In case we had little problem with the coronavirus pandemic, several people in Seville have tested positive for the West Nile virus (WNV). The cause would be in the mosquito bite that is infected with the virus and, although not much is known about its transmission, we want to analyze the symptoms and the severity that it can cause in the population.
How are human beings infected?
WNV disease was first identified in a woman from the West Nile district of Uganda in East Africa in 1939. Since then, it has spread throughout the world, being described for the first time in the US in 1999. This is a flavivirus, from the same family as that of dengue (common disease in tropical countries) and Zika (which was talked about a lot 4 years ago, due to the outbreak in Ibero-America) and related to that of hepatitis C.
The main carriers of this virus are birds , and their migratory movements allow it to spread from one area to another. Domestic animals can acquire the infection, being the horse where more symptomatic cases occur.
WNV is transmitted to man when a Culex, Aedes, or Mansonia mosquito (not just any breed) bites an infected animal and then a person. Mosquitoes carry the largest amounts of West Nile virus between August and October , so disease cases are more common at this time.
The risk of suffering from it decreases as the weather gets colder and the mosquitoes begin to die out. In the last decade there have been few cases of WNV disease in Andalusia, although in the last month more than 18 people have reported cases of meningoencephalitis.
Is it a highly contagious virus?
Despite the possible alarm due to mosquito bites, 80% of human infections are asymptomatic and unnoticed. They can only be diagnosed by the presence of antibodies in a blood test. If there are symptoms, they are fever, headache, muscle aches, and sometimes patches on the skin spread throughout the body.
Experts assure that in 0.70% of cases there is neuroinvasive disease , with meningoencephalitis (lethargy, behavioral disturbances, muscle leaps, seizures) and / or flaccid paralysis of limbs due to spinal cord injury.
In other words, if the 18 cases of meningoencephalitis that have been reported to the Andalusian Regional Government Health Department were caused by the West Nile virus, at least several hundred / thousand people would have been infected without knowledge.
Logically, the people most at risk of contracting the disease are those who live in outbreak areas and where there are transmitting mosquitoes, such as in the Seville Marsh . Furthermore, risk groups (older adults and immunocompromised people) are the most affected.
How is West Nile Virus diagnosed?
The diagnosis can be made by serology (blood test), but it can give false positives as with any virus. For this reason, PCR should also be performed in blood , which is positive in the fever phase, and in cerebrospinal fluid , although there may be false negatives.
Unfortunately, there is currently no specific treatment or vaccine for this disease. So there are only supportive treatments until the disease is eliminated on its own.
Of course, any anti-mosquito prevention measure will go a long way toward avoiding bites. These include: mosquito nets, repellants for mosquitoes, long clothing (especially at dusk and dawn) in outbreak areas and avoid areas of still water (ponds, cans, pot plates, etc).
