Brucellosis of camels in Iran
Ahmad Rafieipour and Nemat Ziaei
Shahid Bahonar University of Kerman, Iran
This study was done in the town of Baft, located in southeast of Iran, home of about 1350 camels. To investigate brucellosis in these animals, serological examinations including rose Bengal plat test (RBPT), MRT and 2ME were performed on 1123 camel’s serum samples. Positive results were obtained in 118 (10.5%), 96 (8.54%) and 89 (7.92%) camels thus tested, respectively.
Sixty-nine percent of the positive camels were adult ≥ than 4 years old and the remaining 31 percent were young, ranging from 6 months to 4 years old. In the infected herds, abortion rates associated with the disease ranged from 10 to 39 percent. Other ailments observed associated with brucellosis were retention of the placenta, fetal death and mummification, delayed maturity and infertility. Recommendations for brucellosis control were given, in order to increase the awareness of shepherds, by suggesting regular testing, slaughtering of infected animals and vaccinations.
Keywords: Serology, camel, brucellosis, Brucella spp., public health, Batf, Iran.
Baft is located in the province of Kerman in southeast Iran. The weather in this town is hot-arid and its desert is suitable for rearing camels. About 1350 camels live in this area where cattle, sheep and goats also are intensively bred. Camel husbandry has a vital role in the life of a number of shepherd ethnic groups in Iran. The camel's ability to survive under harsh conditions made it possible to use marginal and desert ecosystems (Abbas et al., 1992). Recently there is an increased awareness of role of camels as the main sources of milk and meat (Al-Khalaf and El-Khaldi, 1989; Knoess and Wilson, 1977) and today in Iran, not only shepherds but also the urban population consumes camel's milk and meat. Brucellosis is transmitted from animals to humans by ingestion of raw milk, milk products, raw liver, and close contact with animals through breeding, birth, slaughtering and contaminated dust (Cooper, 1992). In some countries including Iran, Iraq, Egypt, Kenya, Kuwait, Pakistan a high sero-prevalence of brucellosis in camels is reported (Table 1). Brucellosis is the most important zoonosis in terms of human incidence: almost all human cases are acquired from animals, particularly camels, goats and sheep (Al-Shamahy, 1999). Brucellosis in animals is caused by five recognized species of the genus Brucella. Four species commonly infect man: B. abortus, B. melitensis, B. suis and B. canis (Al-Shamahy, 1997). As we observed some cases of brucellosis in human beings in the area of Baft, the aim of this study was to investigate the presence of brucellosis in camels and its impact on the livestock rearing system.
Materials and methods
During a 3-month period in early 2007, serum samples were collected from indigenous camels throughout Baft of Kerman of Iran. Age, sex, clinical history, and date and place of sampling were recorded in a structured data collection form. Blood samples were drawn from 1123 camels and three serological tests for brucellosis were applied. These were Rose Bengal Plate Test (RBPT), MRT and 2ME Test. The RBPT was used for all serum samples and both MRT and 2ME were performed on sera positive to RBPT.
Positive test results were recorded in 118 (10.5%) camels by RBPT, in 96 (8.54%) camels by MRT and in 89 (7.92%) camels by 2ME. Sixty-nine percent of the positive camels were adults older than 4 years and the remaining 31% were younger, from 6 months to 4 years old. In infected herds, abortion rates associated with the disease ranged from 10 to 39% depending on the location. Other conditions caused by the disease were retention of placenta, fetal death and mummification, delayed maturity and infertility.
Zoonoses continue to represent an important health hazard in most parts of the world, particularly in developing countries (Stohr and Melsin, 1997). Brucellosis is a classical zoonosis and the major sources of infection remain contact with infected animals or the handling of carcasses. Less frequently it is acquired through food. Camels are not known to be primary hosts of Brucella organisms, but they are susceptible to both B. abortus and B. melitensis (Cooper, 1991). Consequently, infection rate in camels depends upon the infection rate in primary hosts animals in contact with them. In the area studied in Iran, camels with brucellosis were kept in close contact with other animals. Our results concur with those of Zowghi and Ebadi (1988) who isolated B. melitensis in several camels in Iran. In Butana area, Eastern Sudan, where camels are reared together with cattle, sheep and goats, Agab et al. (1994) isolated many strains of B. abortus from lymph nodes of camels serologically positive for brucellosis. In Darfur region, which owns over 25% of cattle, sheep and goats in Sudan, brucellosis is widely spread in large and small ruminants and camels introduced in the area showed high levels of incidence (Mousa, 1995).
The presence of B. abortus antibodies in all age groups in this study indicates that the infection starts in the early life probably through sucking. Similar patterns were found in cattle, and Oloffs et al. (1998) reported that 30% of positive animals in Uganda were younger than 3 years. The high levels of abortions caused by brucellosis and other etiological agents threaten the camel breeding in some parts of Darfur region. Although other causes of abortion were not investigated, trypanosomosis was speculated to be one of them. Brucellosis in camels seems to display less clinical signs and antibody levels than in cattle (Mousa, 1987), probably due to a relative resistance of camels to brucellosis. The disease should be controlled by vaccination of camels and primary hosts.
In the Republic of Yemen, the highest prevalence rate was observed in goats (1.3%) and this was statistically significant when compared with the prevalence rate among other species of animals (0.34%) (Al-Shamahy, 1999).
Camel breeding is common in the hot regions of Iran and camels provide part of the fresh milk used locally for human consumption. Infection may develop in people who are frequently in contact with camel herds, or who drink camel milk and its products. Therefore, the number of human brucellosis cases is expected to increase in some part of Iran as long as the disease persists in the animal reservoir.
Kiel and Khan (1989) reported that the prevalence rates among goats (1.3%) and sheep (0.6%) in Iran were higher than those among goats (0.8%) and sheep (0.3%) in Saudi Arabia. However, these were lower than those reported in Omani goats (6.4%) by Mehta and El-Mauly (1990), indicating a possible risk factor for Omani camels as well.
This survey confirmed the presence of Brucella sp. infection in the Baft region in Iran, showing a significant prevalence rate in camels (10.5%). Intervention strategies should include safe breeding procedures, regular serology testing, slaughtering of infected animals and vaccination of uninfected herds of camels.
The authors would like to thanks Shahid Bahonar University of Kerman for funding the research project.
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First Published June 2007