Bug-Borne Disease Worries

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By Mary Carpenter

SYMPTOMS that stumped doctors treating Philadelphia artist C.J.— sudden, severe intestinal problems that kept him in bed for several weeks and, for almost six months, unable to work and needing to be near a bathroom—became easier to diagnose once he mentioned having traveled to Corsica about four months earlier.

Despite her medical training, Ann Arbor, Michigan occupational medicine physician Deborah Heaney had no clues to explain intense itching over her entire body, red blood spots spreading across her torso and diarrhea that left her severely dehydrated, according to AAMCNews from the Association of American Medical Colleges. Finally, the link of symptoms to a recent vacation on Curaçao led to the diagnosis of dengue fever.

“Our medical systems are not adequately equipped to diagnose tropical diseases, and in a warming climate, that’s a problem,” according to the New York Times headline for Heaney’s report. Such cases also highlight patients’ travel history as a glaring omission in medical records. Even when both incidence of infection and likelihood of serious symptoms are low, vector-borne diseases (VBDs) can be devastating and deadly: for 21 people who recently traveled to Cuba, oropouche, also called “sloth fever”— spread by midges and mosquitos —caused severe illness, infection linked to malformations in fetuses and several deaths.

And closer to home, diagnoses of unfamiliar VBDs—including dengue, West Nile and Rocky Mountain spotted fever — are occurring at unexpected times of the year and “expanding into areas of the country where people have little experience with them,” according to AAMSNews. Said medical biosafety researcher Susan McClelland at the University of Texas in Galveston, “Awareness is low because the incidence is low [but] that’s changing” —for reasons that include climate change.

For infectious disease specialist Anthony Fauci, West Nile virus—that “hit him like a truck,” he said, and led to hospitalization—came from a mosquito in his backyard. And in New York, according to NBCNewYork, trapping and testing in 50 locations found “the number of mosquitoes with West Nile. . . up across the board thus far in Summer 2024 throughout the five boroughs.”

“The high-risk season for West Nile virus is just getting underway,” WebMD reported at the end of August.  While only about 20% of infected people develop symptoms—fever, headache, body aches, vomiting, diarrhea, and rash —“serious and potentially fatal illness affects about 1 in 150.”

In 2022, 1,247 reported arbovirus (arthropodborne virus) infections—most often spread by mosquitos and ticks —led to 968 hospitalizations and 103 deaths. In addition, just one mosquito, tick or other insect that bites someone with an active infection— whether acquired via travel or locally—can spread the disease. A single case of Triple E, eastern equine encephalitis, that killed one man in August caused such a scare that four Massachusetts towns imposed early curfews to avoid the deadly peak hours of dusk for virus-carrying mosquitos.

“It’s time to add travel history to routine information such as temperature and blood pressure collected in electronic medical records,” infectious disease researchers at the University of Texas Southwestern Medical Center wrote in 2020. “We have the infrastructure to do this easily with the electronic medical record, we just need to implement it in a way to make it useful to the care teams . . . we’ll also need to communicate what is called ‘situational awareness’ to ensure that providers know what geographic areas have infections so that they can act accordingly.”

An important reason to add travel history is that treatments vary widely among VBDs. “For example, while Lyme can be treated with antibiotics, the main medical response to dengue is supportive care to reduce certain symptoms, such as pain and so-called ‘break-bone fever,’” according to AAMCNews. “One common misstep for doctors is to pump dengue patients with fluids, because they seem to be suffering from the kind of dehydration that is common with many viral illnesses.”

“Most people who die of dengue die because of shock,”Puerto Rican pediatric infectious disease specialist Ines Esquilín-Rivera told AAMCNews. Hydration has to be administered especially carefully because dengue patients often suffer from capillary leak syndrome, in which fluids leak from small blood vessels, that can lead to low blood pressure and cause shock. Symptoms of dengue include muscle and joint pain along with fever, headache and nausea.

After extensive tests—ultrasound, stool exams and dozens of others—C.J.’s treatment included anti-parasitic drugs for suspected fasciolosis, which has showed “significant increase from the late 1990s to early 2000s,” according to a 2023 report from French researchers titled “Fasciolosis in the Mediterranean Island of Corsica (France).”  “Among the re-emergent human parasitic infections, fasciolosis stands out as one of the most important snail-borne diseases” —with an incubation period of several days to a few months; and spread via contaminated water, either from drinking or eating vegetables washed or irrigated with contaminated water.

Reading about Fauci’s local West Nile infection has made me worry more about mosquitos. “Biting insects seem to be everywhere in the Washington region [and] the typical season runs from July through September,” reported the Washington Post at the end of August—also warning that “risk for serious disease…begins to increase at age 50.” The Post’s experts recommend staying indoors at dusk, wearing long sleeves and pants when outdoors, and treating bare skin and clothing with repellants such as DEET.   For me, turning on a little Thermocell Radius Zone mosquito-repeller device has worked so far—but I remain vigilant and plan on adding counter measures if I see more than one bug flying around.

—Mary Carpenter regularly reports on topical subjects in health and medicine.