LABINFORMATION
Pathogen detection in ticks
Diseases transferred by ticks
A bite from an infected tick can transmit a whole
series of pathogens. Through modern molecular-biological methods a broad range of these pathogens
has become detectable. These methods are generally available nowadays. For many of these pathogens
case studies have been published proving a link or
at least making a link probable between detection
in the tick, transmission through a bite and disease.
After a tick bite those afflicted therefore want to protect themselves against a disease or at least know
whether they have contracted something. Despite
applying molecular biology this is not always possible. Even if a pathogen has been detected in a tick,
no transmission to humans must have taken place
and the disease is not necessarily forced to break out
after a transmission either. Whether any pathogens
have been transmitted at all, depends on many other
factors such as very much on the duration of the tick
bite. Therefore prompt and professional removal is
often the proper and adequate preventive measure. For many people it is nevertheless reassuring if
the tick which they were bitten by probably was not
infected or, if so, they are being closely monitored.
What pathogens are transmitted by ticks? The following summarises the key infections:
The following pathogens can be transmitted by ticks
frequently
TBE-Virus
Borrelia
Ehrlichiosis
possible
Anaplasma
Bartonella
Babesia
Coxiella burnetii
Rickettsia
Francisella tularensis
very rarely
or no occurrence in
Germany
Crimean-Congo haemorrhagic
fever virus
Kyasanur Forest disease virus
Omsk haemorrhagic fever
virus
Borrelia duttonii
Tick Borne Encephalitis virus (TBE virus)
The virus is transmitted by the tick bite right at the
beginning of the bloodsucking process (not until later with borrelia!); no transmission from person to
person. The most important transmitter of the TBE virus is the tick (Ixodes ricinus and Ixodes persulactus);
parallel transmission of B.burgdorferi, Ehrlichia spp.
and Babesia spp. possible. In endemic areas the infection frequency rises during the early summer and
also in the autumn, l.ricinus particularly at a forest‘s
edge and in clearings with high grass, also affects
deciduous and mixed forests or waysides. Forestry
workers, walkers, joggers etc. are at risk. In TBE endemic areas 1-5% of ticks are infected with the virus.
At altitudes > 1,000 m there are no ticks. A minimum
temperature of approx. 8°C is required for the pathogens to multiply. Pathogen reservoirs are small
mammals (esp. mice), birds, deer and red deer.
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The viruses reach the regional lymph nodes via the
lymphatic system, from where they spread into all
organs, also into the central nervous system. Those
infected manifest flu-like symptoms in approx. 30%
of cases after an incubation period of 3 to 14 (up
to 28) days. The first phase of the disease lasts between four and six days, many patients only undergo
this part of the progression of the disease.
However, in 6-10% of these symptomatic progressions after a 4 to 10(20)-day interval without any
symptoms there arises a wide variety of neurological symptoms: fever, headaches, meningitis, meningoencephalitis, which last for 7-10 days. In 10% of
cases lasting neurological damage can occur. The
lethality of the 1-2% of people afflicted with CNS involvement increases with age.
Prevent exposure by wearing closed bright clothing,
check body for ticks, especially between the legs,
the back of the knees, armpits, neck, hairline. Rapid and complete removal of the complete tick(s);
do not squeeze, do not use adhesive or oil, use tick
tweezers.
Active immunisation: people in TBE risk areas or
those whose work exposes them to TBE (e.g. forestry workers), also for children aged one or above.
Start an active immunisation no later than 14 days
before entering a TBE natural focus. Active immunisation is not generally recommended directly after a
tick bite in a risk area. Endemic TBE areas with natural foci are primarily to be found in the south of
Germany in Bavaria, Baden Württemberg, Hessen
(Bergstraße, Odenwaldkreis), east of Marburg, Rhineland-Palatinate, Saarland; very rarely in Brandenburg, Thuringia, Saxony; Europe - Russia, Lithunia,
Tschechia, Slovenia, Austria, South Sweden, Croatia,
Switzerland, Albania; very rarely in France, Italy, Greece; there is no risk on the Iberian peninsula, in the
United Kingdom, Benelux and Denmark.
Borreliosis, Lyme disease, Erythema migrans
In accordance with the activity phase of the ticks
which function as vectors seasonal clustering of
Erythema chronicum migrans from March/April to
the beginning of November. Symptoms affecting the
CNS follow approx. one to two months later. Approx.
60-75% of people afflicted can remember a tick bite;
in a survey some 3⁄4 indicated a recreational visit to
the forest, the remainder work exposure.
Transmission by hard-bodied ticks (Ixodes ricinus);
adult ticks are ca. 20%, nymphs ca. 10% and larvae
ca. 1% infected. About 3-6% of those bitten by a
tick exhibit a seroconversion (infection), in 0.3-1.4%
a manifest disease can be expected. After bites by
infected ticks a seroconversion develops in 20-30%.
Manifestations subject to the stage of the disease:
Stage I from days to weeks: Erythema migrans of the
skin – starting with an initial papule and followed
by a sharply delineated painless circular skin rash,
spreading centrifugally and fading towards the centre. Partial uncharacteristic symptoms such as fever,
headache (meningism), muscular pain, joint pain,
lymph node swelling and inflammation of connective tissue. In stage II neurological manifestations are
centre stage after weeks to months. In stage III after
months to years a symptomatology called acrodermatitis with atrophied skin („cigarette-paper-thin“)
and Lyme arthritis can occur, a phased or also chronically progressing disease of one or more joints affecting ankle, elbow-, finger-, toe- and wrist joints,
also jaw joints.
Coinfections with ehrlichiosis are probably not infrequent in Europe either. With Erythema migrans and
negative borrelia serology rickettsia should also be
chiefly considered if the infection is likely to have
been acquired in southern Europe!
Exposure prevention: removal of the tick within 24
hours reduces the risk of transmission! Vaccines are
in the final phase of development. Those afflicted
are not infectious.
Borreliosis is treated by administering antibiotics
such as tetracyclines, cefalosporines or other penicillins
Ehrlichia, anaplasma
Human diseases were first described in Japan in
1953. In 1987 a patient with Ehrlichiosis was reported
in the USA, now many cases have become known.
These are likely caused by various species of Ehrlichia or Anaplasma phagocytophilum. The first European case occurred in Portugal in 1991. Ehrlichia exhibit
strictly intracellular growth; the host cells are certain
white blood cells (granulocytes or monocytes) depending on the pathogen.
The clinical picture of Ehrlichiosis is mainly found in
animals, in dogs, in horses and in sheep or cattle.
Animals living in the wild are a natural reservoir for
pathogens. Ticks are of importance in the chain of infection, e.g. Rhipicephalus sanguineus or Ixodes spp.
in dogs. Ehrlichia species are found, for example, in
dogs in Switzerland or in Sweden. Ehrlichia are found
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in 1.3% of the tick species Ixodes ricinus in Sweden
and Switzerland, in part also at the same time in
varying combinations with Borrelia burgdorferi.
There are also reports from Italy on the joint existence of Ehrlichia and Borrelia burgdorferi in ticks, tests
from Germany indicate the same trend. Co-infections
with Borrelia burgdorferi also occur in the USA (simultaneous detection of both pathogens in ticks Ixodes scapularis - from 2 to 26%). It can be likewise
assumed that Babesia microti is also simultaneously
transmitted with ticks. The incubation period for Ehrlichiosis is 12 to 14 days. The onset of disease symptoms involving high fever, headache and muscular
pain is sudden, gradual or asymptomatic processes
are observed. Disrupted liver function (hepatocellular damage, hepatitis) is frequently described. There
is occasionally a drop in blood pressure, pneumonia,
gastrointestinal bleeding and kidney failure.
What should we do after a tick bite?
A tick bite in itself still does not justify any drug-based therapy or other therapy other than proper
removal of the tick. The key preventive measure
is to rapidly remove the tick without pinching its
body. So-called tick cards or tick hooks have proved effective; they involve the tick being held in
the slit or hook and being removed by turning.
Contact your doctor if you want to have the tick
tested in a laboratory after being removed. He will
discuss the course of action with you, in particular
whether further action is necessary and what to
do if one of the pathogens described here is positively detected.
Therapy by promptly administering tetracyclines (intracellular storage of the pathogens!). A possible infection with B.burgdorferi is therefore also treated at
the same time.
Babesia
Babesia, classed as protozoa, parasitize in red blood
cells in a similar way to malaria parasites. They also
cause similar symptoms as in malaria. In humans
and animals they cause the clinical picture of babesiosis. In dogs babesiosis (also called dog malaria) is
usually lethal if left untreated, in humans the disease causes high fever, headache and muscle pain and
other serious complications through to kidney failure. Therapy is possible using anti-malarial agents.
Your contact:
PD Dr. med. Matthias Koch
Medical Head of
Microbiology and Molekular-biology
e-mail: [email protected]
phone: +49 751 502-275
MVZ Labor Ravensburg GbR
Elisabethenstrasse 11 | D - 88212 Ravensburg
Phone: +49 751 502-0
www.labor-gaertner.com
© MVZ Labor Ravensburg GbR - LME1001R - 07/2016-V1
It is mainly transmitted by Dermacentor reticulatus,
which is spreading increasingly in Central Europe.
Some 0.5% of these ticks harbour the pathogen. This
is also said to involve co-infections between babesia
and borrelia.