Document Type : Short Commu‌nication
Authors
1 Graduated of Faculty of Veterinary Medicine, Urmia University, Iran
2 Department of Internal Medicine and Clinical pathology, Faculty of Veterinary Medicine, Urmia University, Iran
3 Department of Pathobiology, Faculty of Veterinary Medicine, Urmia University, Iran
4 School of Animal & Veterinary Sciences, Charles Sturt University, Wagga Wagga, Australia
Abstract
Dirofilariasis is a zoonotic infection caused by Dirofilaria immitis (D. immitis) the causative agent of canine and feline cardiopulmonary dirofilariasis (heartworm disease) in temperate and tropical areas throughout the world and Iran. The parasite is transmitted by different species of culicid mosquitoes. In order to study on D. immitis in healthy urban dogs in Urmia region, and comparison of two diagnostic methods i.e. modified knot test and rapid antigen test kit, the number of 100 dogs (63 males and 37 females) were undertaken to this study in a period of April till July (2014). After physical restriction, blood samples were collected from cephalic or saphenous vein in the appropriate tubes which transferred to the laboratory in an ice pack. Modified knot test was used to recognize D. immitis. Then, all samples were tested by Antigen rapid test kit. There was a difference between the result of modified knot test and rapid test kit. The results indicated that out of 100 samples, 3 samples were infected by D. immitis. There were no significant differences in dirofilariasis infection among different gender and ages. It is concluded the antigen rapid test should be accompanied by another diagnostic method in order to avoid false negative results.
Keywords
Introduction
D. immitis is the most important zoonotic species of the genus Dirofilaria in the world (Navarrete et al., 1968; Schlotthauer et al., 1969; Toomes et al., 1983). Dirofilariasis can be an infectious zoonotic disease when humans are bitten by culicid mosquitoes harboring infective third-stage larvae (microfilariae), due to D. immitis. This nematode is a common filarial worm of dogs and cats in the world, accounts for the most number of human infection with over 400 cases recorded (Pampiglione et al., 1995; Vakalis et al., 1997; Brown et al., 1993). Dirofilariasis has been reported as an emerging zoonosis in many countries world-wide such as Iran (Azari-Hamidian, 2007).
D. immitis or heartworm is more important than other filaria in dogs because it can cause some clinical signs (Brown et al., 1993). This worm lives in right ventricle, pulmonary artery and posterior vena cava and its microfilaria is found in the peripheral circulation (Eslami, 1998).
Infection to D. immitis in dogs was reported from different regions of the world (Hatsushika et al., 1992). The first infectious was recorded by Travassol in 1921 (Ettinger, 2010). Dirofilariasis is common in dogs in Iran with infection rates 16/1% (Ranjbar et al., 2011).
D. immitis was first reported from a dog in Iran in 1969 (Sadighian, 1969). Then infection to heartworm was reported from different areas of Iran including: Ardabil (Bokai et al., 1998), Shiraz (Jafari et al., 1996), Tehran (Meshgi et al., 2001), Tabriz (Meshgi et al., 2002), Tonekabon (Ranjbar et al., 2005), Golestan (Ranjbar et al., 2006) and Khozestan provinces (Razmi, 1999).
There is a lack of information about filariasia in the urban area of Urmia in North West of Iran. In this study, filariosis was indicated in urban dogs of Urmia with two diagnostic methods of the modified knot and rapid antigen tests.
Materials and Methods
One hundred dogs from different parts of Urmia were entered to this study. After the recording of necessary information including age, sex, and breed of the dogs, the blood samples (5 ml) were taken from cephalic or lateral saphenous veins for modified knot test and rapid antigen test.
Modified knot method
The blood samples were mixed with 9 ml formaldehyde 2% and were shacked well for RBC hemolysis. In the laboratory, the samples were centrifuged for 5 minutes in 1500 rpm. Methylene blue stain was added and the mixture was examined for the presence of microfilaria with photomicroscope. The differential diagnosis between microfilaria of D. immitis and Dipetalonem recaonditum was done regarding the morphological criteria (Eslami et al., 2004).
Rapid test
Two drops of not coagulated blood, serum or plasma of dogs were added to a concerned place of Heart worm disease kit (manufactured by Bionote, Australia). The result was read after 5-10 minutes.
Results
The results showed that 3 (3 %) of the total 100 urban dogs were infected with D immitis. Blood microfilaria (D. immitis) was observed in 3 samples by modified knot method (Fig. 1). None of the dogs showed positive results based on rapid antigen test kit and all samples were negative with this test (Fig. 2).
Fig 1. Percentage of healthy and D. immitis-infected dogs in Urmia distinct.