Introduction

In northern Iran, one of the favourite birds used as food is the domestic duck (Anas platyrhynchas). It is very delicious, expensive and regarded as a luxury food and as a result plays an important role in the rural economy. The domestic duck is divided into many breeds; the most common in Northern Iran is the Rouen, a heavy-weight breed which originated in France before the nineteenth century and has since spread to all parts of the world. One of the major problems in A. platyrhynchas is parasitic infestation, which can cause diseases in ducks and affect their productivity and growth (Farzana et al., 2008). The common ectoparasites of A. platyrhynchas are lice, mites and ticks that cause production losses because of the irritation and some suck blood which can cause anaemia (Graham, 1986).

Also, it has also been shown that endo- and ectoparasitic infections cause economic loss, weight loss, lowered egg production, decreased feed conversion ratio and death of young ducks (Soulsby, 1982). There is insufficient research into parasitic infection of A. platyrhynchas in this region, and this study was carried out to assess the levels and variety of infections present.

Material and method

This study was carried out during the summer of 2015. Thirty samples of A. platyrhynchas were selected randomly from local markets and villages in Gilan Province, Iran.

Blood samples were collected and thin smears made immediately after collection. The smear was stained with Giemsa (Cable, 1957) and the slides examined for the presence of blood-borne protozoa. Protozoa were recognized according to the keys and descriptions given by Levine (1985), Springer (1997) and Soulsby (1982).

For collection of ectoparasites, an aerosol of 1 % malathion was used on the feathers of the body and left for 5 min. The duck was then shaken over a sheet of white paper and any ectoparasites that fell off were transferred into a vial containing 70 % methanol. Specimens were cleaned with lactophenol and identified using Wall and Shearer keys.

For collection of endoparasites, the gastrointestinal tract was removed and differentiated into the oesophagus, crop, proventriculus, gizzard, duodenum, small intestine, caecum and rectum, and then they were opened and parasites were collected, fixed and kept in 70 % methanol. The endoparasites were stained in borax carmine being cleared with lactophenol. Collected parasites were identified according to Yamaguti (1958a, b) and Soulsby (1982).

Results

In this study, 30 domestic ducks (A. platyrhynchas) from different parts of Gilan Province, Northern Iran, were collected randomly and examined. Based on the finding of this study, 56.6 % of ducks were infected with protozoan parasites, as shown in Table 1.

Table 1 Prevalence and intensity of protozoan parasites in Anas platyrhynchas
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This study also found two species of lice (Menocanthus stranineus and Liperus squalidus), one species of tick (Argas persicus) and one of flea (Ctenocephalides canis) on the domestic ducks’ feathers and body surface. Prevalence and intensity of the parasite infestation varied between species as shown in Table 2.

Table 2 Prevalence and intensity of ectoparasitic infestation in Anas platyrhynchas
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Helminthes parasite infection rate was 50 % in collected samples. Prevalence and intensity of the parasite infestation varied between species as shown in Table 3.

Table 3 Prevalence and intensity of helminth infection in Anas platyrhynchas
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Discussion

The current study was carried out to assess the levels of parasitic infection in 30 domestic ducks (A. platyrhynchas) in Gilan Province, Northern Iran. It was shown 56.6 % of ducks were infected with protozoan parasites. However, in a previous study by Shemshadi et al. (2014) on parasitic protozoan infection of wild waterfowl in southern coastal Caspian Sea lagoons results showed that 184 birds of 293 (62.8 %) harboured protozoan parasites which was higher than the current study. The highest prevalence of protozoan contamination was belonging to Giardia spp. (24.2 %) and the lowest was belonging to Haemoproteus spp. (6.1 %). Cryptosporidium spp., Plasmodium spp. and Trichomonas gallinae were found in 7.2, 8.2 and 17 % of waterfowl, respectively.

In this research, statistical analysis showed no significant difference between male and female ducks in parasitic infection (P > 0.05). However, in a previous study by Shemshadi et al. (2014) in wild fowl, cryptosporidiosis was statistically higher in females than in males (Trichomonas gallinarum has been found in the lower digestive tract and caeca of chickens and other gallinaceous birds (McDougald et al., 1997). Silvanose et al. (1998) studied 114 captive houbara bustards; 49 cases (43 %) were found to be positive for protozoa including 34 cases (29.8 %) T. gallinarum, 12 cases (10.5 %) Chilomastix gallinarum, one case (0 9 %) Lophomonas spp. and one case (0.9 %) Giardia spp. In the current study, 23.3 % of examined domesticated ducks were infected with T. gallinae which the rate of infection was similar to that of Silvanose et al.

Prevalence of haemoprotozoan spp. and pathological changes in ducks were determined by Dey et al. in 2008. They found the prevalence of Lecucocytozoon species such as Leucocytozoon caullery (54.67 %) and Leucocytozoon simondi (5.33 %) in ducks and the rate of haemoprotozoa infection was significantly (P < 0.01) higher in male (78.94 %) than female ducks (53.57 %). Our study did not find Leucocytozoon infection in ducks from Gilan Province. It was suggested that lack of suitable vectors (for example, Stomoxys spp.) for transmission of this kind of haemoprotozoan in this area is the reason of absence of Leucocytozoon spp.

Kuhn et al. in 2002 examined faecal samples from wild ducks and found Cryptosporidium parvum oocysts and Giardia cysts in samples; however, they were not detected in molecular examinations. In this study, Giardia cysts were not identified but Cryptosporidium bailey was.

In conclusion, this study found various kinds of parasitic infection in domesticated ducks in Gilan Province, Northern Iran. Findings indicate that applying protocols of management and applying preventative methods and treatment of infected cases are necessary to restrict parasitic infections in domestic ducks and other birds in this region. Also, more parasitological studies about infections in all kinds of birds in this area were proposed by the authors to find more evidence for solving the problem.