Introduction

Neospora caninum is a protozoan parasite that was first described in a litter of dogs in Norway in 1984 (Bjerkas et al. 1984). Today, it is recognized predominantly worldwide as an infection; sheep, goat, deer, horses, water buffalo, and camel have also infrequently been reported to be naturally infected (Dubey and Lindsay 1996). The dog and coyotes have been identified as definitive hosts for N. caninum (McAllister et al. 1998; Gondim et al. 2004). The etiological agent N. caninum is closely related to the apicomplexan protozoan Toxoplasma gondii, but they can be distinguished by their ultrastructural, antigenic, and genetic properties (Speer and Dubey 1989; Marsh et al. 1995). Serological tests used to diagnose N. caninum infection include the indirect fluorescent antibody test (IFAT), Neospora agglutination test (NAT), immunoblot analysis, and enzyme linked immunosorbent assay (ELISA) (Von Blumroder et al. 2004; Bjorkman and Uggla 1999; Dubey 2003). The aim of this study is to investigate the seroprevalence of N. caninum infection in camel in Mashhad, Iran.

Materials and methods

Collection of sera

Blood samples were taken in 2004–2005 in a slaughterhouse in Mashhad. All the samples were immediately transported to the diagnostic laboratory. Serum was removed after centrifugation at 1,000×g for 10 min. All the sera were kept in a microtube and stored at −20°C until tested for antibodies to T. gondii and N. caninum (Frossling et al. 2003). The source or country of origin of the camels was unknown.

Serology

The test procedures were performed using a Teflon-masked 12-well N. caninum NC-1 antigen slide (VMRD Inc Pullman, WA 99163, USA), within which whole N. caninum tachyzoites were used as antigen and T. gondii tachyzoites as IFAT slide (BIOGENE, Iran), fluorescein-conjugated, affinity-purified rabbit anticamel IgG (Central laboratory, Veterinary Faculty, Tehran University, Iran) (Bjorkman and Uggla 1999).

Results

Of the 120 camels, antibodies against N. caninum were found in seven (5.83%), in three (2.5%) in titers of 1:20, and in four (3.3%) in titers of 1:40. Antibodies to T. gondii were found in five (4.16%), in three (2.5%) in titers 1:20, and in two (1.66%) in titers 1:40. All the seven sera with N. caninum antibodies had no T. gondii antibodies in 1:20 titers.

Discussion

Presence of antibodies against N. caninum in aborted and healthy dairy cattle was detected (Sadrebazzaz et al. 2004), but there was no information on N. caninum infection in other hosts in Iran. Camels constitutes an important economical activity in the desert population in east and central regions of Iran. The camel is used as a load animal, which is an important role in transportation in rural areas; in addition, it is also a source of meat, skin, and leathers.

The 5.83% prevalence of N. caninum antibodies in the present study is similar to the 3.72% prevalence in Egypt, but the 4.16% prevalence of T. gondii antibodies in our study is lower than that of the 17.4% of the camels from Egypt (Hilali et al. 1998), 11.8% of the camels from eastern Sudan (Elamin et al. 1992), and 16% of the camels from Saudi Arabia (Hussein et al. 1988). However, seroprevalence rates do vary depending on the serologic test and the initial serum dilution tested. The sylvatic and heteroxenous transmission cycle of N. caninum is unknown in Iran, and finding of N. caninum antibodies in camels extend geographic range and host for N. caninum.