July 26 (UPI) -- Officials at the National Institutes of Health, alarmed by increasing tickborne infections in the United States, are urging improved diagnostics and preventive vaccines development.
In commentary published Wednesday in the New England Journal of Medicine, researchers from the National Institute of Allergy and Infectious Diseases, which is part of NIH, also urged public health officials and scientists to build a robust understanding of pathogenesis.
"The burden of tickborne diseases seems likely to continue to grow substantially," the authors wrote. "Prevention and management are hampered by suboptimal diagnostics, lack of treatment options for emerging viruses and a paucity of vaccines. If public health and biomedical research professionals accelerate their efforts to address this threat, we may be able to fill these gaps."
In the meantime, they said patients should use insect repellent and wear long pants when walking in the woods or tending their gardens. They also should check themselves for ticks afterward.
Most tickborne diseases in the United States are caused by bacteria. Lyme disease represents 82 percent of reported cases.
Most cases of Lyme disease are successfully treated with antibiotics, but 10 percent to 20 percent of patients report lingering symptoms after effective treatment. The ixodes scapularis tick is the primary cause of Lyme disease in North America.
The authors noted spirochete transmission patterns are geographically influenced, involving small-mammal reservoir hosts, such as white-footed mice, and larger animals, such as white-tailed deer.
"The rising incidence and expanding distribution of Lyme disease in the United States are probably multifactorial, but increased density and range of the tick vectors play a key role," the researchers wrote. "The geographic range of I. scapularis is apparently increasing: by 2015, it had been detected in nearly 50 percent more U.S counties than in 1996."
Tickborne virus infections also climbing.
Powassan virus, the only known North American tickborne encephalitis-causing flavivirus, was recognized as a human pathogen in 1958 after being isolated from the brain of a child who died of encephalitis in Powassan, Ontario. Death results in 10 percent to 15 percent of cases, which numbered 99 from 2006 to 2016.
In 1997, an antigenically similar virus, POWV lineage II, or deer tick virus, was discovered in New England in 1997.
"The increase in POWV cases coupled with the apparent expansion of the I. scapularis range highlight the need for increased attention to this emerging virus," the researchers wrote.
The NIH said the number of tickborne cases are "considered underestimated."
In May, the Centers for Disease Control and Prevention reported approximately 30,000 cases of Lyme disease per year but the NIH said the true incidence is 10 times that number.
"Multiple factors contribute to this discrepancy, including limitations in surveillance and reporting systems and constraints imposed by available diagnostics, which rely heavily on serologic assays," the researchers wrote.
The researchers noted there no licensed vaccines for humans targeting any U.S. tickborne pathogen.
LYMErix vaccine was developed to protect against Lyme disease but SmithKline Beechamwas pulled it from the market in 2002.
"Nonetheless, the manufacturer withdrew LYMErix from the market for a combination of reasons, including falling sales, liability concerns, and reports suggesting it might be linked to autoimmune arthritis, although studies supported the vaccine's safety. Similar concerns will probably affect development," the researchers wrote.
