Certain ticks in Georgia carry an emerging virus that can make people sick, new research shows. The study found traces of Heartland virus, one of the most recently discovered tick-borne germs in the US, in the state’s Lone Star tick populations. The virus found in these ticks appears to be genetically distinct from samples collected in other parts of the country, suggesting that it has been present in Georgia for some time.
Heartland virus, also called Heartland bandavirus, was first discovered in 2009 by doctors in Missouri. In 2013, it confirmed that the lone star ticks (Amblyomma americanum) can carry and transmit the virus to humans. Its symptoms include fever, headaches, muscle aches and a large loss of platelets, a blood component crucial for the formation of clots that prevent bleeding.
Rare cases of Heartland have been documented since 2009. As of January 2021, according to the Centers for Disease Control and Prevention, there have been informed more than 50 cases in 11 states in the midwestern and southeastern US. The identified victims have been routinely hospitalized and some have died, although these cases tended to involve people who were already in poorer health. However, Heartland is not easily identified and is usually diagnosed after excluding other diseases with similar symptoms, including other tick-borne diseases. Therefore, it is suspected that more cases have occurred than have been officially documented.
Heartland has been seen in Georgia, where lone star ticks are abundant and the most common source of human tick bites. Until now, however, evidence of infection in Georgia had only been found in white-tailed deer, a common tick host, and in a single human death. This new research published in Emerging Infectious Disease, appears to be the first to confirm that the virus is actively circulating among lone star ticks in the state.
The researchers, hailing from Emory University and the University of Georgia School of Veterinary Medicine, collected nearly 10,000 juvenile and adult ticks between 2018 and 2019 and matched their DNA to look for traces of the virus. They were able to identify and isolate three different samples of the virus, collected from young and adult ticks at different times and places. Overall, they estimated that Heartland could be found on about one in 2,000 ticks.
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The infection rate found in these ticks is relatively low, compared to studies of lone star ticks elsewhere. But all the virus samples collected by the team looked genetically similar to each other and not so much to samples collected in other regions. That indicates that it has made a comfortable home for itself in Georgia, having had enough time to evolve in unique ways from other populations of the virus. Even if the virus is only found in a small number of ticks, the large amount of exposure residents have during peak season (April through May) is likely enough to put the state at risk of transmission, study finds principal. author Gonzalo Vazquez-Prokopec, an ecologist specializing in vector-borne diseases at Emory University.
“This study confirms the presence of the virus in Georgia and, more importantly, that it is being transmitted by the most abundant tick species that bite humans in the state,” Vázquez-Prokopec told Gizmodo in an email.
Very little is known about the Heartland virus, the authors note, including its life cycle and how common it is in humans. This lack of knowledge is even more dangerous as tick-borne diseases are generally on the rise (largely due to climate change). Another potential problem has arisen with the arrival and rapid spread of the invasive tick species Haemaphysalis longicornisor the Asian longhorned tick.
These ticks, in their native Asian home, are known to carry a Heartland-related virus that can cause a serious, sometimes fatal condition called severe fever with thrombocytopenia syndrome. if you are new bad ticks they can also carry and spread Heartland, the researchers warn, that could “lead to major changes” in their transmission potential in areas where the two species overlap. After first being seen in the United States in New Jersey in 2017, Asian longhorned ticks have been detected throughout the eastern US, including Georgia in 2021.
The researchers plan to continue studying Heartland in lone star ticks, and are now preparing to track the Asian longhorned tick as well. They also hope their research will remind people that ticks and the diseases they carry are a serious threat to public health.