expanding rash is an initial sign of about 80% of<unk>  infections. The rash may look like a ‘bull's eye’, as pictured, in about 80% of cases in Europe and 20% of cases in the US.<unk>  can affect several body systems and produce a broad range of symptoms. Not everyone with<unk>  has all of the symptoms and many of the symptoms are not specific to<unk>  but can occur with other<unk> s as well. The incubation period from infection to the onset of symptoms is usually one to two weeks but can be much shorter (days) or much longer (months to years).<unk>  symptoms most often occur from May to September in the northern hemisphere because the nymphal stage of the tick is responsible for most cases. Asymptomatic infection exists but occurs in less than 7% of infected individuals in the United States. Asymptomatic infection may be much more common among those infected in Europe. Early localized infection Early localized infection can occur when the infection has not yet spread throughout the body. Only the site where the infection has first come into contact with the skin is affected. The initial sign of about 80% of<unk>  infections is an erythema migrans (EM) rash at the site of a tick bite, often near skin folds such as the armpit, groin or back of the knee, on the trunk, under clothing straps, or in children's hair, ears or neck. Most people who get infected do not remember seeing a tick or a bite. The rash appears typically one or two weeks (range 3–32 days) after the bite and expands 2–3 cm per day up to a diameter of 5–70 cm (median 16 cm). The rash is usually circular or oval, red or bluish, and may have an elevated or darker center. In about 79% of cases in Europe but only 19% of cases in endemic areas of the U.S. the rash gradually clears from the center toward the edges, possibly forming a ‘bull's eye’ pattern. The rash may feel warm but usually is not itchy, is rarely tender or painful and takes up to four weeks to resolve if untreated. The EM rash is often accompanied by symptoms of a viral-like illness, including fatigue, headache, body aches, fever and chills but usually not nausea or upper-respiratory problems. These symptoms may also appear without a rash or linger after the rash has disappeared.<unk>  can progress to later stages without these symptoms or a rash. People with high fever for more than two days or whose other symptoms of viral-like illness do not improve despite antibiotic treatment for<unk> , or who have abnormally low levels of white or red cells or platelets in the blood, should be investigated for possible coinfection with other tick-borne<unk> s such as ehrlichiosis and babesiosis. Early disseminated infection Within days to weeks after the onset of local infection the Borrelia bacteria may spread through the lymphatic system or bloodstream. In 10–20% of untreated cases EM rashes develop at sites across the body that bear no relation to the original tick bite. Transient muscle pains and joint pains are also common. In about 10–15% of untreated people<unk>  causes neurological problems known as neuroborreliosis. Early neuroborreliosis typically appears 4–6 weeks (range 1–12 weeks) after the tick bite and involves some combination of lymphocytic meningitis, cranial neuritis, radiculopathy and/or mononeuritis multiplex. Lymphocytic meningitis causes characteristic changes in the cerebrospinal fluid (CSF) and may be accompanied for several weeks by variable headache and, less commonly, usually mild meningitis signs such as inability to flex the neck fully and intolerance to bright lights but typically no or only very low fever. After several months neuroborreliosis can also present otolaryngological symptoms. Up to 76.5% of these otolaryngological present as tinnitus, the most common symptom. Vertigo and dizziness (53.7%) and hearing loss (16.7%) were the next most common symptoms. In children partial loss of vision may also occur. Cranial neuritis is an inflammation of cranial nerves. When due to<unk>  it most typically causes facial palsy, impairing blinking, smiling and chewing on one or both sides of the face. It may also cause intermittent double vision.<unk>  radiculopathy is an inflammation of spinal nerve roots that often causes pain and less often weakness, numbness, or altered sensation in the areas of the body served by nerves connected to the affected roots, e.g. limb(s) or part(s) of trunk. The pain is often described as unlike any other previously felt, excruciating, migrating, worse at night, rarely symmetrical, and often accompanied by extreme sleep disturbance. Mononeuritis multiplex is an inflammation causing similar symptoms in one or more unrelated peripheral nerves. Rarely, early neuroborreliosis may involve inflammation of the brain or spinal cord, with symptoms such as confusion, abnormal gait, ocular movements, or speech, impaired movement, impaired motor planning, or shaking. In North America, facial palsy is the typical early neuroborreliosis presentation, occurring in 5–10% of untreated people, in about 75% of cases accompanied by lymphocytic meningitis.<unk>  radiculopathy is reported half as frequently, but many cases may be unrecognized. In European adults, the most common presentation is a combination of lymphocytic meningitis and radiculopathy known as Bannwarth syndrome, accompanied in 36-89% of cases by facial palsy. In this syndrome, radicular pain tends to start in the same body region as the initial erythema migrans rash, if there was one, and precedes possible facial palsy and other impaired movement. In extreme cases, permanent impairment of motor or sensory function of the lower limbs may occur. In European children, the most common manifestations are facial palsy (in 55%), other cranial neuritis, and lymphocytic meningitis (in 27%). In about 4–10% of untreated cases in the U.S. and 0.3–4% of untreated cases in Europe, typically between June and December, about one month (range 4 days-7 months) after the tick bite, the infection may cause heart complications known as<unk>  carditis. Symptoms may include heart palpitations (in 69% of people), dizziness, fainting, shortness of breath, and chest pain. Other symptoms of<unk>  may also be present, such as EM rash, joint aches, facial palsy, headaches, or radicular pain. In some people, however, carditis may be the first manifestation of<unk> .<unk>  carditis in 19–87% of people adversely impacts the heart's electrical conduction system, causing atrioventricular block that often manifests as heart rhythms that alternate within minutes between abnormally slow and abnormally fast. In 10–15% of people,<unk>  causes myocardial complications such as cardiomegaly, left ventricular dysfunction, or congestive heart failure. Another skin condition, found in Europe but not in North America, is borrelial lymphocytoma, a purplish lump that develops on the ear lobe, nipple, or scrotum. Late disseminated infection After several months, untreated or inadequately treated people may go on to develop chronic symptoms that affect many parts of the body, including the joints, nerves, brain, eyes, and heart.<unk>  arthritis occurs in up to 60% of untreated people, typically starting about six months after infection. It usually affects only one or a few joints, often a knee or possibly the hip, other large joints, or the temporomandibular joint. There is usually large joint effusion and swelling, but only mild or moderate pain. Without treatment, swelling and pain typically resolve over time but periodically return. Baker's cysts may form and rupture. In some cases, joint erosion occurs. Chronic neurologic symptoms occur in up to 5% of untreated people. A peripheral neuropathy or polyneuropathy may develop, causing abnormal sensations such as numbness, tingling or burning starting at the feet or hands and over time possibly moving up the limbs. A test may show reduced sensation of vibrations in the feet. An affected person may feel as if wearing a stocking or glove without actually doing so. A neurologic syndrome called<unk>  encephalopathy is associated with subtle memory and cognitive difficulties, insomnia, a general sense of feeling unwell, and changes in personality. However, problems such as depression and fibromyalgia are as common in people with<unk>  as in the general population.<unk>  can cause a chronic encephalomyelitis that resembles multiple sclerosis. It may be progressive and can involve cognitive impairment, brain fog, migraines, balance issues, weakness in the legs, awkward gait, facial palsy, bladder problems, vertigo, and back pain. In rare cases, untreated<unk>  may cause frank psychosis, which has been misdiagnosed as schizophrenia or bipolar disorder. Panic attacks and anxiety can occur; also, delusional behavior may be seen, including somatoform delusions, sometimes accompanied by a depersonalization or derealization syndrome, where the people begin to feel detached from themselves or from reality. Acrodermatitis chronica atrophicans (ACA) is a chronic skin disorder observed primarily in Europe among the elderly. ACA begins as a reddish-blue patch of discolored skin, often on the backs of the hands or feet. The lesion slowly atrophies over several weeks or months, with the skin becoming first thin and wrinkled and then, if untreated, completely dry and hairless.
Lyme disease
Cellulitis
Mumps
Bell's palsy
Rabies
Meningitis
Rickettsialpox
Scarlet fever