Mississippi ranks fifth for West Nile virus cases in the U.S. for 2024, with four known deaths. The deaths have involved people with severe preexisting health conditions, the Mississippi State Department of Health confirmed to the Mississippi Free Press on Oct. 2. At least 45 Mississippians have contracted West Nile this year, MSDH reports.
West Nile cases are slightly higher in Mississippi this year compared to last year partially because of the drought the state endured in August, Mississippi State University entomologist and extension professor Dr. Jerome Goddard told the Mississippi Free Press.
Having dry weather means standing water is thick, “soupy” and full of “organic material” like grass and dirt, in which mosquitoes like to lay their eggs, he said on Sept. 11. Ditches and malfunctioning septic tanks and sewer pipes can become breeding grounds for mosquitoes along with old tires and buckets, the entomologist added.
“So when it’s dry, there’s more West Nile than when it’s wet. If it rains a lot, you have less West Nile,” Goddard said.
Mississippi State Health Officer Dr. Daniel Edney said the Mississippi Gulf Coast and areas around the Mississippi River are seeing higher numbers of mosquitoes this time of year. West Nile virus and Eastern Equine Encephalitis are at their peaks in late summer and early fall, about July through October, he said. Goddard said most mosquitoes die in the winter because they are cold-blooded, meaning they need to get warm from the sun to survive.
“Say it’s March and it’s been a warm winter, people will ask me, ‘Well doesn’t that mean there’s going to be more mosquitoes or worse mosquitoes this summer?’ Well, you don’t know. Nobody knows. It’s not just the winter, it’s the onset of spring and then the pattern of the rains,” he said.
Contracting and Spreading Diseases
The state health officer said people with mosquito-borne illnesses cannot spread them to one another or to animals, but mosquitoes could ingest a person’s infected blood and pass the disease to another person or animal.
Most people who get West Nile have many mosquito bites, not just one or two, Edney added.
“All of us are going to have the occasional mosquito bite, it’s just we don’t want multiple bites in a short amount of time. It increases the risk,” he told the Mississippi Free Press on Aug. 30.
While it is more difficult for mosquitoes to bite animals with fur, the state health officer said dogs and cats could still get bites and be infected with West Nile or other mosquito-borne illnesses, but it is rare. State Veterinarian Dr. Jim Watson said mosquitoes almost exclusively bite and infect horses, mules and donkeys with Eastern Equine Encephalitis.
EEE also lives in wild birds, and mosquitoes can contract the disease from feeding on infected birds, the state veterinarian said. He said horse owners should vaccinate their animals against EEE annually to protect them from contracting the disease.
Edney said Mississippi is not currently screening for EEE because the disease is not highly prevalent in the state and because the Mississippi State Department of Health does not have enough funding to add EEE to its screening list. Watson said the state’s first case this year was in Lincoln County in early September.
Dr. Jerome Goddard said mosquitoes can contract diseases like West Nile from feeding on the blood of an infected animal—dead birds especially carry risks of West Nile. When a mosquito feeds on a dead bird and then bites a human, the human could get West Nile. Edney warned people not to touch dead birds with their bare hands to avoid spreading diseases.
But not all mosquito-borne illnesses are contracted through birds. Goddard said mosquitoes contract dengue fever, the Zika virus and malaria from humans and spread it to other humans.
“You can’t just say for all mosquito diseases that it’s birds,” he said. “You can’t say that because for some of those diseases, it’s a small mammal like a chipmunk. And for things like dengue fever or malaria, it’s a human; the human is the host. So it varies by disease.”
Female mosquitoes could also infect their offspring if they have a disease while breeding. If they are not born with a disease, Goddard said most infected mosquitoes contract an illness from their first blood meal. Once a mosquito contracts a disease, the entomologist said he assumes that the insect stays infected for the rest of its life, which is about two to three weeks.
“It’s not every day. It might be a few days or a week before they feed again. That’s when they would transmit it,” Goddard said, adding that mosquitoes are only able to feed on a couple of people or animals in their short lifespan.
Male mosquitoes do not drink blood and instead get their nutrition from plant nectar. Female mosquitoes drink blood to get protein to lay their eggs but may eat plant nectar occasionally.
Symptoms and Treatment for Mosquito-Borne Illnesses
West Nile and Zika are in the same family of viruses and cause similar symptoms like headaches, muscle aches and fatigue. West Nile can also cause serious neurological problems that could make a person or animal feel dizzy and unbalanced.
“Never ignore fever and a bad headache,” Dr. Daniel Edney warned.
Eastern Equine Encephalitis affects horses, donkeys and mules and is “almost 100% fatal,” Dr. Jim Watson said. West Nile virus infections do not cause many animal deaths, though, he added. Animals with mosquito-borne illnesses will sometimes experience neurological issues and stagger due to a loss of balance, he said.
“With West Nile virus in particular, not every horse that gets the disease gets sick,” the state veterinarian told the Mississippi Free Press on Sept. 11. “It’s like people: Not everybody that gets infected with West Nile virus gets sick.”
Dr. Jerome Goddard said that many people who have had West Nile are asymptomatic and never knew they had the disease, meaning case numbers could be significantly higher than the health department reports. Edney said many people who have mild forms of the disease never seek treatment and heal on their own.
While many people who have West Nile recover from the disease, Edney said it could be fatal if it causes neurological damage. Those with more severe symptoms may go to the doctor and get bloodwork done to check for West Nile. Watson said animals also need to get bloodwork done to detect West Nile and EEE. If a horse has EEE, he said the vet may need to humanely euthanize the animal to prevent pain and suffering.
“It’s important to know which disease we’re dealing with so that we can determine whether to try to treat them and keep them comfortable until they recover or whether it’s a fatal disease where the most humane thing to do is to go ahead and humanely euthanize them so they don’t suffer,” the state veterinarian said.
Edney said a doctor cannot tell for certain whether a patient has West Nile unless the doctor tests blood samples. While there’s not a one-size-fits-all treatment for West Nile, he said most doctors work to treat the patients’ symptoms while advising them to stay indoors, rest and keep cool. Staying indoors is crucial to avoiding additional mosquito bites, he said.
“What we really worry about with West Nile is developing chronic neurological issues like chronic weakness or unilateral weakened state, which we call hemiparesis, where the arm and leg on one side become weaker than the other side not in the form of a stroke,” the state health officer said.
Eradicating Mosquito-Borne Illnesses
Dr. Edney remarked on the progressions science, health and medicine have made since the early 1900s, when yellow fever was on the rise. Mississippi eradicated yellow fever and malaria by killing the mosquito populations that spread the diseases, he said.
“We’ve got mosquito populations under control,” the state health officer said. “We got rid of all the bad mosquito-borne diseases, but they’re trying to make a comeback. It’s not anything to alarm folks, but it is a reason to talk to your boards of supervisors and your city officials about spraying for mosquitoes and keeping the mosquito population in your community in control.”
His top tip for avoiding mosquito bites is to avoid or limit time spent outdoors at night, and if someone needs to be outside, use bug spray or wear long sleeves and pants. Homeowners and landlords should spray bushes and landscaping with insecticide to draw out mosquitoes and inspect their land for standing water, especially in old tires and buckets. Freshen water in birdbaths and animal troughs daily to prevent mosquitoes from breeding, he said.
Goddard said mosquitoes like to breed in thick, murky water—not clean, clear water. Dr. Jim Watson said mosquitoes do not usually like to breed in animal troughs because their water is fresh and constantly being used. Ponds and streams also don’t attract mosquitoes for similar reasons, he added.
Goddard said MSU recommends home and property owners use larvicide to kill mosquito offspring before they leave the water their mother hatched them in.
Spraying for mosquitoes, which kills the adult pests, also works, but the entomologist said larvicide is more effective. But he said the mosquito spray kills other insects besides mosquitoes, which could be harmful for the natural environment. Mosquitoes can also become resistant to the spray the more it is used, he added.
Edney pointed to cases of endemic malaria and dengue fever popping up in Texas and said the health department is being watchful for other mosquito-borne illnesses that could enter Mississippi.
“We all need to take mosquito bites seriously. We’re all Mississippians and we’re all going to be mosquito bitten … We do need to try to prevent it and do the things that folks in Mississippi do this time of year,” he said.
