Ticks that contribute to the spread of Lyme disease, anaplasmosis and other diseases have undergone various tracking methods to prevent the spread of disease change in the last few decades. However, most tracking methods, which are cost-effective, depend on nationwide coverage, which is not precise enough to predict disease prevalence, especially in the counties of the American West, many of which are larger than some Eastern states.
Nationwide coverage not only fails to pinpoint tick prevalence, but it also overlooks disease reservoirs in small areas of western counties. Researchers for the US Centers for Disease Control and Prevention have long called for more accurate epidemiological data collection, but most methods are far too expensive to pass.
In an article published in April Journal of Medical Entomology researchers from CDC scientist Rebecca Eisen, Ph.D., reviewed tick collection and tracking models for the detection of Ixodes pacificus of the western Black-legged ticks that are largely responsible for the spread of Lyme disease in the Pacific United States. A look at the tick collection records from 1980 to 2014 showed a large spatial variability of the tick, and this variability – in California – was largely due to higher temperatures and more rainfall during the coldest seasons. Environmental sanity maps pointed to the northern California coast and the western foothills of the Sierra Nevada as the most probable habitat for I. pacificus and could more accurately determine the regions most at risk for Lyme disease. In addition, the researchers observed that the models used are now largely available for free on the Internet.
According to state sources, about 1-2 percent of adults in California I. pacificus carry ticks and 2-15 percent nymphs Borrelia burgdorferi the bacterium that causes Lyme disease , In California, approximately 2600 cases of Lyme disease were reported between 1989 and 2014. Meanwhile, cases of human granulocytic anaplasmosis have increased since its discovery in 1990 and, according to the CDC, can infect up to 36 percent of endemic ticks populations. While the tick was reported in 56 out of 58 California counties, this new study indicates that the tick is concentrated in certain areas that should be better defined for disease control. The researchers reviewed data on tick larvae, nymphs, and adults were collected in California and focused on records between 1980 and 2014. They then compared the tick population with climate data and examined 35 climate variables, including precipitation, maximum temperature, minimum temperature, vapor pressure, and daylength , A total of 4,546  I. Pacificus locations were entered into the researchers' models; About 77 percent of these ticks were collected from forest, grass, scrub, or shore land, the most common habitat for the tick.
The team's models consistently showed that precipitation and average temperatures during the coldest quarter of the year were the ecological niche of I. Pacificus in the state. Most suitable were areas that were wet and warm in winter, overlooking the northwest coast (including the districts of Mendocino, Humboldt and Del Norte) and the western slopes of the northern foothills of the Sierra Nevada. Other parts of these districts were not so suitable for the tick.
"A suitable habitat for vectors for survival and multiplication is not uniform within counties, and in these areas, information about subplants in which vectors are present can help to target limited resources for the monitoring and prevention of vector diseases Our models identified suitable habitat for the tick in 55 out of 58 counties in California, but there were significant differences in the percentage of land in each district deemed fit for the tick, for example, less than 1 percent of the district was let ( in northeastern California), while more than 90 percent of the Mendocino district (Northern California) has been deemed suitable, "says Eisen. Knowing where ticks are likely to be found is the key to avoiding the tick habitat when ticks are active and empowering people to protect themselves In our study, we modeled the potential range of vectors for Lyme disease in California, and this information improves our knowledge of where Lyme disease vectors are likely to be found in California. "
The study did not focus on the effects of English: bio-pro.de/en/region/stern/magazine/…1/ index.html Eisenberg notes that "based on our models, California's forests, grasslands, scrubland and shoreline areas, which become warmer and wetter in winter, are better suited for this tick to survive and multiply . " Ticks monitoring and reporting are not standardized in districts and cities, and there is no long-term data available to determine if climate resilience has changed over time.
Andrew Porterfield is a writer, editor and communications consultant for academic institutions, businesses and nonprofit organizations in the life sciences. He often writes about agriculture topics for the Genetic Literacy Project. He is based in Camarillo, California. Follow him on Twitter at @AMPorterfield or visit his Facebook page.