HVIDLØG som flåt-afskrækkelses middel
Nedenfor en oversigt over hvad der
er publiceret om dette emne. Jeg opgiver fuld tekst (engelsk) af både den
originale svenske artikel publiceret i JAMA med efterflg. korrespondance, samt i dansk oversættelse – fordi der
er mange der har vist interesse for dette emne og spørger..
Essensen:
A greater number of the
participants were bitten by ticks during placebo consumption (normal
approximation of binomial assumption, relative risk by intention to treat, 0.79
[95% confidence interval {CI}, 0.65-0.96]; relative risk per protocol, 0.70
[95% CI, 0.54-0.90]).
Værdien for Relativ risiko (ofte forkortet RR) var altså
henholdsvis 0.70 og 0.79 afhængig af hvilken statistiske analysemetode man
anlægger ...
Og skal vurderes i forhold til en værdi på 1.
Under 1 = der var færre flåtbid i interventionsgruppen end i
ikke-interventionsgruppen.
- omsat til daglig sprog: hvis soldaterne ellers ville have fået 100 flåtbid uden indtag af
hvidløgskapsler, så kunne de altså åbenbart "nøjes" med at få 70-79
flåtbid under indtagelse af hvidløgskapslerne - hvilket jo IKKE er nogen
særlig effektiv forebyggelse, men dog trods alt LIDT bedre end slet ingenting !
Som det påpeges i kommentarerne findes der langt mere
(nærmest 100%) effektive kemiske flåt-afskrækkelses midler til behandling af
henholdsvis uniformen (permetrin - holder tøjets levetid!), henholdsvis til at
spraye på huden (33% DEET) - end hvidløg ! - midler som også vides at afskrække
andre arthropoder f.eks. malariamyg og som derfor yder langt større beskyttelse
og som anvendes af det amerikanske forsvar og der efterlyses en sammenligning
mellem hvidløg og disse anerkendte midler – men som også er temmelig giftigt
(se senere) !!!!
Der rejses i kommentarerne endvidere spørgsmålet: Er
kompliance god nok, dvs. tager soldaterne midlet som foreskrevet, eller er der
nogen der ikke vil pga. lugten ? - samt der stilles spørgsmål ved om
præparationen af hvidløg i kapselform mon sikrer et tilstrækkeligt indhold af
det effektive stof i dette præparat - eller kunne man måske have opnået en
BEDRE effekt ved at bruge FRISK hvidløg i stedet for kapslerne?
I erhverv, hvor flåtbid og dermed flåtbårne
infektioner udgør en reel risiko, bliver (men givende) borreliose (m.v. hvis
det diagnosticeres og det kan bevises at man har fået flåtbiddet under erhvervsudøvelse
- sørg for god dokumentation: billeder, dateret skadesanmeldelse !!!) regnet
for en "arbejdsskade" der giver ret til kompensation fra forsikringer
/ arbejdsskade erstatning (eks. hvis en pædagog der bliver syg efter erkendt
flåtbid erhvervet under arbejde i en skovbørnehave, en skovarbejder etc. etc. -
hvis h?n kan bevise biddet IKKE er erhvervet i fritiden - så er det ens private
fritids- og ulykkesforsikring man skal henvende sig til, hvis man har en sådan
!)
Hvis arbejdsgiveren - i dette tilfælde marinen - vælger at
ANBEFALE eller ligefrem BEORDRER soldater at bruge et flåtforebyggende middel
som hvidløg og det så IKKE virker, dvs. der er en soldat der alligevel bliver
bidt og udvikler (men givende) sygdom - så kan der blive tale om dels en
arbejdsskadesag og dermed en erstatningssag, fordi man ikke gjorde det godt nok
!
Det kan der selvfølgelig også hvis arbejdsgiveren med vilje
UNDLADER at forsøge at forebygge noget der KAN forebygges med godkendte midler
(moralsk forpligtigelse til at beskytte medarbejdere mod skader der kan
forebygges) !
De svenske forfattere svarer netop at de sammenlignede
hvidløg med placebo (inaktivt middel) og ikke med andre kendte EFFEKTIVE
flåtafskrækkelses-midler, fordi de mere effektive midler simpelthen er forbudt
i Sverige (og DK?) af miljøhensyn !
Der er imidlertid nogle flere spørgsmål JEG savner besvaret
/ kommenteret:
Soldaterne får enten placebo eller effektivt middel i 8
uger, efterfulgt af en "udvaskningsperiode" på 2 uger efterfulgt af
10 ugers "behandling" med det modsatte stof sv.t. dobbeltblindet
overkrydsnings-forsøg, som er en anerkendt videnskabelig konstruktion - jeg har
dog svært ved at forstå hvordan et forsøg med hvidløg kan være blindet for
nogen, eftersom folk der tager hvidløgskapsler godt kan lugte af det !!! (der
står dog heller ikke ordet "blindet" men det bør det være når man
sammenligner med placebo eller andet i et overkrydsnings-forsøg !!!)
Der tages heller ikke højde for at der over så lang tid som
20 uger faktisk kan være en betydelig forskel i flåternes antal, sammensætning
(antals-fordeling af larver, nymfer, henh. voksne) og bide-villighed. Der
mangler simpelthen oplysninger om de nøjagtige klima- og miljø forhold, som
undersøgelsen specifikt foregik i ...
Marinere er mig bekendt søfolk og der er ikke mange flåter
at finde ude på havet - så hvor meget tid opholdt de sig mon i 'flåtland' og
var de der i nøjagtig samme timetal og under nøjagtig de samme klimatiske og
miljø-forhold i de to perioder så antal flåtbid er sammenlignelige før og efter
udvaskningsfasen ?????
Flåter har en kendt årstidsvariation, er mest aktive i
april-juni og august til oktober. Det er derfor ikke uden betydning om
testperioden overlapper især en VARM juli - hvor flåterne holder sig nede i
bundvegetationen for at undgå udtørring - eller ej !
- forskellige i disse forhold KUNNE faktisk godt tænkes at
have influeret afgørende på "resultatet" af undersøgelsen !
HVORDAN vi som privat-personer vælger at
beskytte os mod flåtoverførte infektioner er en lidt anden sag ....
Hvis man elsker hvidløg og ens omgangskreds ikke skyer en
som pesten pga. lugten, så kan man bare bruge det, men man kan på ingen måde
tillade sig at forlade sig alene på den flåtafskrækkende effekt af hvidløg og
undlade flåtcheck !!!!
Personlige erfaringer:
Her i familien spiser vi MASSER AF HVIDLØG og det har altså
ikke hindret os i at få adskillige flåtbid - jeg har fået 3-4 flåtbid i år selvom
jeg næsten ikke går ned i baghaven mere - i hvert fald ikke uden flåtcheck
bagefter !
Datteren mener hun har haft færre flåtbid i år – vel omkring
10 stk.? – men hun er meget opmærksom på flåter, mærker som regel når
de kravler på huden og fanger dem derfor ofte inden de bider ! - og har i
højsæsonen desuden brugt midlet AUTAN ACTIVE, som nu kan købes her i
landet – som hun mener har effekt …
Læs mere om AUTAN:
http://www.google.com/search?sourceid=navclient&hl=da&ie=UTF-8&oe=UTF-8&q=autan
Den tyske reklameside reklamerer i modsætning til de danske
med 'zeckenschutz' = beskyttelse mod flåtbid - men jeg har endnu ikke set den
VIDENSKABELIG DOKUMENTATION FOR VIRKNINGEN / EFFEKTIVITETEN - er der
sammenlignet med placebo og andet ? ...
- så det KAN VÆRE REKLAMEGAS meget af det ?????
Det aktive indholdstof i AUTAN er:
1-piperidinecarboxylic acid, 2-(2-hydroxyethyl)-,
1-methylpropylester (også kaldet Bayrepel af producenten Bayer)
Søgning på Medline på piperid*+tick finder 10 artikler.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=PubMed&term=piperid*+tick
leder til en ny (publiceret juni 2003) videnskabelig
oversigts-artikel fra producenten af AUTAN (Bayer), som er online
i PDF:
Forf. konkluderer i abstract "to date, neither strategy
has led to succesful solutions" og selvfølgelig fremhæves Bayrepel pga.
mindre toksicitet end hidtil kendte.
I tabel 2 gives en lang oversigt over artikler om 'efficacy' af forskellige
præparater og specielt vedr. Bayrepels virkning på flåter henvises til Dautel H
(2002) Ein testsystem zur Detektion von Zechenrepellentien. Entmologogentagung
Düsseldorf March 26-April 1. (konference hvorfra jeg ikke kan finde noget
skriftligt materiale)
Søgning på Google efter Dautel H leder imidlertid til denne
side: http://www.insectservices.de/referenz.htm
- hvor der nævnes en publikation fra 1999 med næsten
samme titel (som IKKE fremkom ved søgning efter samme forfatter på Medline, og
som jeg ikke har fået bestilt endnu ...)
Dautel, H, Kahl, O., Siems, K.,
Oppenrieder, M., Müller-Kuhrt, L., Hilker, M. (1999).
A novel test system for the
detection of tick repellents. Entomologia Experimentalis et Applicata 91:
431-441.
Det aktive stof Bayrepel angives i det danske
sikkerhedsblad at være lokalirriterende, miljøfarlig og reproduktions-toksisk
(fosterskade? / forplantningsevne?) - det bør derfor ikke anvendes
dagligt hverken af børn eller voksne og især ikke på små børn under 2 år ! - og
kun ved stor risiko for bid/stik.
Virkningstiden af AUTAN ACTIVE synes at holde sig nogle dage
? - de andre præparater har så kort virkningstid som 4-8 timer!
Vi bedømmer her i familien vores risiko for flåtbid som
værende stor nok til at bruge AUTAN, når vi skal være ude i haven i længere tid
eller på camping i flåtland
- plus indtager meget frisk hvidløg, dels fordi vi godt kan lide det og dels
pga. den milde antibiotiske og andre gode effekter hvidløg har, inkl. en mulig
flåtafskrækkelses-effekt :))))
Marie Kroun
2003
Referencer (dansk oversættelse)
Medline ’garlic+tick’: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=PubMed&term=garlic+tick
JAMA articles on garlic: http://jama.ama-assn.org/cgi/search?fulltext=garlic+tick&submit.x=23&submit.y=15
Stjernberg L, Berglund J. Garlic as an insect repellent.. JAMA 2000 Aug
16;284(7):831
To the Editor: Lyme
borreliosis is the most common vector-borne disease in Sweden, and as many as
10,000 individuals are thought to be affected each year.1 Recent studies have
suggested that individual variability in vector attachment may be linked to
different body odors.2, 3 Other studies suggested that diethyltoluamide is the
best repellent against insect vectors and permethrin against ticks, in
particular. However, insect repellents may have adverse effects on humans and
animals.4
Because military personnel
are at particularly high risk for tick bites and tick-borne diseases,5 we
conducted a prospective, randomized, double-blind intervention trial of garlic
(Allium sativum) to prevent tick bites among Swedish marines.
Methods
Of 100 individuals in Swedish
military service in 1998, 50 consumed 1200 mg/d Allium sativum in capsule form
and 50 consumed placebo for 8 weeks, followed by a washout period of 2 weeks,
and then a crossover to placebo or Allium sativum consumption for another 10
weeks. All participants wore the same type of uniforms, consumed approximately
the same diet, participated in similar activities, and spent equal amounts of
time in tick-endemic areas. Tick bites were recorded in a diary after daily
self-inspection of the skin. Written informed consent was obtained from all
participants. The study was approved by the Research Ethics Committee of Lund
University and the Swedish Medical Products Agency. Data were analyzed by both
intention to treat (involving all participants present at the start of the
study) and per protocol (only the 80 individuals who completed the study).
Results
In the intention-to-treat
analysis, 66 (66%) of 100 participants recorded tick bites vs 55 (69%) of 80
participants in the per-protocol analysis. A total of 286 tick bites were
recorded by the participants. On average, the participants recorded 0.2 tick
bites per week during military service, compared with 0.03 tick bites during
leave. There was significant reduction in tick bites when consuming garlic
compared with placebo in per protocol analysis (Wilcoxon test, P = .04). A
greater number of the participants were bitten by ticks during placebo
consumption (normal approximation of binomial assumption, relative risk by
intention to treat, 0.79 [95% confidence interval {CI}, 0.65-0.96]; relative
risk per protocol, 0.70 [95% CI, 0.54-0.90]).
Comment
Swedish marine conscripts are
at high risk of tick bites during military service. Preventive measures,
including vaccinations against tick-transmitted diseases, should be considered.
However, our results suggest that garlic may be considered as a tick repellent
for individuals and populations at high risk for tick bite, rather than other
agents that might have more adverse effects.
Louise Stjernberg, RN, MPH
Johan Berglund, MD, PhD
Lund University
Malmö, Sweden
1. Berglund J, Eitrem R,
Ornstein K, et al. An epidemiological study of
Lyme disease in southern Sweden. N Engl J Med. 1995;333:1319-1324.
2. Mwase ET, Pegram RG, Mather TN. New strategies for controlling ticks. In: Curtis, ed. Control of Disease
Vector in the Community. London, England: Wolfe Publishers; 1991:93-102.
3. Keystone JS. Of bites and
body odor. Lancet. 1996;347:1423.
4. Brown M, Herbert AA.
Insect repellents: an overview. J Am Acad Dermatol. 1997;36:243-249.
5. Schmutzhard E, Stanek G,
Pletschette M, et al. Infections following tickbites: tick-borne encephalitis
and Lyme borreliosis: a prospective epidemiological study from Tyrol. Infection.
1988;16:269-272.
McHugh
CP. Garlic as a tick repellent. JAMA 2001 Jan 3;285(1):41-2
To the Editor: In their
Research Letter, Ms Stjernberg and Dr Berglund1 documented a repellent effect
of garlic against an unnamed species of tick and stated that daily consumption
of 1200 mg of garlic was an alternative to ""other agents that might
have more adverse effects."" Based on the design of their study, any
conclusions concerning the relative effectiveness and safety of garlic as a
tick repellent are unfounded. They compared garlic to a placebo, not to other
currently available repellents, and they did not present any data on the
comparative safety of garlic vs other repellents.
In fact, consumption of
garlic appeared to be only marginally better than doing nothing at all to
prevent tick bites. By contrast, treatment of clothing with permethrin, a
synthetic pyrethroid, has been shown to be 100% effective against Ixodes
scapularis,2 the vector of Borrelia burgdorferi in the northeastern United
States, and to provide nearly 100% protection against Amblyomma americanum and
Dermacentor variabilis.3 Diethyltoluamide (DEET)-based repellents also are
effective in repelling ticks2 and can be applied to skin, as well as to
clothing. The US Department of Defense (DoD) promotes the concurrent use of a
33% DEET-based lotion on exposed skin, treatment of uniforms with permethrin,
and proper wearing of the uniform. This strategy has been termed the DoD
Repellent System and is believed to be the most effective method for reducing
the risk of arthropod bites.4
Brown and Hebert5 were cited
as the source of information on adverse effects of repellents other than
garlic. In fact, they concluded that appropriate use of repellents was a
""safe means of minimizing the risk of bites and vector-borne
diseases."" In additional reviews, DEET has been associated with
""remarkably few problems""6 while the concurrent use of
DEET and permethrin was judged ""safe and effective.""4
The study by Stjernberg and
Berglund raises 2 additional questions. First, does garlic effectively repel
other arthropods of medical importance? Troops frequently are at risk of attack
by several arthropod taxa and need a repellent that is broadly effective. The
DoD Repellent System is extremely effective in repelling a number of arthropods
in addition to ticks.4 Second, how difficult is it to ensure compliance with a
daily regimen of 1200 mg garlic? That is, do troops find garlic acceptable, and
can they be relied on to remember to take daily doses? Treatment of uniforms
with permethrin can provide repellency for the life of the garment while
requiring no action on the part of the wearer.4 For troops and other
populations at high risk for arthropod bites, the use of DEET and permethrin
remains the most effective and safe method of protection.
Chad P. McHugh, MPH, PhD
Air Force Institute for
Environment, Safety and Occupational Health Risk Analysis
Brooks Air Force Base, Tex
1. Stjernberg L, Berglund J.
Garlic as an insect repellent. JAMA. 2000;284:831.
2. Schreck CE, Snoddy EL,
Spielman A. Pressurized sprays of permethrin or DEET on military clothing for
personal protection against Ixodes dammini (Acari: Ixodidae). J Med
Entomol. 1986;23:396-399.
3. Evans SR, Korch GW, Lawson
MA. Comparative field evaluation of
permethrin and DEET-treated military uniforms for personal protection against
ticks (Acari). J Med Entomol. 1990;27:829-834.
4. Young GD, Evans S. Safety
and efficacy of DEET and permethrin in the prevention of arthropod attack. Mil
Med. 1998;163:324-330.
5. Brown M, Hebert AA. Insect
repellents: an overview. J Am Acad Dermatol. 1997;36:243-249.
6. Goodyear L, Behrens RH. Short
report: the safety and toxicity of insect repellents. Am J Trop
Med Hyg. 1998;59:323-324.
Tunon
H. Garlic as a tick repellent. JAMA 2001 Jan 3;285(1):41-2
To the Editor: Ms Stjernberg
and Dr Berglund1 reported that garlic may be an effective tick repellent. However,
the content of sulfuric compounds in garlic is subject to large variations that
influence pharmacological effects and the only information about the garlic
preparation in their study is "1200 mg/d Allium sativum in capsule
form." There was no information about whether the plant material was
fresh, dried, or treated in any way. Herbal preparations containing garlic are
normally prepared in several different ways, such as dried, fermented, oil
macerated, or solvent extracted.
Stjernberg and Berglund also
state that ""diethyltoluamide is the best repellent against insect
vectors."" DEET is the most commonly used mosquito repellent and has
activity against other insects. However, several other compounds and even plant
extracts have a mosquito-repellent effect of the same magnitude as that of
DEET.2, 3 Furthermore, permethrin is a synthetic pyrethroid, ie, insecticide
and acaricide, and not a true repellent.
Håkan Tunón, PhD
Swedish Biodiversity Centre
Swedish Agricultural
University
Uppsala, Sweden
1. Stjernberg L, Berglund J.
Garlic as an insect repellent. JAMA. 2000;284:831.
2. Tunón H, Thorsell W,
Bohlin L. Mosquito-repelling activity of compounds occurring in Achillea
millefolium L. (Asteraceae). Econ Bot. 1994;48:111-120.
3. Thorsell W, Mikiver A,
Malander I, Tunón H. Efficacy of plant extracts and oils as mosquito
repellents. Phytomedicine. 1998;5:311-323.
Ranstam
J. Garlic as a tick repellent. JAMA 2001 Jan 3;285(1):41-2
To the Editor: Ms Stjernberg
and Dr Berglund1 recently presented a randomized, double-blind, crossover trial
of garlic to prevent tick bites among Swedish military conscripts. Fifty
subjects were treated with garlic first and placebo second while another 50
were given placebo first and then garlic. The total number of subjects was thus
100. Of these, 66 were reported to have been bitten by ticks. The authors
presented a relative risk (RR) of 0.79 with the 95% confidence interval (CI)
0.65-0.96. They did not reveal the number of bitten subjects per sequence.
In a crossover trial the RR
is calculated from discordant pairs, ie, the number of subjects with more
events on active treatment than on placebo is compared with the number of
subjects with more events on placebo than on active treatment. The more
effective the treatment is the lower ratio between the 2 numbers. In this
trial, a discordant pair is a subject with at least 1 bite while receiving
either active or placebo treatment. The number of subjects entering the
analysis could therefore be lower, but not greater, than 66. Several possible
sets of discordant pairs among these 66 conscripts could give a RR of
approximately 0.79, but the P value could not be lower than .39 (exact McNemar
test using maximum possible sample size, 37 + 29 = 66 discordant pairs). The
corresponding CI is 0.46-1.31.
The authors also present a P
value of .04 for the difference in number of tick bites between treatments. However,
using tick bite as analysis unit instead of conscript is incorrect since the
risk of a tick bite differs between conscripts; counting tick bites instead of
conscripts in a traditional single-level analysis exaggerates the statistical
significance of the findings.2
Jonas Ranstam, PhD
School of Health and Society
Malmö University
Malmö, Sweden
1. Stjernberg L, Berglund J.
Garlic as an insect repellent. JAMA. 2000;284:831.
2. Ranstam J. Repeated
measurement and analysis units. Acta Orthop Scand. 1998;69:345-346.
Stjernberg L, Berglund J. Garlic as
a tick repellent. JAMA 2001 Jan 3;285(1):41-2
In Reply: In response to Dr
McHugh, our study specifically assessed the effectiveness of garlic as a
repellent for tick bites. We did not measure its effectiveness for other
arthropods or insects, nor did we compare it with other repellents. We choose
military personnel because their behavior is relatively consistent.
Both McHugh and Dr Tunón
point out that there are other effective insecticides and repellents. However,
the adverse effects of DEET and permethrin are a subject of recurrent debate. Swedish
regulations concerning the use of these products are very strict, for permethrin
because of toxicity in aquatic organisms1 and for DEET because of studies
showing adverse effects in humans.2, 3 Thus, Swedish troops cannot use
permethrin- or DEET-treated uniforms. In Sweden, garlic might be considered as
an alternative to other repellents for people staying in tick endemic areas. Of
course, treatment of clothes with permethrin guarantees a much higher level of
protection as long as the clothing are worn. Garlic should certainly not be
substituted for more effective protective measurements in areas that are
endemic to other vector borne diseases, such as malaria.
In response to Dr Ranstam,
all participants in our trial recorded in a diary the time of exposure and
observed tick bites. This allowed us to standardize for time of exposure. Our
statements were related to per protocol analysis only, which lead us to be
conservative in our conclusions. Per protocol statements included all
individuals fulfilling the study requirements and describes the time the study
drug was taken as directed; all episodes with deviating compliance were
excluded.
The 2 periods of observation
differed in length, and some units spent different amounts of time within each
period. Therefore, we considered the Wilcoxon test for paired observations a
more appropriate method to test our hypothesis. This test for paired samples
compared the individual number of tick bites per unit of time (days) between
placebo and active treatment.
However, when presenting the
RRs we compared (standardized for time of exposure) the number of bitten
participants in the placebo groups with the number of bitten participants in
the garlic groups and did not take into consideration the crossover design when
comparing paired samples. We agree that this is inappropriate and that CIs
should not have been presented.
Louise Stjernberg, RN, MPH
Department of Science and
Health
Blekinge Institute of
Technology
Karlskrona, Sweden
Johan Berglund, MD, PhD
Department of Community
Medicine
Lund University
Malmö, Sweden
1. Torstensson L. Ecotoxicity
Evaluation of Permethrin. Uppsala: Swedish Agricultural University; 1989.
2. Brown M, Hebert AA. Insect
repellents: an overview. J Am Acad
Dermatol. 1997;36:243-249.
3. Clem JR, Havemann DF, Raebel
MA. Insect repellent (N,N-diethyl-m-toluamide)
cardiovascular toxicity in an adult. Ann Pharmacother. 1993;27:289-293.