- Diseases, Disorders & Conditions
Lyme Disease - A Multisystem Disorder With Joint Pains, Heart Block, And Nerve Damage
Deer Ticks Are the Most Common Carriers of Infection
Lyme Disease - An Overview
Are you an avid traveler who occasionally wanders in the woods, explores new destinations, has a keen interest in wildlife, or a bird watcher, or a naturalist? Do you have pets at home? Do you stay in a stud farm or a dairy farm with lots of cattle grazing around/ (even though you might be regularly taking them to a veterinary practitioner !)
Reading this long list of queries you might think of me to be an obsessive compulsive who washes hands as a ritual or an overzealous health worker who looks for disease and illnesses in every grain of barley. But after reading the following facts, you might pay more attention to this subject.
- Named after the town of Old Lyme, Connecticut, Lyme disease is the most common vector-borne disease of bacterial origin in the Northern hemisphere.
- Mice and deer make up the major animal reservoirs of infection.
- The primary vectors of the disease are hard ticks that parasitize a wide range of animals, including humans.
- In endemic areas the domestic animals like pets, horses and cattle are frequently infected.
- The disease can also be transmitted by deerflies, horseflies, and mosquitoes or by direct contact with fluid from infected animals.
- Once established, the infection can manifest as a skin rash, headache, stiffness of the neck, joint pain, muscle ache and later become a multi-system disorder with nerve damage, cognitive decline and can even lead to paraparesis or weakness and reduced power of the limbs.
Lyme borreliosis is a vector-borne infection mainly transmitted by Ixodid or wood ticks and caused by three different species of a spirochete borrelia, that include the following:
- Borrelia burgdorferi sensu stricto (found mainly in the U.S.)
- Borrelia garinii
- Borrelia afzeli (found in other parts of the world).
- Borrelia bisseti nov (found in California).
The Ixodid ticks may also transmit other infections like babesiosis, ehrlichiosis, and tick-borne encephalitis along with borreliosis.
The Bacterium Borrelia burgdorfei
Borrelia burgdorferi, the causative agent of this disease is a fastidious, microaerophilic (can grow in low oxygen concentrations) bacterium that grows best at 33 degree Celsius temperature, in a complex liquid medium called Barbour, Stoenner, Kelly (BSK) medium.
Systems That Bear the Brunt of Lyme Disease
Lyme causing bacteria affects which of the following organ systems in our body ?
Worldwide Distribution of Lyme Disease
The endemicity of this disease correlates with the geographic ranges of certain species of Ixodes vectors.
- Ixodes damminni is the principal vector in the North Eastern United States, from Massachusetts to Maryland and in the Mid-Western states of Wisconsin and Minnesota.
- Ixodes pacificus is the vector in the Western states of California and Oregon.
- Throughout Europe, Ixodes ricinus is the vector.
- In Asia, China, and Japan, Ixodes persulcatus is the vector.
In the United States Ixodes damminni also transmits Babesiosis and Ehrlichiosis; In Europe and Asia, Ixodes ricinus and Ixodes persulcatus also harbor and spread encephalitis infections.
Mice and deer make up the major animal reservoirs of Borrelia burgdorferi, but other rodents and birds may also harbor the infection. Domestic animals such as dogs, cattle, and horses can also develop clinical illness usually manifested as arthritis.
Seasonal Variation In Lyme Disease
Lyme Like Illness
There is also a non-culturable spirochete that is transmitted by the Lone Star tick (Amblyomma americanum). This organism produces a Lyme disease-like illness with a skin lesion very similar to that caused by Borrelia.
As the Lone Star tick is found in the Midwest and Southern areas, cases of Lyme disease reported from these areas are probably due to this organism. This condition is better known as Southern tick-associated rash illness (STAR) or Master's disease.
Peculiar Behavior of Lyme Disease Vectors
Lyme disease-carrying ticks feed once during each of the three stages of their life cycle. Larval ticks feed in late summer, nymphs in the following spring and early summer, and adults during the fall.
The mouse is tolerant of the borrelia microbe, a fact that is critical for maintaining the infection.It is the mouse that transmits the infection to larvae in late summer after being infected from the nymphs in early summer.
Most infections occur in spring and summer when nymphs are active, and fewer cases in cooler months (October to April) when adults feed.
This is due to the greater abundance of nymphs; human outdoor activity in spring and summer; and the fact that adult ticks are larger, easier to detect and thus can be removed before the disease gets transmitted (ticks must feed for 24 hours or longer to transmit the infection).
Removal of Lyme Disease Vector
Ixodes ticks are smaller than the more common dog ticks. Because the ticks are so small, the bite is usually painless and goes unnoticed.
After feeding the tick drops off in 2-4 days. If a tick is found, it should be removed immediately.
The best way to accomplish this is to grab the mouth part- not the body - where it enters the skin, with a pair of fine-tipped tweezers and pull firmly and repeatedly until the tick releases its hold.
You can even save the tick in a bottle of alcohol for future identification, especially if symptoms develop.
Lyme Disease in a Summary
- Lyme disease is a common vector-borne infection that can occur during hiking, camping, or hunting trips and residence in wooded and rural areas.
- Mice and deer are the common animal hosts to the disease carrying Ixodes sp of ticks.
- The infection begins with an annular, red-colored patch on the skin, and can spread throughout the body.
- During early stages of infection severe headache, migratory muscle, bone, and joint pains are common, along with a mild degree of heart block.
- In late stages of the disease, the immune system gets affected, leading to chronic severe disabling knee joint arthritis, mood disturbances, and memory loss.
Signs and Symptoms of Stage - 1 (Early Localized Infection)
After being inoculated into the skin, borrelia organism may migrate outward, producing a characteristic skin lesion, and may also spread via the bloodstream to other parts of the body.
Following an incubation period of 3 to 32 days, Erythema migrans (a skin rash characteristic of the disease) occurs at the site of tick bite, beginning as a red spot or a pimple that expands to form a large annular lesion, with a bright red outer border, and central clearing.
Due to the very small size of Ixodes species, most people do not remember a preceding tick bite.
Sometimes the center of the lesion may become intensely red and swollen, else the expanding patch shows several rings within the outer ring. Areas where clothes are tightly fitted to the skin, such as the thigh, groin, and underarm area are the most common sites where this lesion develops.
Perhaps as many as 25% of the people do not exhibit this characteristic skin sign, or it may go unnoticed.
A flu-like illness, with fever, chills, and muscle ache occur in about half of the individuals.
The skin rash resolves within a month even without treatment.
Clinical Presentation of Lyme Disease
Erythema migrans skin rash
Headache and neck stiffness
Chronic knee arthritis
Migratory joint pains without swelling
Red-violet patches on front of forearms and legs
Clinical Manifestations of Stage - 2 (Early Disseminated Infection)
Within days to weeks after the onset of skin rash, the microbe spreads through the bloodstream to different parts of the body.
It then causes annular skin lesions similar to the initial lesion but smaller in size at multiple sites, along with a severe headache, a mild stiffness of neck, fever, chills, migratory muscular and bone pains, joint pains (usually without joint swelling) lasting for hours or days, and severe fatigue.
Various other signs like swelling of lymph nodes, enlargement of spleen and liver, sore throat, dry cough, and conjunctivitis may also accompany.
These early symptoms reduce in intensity or disappear completely within several weeks even without taking any treatment.
Within several weeks after the onset of illness, around 8% of the individuals suffer from cardiac problems. The most common abnormality is a fluctuating degree of atrioventricular block (first degree, Wenckebach, or complete heart block).
In some people the borrelia spirochete bites the heart harder, leading to inflammation of the heart muscle, left ventricular dysfunction, and enlargement of heart as a whole.
In rare instances, it can even lead to a chronic cardiomyopathy.
Signs and Symptoms of Stage - 3 (Late Persistent Infection)
Months after the onset of infection about 60% of the individuals who have received no antibiotic treatment, develop frank arthritis.
The typical pattern comprises of intermittent attacks of arthritis in large joints (especially the knees), lasting for weeks to months in a given joint.
Small joints and structures around them may also be affected, mainly during early attacks.
The rate of recurrence reduces each year. However in a small percentage of cases, the involvement of large joints - usually one or both knees - becomes chronic, and may lead to erosion of bone and cartilage.
In such people, on analysis their joint fluid has a very high count of white blood cells (on an average, 25,000/micro liter) and antibodies to OspA and OspB protein (major outer surface protein of Borrelia), but lack Borrelia DNA in synovial fluid as detected by PCR.
Tests for rheumatoid factor or antinuclear antibody test for lupus erythematosus usually give negative results.
Although less common, chronic nervous system involvement may become apparent months or years after the onset of infection, sometimes following long periods of latent infection.
It begins as subtle changes in mood, memory, or sleep disturbances and progresses to tingling in the nerves or pain along particular spinal nerve segments.
Acrodermatitis Chronica atrophicans is a late skin manifestation associated with Borrelia afzelli infection in Europe and Asia. Seen mainly in elderly women, the lesion begins insidiously with reddish to violaceous discoloration on acral surfaces of arms and legs (on the front of forearms and legs) and gradually develop hardening and thinning of skin over a period of years.
Lyme disease is caused by the spirochete Borrelia burgdorferi and transmitted by vectors of Ixodes species that carry the microbe in their intestines.
It progresses in three phases, consisting of expanding skin lesions, cardiac and neurological disease, and progressing into arthritis and a chronic neurological syndrome.