Several vector diseases are not as common in the United States as they are in tropical countries. But Lyme disease is perhaps one of the most common vector diseases in North America. It is caused by a type of spirochete bacteria and transmitted through a tick bite.
In this article, we’re explaining the basics of Lyme disease, a disease that causes a vast array of signs and symptoms, sometimes very mysterious and difficult to diagnose. After understanding the symptoms and the cause of the disease, we’re also going through the diagnostic steps and the treatment options available for Lyme disease patients.
Overview
Lyme disease is a vector-borne disease, one that is transmitted through a tick bite. The animal is infected with a spirochete bacterium known as Borrelia burgdorferi, it is transmitted to humans, and they develop a multi-system disease.
In the United States, Lyme disease is diagnosed in over 30,000 patients every year. It is also common in many countries in Asia and Europe. However, most patients do not recall any tick bite, and not every physical exam shows one of them. Tick bites and Lyme disease are more common in people who spend time in grassy spaces or those who live or travel to endemic areas.
The disease has been recognized for many years, and the first records that suggest Lyme disease go back to 1883. However, the name Lyme disease came from the decade of 1970 due to an arthritis outbreak in pediatric patients in Lyme, Connecticut.
Lyme disease causes
The disease is caused by the bacteria Borrelia burgdorferi, which has an infectious cycle that involves ticks of the genus Ixodes and mammalian animals. Only tick females need blood meals, and only nymphs and adults transmit the disease. Every adult female lays new eggs during springtime, and they hatch on summer days. Larvae feed on mice, blood, and other animals and become nymphs the next spring and become adults the following fall.
Throughout their life cycle, ticks usually get infected with Borrelia burgdorferi when feeding on an infected animal in one of the three stages in their life cycle. The most common carrier of the disease is a type of mice known as white-footed mice. They do not develop the disease and only carry the bacteria in their midgut. Then, and only when the tick is infected and bites humans, they are at risk, but do not always get the disease.
Impressively, nymphs are more likely to transmit the disease as compared to adults. Being bitten by an adult tick is more noticeable. Nymphs sneak around easier due to their smaller size, and they are not easily detected before they are done feeding and transmitting the disease. Ticks can take hours to attach to the skin, and they should stay in place for 48 hours (nymphs) and up to 72 hours (adults) to transmit the disease.
Even when the spirochete is transmitted to a human host, there’s no 100% chance of getting the disease. Sometimes the bacteria are caught by the immune system and eliminated before infecting the patient. In other cases, the spirochete stays in the skin and starts causing the disease with a skin rash. But sometimes, it is disseminated in the blood or lymph instead of staying in the skin. Depending on what happens, the patient gets different clinical manifestations.
The bacteria have a preference for the skin tissue, the nervous system, the heart, joints, and the patient’s eyes. These organs are the most commonly affected, but the disease can spread anywhere, including the testes, liver, lymph nodes, and more.
Types and stages of the disease
Lyme disease goes through a series of stages. But before that, the bacterium needs to multiply in the body during an incubation period. This period is variable, lasting a maximum of 30 days. Throughout this time, patients are usually asymptomatic.
There are three primary stages of the disease, according to its progression. It is possible to treat and cure the disease in all of these stages, and half of the patients without the disease go through all three stages before the immune system takes care of the disease.
The stages of Lyme disease include:
- A stage 1 disease, or early localized disease: This is the first symptomatic stage after the incubation period. It usually starts within 30 days after being bitten and when the condition is only localized in the skin. The most common symptom is an erythema migrans, a type of skin rash we will describe in the section “signs and symptoms.” This stage includes nonspecific symptoms such as headache, fever, chills, fatigue, neck stiffness, and muscle and joint pain.
- A stage 2 disease, or early disseminated disease: Borrelia burgdorferi does not stay in the skin in all patients. It disseminates to the blood and other tissues. This usually happens a few weeks or a few months after the tick bite, depending on each particular case. In this stage, the most common complaint includes musculoskeletal symptoms, cardiac problems, and other skin signs. In this stage, the DNA of B burgdorferi can be found in the skin and bloodstream, sometimes in the cerebrospinal tissue, too, even in patients who do not display neurologic symptoms.
- A stage 3 disease or chronic disseminated disease: This is the final stage of Lyme disease and only happens several months or some years after the tick bite. In some cases, patients go through a latent Lyme disease without any symptoms before starting a stage 3 Lyme disease. In this case, the symptoms are triggered by the immune system reacting against the spirochete in various organs. There is a vast number of possibilities because the bacterium can be found in many organs, as noted above. Thus, the signs and symptoms depend on the type of tissue involved.
We can also say that there are different types of Lyme disease, depending on the Borrelia strain that is infecting the individual. Each one is more commonly associated with specific manifestations. For example, B. burgdorferi sensu stricto is a type of spirochete with a particular tropism to joint tissues. It causes many cases of arthritis in the United States and Europe. On the other hand, B burgdorferi afzelii is another type with intense tropism to the skin tissue and causes a kind of dermatitis known as acrodermatitis chronica atrophicans.
Signs and symptoms
Let us review each stage of Lyme disease and list the most important signs and symptoms of each one.
In stage 1 Lyme disease, patients usually report these signs and symptoms:
- Erythema migrans: It is perhaps the most important sign in the early stage of the disease. It is a type of skin rash that starts around the area of the bite and then starts to expand. As the rash expands, some portions begin to clear, forming a characteristic series of concentric rings known as Bull’s Eye rash. But sometimes, erythema migrans does not have concentric circles and instead adopt a uniform color. This sign is often persistent for 2 or 3 weeks, and after disappearing, it can reappear in recurrent episodes. In some cases, there’s not only one lesion but multiple areas with Bull’s Eye rash. In other cases, the lesion is found in difficult to reach areas, and patients do not realize they had a rash in the first place.
- Flu-like symptoms: Half of the patients with Lyme disease start experiencing flu-like symptoms 1 week after being bitter by the infected tick. These symptoms typically include fatigue and muscle pain or myalgia in up to 80% of them. They also report joint pain (arthralgia), neck stiffness, and headaches.
- Redness and tearing of the eyes: This is the earliest ocular manifestation of Lyme disease. As noted above, the bacterium has a tropism for the eye as well, but in the early stage, this does not lead to any permanent damage.
In stage 2 Lyme disease, these symptoms are more common:
- Malaise and fever: In this stage, the immune response starts to defend the body against the disease, and the body increases its temperature.
- Musculoskeletal symptoms: They are probably the most common symptoms. Patients feel joint pain and stiffness. It is usually a monoarticular joint problem in the ankle, knee, or wrist joint
- Neurologic symptoms: They are also common and include neuropathies of the cranial nerves causing facial nerve palsy. In other patients, it may trigger encephalopathy and meningitis. Headache is also prevalent, especially after the meningeal tissue is involved, and the most common signs of encephalopathy are confusion, changes in personality, and memory problems.
- Skin symptoms: After erythema migrans, patients may also develop smaller macular rashes of 1 to 5 cm. We can find a bluish to red swelling located on the nipple’s areola or the ear’s lobe in some patients.
In stage 3 Lyme disease, we would find these signs and symptoms:
- Acrodermatitis Chronica atrophicans: This is the worst skin consequence of Lyme disease, and it is more common in European patients. Patients initially get a reddish rash and swelling in a tender area of the skin. Then, the skin starts to change, destroying the sweat gland, hair follicles, and its normal fibers. Sometimes the skin ulcerates, too.
- Lyme arthritis: This is the late-stage manifestation of Lyme disease in the joints. The patient reports significant pain in larger joints, usually the knee. It is more severe than the usual arthralgia found in stage 2 Lyme disease.
- Late neurologic abnormalities: In stage 3, the disease causes chronic progressive encephalomyelitis and other anomalies that feature radicular pain and symptoms similar to fibromyalgia. The array of signs and symptoms is significantly large, including cognitive impairment, seizures, hearing loss, and much more.
Diagnosis and treatment
Diagnosis of Lyme disease is easier when doctors get to see the Bull’s Eye rash at the site of the tick bite. That would be by itself a significant sign that leads the diagnosis and treatment, especially when it is in concordance to the clinical signs and symptoms.
However, many patients do not refer or do not remember about any tick bite, and diagnostic tests become relevant to rule out this and other causes. The most common test to confirm the diagnosis is an antibody detection test. Serologic testing is sometimes negative in infected patients. So, in some cases, it is necessary to perform a joint aspiration, skin biopsies, and other tests to figure out what’s happening.
After diagnosing the ailment, treating Lyme disease is relatively easy because it only requires antibiotic treatment in early-stage patients or antibiotic and supportive therapy in patients with complications. The type of treatment, doses, and mode of administration depends on the stage of the disease, and late-stage Lyme disease usually requires hospitalization with intravenous therapy.
When an individual is diagnosed in endemic areas, others may also get antibiotic treatment to prevent latent Lyme disease and its complications. This prophylactic antibiotic therapy should only be administered in selected patients inside particular populations. Ask your doctor if a relative or someone close to you was recently diagnosed and you’re not entirely sure about receiving prophylaxis or not.
Conclusion
Lyme disease is caused by Borrelia burgdorferi, a spirochete bacterium that travels inside ticks and infects humans and other mammals. It goes through an incubation period, and the initial sign is a characteristic rash located in the site of the tick bite. Some patients do not notice the initial rash or do not remember being bitten by a tick. Thus, it is essential to consider Lyme disease’s diagnosis in patients with unexplained joint pain, headaches, malaise, neck stiffness, or fever of unknown origin.