A new human case of West Nile Virus confirmed Friday brings this year’s total to nine in Louisiana, the state Department of Health and Hospitals is reporting.

The newest case is from Calcasieu Parish and is the most-severe form of the virus, which can cause swelling of the brain or spinal cord.

The West Nile virus is transmitted through mosquito bites.

According to DHH, health officials put West Nile infections into three categories: neuroinvasive, West Nile fever and asymptomatic.

A neuroinvasive illness is severe and typically results in a swelling of the brain or spinal cord. People with this illness are at risk of brain damage or death.

West Nile fever is less severe, with most people only suffering mild, flu-like symptoms.

Asymptomatic individuals were never ill and were only discovered to have the West Nile virus in their blood when blood work was done for some other reason, such as blood donation.

So far this year, Louisiana has confirmed four neuroinvasive, three West Nile fever and two asymptomatic cases.

About 90 percent of all cases are asymptomatic, while about 10 percent will develop West Nile fever.

Only a very small number of infected individuals will show the serious symptoms associated with the neuroinvasive disease.