Although locally acquired malaria cases were recently discovered in the United States for the first time in 20 years, infectious disease experts say they do not signal imminent danger but instead are an indicator that the number of cases of diseases transmitted by mosquitoes to humans will likely increase in the coming decades.
“It’s a warning sign for ensuring that there are good public health interventions in place, good mosquito surveillance in place, and that people are just aware that this could be a growing problem,” said Jackie Cook, associate professor of malaria epidemiology at the London School of Hygiene & Tropical Medicine.
Earlier this month, a handful of malaria cases cropped up in Florida and Texas. The Florida department of health reported that there were two locally acquired malaria cases in Sarasota county, following two other locally acquired malaria cases that were reported in the state earlier this year. In Texas, a single resident “who spent time working outdoors in Cameron county” was diagnosed with malaria.
These cases are particularly significant because the patients were infected with the disease locally, rather than becoming sick after traveling to places where the disease is endemic, such as sub-Saharan Africa. The last time there were cases identified in the United States in which people acquired malaria locally was in 2003.
Now, experts project an increase in mosquito-borne disease cases because of warming global temperatures.
Malaria is a potentially fatal disease transmitted through the bite of an infected mosquito. Symptoms include fever, shaking, chills, headache, muscle aches and tiredness, according to the CDC.
People who traveled to an area where malaria occurred and are experiencing such symptoms should seek medical care and tell the healthcare provider where they traveled.
The Centers for Disease Control and Prevention issued a health advisory on Monday stating that the Florida and Texas cases could mean a rise in imported malaria cases due to international summer travel.
There are effective treatments against malaria – “as long as you get them promptly”, Cook said.
“If you don’t get treated, that’s when you get the much more severe symptoms. That’s when you can end up with respiratory failure, kidney failure and coma.”
It’s also important that people take measures to protect themselves from mosquitoes, Cook said. Precautions include wearing insect repellent, lighting citronella candles and installing window screens to prevent mosquitoes flying indoors.
“Public health officials need to get everyone attuned to the reality that they should be using mosquito control, which means that if they are going to be outdoors,” especially at dawn and dusk, because the mosquitoes that can transmit malaria tend to bite then, “they absolutely need to be wearing mosquito repellent”, said Dr Aileen Marty, an infectious disease expert at Florida International University.
The public can also expect mosquitoes to transmit malaria more easily in the future for the same reason that wildfires are worsening across the United States: the climate crisis, according to climate and disease experts.
The warming temperatures and increased rainfall mean that there will be more mosquito breeding sites, Cook said. Mosquitoes will also be able to breed faster and feed more, “so they bite more people” and have “more chances to spread the infection”.
“The prediction from climate change scientists is that we are going to see this greater spread of vector-borne diseases in places where we have previously eliminated [them],” Cook said.
She suggested that public health officials take steps such as fogging (spraying small amounts of insecticide into the air to kill mosquitoes), draining standing water and educating people on how they can protect themselves from mosquitoes.
In spite of the projected increase in malaria cases, Marty and Cook both said the Texas and Florida cases are not cause for panic.
“It’s cause for knowledge,” Marty said. “It’s cause for appropriate behavior to reduce risk.”