LOS ANGELES (CNS) — Angelenos should expect West Nile virus to be an annual threat and this year’s El Nino could increase the number of cases in 2016, a county health official said.

The high number of cases seen over the last three years makes it likely that the danger is here to stay, Dr. Benjamin Schwartz of the county’s Acute Communicable Disease Control group told the Board of Supervisors on Tuesday. Oct. 27.

“Everybody should take precautions,” Schwartz told the board.

However, he noted that some areas seem to be at higher risk than others, including the eastern San Gabriel Valley, the San Fernando Valley and southeast Los Angeles County near Whittier and Bellflower.

There were 218 incidences of infection and seven deaths in 2014, followed by 110 infections and eight deaths this year as of Oct. 22, Schwartz said. Those numbers do not include Long Beach and Pasadena, which have their own health departments.

“We just had another death in the Antelope Valley,” Supervisor Michael Antonovich said.

The first case in Los Angeles County was seen in 2003 and the first death was reported in 2004.

The rising number of infections is probably due to a complex set of factors that could include changes in the climate and changes in the die-off of birds who carry the disease, Schwartz said.

The incidences of infection tend to peak in September or early October, according to a health department report.

This year’s expected El Nino may make things worse next year. More rain and higher temperatures could allow mosquitoes that spread the disease from birds to humans to better survive the winter and breed more aggressively next spring.

Though deaths are rare and typically involve patients who are already vulnerable, the virus can also cause paralysis, encephalitis and meningitis.

The most effective way to prevent the spread of the virus is by reducing mosquito breeding sites and using pesticides to kill off the pests.

Getting residents to wear protective clothing and use insect repellent, particularly during the hours of dawn and dusk, can also be effective, but difficult to encourage in hot weather.

Two new species of mosquito have also raised concerns about the possibility of spreading dengue fever and Chikungunya.

One of the species, colloquially referred to as the Asian Tiger Mosquito, was first found in El Monte but has now spread to 17 cities.

“Currently, these (particular) mosquitoes are just a nuisance,” Schwartz said, but the county is closely monitoring any possible links to the spread of disease.