Lyme borreliosis
(Lyme disease)
Bacterial infection
Many possible symptoms
May resemble other diseases
Unreliable tests
Treatments often inappropriate
Can become chronic
Lyme borreliosis
Bacterial infection
Many possible symptoms
May resemble other diseases
Unreliable tests and often inappropriate treatments
No vaccination possible
Can become chronic
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THE INFECTION
What is Lyme borreliosis?
Lyme borreliosis (often referred to as Lyme disease) is a tick-borne infection caused by bacteria of the Borrelia genus, closely related to those responsible for syphilis. The disease was first identified in 1975 in the town of Lyme, USA, after children developed chronic joint pain following tick bites [1].
The first bacterium identified as responsible for this disease was Borrelia burgdorferi, discovered by Willy Burgdorfer. Since then, many other Borrelia species (such as B. garinii, B. afzelii, B. bavariensis, etc.) have been recognized as sources of human infection [1].
The various Borrelia species are geographically present all over the globe, in both urban and rural areas, and not just in the USA, as the disease's name suggests. Contrary to the preconceived ideas of some healthcare professionals, it is possible to contract Lyme borreliosis in almost all parts of the world [2-3].
A bacterium among many infections:
Borrelia is one of many other infectious pathogens that can be transmitted by tick or insect bites [4-5]. When other pathogens are present in addition to Borrelia, it is referred to as "co-infections" [6]. In many cases, it is the combination of these different pathogens in the same patient, as well as the complex immune response to their simultaneous presence, that is responsible for the severe and disabling chronic symptoms [7-8-9].
How is it transmitted?
The bacterium is transmitted to humans by the bite of an infected tick. Ticks feed on the blood of a variety of animals, while humans have now become frequent targets. They live in forests, undergrowth and meadows, and can also be found in urban woodlands, city parks and private gardens [10].
Ticks have 3 developmental stages (larva -> nymph -> adult). Only ticks in the nymph (spring) and adult (autumn) stages can transmit Borrelia [11]. Larvae do not contain Borrelia, and get infected after a blood meal on small mammals and birds in summer.
It is commonly accepted that the bacterium takes between 24 and 72 hours to be transmitted from tick to host [12]. However, a study on mice reported a delay of only 12 hours [13]. Some experts even believe that the bacterium can be transmitted in a matter of minutes if the tick has already fed on another host before biting a human.
Their extremely small size (1mm to 3mm) means they often go unnoticed and are difficult to spot on the body.
How many ticks carry Borrelia?
In Switzerland, between 5% and 50% of ticks are infected with a Borrelia species. The Swiss Federal Office of Public Health estimates that 10,000 people in Switzerland contract Lyme borreliosis every year [15].
Ticks are also often carriers of numerous other infections (Babesia, Bartonella, Rickettsia, Anaplasma, etc.). In Switzerland, between 79% and 83% of ticks have been reported to carry at least one infectious pathogen [16].
Most studies on Borrelia transmission have focused on the Ixodes Ricinus species. However, the bacterium has been found in over 25 different species of Ixodes and at least 15 other tick genera such as Amblyomma, Boophilus, Dermacentor, Haemaphysalis, Hyalomma, etc. [17].
Ixodes
Ricinus
Dermacentor
Reticulatus
Hyalomma
Marginatum
Rhipicephalus
sanguineus
Contrary to popular belief, ticks do not "jump" onto their hosts or fall from trees, but simply use static electricity to stick to the fur or skin of their targets as they pass near infested bushes/grasses [14].
REFERENCES
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