Iraqi Journal of Veterinary Sciences

Introduction

Toxocariasis is a zoonotic disease caused by Toxocara canis and Toxocara cati, which belong to the family Toxocaridae and genus Toxocara.Adult worms live in the small intestine of dogs and cats. Eggs are shed into the environment through feces and become embryonated within 3-6 weeks (1) and infect the host and paratenic host animals, including dogs, cats, cattle, sheep, goats, rodents, birds, and man through ingestion of contaminated food (2). Lactating puppies and kittens appear to get vertically infected via milk during lactation (3), and tans-placental transmission was reported in dogs (4). The disease can be transmitted to humans by ingesting contaminated food and soil with embryonated eggs (5). The ingested eggs hatch, and the larvae migrate to other tissues and organs, where they remain encapsulated third larval stage (1). In humans, the migration of larvae produces ocular larval migrans (OLM) or visceral larval migrans (VLM) (6). Few studies have been carried out in the South and Middle cities of Iraq, and they showed the presence of Toxocara infection in dogs, cats, and humans. A study in Kirkuk province recorded that the prevalence of Toxocara canis and Toxocara cati infection was high in stray dogs and cats (25.98%) and (39.58%), respectively (7). In the last couple of years, stray dogs and cats have been increasing in Sulaimaniyah province, especially in public parks and residential areas, which might significantly impact public health by spreading zoonotic diseases, including toxocariasis (6). The spread of the Toxocara spp.worms among domicile cats and dogs seem to be related to the owners (8), probably due to the lack of deworming programs, which makes the prevalence of the infestation high, consequently affecting human health. Therefore, the study aimed to investigate the prevalence of Toxocara canis and Toxocara cati among domicile and stray dogs and cats in the region and identify the influence of lifestyle and age on the infectious rate.

Materials and methods

Ethical approve

The proposal of the study was approved by the University of Sulaimani, College of Veterinary Medicine Scientific, and Ethics Committee numbered No-14, section-3, 10.04.2021.

Study area and sample collection

About 5-7 gm of the fecal sample was collected randomly from each presented animal (Cat; 78, Dogs; 52) at some veterinary clinics in the Sulaimani city and preserved in 50 ml of 10% formalin (9). The samples were transported to the Microbiology Laboratory for investigation at the College of Veterinary Medicine, University of Sulaimani. The study was carried out from December 2020 to August 2021.

Direct fecal smear

A direct fecal smear technique was applied to detect the eggs of the parasite by putting a small amount of the animal feces on a glass slide and mixing it properly with 1-2 drops of distilled water using tooth sticks mounted with a coverslip, and checked under a light microscope at 4X and 10X to detect Toxocara eggs.

Floatation technique

About 1-5g of homogenized fecal sample mixed thoroughly with 50ml of saturated sodium chloride solution. The mixture was filtered using gauze. The filtrate was divided between three test tubes to form a convex surface, then a coverslip was mounted on the surface of each test tube, waited for 25 minutes to let nematode eggs float, and touch the coverslip. The coverslips were removed horizontally, placed on the glass slides, and examined under power 10X (9).

Statistical analysis

Frequency, Crosstabulation, non-parametric correlation, and Chi-square were used to analyze the data using IBM SPSS v20. P-values less than0.05 were considered significant, and the confidence interval depended on 95%.

Results

The influence of lifestyle on the rate of T. cati and T. canis infection in cats and dogs

The samples (Cats; 78, Dogs; 52) were randomly collected from different veterinary clinics in Sulaimani city. 46.2% of the samples were taken from domiciles, and 53.8% were from stray cats. 34.6% and 65.4% of the samples were collected from domiciled and stray dogs, respectively (Table 1). The T. cati and T. canis infection rate was 22/78 (28.2%) and 6/52 (11.5%) in cats and dogs, respectively.

Table 1: Frequency and percentage of T. cati and T. canis infection in cats and dogs

Stray cats were more likely to get infected (47.62%) compared to the domiciled (5.56%) cats (P< 0.001). Meanwhile, only 11.11% (n=2) of domicile and 11.76% (n= 4) of stray dogs were positive for T. canis (P> 0.661) (Table 2). The total rate of infection in both cats(n=22) and dogs(n=6) was 21.53%. There was a moderate and highly significant positive correlation between the lifestyle and the rate of infection in cats (r = 0.466**, P< 0.001, n = 78) (Table 3). There was a very low and no significant positive correlation between the lifestyle and the infection rate in dogs (r= 0.1, P> 0.945, n= 52) (Table 3).

Table 2: Frequency and percentage of infection among domicile and stray dogs and cats

- P-value less than 0.05 was considered statistically significant.

 Table 3: Spearsman’s correlation between the lifestyle and the rate of infection

P-value less than 0.05 was considered statistically significant.

The influence of age on the rate of infection

 A total of 58 (74.36%) of the cats were aged between 0-and six months. 16 (27.58%) of them were infected, and 35.64% were over six-month age, 30% of them were infected. While 47.8% of the dogs were aged under 12 months, and 52.2% were aged between 13-and 72 months. Only 8% and 14.81% were positive for T. canis, respectively (Table 4). The results showed that there was not any significant correlation between the age and the rate of infection in cats (r= - 0.023, P> 0.823, n= 78) and dogs (r =- 0.107, P> 0.452, n= 52) (Table 3).

Table 4: Influence of age on the frequency and infection rate in dogs and cats

P-value less than 0.05 was considered statistically significant.

Discussion

The results of the study showed that the rate of Toxocara spp. Infection was higher, particularly among cats versus dogs, and there were moderate and high significant correlations between the lifestyle and rate of infection, especially in cats. In support of our study, in Kirkuk province/ Northern Iraq, Canada, and the US, it was reported that Toxocara spp. Infection was higher among cats than dogs, and the highest prevalence was recorded among stray cats (7,10,11). Additionally, other studies in Southern Iraq, Duhok governorate in Kurdistan region/Iraq, and Turkey revealed that the soil of public and school parks in rural and urban areas (12,13) were contaminated with the eggs of Toxocara spp. (14). The egg shedding of Toxocara spp. was higher among cats than dogs in the USA except for the southwest of the country, where the egg shedding was found to be higher in dogs versus cats (10). Several studies reported a high prevalence of T. cati among cat populations in Europe (15). Another study in the Kalar city/ Iraq found that 25% of stray dogs were infected with Toxocara spp., and 50% of the infected dogs were living around abattoirs (8). Meanwhile, an investigation in Northern Belgium reported a low prevalence 4.4% of the parasite among pet dogs, and a low rate of infection seems to be related to the regular use of anthelmintic agents (16). Several other studies showed that infection with Toxocara spp. is still high among cats and dogs in India T. canis; 52.54% (17), South Africa T. canis;16.8%, T. cati; 27.9% (18), and Musol, Iraq T. canis; 40.47% (19).

The results revealed that the infection rate was higher among younger cats than in the older age groups. However, in dogs, the infection rate was a bit high among older age groups compared to the younger age groups. In support of this finding, the rate of infection was found to be higher in younger cats in Canada (11) and among cats and dogs, which were less than one year in the US, Mexico, the Caribbean, and Central America (20) and older dogs in Al-Diwaniya province, Iraq (21). Studies in India and Europe reported that the prevalence of the T. canis was higher in younger India; 38%, Europe; 33.5% compared to the older dogs and cats India; 8%, Europe; 14.7% (22-24). Dogs older than six months of age, with a more robust immune system, appear less likely to get infected than the younger age groups (16). The discrepancy between our observation and the other finding regarding the rate of T. canis infection in dogs, which was higher in the older age groups, might be related to the sample size or the sensitivity of the used method. Even though T. canis might go undetectable sometimes, there is a possibility of somatic tissue larvae, especially in females. However, the organism might be reactivated during pregnancy and infect the offspring (25) before or after birth through the placenta or lactation (26,27).

To prevent the incidence of toxocariasis, it is advisable to follow regular deworming programs in both cat and dog populations according to the age, sex, and purpose of use (28). Lactating bitches and queens and puppies and kittens should be treated simultaneously from two weeks after delivery to two weeks after weaning at 14-day intervals, then every six months. Dogs and cats used in sports, competitions, and show programs, which have a higher chance of getting infected, should be dewormed one month before and after the occasions. In addition, domiciled dogs and cats in contact with children should routinely be tested every month for Toxocara worms and be treated if required (29-31).

Conclusion

The infectious rate of T. canis and T. cati are still high, especially among stray cats. There was a strong, positive correlation between the animal's lifestyle and the infection rate in cats. However, there were no correlations between age and the rate of infections in both cats and dogs.

Acknowledgment

We Cordially thank the College of Veterinary Medicine, the University of Sulaimani. and the private veterinary clinics for providing the required materials and Lab. during the study.

Conflict of interest

None of the authors has any conflict of interest to declare.

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