As the summer season begins, which mosquito borne illness poses a more serious threat: Zika or West Nile virus?

Most experts believe the answer is not clear cut.

West Nile has been in the Garden State for more than a decade. Now health officials fear Zika virus could emerge and spread here as well.

Previously it was believed mosquitoes carrying Zika were only found in southern parts of the United States. But last month the Centers for Disease Control and Prevention announced scientists now believe two species of mosquito found in New Jersey may also carry Zika — Aedes aedgypti and Aedes albopictus.

According to Ted Louie, an infectious disease expert with the Medical Society of New Jersey, affiliated with Robert Wood Johnson University Hospital and Saint Peter’s University Hospital and Highland Park Medical, both West Nile and Zika virus pose serious threats.

“The majority of people who get West Nile are not terribly symptomatic. You may get a little bit of a flu-like illness or you may not even know you have it and it will just pass. But sometimes you can get what we call encephalitis, which is you can get very confused, headache, fever and often people can get paralyzed as well, they can’t move their legs,” he said.

West Nile can also be deadly.

West Nile Virus deaths in New Jersey from 2011-2015:
Cases                                 Fatalities
2011                            7                                        0
2012                          48                                        6
2013                          13                                        2
2014                           8                                         0
2015                         26                                         3

Zika can affect the fetus.

"The worst possible scenario is the fetus getting what we call microcephaly, which is the brain is not as big as it should be.”

He said extreme illness or death is possible with Zika but it’s very rare.

“If you’re extremely elderly, if you’re extremely young or have some problem with your immune system, it’s always possible to have a very bad illness from a relatively benign virus,” he said.

Louie added it is possible to get West Nile from a mosquito, or from an infected bird, so “tell your kids if there’s a dead bird in the backyard, a dead crow, don’t go near it. You’ll have to be very careful disposing of it and assume the bird is contagious.”

New Jersey is one of just a handful of states with the capacity to test residents’ blood samples for Zika.

Last month the state Health Department announced their labs have started testing blood samples for Zika and other mosquito-transmitted viruses.