Maine experienced a dramatic decline in reported Lyme disease cases in 2018, and the dry weather last summer may have played a role.
The state had 1,310 Lyme cases by December 27, according to the Maine Center for Disease Control and Prevention of 1,852 in 2017. This represents a decline of 29 percent, although the final number of cases is slight due to a delayed notification can rise.
Lyme is an infectious disease caused by the deer tick has expanded its range in Maine over the last 20 years. Lyme disease cases have increased in Maine every year since 2011, with the exception of 2015, before declining in 2018.
The 1,852 Lyme cases in 201
Some, but not all, people get a bull's-eye rash, where they were bitten by a tick. Lyme disease can be treated early with antibiotics, but if left untreated it can lead to long-term health problems, especially in the joints and nervous system, according to the US Centers for Disease Control and Prevention.
Anaplasmosis, another Hirschkeil disease, also saw a sharp decline in 2018 from 663 cases in 2017 to 476 cases by 27 December this year.
Researchers are still learning what causes fluctuations in the deer tickling population and interactions with humans. Except for Lyme cases, there were fewer submissions of dead ticks to the University of Maine Cooperative Extension and fewer ticks conducted in field surveys by employees of the Maine Medical Center Research Institute.
"The Big Challenge for Surviving the Tick May Be Not Summer, but Summer," said Susan Elias, a research associate at the Scarborough Maine Medical Center Research Institute, who is studying arachnids and Lyme disease. 
Rainfall was below average This summer, while the high temperatures in July and August were above average, according to the National Weather Service in Gray.
Elias said the researchers had investigated how the ticks survive in their southern area, such as Georgia or South Carolina, in the south the ticks can survive in hot weather, but they remain under the leaf litter and do not look for humans as often as hosts, preferring animals like lizards.
Ticks are like Goldilocks, it can not be too hot or too cold or too dry, it has to be just right, "said Elias." But they are Exper to find the right microclimate for them. For example, if it is too hot and dry, they will fall back under the leaf litter. "
However, if the weather is hot and dry enough for long periods of time, that could lead to a reduction in ticks, researchers say.
Researchers will compare Maine's dry summers in summer 2016 with moisture and temperature patterns to see if there is a link to tick activity: in 2016, Lyme Falls declined in the summer, but increased in the fall and Maine ended this year with 1,464 cases.
This year, Lyme Falls began strongly in the spring and early summer, but declined in the late summer from the summer compared to previous years, and did not recover in the fall, as in 2016
Extreme cold without snow can also kill ticks, but temperatures must be consistently below or close to 0 degrees Fahrenheit for weeks before Fors They believe that tick-stock would be significantly affected. Snow has an insulating effect and helps the ticks survive the winter.
Griffin Dill, an integrated pest control expert at the University of Maine Cooperative Extension, said it was difficult to say whether 2017 was a departure or whether 2018 would be a one-year decline. off before Lyme Falls rise again.
Dill said 20 percent fewer tick marks were submitted to University of Maine's "tick lab" this year, with a steeper decline in the fall. People who are bitten by ticks can present them to the laboratory for identification.
"The fall is usually a very active time for ticks, but not this year," said Dill. "There may not have been so many opportunities for tick-human interactions."
Dill said the November snow and cold temperatures were likely to reduce tick activity at a time when people were still out. For example, hunters might have found fewer active ticks.
"Under these conditions, there will not be much tick activity," he said.
Researchers are also investigating how Lyme correlates with the rodent population. Maine had a plethora of squirrels in 2018, probably caused by an above-average acorn harvest in 2017. The theory is that the increase in rodent populations this year will lead to more ticks in the next year, but Dill said he is skeptical about this. Further research is needed.