Dec. 30, 2008 -- The brown dog tick (Rhipicephalus sanguineus) rarely bites people, far preferring the taste of dog. But global warming could be changing that, exposing people to dangerous diseases as a result. In the spring of 2007, three men in France became seriously ill after sustaining bites from disease-infected dog ticks. The bites occurred after the hottest April since 1950, said Didier Raoult, a professor at the University of Marseille School of Medicine in France. The incident reminded Raoult of two other recent cases. A 2004 outbreak of Rocky Mountain spotted fever in Arizona was also associated with dog ticks. And during the exceptionally hot summer of 2003, a man died after 20 brown dog ticks bit him at once. Related Content: Discovery News Home: Where Science Meets World Project Earth HowStuffWorks.com: Ticks and Disease Raoult suspected that, in each of these cases, hot weather made dog ticks turn on humans. He decided to investigate. First, he and colleagues visited the site of the most recent outbreak: a house in southern France, where a 50-year-old woman had been living with her tick-infested dog. The dog died shortly before the outbreak began. The woman said the ticks became particularly aggressive in April 2007. In less than an hour of searching, the researchers collected 218 brown dog ticks from around the house and garage. Of the 133 ticks they tested, nearly 30 percent were infected with varieties of Rickettsia, a genus of bacteria that causes Rocky Mountain spotted fever, Mediterranean spotted fever, and other life-threatening diseases. In the general dog tick population, fewer than 1 percent are usually infected. Next, the doctors examined two of the patients -- a 25-year-old man and a 30-year-old man. Their symptoms were similar: fevers, headaches, night sweats, rashes, and loss of vision. Both were diagnosed with severe spotted fevers, but the species of pathogens they carried were different: Tests showed that the older man was infected with Rickettsia conorii, the agent of Mediterranean spotted fever, while the younger carried R. massiliae, an emerging pathogen. "You had a set of conditions at this particular household that created, for lack of a better term, a perfect-storm scenario," said Christopher Paddock, a pathologist with the Centers for Disease Control and Prevention in Atlanta. "There were lots of ticks, lots of infected ticks, warm temperatures, and the dog dying, which is the normal host. All that adds up to ticks feeding on people and transmitting infection." Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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