Ebola Virus Disease

Ebola virus disease “Ebola” redirects here. For other uses, see Ebola body fluids and tissues from people with the disease (disambiguation). should be handled with special caution.[1] No specific treatment or vaccine for the virus is commer- Ebola virus disease (EVD; also Ebola hemorrhagic cially available, although a number of potential treatments fever, or EHF), or simply Ebola, is a disease of hu- are being studied. Efforts to help those who are infected mans and other primates caused by ebolaviruses. Signs are supportive; they include either oral rehydration ther- and symptoms typically start between two days and three apy (drinking slightly sweetened and salty water) or giv- weeks after contracting the virus as a fever, sore throat, ing intravenous fluids as well as treating symptoms. This muscle pain, and headaches. Then, vomiting, diarrhea supportive care improves outcomes. EVD was first iden- and rash usually follow, along with decreased function of tified in 1976 in an area of Sudan (now part of South the liver and kidneys. At this time some people begin to Sudan), and in Zaire (now the Democratic Republic of bleed both internally and externally.[1] The disease has a the Congo). The disease typically occurs in outbreaks in high risk of death, killing between 25 percent and 90 per- tropical regions of sub-Saharan Africa.[1] Through 2013, cent of those infected with the virus, averaging out at 50 the World Health Organization reported a total of 1,716 percent.[1] This is often due to low blood pressure from cases in 24 outbreaks.[1][6] The largest outbreak to date fluid loss, and typically follows six to sixteen days after is the ongoing epidemic in West Africa, which is cen- symptoms appear.[2] tered in Guinea, Sierra Leone and Liberia.[7][8][9] As of 23 November 2014, this outbreak has 15,963 reported The virus spreads by direct contact with blood or other [10][11][12] body fluids of an infected human or other animal.[1] In- cases resulting in 6,003 deaths. fection with the virus may also occur by direct contact with a recently contaminated item or surface.[1] Spread of the disease through the air between primates, includ- 1 Signs and symptoms ing humans, has not been documented in either labora- tory or natural conditions.[3] The virus may be spread by semen or breast milk for several weeks to months after recovery.[1][4] Fruit bats are believed to be the normal carrier in nature, able to spread the virus without being affected by it. Humans become infected by contact with the bats or with a living or dead animal that has been infected by bats. After human infection occurs, the disease may also spread between people. Other diseases such as malaria, cholera, typhoid fever, meningitis and other viral hemorrhagic fevers may resemble EVD. Blood samples are tested for viral RNA, viral antibodies or for the virus itself to confirm the diagnosis.[1] Control of outbreaks requires coordinated medical services, along with a certain level of community engage- ment. The medical services include: rapid detection of cases of disease, contact tracing of those who have come into contact with infected individuals, quick access to lab- oratory services, proper care and management of those who are infected and proper disposal of the dead through [1][5] cremation or burial. Prevention includes limiting the Signs and symptoms of Ebola[13] spread of disease from infected animals to humans.[1] This may be done by handling potentially infected bush The length of time between exposure to the virus and meat only while wearing protective clothing and by thor- the development of symptoms (incubation period) is be- [1] oughly cooking it before consumption. It also includes tween 2 to 21 days.[1][13] Most often this is between 4 to wearing proper protective clothing and washing hands 10 days.[14] However, recent estimates based on mathe- [1] when around a person with the disease. Samples of matical models predict that around 5% of cases may take 1 2 2 CAUSE greater than 21 days to develop.[15] 2.1 Transmission Symptoms usually begin with a sudden influenza-like stage characterized by feeling tired, fever, weakness, decreased appetite, muscle pain, joint pain, headache, and sore throat.[1][14][16][17] The fever is usually higher than 38.3 °C (100.9 °F).[18] This is often followed by vomiting, diarrhea and abdominal pain.[17] Next, shortness of breath and chest pain may occur, along with swelling, headaches and confusion.[17] In about half of the cases, the skin may develop a maculopapular rash (a flat red area covered with small bumps), which may be seen 5 to 7 days after symptoms begin.[14][18] In some cases, internal and external bleeding may occur.[1] This typically begins five to seven days after the first symptoms.[19] All infected people show some decreased blood clotting.[18] Bleeding from mucous Life cycles of the Ebolavirus membranes or from sites of needle punctures has been reported in 40–50 percent of cases.[20] This may result Between people, Ebola disease spreads only by direct in the vomiting of blood, coughing up of blood or blood contact with the blood or body fluids of a person who in stool.[21] Bleeding into the skin may create petechiae, has developed symptoms of the disease.[29][30][31] Body purpura, ecchymoses or hematomas (especially around fluids that may contain ebola viruses include saliva, mu- needle injection sites).[22] Bleeding into the whites of the cus, vomit, feces, sweat, tears, breast milk, urine and eyes may also occur. Heavy bleeding is uncommon, and semen.[24] The WHO states that only people who are very if it occurs, it is usually located within the gastrointestinal sick are able to spread Ebola disease in saliva, and whole tract.[18][23] virus has not been reported to be transmitted through sweat. Most people spread the virus through blood, feces Recovery may begin between 7 and 14 days after the start [32] [17] and vomit. Entry points for the virus include the nose, of symptoms. Death, if it occurs, follows typically 6 to [24] 16 days from the start of symptoms and is often due to mouth, eyes, open wounds, cuts and abrasions. Ebola low blood pressure from fluid loss.[2] In general, bleeding may be spread through large droplets; however, this is believed to occur only when a person is very sick.[33] This often indicates a worse outcome, and this blood loss may [33] result in death.[16] People are often in a coma near the end can happen if a person is splashed with droplets. Con- of life.[17] Those who survive often have ongoing muscle tact with surfaces or objects contaminated by the virus, particularly needles and syringes, may also transmit the and joint pain, liver inflammation, and decreased hear- [34][35] ing among other difficulties.[17] Additionally they develop infection. The virus is able to survive on objects for a few hours in a dried state and can survive for a few antibodies against Ebola that last at least 10 years but it is [24] unclear if they are immune to repeated infections.[24] If days within body fluids. someone survives Ebola, they can no longer transmit the The Ebola virus may be able to persist for up to 8 weeks in disease.[24] the semen of survivors after they recovered, which could lead to infections via sexual intercourse.[1] Ebola may also occur in the breast milk of women after recovery, and it [4] 2 Cause is not known when it is safe to breastfeed again. Other- wise, people who have recovered are not infectious.[34] Main articles: Ebolavirus (taxonomic group) and Ebola The potential for widespread infections in countries with virus (specific virus) medical systems capable of observing correct medical isolation procedures is considered low.[36] Usually when someone has symptoms of the disease, they are unable to EVD in humans is caused by four of five viruses of travel without assistance.[37] the genus Ebolavirus. The four are Bundibugyo virus (BDBV), Sudan virus (SUDV), Taï Forest virus (TAFV) Dead bodies remain infectious; thus, people handling hu- and one simply called Ebola virus (EBOV, formerly Zaire man remains in practices such as traditional burial ritu- [25] als or more modern processes such as embalming are at Ebola virus). EBOV, species Zaire ebolavirus, is the [36] most dangerous of the known EVD-causing viruses, and risk. 69% of the cases of Ebola infections in Guinea is responsible for the largest number of outbreaks.[26] during the 2014 outbreak are believed to have been con- The fifth virus, Reston virus (RESTV), is not thought tracted via unprotected (or unsuitably protected) contact with infected corpses during certain Guinean burial to cause disease in humans, but has caused disease in [38][39] other primates.[27][28] All five viruses are closely related rituals. to marburgviruses.[25] Health-care workers treating those who are infected are 2.3 Reservoir 3 at greatest risk of getting infected themselves.[34] The risk increases when these workers do not have appro- priate protective clothing such as masks, gowns, gloves and eye protection; do not wear it properly; or han- dle contaminated clothing incorrectly.[34] This risk is particularly common in parts of Africa where health systems function poorly and where the disease mostly occurs.[40] Hospital-acquired transmission has also oc- curred in some African countries resulting from the reuse of needles.[41][42] Some health-care centers caring for people with the disease do not have running water.[43] In the United States the spread to two medical workers treating infected patients prompted criticism of inadequate training and procedures.[44] Bushmeat being prepared for cooking in Ghana.

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