Description hemorrhagic fevers
Hemorrhagic (bleeding) fevers are a group of infectious diseases caused by viruses. These are diseases in our countries, mostly exotic, public exceptions, not very well known. Usually characterized by feverish with bleeding and a large percentage of mortality. These are very serious diseases that are highly contagious and when infection is therefore necessary to adhere to strict security measures.
Viruses that cause hemorrhagic fever, we already know a large number of (classified into four different families) and from time to time will emergence of a new, hitherto unknown virus that usually gets its name from the area of its occurrence. For hemorrhagic fever is typically do not occur as a sporadic disease (sporadic cases) or put in the form of small local epidemics affecting certain area. Exceptions are areas of occurrence are located in tropical regions, and therefore it is very important to know this issue mainly for tourists going to risk areas. But only for them.With the current huge increase in population migration, tourism and imports of animals there is a real danger of the introduction of these diseases into our area.
Due to the danger of these diseases and their high contagiousness, there are well-founded fear of misuse of some of these agents, particularly viruses, Marburg fever and Ebola, as combat biological weapons or the means to terrorist attacks.
Hemorrhagic fever viruses are transmitted to humans mostly various external parasites, or contact with an infected animal or its excretions. They talk about the so-called “natural reservoir”, which are animals who themselves contain viruses and thus maintain their existence. Among them can be further spread to the surroundings for example by ticks and mosquitoes, which are in turn known.“Vectors” that transmit the disease. It is also possible to infect directly from the infected animal, by direct contact with the excrement or inhalation of contaminated aerosols. Some, however, may lead to so-called. “Interhumánnímu transmission” (human to human), most often by contact with body fluids of infected persons. Risk are then mostly healthcare professionals treating patients and family members as well as the ritual washing of the dead, which is traditionally performed by African natives.
Thus causing the disease are viruses that belong to four families:
Bunyaviridae
Do Bunyaviridae include agents that cause these diseases: Crimean-Congo hemorrhagic fever and hemorrhagic fever with renal syndrome, which can occur even in Southeast Europe. The reservoir may be different mammals and birds, and a vector (carrier) is usually a tick or mosquito.
Flaviviridae
Viruses Flaviviridae family includes several types of hemorrhagic fevers, of which the most famous is the yellow fever and dengue fever. Also included are the Omsk hemorrhagic fever and fever Kyasanurského forest. Reservoirs are rodents, bats, primates, but also the person and the disease is transmitted by mosquitoes and ticks.
Arenaviridae
Representatives of the families Arenaviridae are responsible for the following diseases: Lassa fever, Bolivian hemorrhagic fever (Machupo virus), Argentine hemorrhagic fever (Junin virus), Venezuelan hemorrhagic fever (Guanarito), Brazilian hemorrhagic fever virus (Sabia). The reservoir of such viruses are rodents, and the vector is unknown.
Rhabdoviridae
Last is the Rhabdoviridae family, which belongs to the Ebola virus and Marburg virus.
Ebola fever and Marburg disease are the most serious of all hemorrhagic fevers and also have the worst prognosis – from patients infected with Ebola die up to 90% and Marburg disease is 80%. For other hemorrhagic fever with case fatality rate is around 10-40%, but of course very much depends on the quality of medical care and medical facility, where only ensure adequate hydration, basic treatment and possibly early treatment can reduce mortality drastically.
Symptoms of hemorrhagic fevers
The course of the disease begins like other acute viral diseases. Once the virus enters the body, it begins to multiply and blood is drifting throughout the body. The period from penetration of the virus into the body is called the “incubation period” and is different according to the particular disease (varying from few days to three weeks). The initial symptoms are caused precisely the occurrence of viral particles in the blood (so-called. “Viremia”) and are similar to other severe viral diseases.This so-called. “Prodromal period” is characterized by high temperature, which is often accompanied by headache, myalgia, nausea, dizziness, feelings of fatigue. After this initial stage, the clinical picture continues to deteriorate, further develops symptoms already differently depending on the causative agent, thus depending on what organs or structures virus preferentially infects and how it is devastating.
Some temperatures leads to central nervous system, it manifests as meningitis and brain (so-called. “Meningoencephalitis”). The involvement of the gastrointestinal tract cause gastrointestinal symptoms such as nausea, vomiting and diarrhea. For some, the disease is characterized by liver damage, jaundice ever arises, may be affected in some cases heart.
The significance of each disease vary, the most severe haemorrhagic manifestations are present with fever Ebola and Marburg.
Generally occurs after the initial symptoms to develop more or less major bleeding complications, which can result in serious damage to internal organs, especially the liver and kidneys. Often, the virus attacks while also lining blood vessels (endothelium) and thereby contributes to the development of blood clotting disorders, which is called “disseminated intravascular coagulopathy.” Blood starts in blood vessels and capillaries uncontrolled coagulate (coagulate) and the resulting clots (thrombi) clog and stop the circulation. Simultaneously, depletion of clotting factors in the blood and their lack of blood vessels begin to leak vice versa. Develops bleeding and shock-like state, which further worsen the patient’s condition. If the disease reaches that stage, there is only a small probability that the patient will be able to save, there is a failure of vital organs and death.
Other manifestations are a certain type differs from this basic diagram disease.
Risk factors for hemorrhagic fevers
The risk is especially staying in an environment where these diseases occur and come into contact with infected animals or humans.
Causes of haemorrhagic fevers
The cause of the infection is insidious virus hemorrhagic fevers, mostly animal diseases that are transmitted to humans, so-called. Zoonoses.
Prevention of hemorrhagic fevers
Prevention is especially important in the case of travelers heading to tropical areas. We need to know where the place of occurrence of these diseases and, if possible, avoid them. It is also necessary to use protective equipment against mosquitoes, ticks and other vectors of potential. Efficient and reliable vaccination against yellow fever only against others unfortunately do not yet have an effective prophylaxis.
In our conditions do not constitute hemorrhagic fever too high risk, but the probability of their introduction is constantly increasing due to growing tourism as their occurrence is therefore necessary to calculate. Therefore, it should not be underestimated any febrile illness which arose after returning from abroad, the more the risk areas.
Treatment of hemorrhagic fevers
Options are effective treatments for hemorrhagic fevers is very limited. For some diseases is an effective antiviral drug ribavirin (for Arenavirových and Bunyavirových infections – see above).Virus family Flaviviridae and Rhabdoviridae, however, does not work.
In some cases it has been observed a positive effect of administration of immunoglobulins (antibodies).
The basis of treatment of hemorrhagic fevers but only supportive therapy, which seeks to maintain and promote basic life functions. Is to maintain the parameters of the internal environment, adequate hydration and maintenance of blood volume and supply the necessary ions. This is related to symptomatic treatment, and sometimes it is even necessary and artificial ventilation (breathing apparatus). Invasive procedures must be used very carefully, because there is a possibility of bleeding.
How do I help myself
Generally, it is necessary to ensure an adequate intake of fluids. When a high fever, it is possible to reduce the temperature by applying a cold compress to the underarms and bikini line. Any deterioration, it is necessary to consult with your doctor, because haemorrhagic fever can have serious consequences.
Complications hemorrhagic fevers
The most common complications are bleeding and the formation of disseminated intravascular coagulation (uncontrolled blood clotting inside the blood vessels). Develops state of shock and failing vital organs (ie. Multi-organ failure). The occurrence of these complications has been the patient often does not survive.
Other names: Haemorrhagic fever
