The new reported West Nile case is in Rankin County. Earlier, health officials reported cases in Newton and Hinds counties.
The state health department only reports laboratory-confirmed cases to the public. In 2013, Mississippi had 45 West Nile cases and five deaths.
State Epidemiologist Dr. Thomas Dobbs says the second case is a reminder of the importance of preventing mosquito exposures, particularly ahead of the active summer months.
In 2012, Mississippi had 247 West Nile cases and five deaths.
Health officials say in a news release the newest case of chikungunya occurred in a resident who recently returned from the Dominican Republic.
The four cases previously reported occurred in travelers to Haiti and the Dominican Republic.
Symptoms include fever, muscle and joint pain and joint swelling. Deaths are rare, but officials say anyone with a compromised immune system is at a higher risk of complications from the infection.
Officials say the virus recently appeared in the Caribbean, and could possibly infect Mississippians who travel there.
Health officials say individuals who think they might be infected with chikungunya virus should see their health care provider.