Kathleen Z. Rooney
Medically, we know quite a bit about these two diseases. In Lyme disease, the tick transmits the bacteria Bb as it feeds on the host's blood. After the tick attaches itself to the human, it uses its mouthparts to open a tiny wound in the skin, into which blood will pool and from which the tick will drink. The tick has special secretions in its saliva to anesthetize the wound and to keep the blood from clotting. The tick drinks blood, and pumps out these secretions as it stays attached to the person. As the blood collects in the tick's midgut, the Bb inside of the tick multiplies in the presence and nutrients of the blood. This process creates a mini factory for Bb to multiply exponentially and be injected into the person's body. As a result, the usual acquisition of Bb occurs only after an attachment of 48 hours.
Once inside a human the bacteria can create three stages of Lyme disease. The acute stage occurs 7-14 days from the tick bite and presents itself as a rash called erythema migrans. In light skinned people it resembles a "bull's-eye" pattern - in dark skinned people it resembles a bruise. Flu-like symptoms may begin to occur at this point. Stage 2 occurs several days to weeks after the initial infection and may include fever, fatigue, head and neck pain and stiffness in joints. Stage 3 is a persistent infection in untreated or inadequately treated patients. This includes arthritis, persistent pain, swelling (often in the knees) and neurological symptoms.
Treatment for Lyme disease is an antibiotic such as Doxycycline, for 14 -21 days. Most infections respond to treatment, although there remains a controversy over lingering infections. Some believe that Bb can evade antibiotics and live silently in the body for some time, causing problems after many months or years. This controversy led to major schisms about treatment and eventually to Senate hearings in 1993.
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West Nile Virus can cause a range of disease in humans. It is caused by a virus called a flavivirus, and is related to several other disease agents such as Japanese encephalitis virus and St. Louis encephalitis virus. The incubation from the time of bite is 2-24 days. It has three potential clinical outcomes. One is asymptomatic. It is believed that 80% of infections result in no noticeable symptoms. The second is known as West Nile Fever. This disease is a flu-like illness that can present sore throat, fever, and even vomiting in a third of cases. The third possible outcome is West Nile Neurological Disease (WNND). This syndrome is the most severe and can include neurological impairment, encephalitis and death. Forty-one percent of reported infections are WNND; however only 4% of all WNV cases are fatal. It is believed that the number of WNND disease cases is an excellent indication of overall infection rates. The estimate is that for every case of WNND there are 28 cases of WN Fever and 140 infections with the virus, again most being asymptomatic.
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Treatment is for relief of symptoms and supportive therapies such as hydration and fever reduction.
