Article Contents
Migratory birds can bring along some dangerous stowaways during their epic journeys – ticks. These blood-sucking arachnids can carry serious pathogens such as Lyme disease, anaplasmosis, and Powassan virus infection. Now, bird-riding ticks may spread more easily and settle in newer areas due to climate change. The findings are detailed in a study published Nov. 18 in the journal Frontiers in Cell and Infection Microbiology.
"If conditions become more hospitable for tropical tick species to establish in areas where they previously would have been unsuccessful, then there is a chance that they will bring new diseases with them," study co-author and University of Southern Mississippi biologist Shahid Karim. he said in a statement.
Unwanted travel companions
Ticks are some of the most effective on Earth disease carriers. They can link people and pets to diseases that normally only live in the wild, such as Lyme disease. Ticks can also bite birds – especially migratory birds that travel thousands of miles. This hitchhiking allows ticks to travel vast distances.
[Related: You're less likely to get a tick bite if you steer clear of these spots.]
Increases in global temperatures due to climate change are now making it easier for some tick species to live as invasive species. This can also happen very quickly. For example, the Asian long-horned tick (Haemaphysalis longicornis) was first identified in the state of New Jersey 2017 and can now be found in 14 additional states.
"The geographic distribution is changing very rapidly in many tick species," study co-author and Georgia Southern University biologist Lorenza Beati. he said in a statement. “For some migratory exotic ticks, global warming may create conditions in their northern destination[s] that are similar to their usual range. If warmer climatic conditions are combined with the presence of suitable vertebrate hosts for all tick life stages, the likelihood of establishment will increase."
Bird watching
In new studythe team investigated the dispersal of ticks by migratory birds. The team set nets at six sites where the birds typically stop to rest along the northern Gulf of Mexico. Each of the birds was fitted for a numbered identification band, measured, given a physical and cleaned for ticks. If and when ticks were found, the arachnids were preserved for later DNA analysis to confirm the species and identify the pathogens they carried.
Next, the team divided the birds into three categories– residents, short-distance migrants and long-distance migrants. They also mapped the geographic distribution of each bird species to understand where they would gather ticks. These maps highlighted how far ticks could be transported. Average dispersal distances increased up to 3.100 miles (5.000 km)
However, the number of ticks turned out to be quite low. Nearly 15.000 birds were sampled – nearly 2.000 of them more than once – yet only 421 ticks were collected from 164 birds. While 18 different species of ticks were identifiedjust four species accounted for 81 percent of the ticks the scientists identified. Short-distance migrants carried more ticks than long-distance migrants, and several of the tick samples were neotropical species not established in the United States.
Under the microscope
The team then analyzed the bacteria carried by the ticks. Franciella bacteria were the most common. These endosymbiotic bacteria help ticks function, but some species can cause a disease called tularemia. Higher levels of Franciella bacteria in a tick have been associated with lower levels of two other bacteria –Rickettsia ή Cutibacterium.
Rickettsia species were the second most abundant bacteria. These bacteria cause fevers or rashes depending on the species. This could suggest that they have a symbiotic relationship with ticks that was currently unknown to scientists. Bloodsucking of migratory birds over long distances requires a significant amount of energy from ticks to stay tied.
It is possible that the Rickettsia species may help ticks cope with the energy loss of travel. Some species of Rickettsia can cause diseases in humans, including spotted fevers. However, scientists do not yet know whether invasive tick species are likely to transmit these diseases to humans
According to the teammore research is needed to better understand how large the impact of bird-assisted tick dispersal is. Future studies could investigate whether birds act as reservoirs by carrying tick-borne diseases when they are not hosting ticks.
"Not only could these ticks carry new pathogens, but if they manage to establish themselves in the U.S., they could become additional carriers of pathogens already present in this country or maintain pathogens in wildlife reservoirs that can then become sources contamination," Karim said. .
The best ways to protect yourself from tick-borne diseases are to wear long sleeves when outdoors, use a good bug repellant, and do tick checks after being outside or spending time in tick-infested areas .
VIA: popsci.com
