Lyme disease, also known as borreliosis, is a Borrelia burgdorferi bacterium infection. The bacterium is transmitted to humans when they are bitten by an infected tick.
Borrelia burgdorferi has a unique feature not present in any other known organism - it can exist without iron. All other life requires iron to make proteins and enzymes. The bacterium that causes Lyme disease substitutes manganese to make an essential enzyme. With this characteristic it is able to elude immune system defenses that protect the body by starving harmful bacteria of iron.
According to the National Institute of Allergies & Infectious Diseases, Lyme disease is the most common tickborne infectious disease in the USA.1
The U.S. CDC (Centers for Disease Control and Prevention) registered 25,359 confirmed cases of Lyme disease and 8102 probable cases in 2014. Ninety-six percent of Lyme disease cases were reported from 14 states: Wisconsin, Virginia, Vermont, Rhode Island, Pennsylvania, New York, New Jersey, New Hampshire, Minnesota, Massachusetts, Maryland, Maine, Delaware and Connecticut.2
However, figures released by the CDC in August 2013 have suggested that the diagnoses of Lyme disease may be ten times higher than the officially reported number, with approximately 300,000 cases of Lyme disease each year in the USA.
How is Lyme disease transmitted?
Borrelia burgdorferi, the Lyme disease-causing bacterium, enters humans through the bite of:
- An infected blacklegged tick (Ixodes scapularis), formerly known as the deer tick, where the disease is spread in the north-central, northeastern and mid-Atlantic USA.
- The infected western blacklegged tick (Ixodes pacificus), where the disease spreads on the Pacific Coast of the USA.
- An infected sheep tick (Ixodes ricinus), a European species of hard-bodied tick.
A blacklegged tick, formerly known as the deer tick.
Apart from Lyme disease, blacklegged ticks can also spread human anaplasmosis, babesiosis, and Powassan encephalitis.
The adult tick or the young nymph bores a tiny hole in the skin and inserts its mouthparts into the opening, attaching itself to the host. Ticks tend to attach to hard-to-see areas of the human body, such as the scalp, armpits and groin.
Generally, the tick must remain attached for at least 24 hours before transmitting the Borrelia burgdorferi bacterium into a human.
Nymphs are the hardest to find because they are so small. Human infections usually occur as a result of nymph bites because people tend to get rid of the larger adults, even though they are about the size of a pencil point, before they have time to transmit the bacterium.
The Blacklegged Tick (Ixodes scapularis). Source: CDC
Lyme disease transmission - faq
We will answer some of the most frequently asked questions about Lyme disease in the section below.
1) Can Lyme disease spread from human-to-human?
No. You cannot become infected by touching, kissing or having sex with an infected person.3
2) What happens if I am pregnant and have Lyme disease?
There is a risk the bacterium can infect the placenta, resulting in a higher risk of stillbirth. According to the CDC, antibiotic treatment given to a pregnant mother for Lyme disease does not effect the fetus.4
3) Can I breastfeed if I have Lyme disease?
The CDC says there are no reports of Lyme disease transmission from breast milk.5 However, in the U.S. Department of Agriculture's (USDA's) guidelines on Infant Nutrition and Feeding, it states "Other infectious diseases for which breastfeeding may need to be temporarily discontinued while therapy is initiated or the risk of transmission is passed include hepatitis, cytomegalovirus (CMV), herpes simplex virus, varicella-zoster virus, tuberculosis, and Lyme disease."6
The National Health Service (NHS), UK, says that the Lyme disease-causing bacterium Borrelia burgdorferi cannot be passed on through breast milk.7
A doctor will ask a nursing mother to stop breastfeeding until her course of antibiotic treatment has been completed.
4) Can Lyme disease be transmitted through blood transfusion?
Experts say this is highly unlikely. There have been no documented cases of Lyme disease being transmitted via blood transfusions. If you are being treated with an antibiotic you should not donate blood.
5) Can my dog or cat transmit Lyme disease?
Dogs and cats can get Lyme disease. However, they cannot infect humans. It is important to check your pets for ticks because they can bring them into the house.
6) Can I get Lyme disease from eating venison?
According to the Missouri Department of Conservation "there has never been a documented case of a human contracting Lyme disease through the handling or consumption of venison."
7) Can I get Lyme disease from the environment?
You cannot get Lyme disease from the air, food or water. It is not possible either to become infected from the bites of lice, mosquitoes, fleas or flies.
8) How worried should we be about ticks?
With the arrival of the warmer months each year comes the re-emergence of ticks. If you're wondering how worried you should be about ticks, read our article here.
Recent developments on Lyme disease causes from MNT news
Lyme disease is the most commonly reported vector-borne malady in the US. Caused by the bacterium Borrelia burgdorferi, it is passed to humans through the bites of infected blacklegged ticks, also called deer ticks. But health officials are now reporting the discovery of a new species of bacteria that also leads to Lyme disease in humans.
Symptoms of Lyme disease
Lyme disease has three stages: 1. Early Lyme disease. 2. Early disseminated Lyme disease. 3. Late Lyme disease.
Initial signs and symptoms of Lyme disease are usually very mild. In fact, many people may notice nothing at all, unless they are aware of the telltale signs. If you do suspect Lyme disease, get medical help immediately. Early treatment is much more effective.
Early Lyme disease (Stage 1)
Erythema migrans (EM), which in Latin means "migrating redness", refers to a rash that often appears in the early stage of Lyme disease. In some cases the patient might have it but does not know, especially if it develops on the scalp or buttocks.
The rash is not an allergic reaction to a tick bite - it is a skin infection.
Erythema migrans (EM) usually appears between 7 to 14 days after exposure to the Borrelia burgdorferi bacterium. However, this can vary from three to thirty-one days.
Erythema migrans rash in the pattern of a "bull's-eye"
- The EM rash typically begins as a small red area which expands over a period of several days. It may eventually reach a diameter of 12 inches (30 cms). The rash is less evident in people with dark skin.
- In some cases the center of the rash loses its color, giving the whole area a bull's-eye appearance.
- The most common areas for the rash are the armpits, trunk, groin, buttocks, scalp, the nape of the neck, and thighs. It usually starts off at the site of the tickbite, but not always.
- The rash usually feels warm when touched (not always)
- There is no pain or itchiness
- As Borrelia burgdorferi bacteria circulate through the blood, patches of rash may appear in other parts of the body.
- The rash gradually clears up after about four weeks, even if the Lyme disease is left untreated.
Other symptoms may occur at the same time as the rash, including fever, swollen lymph nodes, fatigue, chills and joint pains. However, in most cases the affected person may not perceive them as serious enough to see a doctor. These symptoms may be short-lived, only to appear later on as the infection develops.
Early disseminated Lyme disease (Stage 2)
If left untreated, the bacterium may spread elsewhere in the body and cause a range of symptoms, including some body functions. This stage appears weeks to months after initial infection.
Signs and symptoms may include:
- Other Erythema migrans rashes. These can appear anywhere.
- Bell's palsy - the muscles on one side of the face lose their tone. In some cases, both sides might be affected.
- Meningitis - spinal cord inflammation. The patient experiences painful headaches and has a stiff neck.
- The large joints, such as the knees become painful and swollen.
- Numbness and/or shooting pains in the arms and legs - in some cases the patient may find it hard to sleep.
- In rare cases, abnormal heartbeat
In most cases, within a few weeks or months, these symptoms will gradually go away, even if the patient remains untreated.
However, if no proper treatment is administered, complications may develop.
Late disseminated Lyme disease (Stage 3)
This stage is also known as chronic Lyme disease. In untreated patients it can occur weeks, months and even years after initial infection. Even treated patients whose antibiotics did not kill off all the bacteria can reach this stage.
The following symptoms are associated with late disseminated Lyme disease:
- Chronic Lyme arthritis - over 50% of untreated patients may start having recurrent bouts of arthritis, with severe joint swelling, especially of the large joints, such as the knees, according to a study published in Annals of Internal Medicine.
- Difficulty concentrating
- Unrestful sleep
- Chronic muscle pain
- Memory loss
- Tingling and/or numbness in the hands or feet.
On the next page we look at how Lyme disease is diagnosed and the available treatments for Lyme disease. On the final page we demonstrate how to remove a tick and discuss how some animals are genetically protected against Lyme disease.