Mycobacterium bovisInfection in Holstein Friesian Cattle, Iran

Abstract

To identify strains of Mycobacterium bovis circulating in Iran, we used region of difference, spoligotypes, and variable number tandem repeats to genotype 132 M. bovis isolates from Holstein Friesian cattle. Despite wide geographic origins, the strains were genetically homogeneous. Increased distribution of cattle herds and inadequate control measures may have contributed to strain dispersion. E stimates suggest that globally >50 million cattle are infected with Mycobacterium bovis, causing an annual loss of ≈$3 billion US (1). In Asia, 94% of the 460-million cattle herd (33% of the world's cattle) are in areas with either no or only partial tuberculosis (TB) control programs (2). In 2006, the prevalence of bovine TB in Iran was 0.12% (Iranian Veterinary Organisation [IVO], unpub. data), yet few studies have been conducted on M. bovis in Iran (3-5). To identify the strains of M. bovis in Iran, we used region of difference (RD) typing, spoligotyping, and variable number tandem repeats (VNTR) typing. The StudyFrom 1996 through 2003, we collected necropsy specimens from TB-test reactor cattle from abattoirs in 21 of the 28 Iranian provinces where bovine TB has been reported. Specimens were all respiratory and gastrointestinal lymph nodes and any lungs, spleens, or livers that were visibly affected. All specimens were cultured for M. tuberculosis complex bacteria and incubated for >10 weeks. Of the 470 animals tested, results were positive for 216; however, because of delays in exporting samples to the United Kingdom, only 132 samples contained reculturable isolates with suffi cient growth for DNA extraction. Molecular speciation was determined by RD-PCR (RD1, RD5, RD9, RD10, and RD11) (6). Spoligotyping was conducted according to the method of Kamerbeek et al. RD-PCR showed that all 132 isolates were M. bovis. Spoligotyping identifi ed 8 types (Figure 1). SB0120 was the most common, and 5 others (SB1167-SB1171) were novel patterns and, thus, were specifi c to Iran. VNTR typing identifi ed 23 profi les (Figure 2). ConclusionsRD typing of the 132 isolates confi rmed that they were all wild type M. bovis; none were the M. bovis BCG vaccine strain because they carried the RD1 region. This fi nding is noteworthy because unauthorized vaccination of cattle with BCG has been reported in Iran (IVO, unpub. data). Although previous studies in Iran have reported the isolation of M. tuberculosis from tuberculin-positive cattle (3), our RD9 and RD10 analyses indicated that no isolates were M. tuberculosis. This fi nding suggests that M. tuberculosis is unlikely to be abundant, if even present, on cattle farms of Iran. Similarly, RD5 and RD11 analyses indicated that no isolates were M. africanum or M. microti.The spoligotypes were either identical to the BCG-like (SB0120) pattern (41% of isolates) or were simple variants of it by the deletion of 1 or occasionally 2 single or contiguous blocks of spacers (Figure 1). Because spoligotype changes have been attributed solely to the deletion of spacer units, the BCG-like strains here ...

Post-mortem examination and laboratory-based analysis for the diagnosis of bovine tuberculosis among dairy cattle in Ecuador

“…Mild lesions in lungs were found in only one slaughtered bovine. Similar observations were published in the United States and Iran, where no gross lesions suggestive of BTB were observed in lungs from dairy cattle, but frequently in lymph nodes of the thoracic region (Whipple et al, 1996;Tadayon et al, 2008). On the contrary, affection of lungs and other organs has been reported in cattle in Africa.…”

Epidemiology of bovine tuberculosis in Mexico, bordering the United States, at establishment of controlling strategies

“…In addition, the prevalence of BTB in cattle from Tamaulipas that were exported to and slaughtered in The considerably higher prevalence for the year 1995 was expected because at that time, there were no activities focused in the control of BTB. After the reduction of the prevalence in 1996, there was a slightly rising of this pattern in subsequent years (1997 and 1998), which is consistent with the previously reported in other studies (PAHO, 1992;Tadayon et al, 2008;Demelash et al, 2009). The aforementioned increment is consequence of detecting as positive to skin test animals infected with other Mycobacterium spp.…”

“…Regarding risk factors, the association between breed, specifically B. taurus genotypes, reported in this study, also has been reported by other authors (Kazwala et al, 2001;Ameni et al, 2007;Tadayon et al, 2008;Ngandolo et al, 2009). However, Elias et al (2008) stated that the breed of cattle is not associated with BTB.…”

“…The main strategy of these programs consists in using the tuberculin skin testing prior to cattle movement, after which the positive animals are segregated and/or slaughtered (Diguimbaye-Djaibé et al, 2006;Proaño-Perez et al, 2006;Ameni et al, 2007;Tadayon et al, 2008). In Mexico, the campaign against BTB was officially implemented in 1996, and comprises the mandatory execution of activities concerning the control, eradication, and accreditation of freestatus of the disease; i.e., diagnosis of BTB using the intradermal tuberculin skin and/or histological and microbiological techniques, slaughtering of positive cattle, movement restrictions of livestock from prevalent to free areas, and a permanent inspection and surveillance system in both, herds and slaughterhouses (DOF, 1996).…”

Zoonotic tuberculosis caused by Mycobacterium bovis, Central province, Iran

“…6 On the other hand, Iran is among the seven Asian States with an existing bovine TB control scheme operating at national scale with a very homogenous of bovine M. bovis. This appears in concordance with few previously reported observations 7 that cases of zoonotic TB in Iranian population is lower compared to its neighboring countries. 8 Different approaches to differentiate M. bovis from M. tuberculosis complex are done but the PCR-RFLP using OxyR gene is highly sensitive and inexpensive method.…”