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

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, according to DHH.

The West Nile virus is transmitted through mosquito bites.

Health officials put West Nile infections into three categories: neuro-invasive, West Nile fever and asymptomatic.

A neuro-invasive illness 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 when blood work was done for some other reason, such as blood donation.

So far this year, Louisiana has confirmed four neuro-invasive cases, three West Nile fever cases 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 neuro-invasive disease.