Fewer reported Lyme disease cases may not tell whole story

February 5, 2016 by Paul Schattenberg
Ticks in the genus Ixodes,such as the male and female shown here, can be vectors for Lyme disease. The Ixodes scapularis is considered the primary vector in Texas. Credit: A&M AgriLife photo courtesy of Dr. Pete Teel

Though Texas had almost 300 cases of Lyme disease reported in 2009, the number of reported cases since then has gone down considerably, leading experts to wonder if the disease is truly on the decline in the Lone Star State.

"Typically we see dozens of cases every year, mostly within the triangular region between Houston, Dallas and Austin," said Dr. Mike Merchant, Texas A&M AgriLife Extension Service urban entomologist based in Dallas. "Some of these cases occur in individuals who have been bitten by ticks outside the state, but many infections occur when people come in contact with a tick here in Texas."

In the past several years, reports to the Texas Department of State Health Services have gone from a high of 276 in 2009 to alow of 40 reported in 2014.

Merchant said while people typically don't hear much about Lyme disease in Texas, it's the most common insect-transmitted disease in the U.S. The greatest number of cases, over 20,000 a year, occur in the upper midwestern and northeastern states.

"Lyme disease is caused by the Borrelia burgdorferi bacterium and is carried by infected black-legged ticks," Merchant explained. "It can be a chronic debilitating disease of humans. Initial symptoms include fever, headache, fatigue and skin rash. Left undiagnosed and untreated, the disease can spread to the heart, joints and the nervous system."

The black-legged tick, Ixodes scapularis, is thought to be the principal vector of Lyme disease in Texas, he said.

"The adult is active during the fall and winter, and nymphs are active in spring and summer. Both nymphs and adults are capable of transmitting the bacterium to humans."

Merchant said while these statistics seem to bode well, Texas has the Lyme-disease carrying tick, and a few to dozens of people contract the disease from outdoor activity in Texas every year. He said said recent year's reported numbers likely underestimate the true instances of Lyme disease as it is less frequently tested in Texas than in parts of the country where it is better known and far more common.

"We also know that the ticks that carry Lyme disease are doing well enough to be showing up in more, rather than fewer, counties in Texas every year," he said. "The tick that carries Lyme disease is well established in Texas and its range appears to be expanding."

Wizzie Brown, AgriLife Extension entomologist for Travis County, is also hesitant to declare the disease is on the decline in Texas.

"The ticks that vector the disease are a fairly common species and it's fairly easy for humans to contract the disease," she said. "Most likely the statistical decline is in large part due to people not being tested for it or possibly being misdiagnosed because it's less common in Texas than other states."

Merchant added that doctors are concerned about the rising number of cases in some parts of the country, and that a new study by Centers for Disease Control researchers has shown a geographical expansion of the area where Lyme disease occurs.

"Researchers have now found black-legged ticks in 49 percent of all U.S. counties spread across 43 states," he said. "This represents an increase of almost 45 percent from 1998, when tick distribution was last mapped."

He added that the CDC report suggests that the tick's range is expanding in Texas. The tick status in the report has been upgraded in nine Texas counties to "reported" or "established," with established denoting six or more ticks or two or more life stages collected in a year.

"According to the study, the tick has now been found in 71 of the 254 Texas counties," he said.

Additional details on ticks, their identification, biology, geography, control and other factors can be found using the TickApp, http://tickapp.tamu.edu/, which was developed by Texas A&M AgriLife and the Southern IPM Center.

Merchant said even though reports of the Lyme disease in Texas are fewer, the need to be aware of ticks and the possibility of bringing home a tick or infection from the outdoors remains a distinct possibility, meaning precautions still need to be taken.

"We should all use tick repellent and inspect ourselves and our companions for ticks when venturing outdoors," he said. "Permethrin-containing sprays applied to clothing are the most effective repellents for , though skin-applied repellents can also help.

He also noted that individuals should take time to learn the proper method of removing a tick, which is grasping close to the head with tweezers or protected fingers and pulling straight out.

"The sooner a tick is removed the less chance for disease transmission, he said. "The CDC advises to avoid folklore remedies such as 'painting' the tick with nail polish or petroleum jelly, or using heat to make the tick detach from the skin.

"The goal is to remove the tick as quickly as possible and not waiting for it to detach. Plus, heat and suffocants, like grease, may actually stimulate the tick to salivate, increasing your potential for infection."

He said although chances of infection with a tick-borne disease in Texas are relatively low, those experiencing a rash, fever, headache, joint or muscle pains or swollen lymph nodes within 30 days after possibly being bitten by a tick should tell their doctor.

"Knowing that a tick might have been involved will provide the information needed to properly diagnose the problem," Merchant said.

Explore further: Ticks that transmit Lyme disease reported in nearly half of all US counties

Related Stories

Ticks that transmit Lyme disease reported in nearly half of all US counties

January 18, 2016
Lyme disease is transmitted by the blacklegged tick (Ixodes scapularis) and the western blacklegged tick (Ixodes pacificus), and the range of these ticks is spreading, according to research published in the Journal of Medical ...

Ticks that vector Lyme disease move west into North Dakota

September 11, 2014
According to the U.S. Centers for Disease Control, there are more than 300,000 cases of Lyme disease in the U.S. each year. Last year, most Lyme disease cases reported to the CDC were concentrated heavily in the Northeast ...

Tickborne bacteria identified in ticks from Texas

January 14, 2016
(HealthDay)—About 23 percent of ticks from Texas carry bacterial DNA from at least one of the following: Rickettsia, Borrelia, and Ehrlichia spp., according to a report published online Jan. 13 in the U.S. Centers for Disease ...

Lyme disease on the uptick in upstate New York

July 26, 2013
Why are Lyme disease-carrying deer tick populations growing in central New York?

Tips to handle those rare Florida tick-borne diseases

May 19, 2015
Though uncommon, Floridians can get tick diseases.

Key to Lyme disease's locale may be found in the gut of a tick

January 16, 2014
The prevalence of Lyme disease varies greatly between different locales throughout the Northeast, even though the deer ticks that transmit Lyme bacterium are common throughout the entire region.

Recommended for you

New approach to tracking how deadly 'superbugs' travel could slow their spread

November 22, 2017
Killer bacteria - ones that have out-evolved our best antibiotics—may not go away anytime soon. But a new approach to tracking their spread could eventually give us a fighting chance to keep their death toll down.

Research points to diagnostic test for top cause of liver transplant in kids

November 22, 2017
Biliary atresia is the most common cause of liver transplants for children in the United States. Now researchers report in Science Translational Medicine finding a strong biomarker candidate that could be used for earlier ...

Metabolites altered in chronic kidney disease

November 22, 2017
Chronic kidney disease (CKD) affects 1 in 7 people in the United States, according to the U.S. National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK). These individuals have a very high risk of cardiovascular ...

Rainfall can indicate that mosquito-borne epidemics will occur weeks later

November 22, 2017
A new study demonstrates that outbreaks of mosquito-borne viruses Zika and Chikungunya generally occur about three weeks after heavy rainfall.Researchers also found that Chikungunya will predominate over Zika when both circulate ...

Alcohol consumption and metabolic factors act together to increase the risk of severe liver disease

November 22, 2017
A new study provides insights into the interaction between alcohol consumption and metabolic factors in predicting severe liver disease in the general population. The findings, which are published in Hepatology, indicate ...

Gastric acid suppressant lansoprazole may target tuberculosis

November 21, 2017
A cheap and widely used drug, used to treat conditions such as heartburn, gastritis and ulcers, could work against the bacteria that cause tuberculosis (TB), according to new research from UCL and the London School of Hygiene ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Feb 06, 2016
The problem with lyme disease is the ever ending misinformation regarding the disease and where it is prevalent. The testing for the disease is inaccurate. This has been known for years but yet we continue to use a test that utilizes a part of the immune system (IGg subclasses) that is suppressed by the bacteria itself. Documented. If the bite is not seen and a rash is not noted the person moves into a chronic persistent infection and most of the time will not test positive thus they are NOT included in the numbers of documented cases. A&M University studies prove different then this article leads us to believe. Dr. Clark UNF has published a study whereas he found borrelia in other ticks then what has been documented. I live in North Texas where 4 out of 5 ticks from my suburban property tested positive for borrelia burgdorferi. Do I think that our property is somewhat isolated. No I do not . Please lets move forward and get out of the 30 plus years of misinformation.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.