Loop-mediated isothermal amplification as a reliable assay
for Toxocara canis infection in pet dogs
Received: 9 April 2017 /Accepted: 30 June 2017 /Published online: 9 July 2017
Springer-Verlag GmbH Germany 2017
Abstract Keeping of infected dogs as pet results in the po-
tential transmission risk factors for shedding helminthic infec-
tions such as toxocariasis. Lack of accurate identification of
Toxocara canis eggs in non-dewormed infected pet dogs re-
mains a diagnostic concern among researchers. In this study,
dog owners were asked to fill up a questionnaire regarding
their pets and their attitude towards the deworming regimen.
One hundred faecal samples were collected from pet dogs
(Northwest Iran) and were subsequently identified by the
ZnSo4 flotation technique, PCR and loop-mediated isother-
mal amplification (LAMP) assays. The DNA of the recovered
T. canis eggs was then extracted and amplified by LAMP and
PCR. Furthermore, ITS2 amplicons were sequenced for ap-
praisal of the phylogenetic analysis. Nine, 5 and 11% of T.
canis infections were identified by microscopy, PCR and
LAMP, respectively. It was detected that LAMP was 10 times
g/μl) more sensitive than PCR (10
g/μl). The kappa value between LAMP and PCR indi-
cated a faint concurrence (0.463). The kappa coefficient be-
tween LAMP and flotation technique indicated a strong agree-
ment (0.667). The highest infection rate (n = 11) was detected
in non-dewormed pet dogs, particularly those less than
3 months old (P < 0.05). None of the infected dogs had a
history of walking and kennelled behaviours in public places.
The LAMP assay can address as a simple, rapid and highly
sensitive technique for detecting low burden of T. canis eggs
in infected pet dogs. It was proposed that the dog holder’s
awareness is insufficient to implement regular deworming
schedules. Additionally, regional policymakers should broad-
ly revise anthelmintic treatment guidelines.
Keywords Toxocara canis
The close contact between infected pet dogs and their owners
facilitates the transmission of zoonotic helminth infections
(Deplazes et al. 2011). Toxocariasis, as a sapro-zoonotic dis-
ease, is caused by the larval stages of ascaridia including
Toxocara canis and Toxocara cati. Keeping of pet dogs has
led to progressive rise of the toxocariasis seroprevalence
among children (Despommier 2003; Lee et al. 2010).
Although the number of Toxoca ra eggs in faeces of pets less
than 8 weeks old is higher, nevertheless identification of the
low burden of T. canis eggs by coproscopical methods
remained as a diagnostic concern in non-dewormed puppies.
To prohibit the patent toxocariasis, the mature dogs must be
treated by anthelmintic drugs for four times a year (Deplazes
et al. 2011). A number of documentations indicate that about
90% of adult household dogs do not shed Toxocara eggs
(Claerebout et al. 2009). Given that the low numbers of T.
canis eggs may cause ocular/visceral larva migrants in chil-
dren (Glickman and Shofer 1987), the treatment policy man-
ufacturers should generally develop the validation of the sen-
sitive diagnostic tools.
The discrimination of T. cati and T. canis eggs is often
troublesome because of their similar phenotypes. Earlier stud-
ies indicated that the single-round PCR could be distinguished
from the Toxocara spp. by targeting the ITS2-rDNA
(Jacobs et al. 1997). The adverse effects of the faecal
* Adel Spotin
Infectious and Tropical Diseases Research Center, Tabriz University
of Medical Sciences, Tabriz, Iran
Department of Parasitology and Mycology, Faculty of Medicine,
Tabriz University of Medical Sciences, Tabriz, Iran
Parasitol Res (2017) 116:2591–2597