Miliaria

The explosive rise in tick-borne diseases in many parts of the United States over the last five decades represents a major public health threat that demands innovative solutions, warns a group of scientists. They outline why the stakes are so high and describe some potential solutions. Possible solutions include a new class of vaccines for humans and even for the animals that carry the ticks. The explosive rise in tick-borne diseases in many parts of the United States over the last five decades represents a major public health threat that demands innovative solutions, warns a group of Yale scientists. In a review article, they outline why the stakes are so high and describe some potential solutions. Possible solutions include a new class of vaccines for humans, including vaccines being developed at Yale, and even for the animals that carry the ticks. The article is published Oct. 18 in the journal Science Translational Medicine. The research team was led by Sukanya Narasimhan, associate professor in Yale's Department of Internal Medicine (Infectious Diseases) and Erol Fikrig, Waldemar Von Zedtwitz Professor of Medicine (Infectious Diseases) and professor of epidemiology (microbial diseases) and of microbial pathogenesis. The public health threat, they say, is escalating rapidly. It wasn't until 1982 that the threat of tick-borne diseases was recognized after a bacterium transmitted by ticks caused an outbreak of arthritis-like symptoms in children in Lyme, Connecticut. And even then, known cases of the disease were extremely rare. Today an estimated 490,000 people in the United States are infected annually by tick-borne diseases such as Lyme disease, an increase that researchers say has been fueled by the return of formerly depleted forests and a dramatic increase in populations of tick-hosting white-tailed deer. The threat has also spread from isolated areas near the New England coastline into the U.S. Midwest and other parts of the country since the cause of Lyme Disease was identified four decades ago. A single tick species -- Ixodes scapularis, commonly called the black-legged or deer tick -- accounts for 97% of tick-borne diseases in the United States. To date, most efforts to combat tick-borne diseases have concentrated on developing vaccines that target Borrelia burgdorferi, the bacterium that causes Lyme disease. These efforts, however, have had limited success and do nothing to combat other pathogens that can be transmitted by ticks, the researchers say. For example, deer ticks can also transmit six other human pathogens, including the Powassan virus -- named for a town where it was first identified in a young boy who eventually died from it -- which kills 10% of infected people and causes permanent neurologic damage in half of the cases. While still rare, Powassan cases have increased forty-fold in the last two decades. In response to this rapid rise of a host of tick-borne diseases, Fikrig's lab at Yale is developing vaccines that combat a variety of infections by thwarting the ability of ticks to feed and even alert human hosts when they have been bitten by a tick. "If we can keep ticks from feeding, we can control Lyme and other diseases as well," said Narasimhan, first author of the new report. Previous research has shown that multiple exposures to tick bites can increase resistance to tick-borne infections. At Yale, Fikrig's lab capitalized on this insight. In a previous study, the lab showed that a vaccine containing a cocktail of tick salivary proteins can impair tick feeding and even increase the chances that a person will recognize that they've been bitten, which can in turn prompt rapid tick removal and a reduced likelihood of infection. Durland Fish, professor emeritus of epidemiology (microbial diseases) at Yale School of Public Health and a co-author of the article, argues that such a vaccine could also be delivered orally within bait that would be consumed by deer. Ideally, he said, ticks would then be unable to feed upon the blood of that deer, which in turn would reduce tick populations and the risk of disease for humans. "Deer are the keystone host for deer ticks," he said. "They do not exist in areas where there are no deer. I think this should be the Manhattan Project for tick-borne diseases." Similar strategies have already been carried out to prevent racoon rabies in the U.S. and fox rabies in Europe, and also to protect cattle against tick-borne disease. "Toward this goal, we must have a multidisciplinary, One Health approach [an integrated approach that balances the health of humans, animals, and ecosystems] that will harness the vision of molecular biologists, entomologists, ecologists, epidemiologists, physicians, veterinarians and vaccinologists," the authors conclude.

Widespread tree scorch in the Pacific Northwest that became visible shortly after multiple days of record-setting, triple-digit temperatures in June 2021 was more attributable to heat than to drought conditions, researchers say. Widespread tree scorch in the Pacific Northwest that became visible shortly after multiple days of record-setting, triple-digit temperatures in June 2021 was more attributable to heat than to drought conditions, Oregon State University researchers say. In a paper published in Tree Physiology, a team led by Christopher Still of the OSU College of Forestry cites evidence that leaf discoloration and damage are consistent with direct exposure to solar radiation during the hottest afternoons of the "heat dome" that covered northwestern North America. Still and other scientists from OSU were responding to an article published in the same journal in April 2022 that concluded the trees' problems were the result of drought and a failure in the trees' hydraulic system, which helps foliage stay cool through the exhalation of water vapor via a process known as transpiration. The collaboration that produced the response following a literature review includes researchers from Oregon State's colleges of Engineering, Agricultural Sciences, and Earth, Ocean, and Atmospheric Sciences, as well as two other OSU-affiliated organizations, the Oregon Climate Change Research Institute and the PRISM Climate Group. "While we think the drought/hydraulic hypothesis is partly true, we argue that multiple lines of evidence suggest the main issue was in fact direct heat damage," said Still, a tree physiologist who studies forests in the context of climate change impacts and feedbacks. "Tree physiologists have worked a lot to show that hydraulic damage in response to drought drives a lot of tree mortality, and the paper we comment on more or less fits in that vein, implying that what we saw in June 2021 was just another example of drought damage and that the heat dome was a sort of extreme drought event." Still and OSU colleagues including ecologist and plant pathologist Posy Busby, H.J. Andrews Experimental Forest Director Mark Schulze, forest health specialist David Shaw, hydrologist David Rupp and geospatial climatologist Chris Daly say that damage can be driven by extreme heat alone, irrespective of prior hydrologic context and water availability. They note that the heat dome was one of the most extreme heat waves ever recorded anywhere in the world and the most intense ever in the Northwest. The scientists also point out that there is "a clear distinction in the climate and hydrometeorological literature between droughts and heat waves" and that "heat waves are not just associated with droughts, as is commonly assumed, but are increasing in frequency during both wet and dry conditions." Among coastal Douglas-fir and western hemlock plantation forests in western Oregon and Washington, the most extensive impacts of the heat dome were in areas experiencing comparatively low levels of drought, the authors say. Conversely, many forests around Oregon's Willamette Valley and along the western slopes of the Cascade Range that were experiencing severe to exceptional drought during the heat dome showed less foliar damage. "It's also important to remember that conifer needles can discolor for many reasons besides being dried out," Still said. Much of the observed "foliar scorch" resembled what is caused by heat generated from fires, Still said, and also followed patterns that suggest heat was the primary driver of foliar damage during the heat dome. Trees on south- and west-facing slopes and on exposed edges near roadsides generally showed the greatest scorch, and opposite sides of the same trees, or other trees on the same hillsides, displayed little to none. "The scorching that did occur happened fast, within days and sometimes hours, much faster than would typically be associated with a malfunction of the trees' water moving capabilities," Still said. "And the prevalence of scorching in sunlit foliage also challenges the hypothesis that drought and hydraulic failure combined to be the primary cause of leaf damage." "Our prior work has shown drought-induced foliar browning in conifers can take weeks or even months to appear after lethal levels of drought stress," added co-author William Hammond, an assistant professor of plant ecophysiology at the University of Florida. The scientists emphasize that they are not saying hydraulics played no role in the leaf damage, or in the subsequent death of some trees, but that extreme heat is the best explanation for the crown- and landscape-scale scorch patterns seen throughout the Pacific Northwest during and after the heat dome. "Disentangling drought from heat damage is tricky, and we argue the research community needs to work much more on heat stress physiology," Still said. "We need to explore connections between hydraulic properties and heat tolerance -- safety margins, how evolution may have helped some species with heat tolerance, canopies' ability to maintain leaf temperatures below damaging thresholds. What happened during the heat dome argues for a renewed emphasis on understanding the underlying physiological and biophysical mechanisms that can lead to heat resilience." College of Forestry research associate Adam Sibley is a co-author of the commentary, as are scientists from the U.S. Forest Service and a pair of Australian organizations, Biodiversity and Conservation Science and the Commonwealth Scientific and Industrial Research Organization.

A recent study has validated an innovative body temperature monitoring system that predicts heat stress to prevent heat-related injury in industrial workers. The study confirmed that Kenzen’s wearable heat sensor, launched in 2020, provides accurate, continuous core body temperature measurements. The research was conducted at three universities in Australia and New Zealand. When worn on the upper arm during physical labor, the Kenzen sensor continuously records body temperature, heart rate, hydration, and activity. The monitor integrates with a mobile app and a team dashboard. If a worker’s temperature elevates above normal or if the sensor detects dehydration, the system sends an alert to the individual’s smartphone as well as to the manager’s dashboard. After the worker has taken time to rest and hydrate, the system sends another notification that it’s safe to return to work. The study included 75 biological male and female participants between the ages of 18 and 62. The results indicate that the Kenzen sensor has equivalent accuracy to the gold standards for body temperature monitoring: an ingested gastrointestinal pill and a rectal thermometer. Both of these standard approaches are problematic for continuous temperature monitoring in many industrial settings. Kenzen’s system includes algorithms that predict heat stress issues and infections conditions based on individual risk. Using a large-scale dataset, the algorithms factor in metrics such as sweat rate, baseline body temperature, age, and biological sex to deliver accurate alerts regarding possible health risks. The study confirmed that the wearable remained accurate during a range of activities performed in various environmental conditions. In a July 2021 discussion paper comparing 11 million California workers’ compensation claims to local weather data, researchers at UCLA suggest that rising temperatures contribute to an increase in heat-related workplace injuries. The comparison found that hotter weather may cause an estimated 20,000 injuries per year. As summer temps continue to rise in many parts of the world due to climate change, Kenzen’s solution offers some protection against the severe health consequences caused by heatstroke for millions of industrial workers.