The case dates back to July when a 70-year-old man started showing signs of the virus.
As news broke of the “probable case” health officials urged local authorities and the population in general to take preventative measures against mosquitoes.
A note published on the website of the National Health Board (DGS) this week states that neutralisation tests, which are specific for viral identification, carried out by the Dr. Ricardo Jorge National Health Institute, “have confirmed the presence of the [West Nile] virus in the samples gathered.”
“These results do not alter the previous situation, but confirm the cause of the infection”, the DGS explained, stressing that the preventative measures adopted at the time remain in place and that the institutions involved will continue to monitor the situation.
At the time health officials said that infection was “unlikely”, as the virus is only transmitted after a series of bites.
Nonetheless the episode led the DGS to recommend that authorities reinforce their mosquito-fighting mechanisms as well as telling the population to reduce body exposure to the pest, by using repellents and nets.
Regional health authorities also stepped up their fight against mosquito larvae, particularly in water tanks with organic materials.
The man who was infected with the virus has in the meantime been released from hospital and has not suffered any further issues.
The West Nile virus is not transmitted from person-to-person but via bites from the Culex mosquito, which in 20 percent of infections can cause a feverish disease which has light clinical manifestations and only rarely evolves into viral meningitis.
The virus is found in temperate and tropical regions of the world and was first identified in the West Nile sub-region in the East African nation of Uganda in 1937.