When the social alarm about an outbreak such as that of the West Nile virus is turned off, which in 2020 claimed eight deaths and 71 infected in Andalusia (and six in other communities, according to José Miguel Cisneros, director of the infectious diseases unit of the Hospital Virgen del Rocío de Sevilla), only the pain for the dead and the aftermath of the sick remain. To alleviate this discomfort, clinical experts are now investigating, a year and a half later, how those affected react to the pathogen and thus face the next outbreaks with better clinical weapons.
Among the people bitten by a mosquito Culex perexiguus and were affected by meningoencephalitis – 1% of the total – there are children, adolescents and adults with cognitive and motor problems, including quadriplegia and serious neurological problems. “My five-year-old son suffers from endogyrism [marcha con los pies hacia dentro] in the left leg, muscle weakness and, above all, loss of motor skills, although he has been recovering them ”, says hopefully Israel Espinosa, a resident of Coria del Río, a town on the banks of the Guadalquivir river very close to Seville and where the outbreak arose.
The Nile virus travels thanks to migratory birds, bitten by mosquitoes, which later transmit it to horses and people through new bites. In the spring of 2020, confinement, heavy rains and uncontrolled stagnant waters multiplied mosquitoes in the riverside towns near Doñana and unleashed the outbreak – the largest in Spain after five isolated cases in 2010 and 2016.
Last summer, infections were reduced to one deceased person and six infected, but it was evidenced that the virus is here to stay. The available vaccine only protects horses, and development of antivirals or immunizations for humans is pending. In the United States, the virus is the leading cause of meningoencephalitis and as of 2015 45,000 infections had been reported.
While the attack of the virus in adults and its effects are clear, there are gaps in the reaction of infected children. Of the six minors who became ill in Andalusia, only two still have serious sequelae, and one only now begins to recognize his parents and try to verbalize and eat. A team from the Virgen del Rocío Hospital, which has treated the vast majority of those infected, led by the head of pediatric infectious diseases Olaf Neth, has studied the prevalence of the virus in children after taking blood samples from 209 minors of the total of 5,176 who live in Coria del Río. Only three (1.5%) were infected, when the percentage in adults is around 5%, according to experts.
In parallel, the Sevillian pediatric team completed by doctors Inés Marín, Marta Aboza and Dolores Falcón wants to find out, in collaboration with the Necker Hospital in Paris, if the six children who developed severe symptoms had failures in their immune system. “We have to understand why they have suffered symptoms. It could be bad luck, but I don’t believe in it, that’s why we look for why one child gets infected and another doesn’t, and why some develop symptoms and others don’t ”, summarizes Neth. The initial thesis is that the risk of developing meningoencephalitis in children is much higher from infection with the Nile virus than from other pathogens. The researchers also seek to develop a European-wide registry with children affected by this pathogen to prevent future infections and develop supportive treatments.
As a lesson learned, Cisneros emphasizes that meningoencephalitis caused by this virus should be taken into account especially for clinical diagnosis during the summer months and that physicians should be aware that hospitalized patients “are the tip of the iceberg.” “If we advance the clinical suspicion to the fever phase, we could advance the health alert. The diagnostic protocol was useful, but we continue with the need for the training of infectious disease doctors. The listeria virus, the West Nile virus and the coronavirus have given us a lesson in humility by stopping the world and showing that with globalization no one is safe, something that requires very well-trained doctors. It is an anachrony that Spaniards are not cared for by specialists when they have serious infections, it is a hole in the system “, recalls Cisneros, former president of the Spanish Society of Infectious Diseases and Clinical Microbiology, a specialty that does not exist in the MIR system.
Meningoencephalitis (involvement of the brain and meninges) has a high mortality rate of around 9% and serious sequelae also in more than 10% of patients. And it is so harmful because the response of the human body is inflammation, and since it is the brain, it collides with the rigid structure of the skull and damages neurons, the most sensitive cells of the body.
The inflammation of the meninges and the damage caused by the virus leave very serious sequelae. “The complete recovery of patients is very difficult. Sometimes spasticity, painful spasms, and seizures appear. Memory, attention, language difficulties are treated with neuropsychology and specific exercises ”, explains Soledad Pérez, a neurologist at the Virgen de Macarena Hospital in Seville. Patients spend long stays in the hospital, lasting several months, but the Andalusian Health Service does not include in its portfolio the neuropsychological treatment necessary to recover from brain damage. “Most patients feel incredulous and wonder ‘How could it happen to me and how could something as small as a mosquito have made me so sick?” Adds Pérez.
After being admitted to hospital, Espinosa’s family moved with other relatives for a while due to the initial panic of the mosquito and now they do not leave home without repellents. This Coria neighbor formed a platform together with others affected to try to make local and regional authorities aware of the relevance of the virus. “I no longer see the mosquito as before, I no longer worry about the stinging of the bite, but I see it as a transmitter of diseases,” he concludes.
The impact was reduced in 2021
After the serious outbreak of 2020 and after years ignoring the warnings of the CSIC scientists, the Board created a virus surveillance and control program Last spring, more than 40 municipalities of Seville, Huelva and Cádiz with medium-high risk developed plans to kill mosquito larvae, which act as vectors for adults in the summer season. “It is necessary to reinforce preventive treatments and improve the training of companies that do control based on specific larvicides”, says Jordi Figuerola, researcher specialized in field ecology and dynamics of transmission of infectious diseases through mosquitoes at the Biological Station of Doñana (CSIC). “Because if you have them already flying, you must use other products that harm other insects and have less effectiveness and greater environmental impact,” he warns. The mosquitoes do not reach the Andalusian capital because their radius of action is usually restricted to about five kilometers, according to experts.
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