[West Nile virus infection].

The research discusses West Nile virus (WNV) – a mosquito-transmitted virus that primarily infects birds but can also affect humans and horses. It mostly manifests as a febrile illness in humans and can occasionally cause more serious neurological infections. Spain, with its climate and the presence of migratory birds from virus-endemic Africa, is considered a high-risk area for the spread of this virus.

Understanding West Nile Virus (WNV)

• West Nile virus is an arbovirus, spread primarily by mosquitoes. The main hosts for this virus are birds, but it can also infect a range of vertebrate species, such as horses and humans.
• About 80% of human cases of this virus are asymptomatic – that is, they do not show symptoms. When symptoms do occur, the most common manifestation is a fever. In less than 1% of cases, the virus can cause severe neurological damage.

The Risk in Spain

• Spain is considered a high-risk area for WNV due in part to its climate and the presence of migratory birds from Africa, where the virus is endemic, meaning that it is regularly found among particular people or in a certain area. These migratory birds nest around wetlands populated with species that can act as vectors for the virus.

Diagnosing West Nile Virus Infections

• Diagnosis of serious WNV infections can be achieved through the detection of IgM in serum and/or cerebrospinal fluid samples. Another method involves demonstrating a four-fold increase in IgG antibodies between the acute and convalescent phase of infection.
• PCR testing, which involves detecting the viral genome through a method called reverse transcription-polymerase chain reaction, can also be useful, particularly in transplant recipients.
• As WNV is a biosafety level 3 virus, procedures involving cell cultures should be carried out in laboratories certified for that level of biosafety, such as reference laboratories.

Surveillance and Detection Measures

• The National Program for the Surveillance of WNV Encephalitis in Spain helps detect virus circulation among birds and vectors in high-risk areas, particularly wetlands. This surveillance provides valuable data to evaluate the risk of disease in horses and humans and to take appropriate preventive measures.