Comparative in vitro tests on the efficacy and safety of 13 anti-head-lice products

Abstract

Head lice are an emerging social problem, not only in economically poor countries but also in practically all other societies. Several of the common anti-louse products have lost--at least in part--their efficacy due to increasing resistance of lice against insecticides such as permethrin or allethrin. Other compounds, like lindan, were redrawn or banned due to high toxicity. Some recently developed products are based on dimethicones or cyclomethicones and turned out to be easily inflammable. Other styled medicinal products are based on plant extracts-some were proven of high efficacy-others of ineffectivity. The present study investigated in in vitro tests the anti-head louse efficacy of 13 products, the contents of which are used worldwide: Aesculo-Gel L, EtoPril, Goldgeist Forte, InfectoPedicul, Jacutin Pedicul Fluid, K.Laus, Liberalice, Licatack, Mosquito Läuse-Shampoo, Nyda, Paranix, Picksan Louse Stop, and Wash Away Louse. It turned out that several of them are easily inflammable, and therefore, they endanger users (InfectoPedicul, Paranix, EtoPril, Nyda, Goldgeist Forte, and K.Laus, see Table 1). Others have to remain for many hours on the hair in order to reach efficacy (Table 4). During such long periods, highly dosed oils may become inhaled and thus may become dangerous for the user's lung epithelia by covering them. When incubating the lice for 3 or 10 min in vitro, only the following products killed all lice exposed to these products: InfectoPedicul, Paranix, Jacutin Pedicul Fluid, Nyda, K.Laus, Picksan Louse Stop, Licatack, and Wash Away Louse. When evaluating the possible dangers for the users, the last three products, especially, derived from plant extracts, are safe and highly effective at the same time. Furthermore, they had been tested dermatologically as "very good".

Full text

ORIGINAL PAPER
Comparative in vitro tests on the efficacy and safety
of 13 anti-head-lice products
Fathy Abdel-Ghaffar &Margit Semmler &
Khaled Al-Rasheid &Sven Klimpel &Heinz Mehlhorn
Received: 10 October 2009 / Accepted: 30 October 2009 /Published online: 12 November 2009
#Springer-Verlag 2009
Abstract Head lice are an emerging social problem, not
only in economically poor countries but also in practically
all other societies. Several of the common anti-louse
products have lost—at least in part—their efficacy due to
increasing resistance of lice against insecticides such as
permethrin or allethrin. Other compounds, like lindan, were
redrawn or banned due to high toxicity. Some recently
developed products are based on dimethicones or cyclo-
methicones and turned out to be easily inflammable. Other
styled medicinal products are based on plant extracts—
some were proven of high efficacy—others of ineffectivity.
The present study investigated in in vitro tests the anti-head
louse efficacy of 13 products, the contents of which are
used worldwide: Aesculo®-Gel L, EtoPril®, Goldgeist®
Forte, InfectoPedicul®, Jacutin® Pedicul Fluid, K.Laus®,
Liberalice®, Licatack®, Mosquito® Läuse-Shampoo,
Nyda®, Paranix®, Picksan® Louse Stop, and Wash Away
Louse®. It turned out that several of them are easily
inflammable, and therefore, they endanger users (Infecto-
Pedicul®, Paranix®, EtoPril®, Nyda®, Goldgeist® Forte,
and K.Laus®, see Table 1). Others have to remain for many
hours on the hair in order to reach efficacy (Table 4).
During such long periods, highly dosed oils may become
inhaled and thus may become dangerous for the user's lung
epithelia by covering them. When incubating the lice for 3
or 10 min in vitro, only the following products killed all
lice exposed to these products: InfectoPedicul®, Paranix®,
Jacutin® Pedicul Fluid, Nyda®, K.Laus®, Picksan® Louse
Stop, Licatack®, and Wash Away Louse®. When evaluating
the possible dangers for the users, the last three products,
especially, derived from plant extracts, are safe and highly
effective at the same time. Furthermore, they had been
tested dermatologically as “very good”.
Introduction
Head lice (Pediculus humanus capitis) occur worldwide
and go with humans in all corners of the world (Aspöck and
Walochnik 2007; Falagas et al. 2008). Although, in general,
head lice do not transmit agents of disease as it is known
from body lice (Pediculus humanus corporis), they may
have considerable impact on health of humans. Their bites,
especially in cases of huge infestations, may lead to
enormous pruritus, skin inflammation, urticaria, exudations,
lymph node swellings, eczema, scars, hair glue-up to “plica
polonica”, ending in pain and restlessness especially in
children (Burgess 2004,2009; Mumcuoglu and Rufli 1983;
Mumucuoglu et al. 2009; Mehlhorn et al. 1995; Mehlhorn
2008; Mehlhorn and Mehlhorn 2009). All these symptoms
are described as a disease called “pediculosis”which also
includes psychological damages of infested children and
their caring mothers. These effects occur since infestation
with lice is often considered to have its origin in dirtiness of
the infested persons and their families. This wrong belief
ends often in “mobbing”of children infested with lice.
Then, the children refuse to go to the child yard or to
school. This reaction disturbs considerably the normal run
F. Abdel-Ghaffar :M. Semmler
Department of Zoology and Parasitology, Cairo University,
Giza, Egypt
K. Al-Rasheid
Department of Zoology, College of Science,
King Saud University,
Riyadh, Saudi Arabia
S. Klimpel :H. Mehlhorn (*)
Department of Parasitology, Heinrich-Heine-University,
40225 Düsseldorf, Germany
e-mail: mehlhorn@uni-duesseldorf.de
Parasitol Res (2010) 106:423–429
DOI 10.1007/s00436-009-1680-x

of the daily family life. In consideration of these physical
and psychological consequences of an infestation with head
lice, many countries made some anti-louse products
prescribable by physicians, and thus, these products are
given for free to the patients. Since all family members
must be treated at once—they may invisibly be infested—
the additional treatment doses must be paid from the
income of the family. Therefore, many products worldwide
are on the market claiming efficacy. However, many of
them (under different trade names) are dangerous for users
due to their inflammability or by covering the surfaces of
lung epithelia. Others are ineffective, leaving surviving lice
that start another series of reproduction affording further
treatments and thus producing inevitable and considerable
Table 1 Composition and inflammability of different formulations, shampoos, lotions, etc. against head lice (Pediculus humanus capitis)
Number Trade name Company/address Charge
number
Active compound
noted
Inflammability
1 Infecto Pedicul® medical
solution (50 ml)
Infectopharm Arzneimittel
Von-Humboldt-Str. 1 D-64646
Heppenheim, Germany
WO 60819.1 Permethrin Yes
2 Paranix® Medical
solution (60 ml)
Teva Pharmaceutical Industries
Ltd. P.O. Box 3190 Petach–
Tikva Israel
WC 8 E 28-51 Cocos nucifera oil,
Illicium verum
(anise) oil, Cananga
odorata oil
Yes
3 Mosquito® Läuse
Shampoo (100 ml)
WEPA-Apothekenbedarf GmbH
& Co. KG Am Fichtenstrauch 6-10
D-56204 Hillscheid, Germany
08337-F 197 Cocoamido-
propylbetaine,
Glycine soja
No
4 Jacutin® Pedicul Fluid
medical solution
(100 ml)
Almirall Herman GmbH
Scholtzstraße 3 D-21465
Reinbeck, Germany
837442 Dimethicone No
5 EtoPril® Medical
solution (100 ml)
Dr. August Wolff GmbH & Co.
KG Arzneimittel D-33532
Bielefeld, Germany
VM 49 Dimethicone
Cyclomethicon 5
Yes
6 Liberalice® Duo LP-
Pro medical solution
(150 ml)
Duhot S.A. Avenue de Nivelles
7, 1300 Limal Belgium Licence
of Terra Santé, France
08197 Oxypthirine No
Delivery: Trommsdorf GmbH &
Co, KG Arzneimittel 52475
Alsdorf, Germany
7 Nyda® Spray (50 ml) G. Pohl-Boskamp GmbH & Co.
KG Kieler Straße 11 D-25551
Hohenlockstedt, Germany
204716 Dimethicones of high
and low viscosity
Yes
8 Goldgeist® Forte medical solution
(75 ml)
E. Gerlach GmbH D-32292
Lübbecke, Germany
030219 Pyrethrum from
blossom of
Chrysanthemum
cinerarieafolium
Yes, for a
short
period only
9 K.Laus® medical
solution (100 ml)
SSL International plcVenus
1 Old Park Lane, Trafford Park
Manchester, M 417HA, UK
P 712954 Cyclomethicon,
isopropylmyristate
Yes
Distribution: SSL Healthcare
GmbH & Co. KG D-63477
Maintal, Germany
10 Aesculo® Gel "L"
medical gel (100 ml)
Medice Arzneimittel Pütter
GmbH & Co, KG Kuhloweg 37
D-58638 Iserlohn, Germany
82008/1 Cocos nucifera oil No
11 Licatack shampoo
(100 ml)
PM Consumer Products
NL 1184 VW Oudekerk a/d
Amstel, The Netherlands
Pre-production
sample
Grapefruit extract No
12 Wash Away Laus
shampoo (100 ml)
Alpha-Biocare GmbH Merowinger
Platz 1 a D-40225 Düsseldorf,
Germany
K-05-01 MelAza-extract No
13 Picksan® Louse Stop
shampoo (100 ml)
OTC Pharma International BV
Postbus 816 4200 AV Gorinchem, The
Netherlands
20702633 MelAza-extract No
424 Parasitol Res (2010) 106:423–429

costs especially in families with several children (Abdel-
Ghaffar and Semmler 2007; Heukelbach et al. 2006a,b).
The present in vitro study aimed to compare the efficacy
and possible inflammability of 13 European products,
which either contained insecticides (permethrin, pyrethrum
extract), silicon-derivates, or plant extracts. The selected
exposition periods (3 and 10 min) were rather short. This
was done since, in practical use, the procedure of an anti-
lice action should be as short as possible. Such a short time
will bother the families less and will let them better avoid
possible side effects due to the effective compounds in the
anti-lice products.
Materials and methods
Materials
In the present in vitro test (carried out in Cairo, Egypt), the
13 products that were used are listed in Table 1. The head
lice were obtained by combing 20 children that had been
included in an in vivo test of the newly developed anti-
louse product “Licatack®”during the same period in
October 2009 (Fig. 1).
Methods
Efficacy test
Always ten adult = large lice were placed into small baskets
(Fig. 2), the bottom of which consisted of metal net. These
baskets were placed into plastic petri dishes, the bottoms of
which were covered with white filter paper (Fig. 3). Then, the
lice were completely covered by with one of the 13 products
listed in Table 1. The lice were either incubated for 3 or
10 min within the different compounds. After the incubation
period, the baskets were taken out of the petri dishes, and the
lice were washed three times for 30 s with tap water until
they were completely free from any remnants of the
compounds. Then, they were placed onto fresh white filter
paper in another petri dish. After 10, 20, 30, 60 min, 2, 3,
4 h, the lice were inspected with the help of a strong
magnification glass that allowed to see even eventual leg
movements or constrictions of the intestine. The findings
were noted and are documented in Table 2.
Inflammability test
Hair from human heads was collected from local barbershops.
For testing the inflammability of different products against
human head lice, defined portions of hairs, weighing from 1.1
to 1.5 g, were assorted into small heaps measuring about 5 cm
in diameter and about 0.5–1 cm in height. Then, and for each
preparation separately, these hair portions were treated with
the products to be tested in accordance to the consumers
instructions. In all cases, the hair was made fully wet by the
Fig. 1 Obtaining lice by combing from infested head Fig. 3 Partial aspect of the products and vials at the beginning of the test
Fig. 2 Small basket with a metal net as bottom for incubation of lice
in different compounds
Parasitol Res (2010) 106:423–429 425

preparations and then immediately put on a white glazed tile
(14.8×14.8 cm). The tile with the treated hair was placed into
a closed laboratory drain (digestorium). Then, the flame from
a piezoelectric lighter was brought into contact with the
treated hair. The results of each test series were documented
by a digital motion picture camera. As soon as an individual
test series was ended, the glazed tile was thoroughly cleaned
before another test was started. As control, untreated hair was
used for inflammation tests.
Results
Inflammability test
The results of this test are documented in Tables 1and 3.It
turned out that some products, even if their active
compounds are not inflammable without contact to hair,
may become inflamed when there is a mixture consisting
of hair and anti-lice compound. This makes it unpredict-
able when a danger is given for the user of the product. It
must not be open fire that lights up treated hair. In
practice, it had been shown that already the starting flesh
of a fan may inflame hair (report shown by the German
television broadcaster WDR=Westdeutscher Rundfunk as
well as by several newspapers in Austria and The Nether-
lands; Mehlhorn and Mehlhorn 2009).
The inflammable products showed the following burning
features. While untreated, lit-up hair was melting, the
inflammable products initiated the following reactions:
1. InfectoPedicul® (No. 1): treated hair produced flames
up to 4–7 cm high, persisted constantly inflamed, and
wandered along the hair.
Table 2 In vitro test of 13 different anti-louse products after an exposure of ten lice for 3 min or 10 min and after 3 ×30-s washing the lice with
tap water
Product number
(names in Table1)
10min after
washing
20min after
washing
30min after
washing
1h after
washing
2h after
washing
3h after
washing
4h after
washing
1
a
2, m 2, m 1, m 1, m 1, m 1, m 1, m
1
b
nm nm nm nm nm nm nm
2
a
nm nm nm nm nm nm nm
2
b
nm nm nm nm nm nm nm
3
a
5, m all m all m all m all m all m all m
3
b
all m all m all m all m all m all m all m
4
a
nm nm nm nm nm nm nm
4
b
nm nm nm nm nm nm nm
5
a
nm 1, m nm nm nm nm nm
5
b
nm nm nm nm nm nm nm
6
a
4, m all m all m all m all m all m all m
6
b
all m all m all m all m all m all m all m
7
a
nm nm nm nm nm nm nm
7
b
nm nm nm nm nm nm nm
8
a
2, m 2, m 2, m 2, m 2, m 1, m 1, m
8
b
nm 2, m 2, m 2, m 3, m 3, m 3, m
9
a
nm nm nm nm nm nm nm
9
b
nm nm nm nm nm nm nm
10
a
3, m 2, m 2, m 2, m 3, m 3, m 2, m
10
b
3, m 3, m 3, m 3, m nm nm nm
11
a
nm nm nm nm nm nm nm
11
b
nm nm nm nm nm nm nm
12
a
nm nm nm nm nm nm nm
12
b
nm nm nm nm nm nm nm
13
a
nm nm nm nm nm nm nm
13
b
nm nm nm nm nm nm nm
Mmobile, nm non-mobile/dead; lice, n=10 per vial
a
Exposed for 3 min
b
Exposed for 10 min
426 Parasitol Res (2010) 106:423–429

2. Paranix® (No. 2) initiated similar effects like Infecto-
Pedicul®.
3. EtoPril® (No. 5) initiated flames of 4–7 cm in height,
which persisted and wandered.
4. Nyda® (No. 7) reacted like EtroPril®.
5. Goldgeist Forte® (No. 8) initiated only a short burning
of 3–6 s, and the flames did not wander.
6. K.Laus® (No. 9) initiated the same flames like EtoPril®
(No. 5) or Nyda® (No. 7).
Untreated hair and hair treated with Mosquito®, Jacutin®
Pedicul Fluid, Liberalice®, Aesculo® Gel L, Licatack®,
Wash Away Louse®, and Picksan® did not burn but melted,
when coming in contact with open fire.
Efficacy test
When looking at Table 2, which summarizes the results of
the whole in vitro trial, it is clearly seen that only the
products Paranix®, Jacutin® Pedicul Fluid, EtoPril®,
Nyda®, K.Laus®, Licatack®, Wash Away Louse®, and
Picksan® Louse Stop are able to kill/immobilize all lice
within 3 min of exposure (without any recovery within 4 h).
The product InfectoPedicul® left some short-term survi-
vors, who died after 5 h. On the other hand, the products
like Mosquito® Läuse-Shampoo, Liberalice®, and Aes-
culo® Gel L let all lice survive after an exposure period of
3 min. When exposing the lice for 10 min (series b in
Table 1), the products InfectoPedicul®, Paranix®, Jacutin®
Table 4 Recommended period of treatment and elimination of the compound from hair
Number Trade name Producer's recommended time for treatment Elimination of the product from hair after treatment
1 InfectoPedicul® 30–45 min Use of tap water
2 Paranix® 15 min Use of shampoo
3 Mosquito® Läuse Shampoo As normal shampoo, then 2× 30 min Use of tap water
4 Jacutin Pedicul® Fluid 10 min Use of a shampoo
5 EtoPril® At least 8 h Use of a shampoo
6 Liberalice® Overnight and hair cover Use of a shampoo for at least 10 min
7 Nyda® At least 8 h Use of shampoo
8 Goldgeist Forte® 30–45 min Use of tap water
9 K.Laus® 10 min Use of a shampoo
10 Aesculo® Gel L 60 min Use of a shampoo
11 Licatack® 10 min Use of tap water
12 Wash Away Louse® 10–20 min Use of tap water
13 Picksan® Louse Stop 10–20 min Use of tap water
Table 3 Declarations given directly on the bottle, which is used during treatment
Number Trade name Effective compounds
declared
Signs of
inflammability
Age of children given Mode
of use
Hints for
safety
1 InfectoPedicul® Yes No, but written information No In parts No
2 Paranix® No No, although inflammable No No Yes
3 Mosquito® Läuse Shampoo Yes No From 3 years (GB),
3 months (Germany)
Yes No
4 Jacutin Pedicul® Fluid Yes No No No No
5 EtoPril® Yes No, although inflammable From 6 months No Yes
6 Liberalice® No No No Yes Yes
7 Nyda® No Yes No No No
8 Goldgeist Forte® Yes No, although inflammable No No Yes
9 K.Laus® Yes No, although inflammable No No Yes
10 Aesculo® Gel L Yes No No Yes No
11 Licatack® Yes No Yes Yes Yes
12 Wash Away Louse® Yes No No Yes Yes
13 Picksan® Louse Stop Yes No No Yes Yes
Parasitol Res (2010) 106:423–429 427

Pedicul Fluid, EtoPril®, Nyda®, K.Laus®, Licatack®, Wash
Away Louse®, and Picksan® Louse Stop were 100%
successful in killing the exposed lice.
Untreated controls survived for up to 16–24 h when
combed down from hair and placed onto white filter paper
in a closed plastic petri dish.
Discussion
This comparative in vitro study has revealed significant
results, which give more clear insights in the efficacy range
of a certain products than do in vivo tests, since the latter are
always endangered by wrong use or by non-contact of lice to
the active compounds (the lice may crawl away quickly from
the products) when it is brought into hair. It was shown that
several products are inflammable and thus represent a danger,
especially in cases of lack of warning on the bottles (Table 3).
Such a sign was missing in four of six inflammable products.
The design of this in vitro study yielded those products
needing the shortest time until the lice were killed (Tables 2,
4). In case there is a full activity, the shortest time for treatment
is the best, since that way the families are less bothered by the
anti-lice action than in cases when these actions need eight or
more hours, plus an intensive procedure to eliminate the often
gluing product from the hair. Furthermore, a very short period
of treatment also reduces the possibility that some components
of the product may be inhaled and covers the lung epithelia or
may initiate allergic skin reactions. Some products, such as
EtoPril®, Liberalice®, and Nyda® afford at least 8 h on the
head (Table 4). However, the present in vitro tests showed that
they kill the lice in a few minutes, too. Therefore, there must
be a problem in bringing these products in vivo on all regions
of hair when it is applied. This failure is probably due to the
gluing consistency of these products when mingled with hair,
since Oliveira et al. (2007) had also found an in vitro activity
within 5 min.
Cyclo- and dimethicones are commonly used in skin care
products, e.g., conditioners. However, the products contained,
in general, 1% of these compounds and rarely up to 15% (Nair
2003). Reports cited in the latter paper claimed that short-term
inhalation of dimethicones did not initiate adverse effects in
rodents. However, the use of these methicones as “repair
conditioners”which cover the surface of hair make it
understandable that they may also cover lung epithelia, if
they are inhaled while using it in concentrations of more than
50% for many hours. Although the Cosmetic Ingredient
Expert Panel considered it unlikely that any of these polymers
would be significantly absorbed into the skin, there is a cited
case where a cream formulation with 1% dimethicone had
severe adverse effects (Nair 2003). This shows that those
compounds may induce harm if they are transported by a
carrier into the skin. Similar hints are given in a website—
www.nohomis.at—that the weakening compounds in sili-
cones may be harmful. Therefore, it cannot be fully excluded
that silicon-based anti-lice products do not endanger users,
especially children in cases of very high concentrations, very
long exposure periods, and numerous application schemes at
short intervals. Thus, in times of increasing resistance of lice
(Vassena et al. 2003; Picollo et al. 2000;MogabureCuetoet
al. 2008) against pyrethroids and after banning of com-
pounds like lindan there is a need for
(a) quick, easy to use, and fully effective compounds,
(b) skin-safe compounds,
(c) non-inflammable compounds, and
(d) availability at reasonable prices.
Conclusions
The present study clearly shows that the three plant-derived
products Licatack®, Picksan® Louse Stop, and Wash Away
Louse® have many advantages with respect to other
products:
(a) they are not inflammable (Table 1),
(b) their contents are not toxic and are tested “very good”
by a professional dermatological clinical group,
(c) they do not contain components (as do silicon-derivates
or Paranix® with their volatile oils) that may harm
the surface of lung epithelia, especially as it might be the
case, when these components are included in the
products at concentrations higher than 50%.
(d) the period of treatment is very short (10–20 min)
compared with other products which need at least
30 min up to 8 h (Table 4) and peculiar methods to get
them out of the hair after treatment.
(e) The declarations on the bottle itself are clear and allow
safe use, while in other products, important information
is only given on the information sheet in the package.
Acknowledgement We thank the mothers of the children in the
Egyptian village for their kind help to deliver large numbers of lice of
any stage of development. This study was in parts supported by the
Center of Excellence of the College of Science of the King Saud
University at Riyadh, Saudi Arabia.
References
Abdel-Ghaffar F, Semmler M (2007) Efficacy of neem seed extract
shampoo on head lice of naturally infected human in Egypt.
Parasitol Res 100:329–332
Aspöck H, Walochnik J (2007) Die Parasiten des Menschen aus der
Sicht der Ko-Evulotion. Denisia 20:149–254
Burgess IF (2004) Human lice and their control. Annuv Rev Entomol
49:475–481
428 Parasitol Res (2010) 106:423–429

Burgess IF (2009) Current treatments for Pediculosis capitis. Curr
Opin Infect Dis 22:131–136
Falagas M, Matthaiou D, Rafailidis P, Panos G, Pappas G (2008)
Worldwide prevalence of head lice. Emerg Infect Dis 14:1493–
1494
Heukelbach J, Speare R, Canyon D (2006a) Natural products and their
application to the control of head lice: an evidence-based review.
In: Brahmachari G (ed) Chemistry of natural products: recent
trends and developments. Kerala, India, pp 1–26
Heukelbach J, Oliveira FA, Speare R (2006b) A new shampoo based
on neem (Azadirachta indica) is highly effective against head lice
in vitro. Parasitol Res 99:353–356
Mehlhorn H (ed) (2008) Encyclopedia of parasitology. Springer, New
York
Mehlhorn B, Mehlhorn H (2009) Louse alarm. Düsseldorf University
Press, Düsseldorf
Mehlhorn H, Eichenlaub D, Löscher T, Peters W (1995) Diagnosis
and therapy of human parasites. 2nd edition, G. Fischer, Stuttgart
Mogabure Cueto G, Zerba E, Picollo MI (2008) Evidence of
pyrethroid resistance in eggs of Pediculus humanus capitis
(Phthiraptera: Pediculidae) from Argentina. J Med Entomol
45:693–697
Mumcuoglu Y, Rufli T (1983) Dermatologische Entomologie.
Perimed, Erlangen
Mumucuoglu Y, Gilead L, Ingber A (2009) New insights in
pediculosis and scabies. Expert Review Dermatol 4:285–302
Nair B (2003) Cosmetic ingredients review expert panel—final report
on safety assessments. Int J Toxicol 22(2):11–35
Oliveira FA, Speare R, Heukelbach J (2007) High in-vitro efficacy of
Nyda® L, a pediculicide containing dimethicone. J Eur Acad
Dermatol Venerol 21:1325–1329
Picollo MI, Vassena C, Mougabure Cueto G, Vernitti M, Zerba E
(2000) Resistance to insecticides and effects of synergists on
permethrin toxicity in Pediculus capitis (Anoplura: Pediculidae)
from Buenos Aires. J Med Entomol 37:721–725
Vassena CV, Mougabure Cueto G, González Audino P, Alzogaray R,
Zerba E, Picollo MI (2003) Prevalence and levels of permethrin
resistance in Pediculus humanus capitis De Geer (Anoplura:
Pediculidae) from Buenos Aires, Argentina. J Med Entomol
40:477–450
Parasitol Res (2010) 106:423–429 429