Molecular screening approach to identify protozoan and trichostrongylid parasites infecting one-humped camels (Camelus dromedarius)

Little is known about the diversity of many parasites infecting camels, with most relying on morphological parameters. DNA extracted from different tissues (n= 90) and fecal samples (n= 101) from dromedary camels (Camelus dromedarius) in Egypt were screened for multiple parasites using different molecular markers. Screening of tissue samples (heart) for Toxoplasma gondii and Sarcocystis spp. was performed using B1 and 18S rRNA gene markers, respectively. T. gondii was further genotyped using multiplex multilocus nested PCR-RFLP (Mn-PCR-RFLP). Sarcocystis was analyzed using PCR-RFLP characterization (XbaI and MboI restriction enzymes). A taxonomically challenging but important group of nematodes (Trichostrongylidae family) were screened using the ITS-2 ribosomal DNA (rDNA) species-specific markers. Furthermore, nested PCR was used for the detection of Cryptosporidium spp. (SSU rRNA gene) and positive samples were genotyped after RFLP (SspI and VspI) and sequencing. Cryptosporidium parvum isolates were subtyped by sequence analysis of the 60-kDa glycoprotein gene. This study revealed that many parasites infect the investigated camels, including T. gondii (1.1%), Sarcocystis spp. (64.4%), Cryptosporidium spp. (5.9%) and Trichostrongylidae nematodes (22.7%). The species contribution for nematodes was as follows: Haemonchus spp. (95.6%), Trichostrongylus axei (26%), Trichostrongylus colubriformis (65.2%) and Cooperia oncophora (60.8%). Mn-PCR-RFLP typing for Toxoplasma was only successful for three markers: 5'-SAG2 (type II), 3'-SAG2 (type II) and alt. SAG2 (type II). PCR-RFLP using XbaI showed possible mixed Sarcocystis infection. Moreover, the Cryptosporidium genotypes detected were C. parvum (IIdA19G1 and IIaA15G1R1), Cryptosporidium rat genotype IV and a novel genotype (camel genotype). This approach revealed the unique Cryptosporidium genotypes infecting the investigated camels, and the high genetic diversity of the investigated parasites.