Is Lyme Disease Contagious?
The increasing awareness of Lyme disease has many people worried about their risk of infection and has led some to ask: Is Lyme disease contagious? The short answer given by official health authorities such as the CDC is no, Lyme disease is only transmitted through tick bites and cannot be contracted through sexual contact with an infected person or through blood transfusion. The fact that many members of the same family may have Lyme disease is explained by the CDC, and others, as most likely the result of living in a Lyme-endemic area and all those infected having been bitten by an infected tick often without noticing the bite. There is no evidence that Lyme disease can be transmitted by kissing, touching, or sharing food or water. Lyme disease cannot be passed through the air either.
Blood Donation and Lyme Disease
Lyme disease is transmitted by ticks infected with Borrelia bacteria and there is no evidence showing it to be contagious. Scientists have found that the bacteria that cause Lyme disease can live in donated blood from someone with an active infection however, and those being treated for Lyme disease with antibiotics are discouraged from donating blood for this reason. Once Lyme disease infection is cleared these people may be free to donate blood once again. No cases of Lyme disease have been linked to blood transfusions.
Lyme Disease in Pregnancy
The effects of Lyme disease in pregnancy are a little less clear however, with some evidence of teratogenicity of Lyme disease and concerns over Lyme disease complications resulting in autism or stillbirth if left untreated. A study of hamsters carried out by Woodrum and Oliver (1999) found no evidence of infection occurring through sexual contact or through transmission of Lyme disease to offspring of those hamsters deliberately infected with Lyme disease. These researchers also attempted to infect the hamsters through contact with other (infected) hamsters urine and faeces but to no avail. Venereal transmission of Lyme disease may be touted by some Lyme advocates as the cause of thousands of cases of the disease but there is a glaring lack of scientific evidence to show that this is at all possible.
Evidence of Lyme disease being passed from mother to child is also quite scarce, leaving the whole topic open to myth, and scaremongering. Results from animal studies suggests that acute infection with Lyme disease after conception is connected with an increased risk of adverse pregnancy outcome if the infection is not treated. Those animals made pregnant after they were infected with Lyme disease had no apparent increase in their risk of adverse pregnancy outcomes however, providing some reassurance perhaps for those concerned over becoming pregnant whilst suffering with an undiagnosed Lyme disease infection. Where the pregnant animals were treated appropriately with antibiotics no negative effects on the foetus have been observed.
Untreated Lyme Disease in Pregnancy
A review of the treatment and outcome of 95 women in Budapest diagnosed with Lyme disease in the past couple of decades showed an association between untreated infection and adverse pregnancy outcomes (Lakos, et al, 2010). Of the 95 women with Lyme borreliosis during their pregnancy 66 received intravenous antibiotic treatment, 19 received oral antibiotics, and 10 were untreated during their pregnancy. 12.1% of the women receiving IV antibiotics had an adverse outcome of some kind, compared to 31.6% of those treated with oral antibiotics, and 60% of those untreated for the infection. Another finding in this study was that a single course of antibiotics was insufficient to clear the infection in 17 patients and that those patients, deemed ‘slow responders’, had a higher risk of adverse outcome, although this was not statistically significant (i.e. it could have simply been due to chance). The most prevalent adverse outcomes were loss of pregnancy (in seven cases), and hemangioma (in four cases).
The researchers in this study could not demonstrate bacterial infection of the foetus in any case, due to the retrospective nature of the study, but they do suggest that there is no clear evidence for the existence of congenital Lyme borreliosis. Lyme disease is also not considered contagious through breastfeeding although the selection of Lyme disease antibiotic treatment is usually similar for those pregnant and breastfeeding to minimise the risks to the infant.
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Woodrum JE, Oliver JH Jr. Investigation of venereal, transplacental, and contact transmission of the Lyme disease spirochete, Borrelia burgdorferi, in Syrian hamsters. J Parasitol. 1999 Jun;85(3):426-30.
Lakos A, Solymosi N. Maternal Lyme borreliosis and pregnancy outcome. Int J Infect Dis. 2010 Jun;14(6):e494-8. Epub 2009 Nov 18.