorrhagic fever (DHF) is a specific syndrome that tends to affect children under 10 years of age. This complication of dengue fever causes abdominal pain, hemorrhage (bleeding), and circulatory collapse (shock). DHF is also called Philippine, Thai, or Southeast Asian hemorrhagic fever or dengue shock syndrome.
DHF starts abruptly with continuous high fever and headache. There are respiratory and intestinal symptoms with sore throat, cough, nausea, vomiting, and abdominal pain. Shock occurs two to six days after the start of symptoms with sudden collapse, cool, clammy extremities (the trunk is often warm), weak pulse, and blueness around the mouth (circumoral cyanosis).
In DHF, there is bleeding with easy bruising, red or purple blood spots in the skin (petechiae), spitting up blood (hematemesis), blood in the stool (melena), bleeding gums, and nosebleeds (epistaxis). Pneumonia is common, and inflammation of the heart (myocarditis) may be present.
Patients with DHF must be monitored closely for the first few days since shock may occur or recur precipitously (dengue shock syndrome). Cyanotic (having a bluish coloration to the skin and mucus membranes) patients are given oxygen. Vascular collapse (shock) requires immediate fluid replacement. Blood transfusions may be needed to control bleeding.
The mortality (death) rate with DHF is significant. With proper treatment, the World Health Organization estimates a 2.5% mortality rate. However, without proper treatment, the mortality rate rises to 20%. Most deaths occur in children. Infants under 1 year of age are especially at risk of dying from DHF.
What are potential complications of dengue fever?
If dengue fever is severe, complications include leakage of fluid from the bloodstream causing fluid accumulation in the extremities, respiratory distress, severe bleeding, or organ impairment. Without proper treatment, these symptoms can be fatal.
Dengue hemorrhagic fever (DHF; see above) is a complication of dengue that usually affects children under 10 years of age when it occurs. This complication of dengue fever starts abruptly with continuous high fever and headache. DHF causes abdominal pain, sore throat, cough, nausea, vomiting, hemorrhage (bleeding), and circulatory collapse (shock). It can be fatal.
Another complication is postinfectious fatigue syndrome, which can occur in about one-quarter of hospitalized dengue patients.
Is it possible to prevent dengue fever?
The transmission of the virus to mosquitoes must be interrupted to prevent the illness. To this end, patients are kept under mosquito netting until the second bout of fever is over and they are no longer able to transmit the virus to a biting mosquito.
The prevention of dengue fever requires control or eradication of the mosquitoes carrying the virus that causes dengue. In nations plagued by dengue fever, people are urged to empty stagnant water from old tires, trash cans, and flower pots. Governmental initiatives to decrease mosquitoes also help to keep the disease in check but have been poorly effective.
To prevent mosquito bites, wear long pants and long sleeves. For personal protection, use mosquito-repellant sprays that contain DEET when visiting places where dengue is endemic. There are no specific risk factors for contracting dengue fever except living in or traveling to an area where the mosquitoes and virus are endemic. Limiting exposure to mosquitoes by avoiding standing water and staying indoors for two hours after sunrise and before sunset will help, as the Aedes aegypti mosquito is a daytime biter with peak periods of biting around sunrise and sunset. It may bite at any time of the day and is often hidden inside homes or other dwellings, especially in urban areas.
Is there a dengue fever vaccine?
In April 2016, the WHO approved Sanofi Pasteur's Dengvaxia (CYD-TDV), a live recombinant tetravalent vaccine for dengue fever. Dengvaxia can be administered as a three-dose series in people 9-45 years of age who live in areas where dengue is endemic.
In clinical trials in Latin America and Asia involving more than 40,000 children and adolescents, Dengvaxia protected 66% of people aged 9 and older against dengue. Dengvaxia was very effective at protecting against severe dengue, which can be fatal, preventing 93% of severe cases, and reducing hospitalizations due to dengue by 80%.
Dengvaxia was initially approved in 2015 for use only in Mexico, the Philippines, Brazil, and El Salvador.
Several other vaccines for dengue are undergoing clinical trials, but none have yet been approved for use.
Medically Reviewed on 8/2/2017
References
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Viral Hemorrhagic Fever
Viral hemorrhagic fever (VHF) facts*
*Viral hemorrhagic fever facts by Charles Patrick Davis, MD, PhD
- Viral hemorrhagic fevers are defined as a group of illnesses caused by different families of viruses that cause vascular damage that results in symptomatic bleeding (hemorrhage). For example, Arenaviridae cause Lassa fever (Lassa virus), Argentine hemorrhagic fever (Junin virus), and Bolivian hemorrhagic fever (Machupo virus); Bunyaviridae cause Crimean-Congo, Rift Valley, and Hantaan hemorrhagic fevers; Filoviridae cause Ebola and Marburg diseases; and finally, Flaviviridae cause yellow fever, dengue fever, Omsk hemorrhagic fever, and Kyasanur Forest disease. Readers should note that flaviviruses are not the same as filoviruses, as these two viral terms designate two different families of viruses and are easily confused; Ebola is caused by a filovirus, not a flavivirus.
- Hemorrhagic fever viruses are mainly zoonotic diseases caused by viruses that usually reside in an animal or arthropod hosts that may serve as health vectors.
- Viral hemorrhagic fevers are usually seen associated with only one particular of species and consequently are usually contained in geographically restricted areas in Liberia, Uganda, Bolivia, or other countries with such areas; however, if the virus is introduced accidentally to humans in cities, it may become widespread (for example, the recent Ebola outbreak).
- Hemorrhagic fever viruses are usually transmitted among animal or arthropod hosts; however, the viruses carried in these animal or arthropods can be transmitted to humans when humans come in contact with the urine, feces, saliva, or other bodily fluids of infected animals or arthropods, including if the animal is killed and eaten. In some instances, once the viruses infect humans, person-to-person transmission can occur when an uninfected person comes in contact with bodily fluids or (with some viruses) a bite by an arthropod vector.
- Symptoms of viral hemorrhagic fever include fatigue, fever, weakness, dizziness, and muscle aches; patients with more severe infections show bleeding under the skin, internal organs, or even from bodily orifices like the mouth, eyes, or ears. Some patients develop severe diarrhea that may also be bloody, and severely ill patients present with shock, delirium, seizures, kidney failure, and coma that often ends in death.
- Patients with viral hemorrhagic fevers usually receive only supportive therapy; there is no other established cure for viral hemorrhagic fevers. However, ribavirin (Rebetol, Copegus) medical treatment has been effective in treating some individuals with Lassa fever, and treatment with convalescent-phase plasma has been used with success in a few patients -- other experimental antiviral agents have also been tried in a few patients.
- Prevention and control of hemorrhagic fevers is difficult; except for yellow fever and Argentine hemorrhagic fever, no vaccines have been made commercially available so that prevention efforts are concentrated on avoiding contacts with the host species, vectors, or humans infected with the viruses although one recent clinical trial showed effectiveness of a vaccineagainst a strain of Ebola virus.
- Scientists and health researchers are addressing the threat of viral hemorrhagic fevers to humans by attempting to develop immunological, molecular, and containment methods to prevent these hemorrhagic fevers and restore health to individuals who get hemorrhagic fevers.
What are viral hemorrhagic fevers?
Viral hemorrhagic fevers (VHFs) refer to a group of illnesses that are caused by several distinct families of viruses. In general, the term "viral hemorrhagic fever" is used to describe a severe multisystem syndrome (multisystem in that multiple organ systems in the body are affected). Characteristically, the overall vascular system is damaged, and the body's ability to regulate itself is impaired. These symptoms are often accompanied by hemorrhage (bleeding); however, the bleeding is itself rarely life-threatening. While some types of hemorrhagic fever viruses can cause relatively mild illnesses, many of these viruses cause severe, life-threatening disease.
The Special Pathogens Branch (SPB) primarily works with hemorrhagic fever viruses that are classified as biosafety level four (BSL-4) pathogens. A list of these viruses appears in the SPB disease information index. The Division of Vector-Borne Infectious Diseases, also in the National Center for Infectious Diseases, works with the non-BSL-4 viruses that cause two other hemorrhagic fevers, dengue hemorrhagic fever and yellow fever.
How are hemorrhagic fever viruses grouped?
VHFs are caused by viruses of four distinct families: arenaviruses, filoviruses, bunyaviruses, and flaviviruses. Each of these families share a number of features:
- They are all RNA viruses, and all are covered, or enveloped, in a fatty (lipid) coating.
- Their survival is dependent on an animal or insect host, called the natural reservoir.
- The viruses are geographically restricted to the areas where their host species live.
- Humans are not the natural reservoir for any of these viruses. Humans are infected when they come into contact with infected hosts. However, with some viruses, after the accidental transmission from the host, humans can transmit the virus to one another.
- Human cases or outbreaks of hemorrhagic fevers caused by these viruses occur sporadically and irregularly. The occurrence of outbreaks cannot be easily predicted.
- With a few noteworthy exceptions, there is no cure or established drug treatment for VHFs.
In rare cases, other viral and bacterial infections can cause a hemorrhagic fever; scrub typhus is a good example.
Marburg Virus Disease History, Symptoms, and Treatment
The Ugandan Ministry of Health reported on Oct. 5, 2014, that a health-care worker died of Marburg virus disease (formerly known as Marburg hemorrhagic fever [Marburg HF]) on Sept. 30, 2014. The source of his exposure is not clear. This is of interest since Marburg virus is a close relative of the Ebola virus, and both produce clinical signs and symptoms that are often indistinguishable.
What carries viruses that cause viral hemorrhagic fevers?
Viruses associated with most VHFs are zoonotic. This means that these viruses naturally reside in an animal reservoir host or arthropod vector. They are totally dependent on their hosts for replication and overall survival. For the most part, rodents and arthropods are the main reservoirs for viruses causing VHFs. The multimammate rat, cotton rat, deer mouse, house mouse, and other field rodents are examples of reservoir hosts. Arthropod ticks and mosquitoes serve as vectors for some of the illnesses. However, the hosts of some viruses remain unknown -- Ebola and Marburg viruses are well-known examples.
Where are cases of viral hemorrhagic fever found?
Taken together, the viruses that cause VHFs are distributed over much of the globe. However, because each virus is associated with one or more particular host species, the virus and the disease it causes are usually seen only where the host species live(s). Some hosts, such as the rodent species carrying several of the New World arenaviruses, live in geographically restricted areas. Therefore, the risk of getting VHFs caused by these viruses is restricted to those areas. Other hosts range over continents, such as the rodents that carry viruses which cause various forms of hantavirus pulmonary syndrome (HPS) in North and South America, or the different set of rodents that carry viruses which cause hemorrhagic fever with renal syndrome (HFRS) in Europe and Asia. A few hosts are distributed nearly worldwide, such as the common rat. It can carry Seoul virus, a cause of HFRS; therefore, humans can get HFRS anywhere where the common rat is found.
While people usually become infected only in areas where the host lives, occasionally people become infected by a host that has been exported from its native habitat. For example, the first outbreaks of Marburg hemorrhagic fever, in Marburg and Frankfurt, Germany, and in Yugoslavia, occurred when laboratory workers handled imported monkeys infected with Marburg virus. Occasionally, a person becomes infected in an area where the virus occurs naturally and then travels elsewhere. If the virus is a type that can be transmitted further by person-to-person contact, the traveler could infect other people. For instance, in 1996, a medical professional treating patients with Ebola hemorrhagic fever (Ebola HF) in Gabon unknowingly became infected. When he later traveled to South Africa and was treated for Ebola HF in a hospital, the virus was transmitted to a nurse. She became ill and died. Because more and more people travel each year, outbreaks of these diseases are becoming an increasing threat in places where they rarely, if ever, have been seen before.
How are hemorrhagic fever viruses transmitted?
Viruses causing hemorrhagic fever are initially transmitted to humans when the activities of infected reservoir hosts or vectors and humans overlap. The viruses carried in rodent reservoirs are transmitted when humans have contact with urine, fecal matter, saliva, or other body excretions from infected rodents. The viruses associated with arthropod vectors are spread most often when the vector mosquito or tick bites a human, or when a human crushes a tick. However, some of these vectors may spread virus to animals, livestock, for example. Humans then become infected when they care for or slaughter the animals.
Some viruses that cause hemorrhagic fever can spread from one person to another, once an initial person has become infected. Ebola, Marburg, Lassa and Crimean-Congo hemorrhagic fever viruses are examples. This type of secondary transmission of the virus can occur directly, through close contact with infected people or their body fluids. It can also occur indirectly, through contact with objects contaminated with infected body fluids. For example, contaminated syringes and needles have played an important role in spreading infection in outbreaks of Ebola hemorrhagic fever and Lassa fever.
What are the symptoms of viral hemorrhagic fever illnesses?
Specific signs and symptoms vary by the type of VHF, but initial signs and symptoms often include marked fever, fatigue, dizziness, muscle aches, loss of strength, and exhaustion. Patients with severe cases of VHF often show signs of bleeding under the skin, in internal organs, or from body orifices like the mouth, eyes, or ears. However, although they may bleed from many sites around the body, patients rarely die because of blood loss. Severely ill patient cases may also show shock, nervous system malfunction, coma, delirium, and seizures. Some types of VHF are associated with renal (kidney) failure.
How are patients with viral hemorrhagic fever treated?
Patients receive supportive therapy, but generally speaking, there is no other treatment or established cure for VHFs. Ribavirin, an anti-viral drug, has been effective in treating some individuals with Lassa fever or HFRS. Treatment with convalescent-phase plasma has been used with success in some patients with Argentine hemorrhagic fever.
How can cases of viral hemorrhagic fever be prevented and controlled?
With the exception of yellow fever and Argentine hemorrhagic fever, for which vaccineshave been developed, no vaccines exist that can protect against these diseases. Therefore, prevention efforts must concentrate on avoiding contact with host species. If prevention methods fail and a case of VHF does occur, efforts should focus on preventing further transmission from person to person, if the virus can be transmitted in this way. Because many of the hosts that carry hemorrhagic fever viruses are rodents, disease prevention efforts include:
- controlling rodent populations;
- discouraging rodents from entering or living in homes or workplaces;
- encouraging safe cleanup of rodent nests and droppings.
For hemorrhagic fever viruses spread by arthropod vectors, prevention efforts often focus on community-wide insect and arthropod control. In addition, people are encouraged to use insect repellant, proper clothing, bednets, window screens, and other insect barriers to avoid being bitten.
For those hemorrhagic fever viruses that can be transmitted from one person to another, avoiding close physical contact with infected people and their body fluids is the most important way of controlling the spread of disease. Barrier nursing or infection control techniques include isolating infected individuals and wearing protective clothing. Other infection control recommendations include proper use, disinfection, and disposal of instruments and equipment used in treating or caring for patients with VHF, such as needles and thermometers.
In conjunction with the World Health Organization, CDC has developed practical, hospital-based guidelines, Infection Control for Viral Haemorrhagic Fevers In the African Health Care Setting. The manual can help health-care facilities recognize cases and prevent further hospital-based disease transmission using locally available materials and few financial resources.
What needs to be done to address the threat of viral hemorrhagic fevers?
Scientists and researchers are challenged with developing containment, treatment, and vaccine strategies for these diseases. Another goal is to develop immunologic and molecular tools for more rapid disease diagnosis, and to study how the viruses are transmitted and exactly how the disease affects the body (pathogenesis). A third goal is to understand the ecology of these viruses and their hosts in order to offer preventive public health advice for avoiding infection.
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