The present study was designed to assess the role of inulin and sugar beet fibres (SBF) on adult O. dentatum in growing pigs. Four experimental diets were formulated based on barley flour with added insoluble fibre from oat husk (Diet 1), a pure carbohydrate source inulin (Diet 2), soluble fibre from sugar beet fibre (SBF) with a high proportion of soluble fibre components (Diet 3) or inulin plus SBF (Diet 4). Thirty-two 10-week-old pigs were divided randomly into 4 groups each of 8 pigs. After 3 weeks adaptation on Diet 1 all pigs were infected with a single dose of 6000 L8 O. dentatum. At week 7 p.i. one group was switched to Diet 2, another group to Diet 3 and another group to Diet 4. The remaining 8 pigs continued on Diet 1 until the end of the experiment and served as controls. At week 13, all pigs were necropsied and their worm burdens determined. The worm recoveries from the pigs on the inulin supplemented diet (Diet 2) were reduced by 97% compared to the controls (Diet 1). Further, the inulin-fed pigs exhibited markedly reduced faecal egg counts. The pigs on inulin plus SBF diet (Diet 4) and on SBF diet (Diet 3) had 86% and 70% adult worm reductions compared with the controls, respectively. The results from this study indicate that highly degradable and rapidly fermentable carbohydrates such as dietary inulin have a profound deworming effect on O. dentatum infection.
Background
In Lithuania, the first case of canine subcutaneous dirofilariosis was recorded in 2010. Since then, an increasing number of cases of canine dirofilariosis have been documented in different veterinary clinics throughout the country. Human dirofilariosis was diagnosed in Lithuania for the first time in September 2011. However, to the authors’ knowledge, there are no published data on the presence and prevalence of autochthonous dirofilariosis in dogs and humans in the country. The present study provides information about the predominant species and prevalence of
Dirofilaria
in dogs and describes the cases of human dirofilariosis in Lithuania. It also outlines PCR detection of the bacterial endosymbiont
Wolbachia
that contributes to the inflammatory features of filarioid infection.
Results
A total of 2280 blood samples and six adult worms from pet and shelter dogs were collected in the central and eastern regions of Lithuania in 2013–2015. Based on their morphological appearance, morphometric measurements and molecular analysis, all the adult nematodes were identified as
Dirofilaria repens.
The diagnosis of microfilariae in blood samples was based on blood smear analysis and Knott’s test. The PCR and sequence analysis of the ribosomal DNA ITS2 region and
cox
1 gene confirmed the presence of
D. repens
. Overall, 61 (2.7%) of the 2280 blood samples were found to be positive for the presence of
D. repens.
The infection rate of
D. repens
was significantly higher in shelter dogs (19.0%; 19/100) than in pet dogs (1.9%; 42/2180) (
χ
2
= 100.039,
df
= 1,
P
< 0.0001). Forty-nine DNA samples of
D. repens
-infected dogs were tested for the presence of the bacterial endosymbiont
Wolbachia
and, of these, 40 samples (81.6%) were found to be positive. Three ocular and six subcutaneous cases of human dirofilariosis were diagnosed in Lithuania in the period 2011–2018.
Conclusions
To the authors’ knowledge, this is the first report of autochthonous
D. repens
infection in dogs and humans in Lithuania. The present data demonstrate that
D. repens
is the main etiological agent of dirofilariosis in Lithuania. The DNA of the filarioid endosymbiotic bacterium
Wolbachia
was detected in the vast majority of dogs infected with
D. repens
.
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