Lyme disease
Lyme disease (borreliosis) is named after a town in Connecticut. Lyme disease is caused predominantly by Borrelia burgdorferi in United States. The Lyme disease is one of the most common vector borne diseases, transmitted by a tick. It is one of the over reported and over diagnosed diseases. Only quarter of the patients referred to the Lyme disease clinic were found to have the disease. In 2006, 19,931 cases of Lyme disease were reported yielding a national average of 8.2 cases per 100,000 persons.
Causative Organism & features:
Organism: Borrelia burgdorferi, a type of Spirochete. Gram negative and can be cultured. Major animal reservoir: Deer, mice, and squirrels.
Transmission:
The Lyme disease is transmitted by a vector, tick.
The vector varies geographically: 1) In northeast, north central and mid Atlantic regions of the united states; Ixodes scapularis (black-legged tick). 2) In west coast; Ixodes pacificus (also a black-legged tick). 3) In Europe; Ixodes ricinus. 3) In Asia; Ixodes persulcatus.
High Incidence: It is the disease of all age and gender. But most common among boys aged 5-19 and persons aged 30 or older.
Incubationa period:the period between the infection of an individual by a pathogen and the manifestation of the disease it causes first symptom to appear after infected take around 3 to 30days.
Pathophysiology:
In some cases the the infection subsides without any symptoms. After getting infected The causative organism enters the skin causing skin lesions and later spreads via bloodstream or lymps to involve Joints, heart and central nervous system. The organ lesions are mains by immune response.
Symptoms and Signs
The symptoms and signs are discussed under 3 different stages:
Stage I
The stage one is mainly characterized by skin lesion, erythema migrans. After a delay of 1 to 30 days of tick bite a red maculopapular lesion appear at the site of bite. The primary red lesion enlarge up to 12 inches, feels hot and itchy. As the primary red lesion enlarges the centre of the lesion clears and resembles the “Bull Eye”. Other symptoms include fever, chills, headache, and malaisean indefinite feeling of debility or lack of health often indicative of or accompanying the onset of an illness; fever, malaise, and other flulike symptoms. If not treated, the disease progress to next stage.
Stage II
The symptoms and signs of stage II develops days to weeks after the Borrelia burgdorferi inoculation by tick bite. This stage is also called as early disseminated stage as the infection spreads to the different organs. The infective organism spreads throughout the body causing skin lesions (Erythema migrans) on other areas of the body, swollen lymph nodes, migratory joint and muscle pain, cardiac arrhythmias, and meningitis (symptoms include headache, photophobia1) intolerance to light; especially : painful sensitiveness to strong light 2) an abnormal fear of light, and stiff neck) often with cranial nerve involvement.
Stage III
This stage develops couple of years after the initial tick bite in untreated or inadequately treated patents. Stage II is also called as late disseminated stage. The primary systems involved are skin, musculoskeletal and nervous system. Clinical manifestations include chronic arthritis, encephalitis, neuropsychiatric symptoms and ophthalmic manifestations.
Differential diagnosis
Gonococcal arthritis
Gout
SLE
Meningitis
Lab Works
CDC recommends a two-step process
1) The first step uses an ELISA or IFA test. If the ELISA or IFA is positive, a second step should be performed to confirm the results.
2) The second step uses a Western blot test: Highly specific. Helps to rule out false positive in ELISA or IFA
Treatment
1) Erythema migrans:
Doxycycline , amoxicillin , or cefuroxime axetil
2) Lyme meningitis and other manifestations of early neurologic Lyme disease:
ceftriaxone
3) Lyme arthritis:
Doxycycline, amoxicillin , or cefuroxime axetil.