About Tick Time

Understanding Lyme Disease

RUTH SMITH COMMUNICABLE DISEASE INVESTIGATOR ALLENTOWN HEALTH BUREAU

As the weather changes and temperature and humidity levels rise, chances of outdoor encounters with the small parasitic arachnids we know as ticks increase as well. Lyme disease is one of the most common vector-borne diseases in the northeast region of the country and although its reach has expanded and has been reported across all states, its incidence decreases in the southeastern regions due in part to tick density and environmental conditions but mostly due to variable tick-host associations with the shifting of availability and selection of an efficient reservoir host for the tick.

The bacterium that causes Lyme infection in the US, the pathogenic spirochete Borrelia burgdorferi, gets transferred from an infected wildlife host, generally a rodent like the white-footed mouse, to a blacklegged tick: Ixodes scapularis in the northeastern, mid-Atlantic, and north-central areas, commonly known as deer tick; or Ixodes pacificus in all areas west of the Rocky

Mountains. Once inside the tick, Borrelia can be found dormant in the midgut, eventually migrating to the tick’s salivary glands where it gets passed on to humans after a bite and subsequent feeding occurs. In order for any Lyme bacteria to be transmitted, an infected tick needs to remain attached to the host for quite some time. According to CDC, at least 36 to 48 hours of attachment are needed for a tick to be able to transfer the bacteria that causes Lyme disease (Borrelia mayonii has also been found to cause Lyme but rarely).

The immature form of the tick, called a nymph, is responsible for the majority of bites and since at this stage it is only about 1mm, the size of a poppy seed or a pin head, the bite is rather painless and most likely to go unnoticed. Many people do not realize they are infected until symptoms start showing.

One manifestation of infection observed in about 70-80% of people within 3 to 30 days after a tick bite is an erythema migrans rash. While most people are familiar with the well-known guideline of recognizing its bull’s eye appearance; the rash could be quite variable in size, location, and shape, and not everyone with an active infection will develop a rash. Flu-like symptoms such as fever, chills, fatigue, headache, muscle and joint aches, and swollen lymph nodes may appear as well regardless of the presence or absence of a rash. Nonetheless, as the majority of Lyme symptoms are also common in many other infections, people can often be undiagnosed or misdiagnosed with other conditions. When this infection is not treated accordingly, there may be subsequent damage to joints, nervous system, and heart. In such cases, treatment may vary depending on the severity and manifestation of the infection in the affected tissues.

In the majority of cases, Lyme infection can be cured with oral antibiotic treatment, generally doxycycline, during a number

Continued on page 14 of days or weeks depending on symptom manifestations. However, there seems to be a measure of medical controversy on the standards of care, particularly in late diagnosis of Lyme disease, as two divergent approaches from different medical societies are available that could prove confusing or frustrating to patients when they are seeking treatment. In summary, one approach considers shorter treatment with antibiotics and preventive strategies for the patient to be effective with not much emphasis on persistent infections or chronic conditions associated. The other approach recommends longer antibiotic treatment and supports retreating in appropriate clinical situations. These divergent guidelines are mainly based on different interpretations after revaluation of clinical trials results and risk-benefit assessments.

Since Lyme disease could be considered a multistage and multisystem infection, it may be somewhat difficult to diagnose in a timely manner. Isolated serological testing cannot accurately determine the difference between an active infection or a previously treated one because it is measuring antibodies present in blood. Additionally, since antibodies may take a couple of weeks to develop, those with very recent infections may not get a positive result if testing is performed too early. The gold standard remains a 2-tier testing algorithm that involves two immunoassay protocols; modified versions of the same 2-step testing practice have become available in recent years and higher sensitivity during early infection has been observed which is key to achieve a more accurate interpretation of results and a better approach to patient care.

Several factors are important for providers to consider when making an assessment for Lyme infection: signs and symptoms, the history and probability of exposure to an infected blacklegged tick which is determined by the area of residence, the possibility of other infections that may share similar symptoms, and the serological test results if indicated when there is clinical and epidemiological support for a diagnosis and when performed at appropriate times after infection or in case of observation of additional manifestations of disseminated disease.

It is important to also note that some people may still experience symptoms like pain or swelling of joints, insomnia, fatigue, depression, and some cognitive dysfunction that could last several months after they have completed treatment. While there is controversy about the possible cause of this symptom persistence, either lingering bacteria or an auto-immune response, and how close, or if at all, it is related to the initial infection; it is not exactly known why some people develop it and some do not, but it has been observed in as many as 20% of patients after treatment and it is referred to as post-treatment Lyme disease syndrome.

While the only Lyme vaccine available was discontinued in 2002 due to insufficient demand, increasing number of cases and public awareness have prompted more recent efforts for projects of new vaccines, currently at different stages of development. One vaccine is focused on directly delivering a monoclonal antibody to convey immunity quickly; another one on inducing the creation of multiple antibodies to block specific proteins of the bacteria, preventing it from leaving the tick when it bites a human. A different type of vaccine aims to cause an immune response with a noticeable reaction on the site of a bite that would prevent transmission of any bacteria by interfering with proper tick attachment. These are all promising yet still years down the road as trials are ongoing.

Although only the blacklegged tick, or deer tick, is responsible for transmission of Lyme bacteria to humans, other species of ticks may carry other infectious agents. Reducing chances of tick encounters and tick bites is always the best practice especially during the warmer months; wearing bright colored clothing when spending time outdoors to facilitate tick spotting, tucking in shirts and pants when able, spraying EPA-registered repellent on clothing, shoes, and gear before hiking excursions, laundering of clothing worn outdoors with hot water and drying in high heat afterwards, and performing a thorough body check all around yourself, children and dogs when back indoors; even though dog ticks are different than deer ticks and do not transmit Lyme bacteria, they can carry many other tickborne pathogens. Prompt removal of any tick within the first 24 hours is important in decreasing any chances of infection. If an attached tick is found, it is recommended to use fine tweezers to steadily and slowly pull the tick straight up without twisting, thoroughly cleaning with rubbing alcohol, or soap and water, and carefully disposing of the tick by taping it or placing it in a sealed bag. Taking a picture of the tick may be helpful for identification, and while there are available centers offering testing of ticks for pathogens, most scientific organizations find several issues associated with this practice and do not consider the results to have definitive evidence or benefit for the treatment of patients.

Remember not all ticks carry the bacteria responsible for Lyme disease and not all ticks carrying the bacteria will be able to transmit it to humans. Testing of patients that do not show symptoms that are typical of Lyme disease, or whose risk of exposure is low, is not encouraged. As important it is to properly diagnose someone who has Lyme disease, it is equally important to avoid misdiagnosis and treatment of someone who may be suffering from a different condition with similar symptoms.

Even though some recommendations and treatment guidelines available regarding Lyme disease may seem conflicting at first glance, research keeps allowing better tools for clinicians to be developed, testing sensitivity continues to be improved, and ultimately it comes to the importance of effective and trusted communication between a skilled provider and the patient, the value of the use of clinical judgement when some evidence may seem uncertain, the need for individualized patient-centered care and the role of patient medical preferences while making decisions concerning their