What do we know about Crimean-Congo hemorrhagic fever after its discovery in Salamanca?

An elderly man is stable in gravity thanks to Crimean-Congo hemorrhagic fever after a tick bite in the province of Salamanca.

Disease caused by a virus of the genus Nairovirus and family Bunyaviridae It causes high fever, muscle pain, weakness, bleeding and hepatitis, which can worsen to liver or kidney failure on the fifth day after symptoms appear.

Approximately 1 in 3 patients who become ill will die from the disease. Currently There is no vaccine or specific treatment for this virus.although there are several studies trying to understand its life cycle.

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The disease is endemic in Africa, south-eastern Europe and Asia, and cases do not usually occur beyond the 50° north parallel (located at approximately the height of the English Channel). However, due to rising global temperatures, changing bird migration patterns and animal transport, increasingly more regions have discovered a tick carrying the virus.

Presence data available Nairovirus in Spain since 2010, but only recently began trying to establish its presence on the peninsula. The Salamanca case brings together 12 patients whose symptoms have been observed in our country since 2013, when the first transmission of the virus to humans was confirmed in the province of Avila.

Ticks are the main carrier of infection

The disease is transmitted primarily through ticks. floor Gialomma, hematophagous (blood-feeding) parasites that are very common in wetlands and areas of high vegetation. To minimize the risk of being bitten by these arthropods, experts point out the importance of following marked trails, but if contact with grass cannot be avoided, they recommend covering your skin as much as possible. For this reason, it is recommended to wear boots and high socks, long pants and long-sleeved shirts, among other things.

In a hypothetical case of skin contact, it usually takes 24 to 48 hours for a tick to begin feeding. For this reason, it is good practice to check limbs, groin and hair after walking in the countryside. Also recommended check pets and put anti-parasitic collars on them. If any of these arthropods are found, it is ideal to try to remove them with your fingers or tweezers, slowly pulling in the direction of the arthropod’s body and avoiding crushing it.

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This reduces the chance of part of the tick embedding itself in the skin, which can lead to medical complications. After this it is important watch for redness in this area and symptoms compatible with any of the tick-borne diseases, especially heat.

The National Institute of Agricultural and Food Research and Technology is currently conducting Gares project, in which they ask citizens and professionals to collaborate to report the different types of ticks present in Spain. To date, they have managed to create a much more comprehensive map than the Europeans, with the 6 most common tick species in the country. It also identifies the possible diseases that each species transmits to humans.

Besides the virus Crimean-Congo hemorrhagic feverTicks also act as carriers of other viruses, bacteria and parasites. For this reason, health authorities are concerned about the increase in cases in Spain of other tick-borne diseases, such as Lyme disease or rickettsiosis, which are caused by bacteria.

What do we know about the Crimean-Congo hemorrhagic fever virus?

Nairovirus These are spherical viruses covered with a lipid envelope. In the specific case of Crimean-Congo hemorrhagic fever orthonairovirus, its genetic material is encoded by RNA and has an average size of 19,000 nitrogen bases. This RNA can be divided into three segments. depending on size: small (S) and medium (M), responsible for the production of viral envelope proteins, and large (L), where the replication mechanism is encoded.

These are viruses with a high mutation rate, so although 7 options are knownDifferent strains can exist in the same region. In Spain, for example, there are at least 3 known variants of tick infestation that can be transmitted to humans. Once the virus enters the bloodstream through a tick bite or contact with infected fluids, it manages to penetrate the plasma membrane of cells and hijack their replication machinery to reproduce.

The full mechanism remains unknown, but the most recent studies indicate that the route of its entry into the cell depends on clathrin, a protein responsible for the formation of vesicles. That is, the virus “deceives” this mechanism by introducing it inside the cell. Once inside, the virus multiplies its genetic material and converts it into RNA recognized by the host cell using its own enzyme called viral RNA-dependent RNA polymerase.

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Once the process is complete, multiple copies of the viral RNA will be transferred to the cell’s ribosomes, which will create different parts of the virus using cellular resources. The infected cell will assemble parts using its Golgi apparatus to create immature virions and once complete, it injects RNA from inside each virion to form the complete virus and force it out, where Each new virus infects a new cell.

What’s next?

Spain is not the only country at risk of spreading the disease. Recent epidemiological studies show that up to 10% of livestock in Corsica could be infected with the virus

and in countries such as Afghanistan, about 500 human cases are reported annually.

As temperatures rise, mites may continue to expand and colonize new areas, so it is important to study their presence and implement surveillance systems which make it possible to detect the disease in wild or stable fauna. In this way, it is also possible to identify areas in which the virus is already present, but has not yet been detected because monitoring is not carried out.

Another important point is to study the mechanisms of action of the virus in order to develop effective treatment. Now his research is not without complications Because, due to its virulence and the possibility of transmission to humans, the Crimean-Congo hemorrhagic fever virus could only be studied in a laboratory with biosafety level 4, the maximum possible.