Introduction

Cryptosporidium has emerged as one of the most important zoonotic coccidian parasites affecting a wide range of domestic animals and man. Although the parasite was first reported in 1907 (1), its importance was only appreciated in the early 1970s when infections were associated with diarrhea in calves (2). Cryptosporidium has been reported to be second only to rotavirus as a cause of diarrhea in newborn calves in Britain (3, 4) with prevalence of 80% and 62.4% in calves and adult beef cattle, respectively (5). Profuse and severe life-threatening diarrhea occurs in neonates and
immunocompromised individuals, especially those with acquired immunodeficiency syndrome. However, self- limiting or sub clinical disease occurs in adults and immuncompetent animals and humans (6, 7). Cattle are a major source of C.parvum, which is responsible for neonatal diarrhea in calves and for zoonotic contamination (8). Bovine cryptosporidiosis is widespread and prevalence studies show a wide range of oocyst shedding from 14 to over 80% depending on the age, clinical situation and breeding regime of the animals. Overall, prevalence studies in cattle ranging from 3 days old to adult usually give results of appreciatively 20% of animals shedding oocysts, while prevalence in neonates is higher, especially when diarrheic calves are concerned (9). Although several studies on a prevalence of Cryptosporidium spp. have been conducted in developed and developing countries (7,10, 11,12,13,14), little is known on the occurrence of the parasite in Iran. Little information has been published about bovine cryptosporidiosis in Iran and epidemiological studies have not yet been conducted on a wide scale and in large number of animals. The aim of this study was, therefore, to determine the prevalence of Cryptosporidium spp. oocysts in cattle on selected farms within Saghez county of Iran.

Material and methods

Source of animals

Faecal sampling

Cryptosporidium oocyst detection technique

Statistical analysis

Results

The overall prevalence of cryptosporidial infection in cattle was 8.5%. Medium-scale unites had 11.8% of 212 animals, positive for Cryptosporidium spp.oocysts. Cryptosporidium oocysts were detected in 5% of the animals in the small-scale dairy units (Table 1). Oocyst shedding was recorded in bovines ranging from 3 days old to adults, although infection rates were significantly higher than calves (41%) in the remaining age groups (p<0.0001), (Table 2).

The fecal consistency of Cryptosporidium spp-positive and-negative samples was described in Table 3.

While 60% of the oocyst-positive samples were diarrheic (watery and loose or both), only 9% of the oocyst-negative samples were this form (p<0.05). Thus, it was clarified that Cryptosporidium infection is associated with the occurrence of diarrhea in calves. Between 21 diarrheic animals, 13 animals were less than 3-month ages calves and nine (75%) of these were positive for Cryptosporidium spp. oocysts.

Cryptosporidium spp. oocysts from cattle appeared as pink to red spherical to ovoid bodies against a green or purple background under MZN staining and all the positive specimens showed positive reaction with specific anti – Cryptosporidium monoclonal antibody. Because of the limited amount of Cryptosporidium monoclonal antibody we had, none of the negative samples were double-checked for the presence of the oocysts.

Figure 1

Fig1:Map of Kurdistan Province of Iran and green colored is area of interest

Figure 2

Table 1 Prevalence of cryptosporidia infection by dairy calves’ distribution centers survey in Saghez County of Iran (2009-2010).

Figure 3

Table 2. Prevalence of Cryptosporidium infection according to the age range in Saghez County of Iran (2009-2010).

Figure 4

Table 3. Relationship between Cryptosporidium spp. infection and diarrhea in calves of Saghez County, NW Iran (2009-2010)

Discussion

The prevalence of Cryptosporidium oocysts in cattle in this study were relatively lower than that reported in other countries. For instance, in Germany, the examination of field samples from different parts of Germany showed that the prevalence of cryptosporidia in calves (up to the age of 6 months) ranges mostly from 20 to 30%, with 35–36% monoinfections. Considering the fact that C. parvum is most prevalent in calves up to 4 weeks age. This age group probably has considerably higher prevalence’s (12), whereas, in Britain, up to 80% of calves and 62.4% of adult beef cattle have been reported as shedding Cryptosporidium spp. oocysts (5). Little in known on the prevalence of bovine cryptosporidiosis in Middle East (Asia) and Africa countries for comparison purposes. However, studies on human cryptosporidiosis have shown prevalence of 2-6% in Iran (17), 3.1 – 17.6% in Guinea Bissau (18), 0.4-8.2% in Korea (10) and 32% in Zambia (19). Chai et al. (20) reported 7.9% positive rates of cryptosporidiosis among the 3,146 people examined. The study showed a remarkable difference in positive rates between rural area and urban area, from 10.6% to 0.5%.

The high prevalence of Cryptosporidium spp. in young calves was similar to previous reports that Cryptosporidium infection was common in newborn calves. (3, 4).

The occurrence of high infection rates in this age category was attributed to the poor immunity in the newborn calves and the easiness of oocysts contamination through bucket – feeding. Of the screened farms, farm ‘C’ had the highest prevalence of Cryptosporidium spp. with up to 11.8% of animals shedding oocysts. The high prevalence rate may be attributed to the poor management or hygiene on the farm. The presence of a dirty and muddy environment could lead to the persistence of Cryptosporidium spp.oocysts on the farm, leading to increased risk of animals being exposed to the parasite. This low prevalence of infection in farms owned by Kurdistan University could be attributed to the good level of hygiene. Similarly, only ten (5%) out of 200 animals screened on 20 small – scale dairy units were positive for Cryptosporidium spp. oocysts. The low prevalence of Cryptosporidium spp. on the small – scale dairy units could be due to relatively good management and hygiene facilitated by small numbers of animals kept per household.

The prevalence of Cryptosporidium spp. oocysts in the cattle may result in these animals playing an important role as a source of Cryptosporidium spp. infection for livestock and man. However, further studies are required to ascertain this likelihood of this mode of transmission of the disease and to determine the pathogenicity of Cryptosporidium spp. isolates from cattle and other animals for man.

Acknowledgements