Similarly high infection rates of 99% ( Patnaik, 1962), 86% ( Alibasoglu et al., 1969), 92% ( al-Zubaidy, 1973) and 95.4% ( Mtei and Sanga, 1990) have been reported in India (Orissa State), Turkey, Iraq, and Tanzania, respectively. Although no obvious signs of illness are reported in animals infected with O. armillata, the severity of the pathological lesions described must reduce the efficiency of blood flow through the aortic arch. The inflammatory selleck chemicals response in the tunica media with destruction of the muscular structure could result in weakening of the aorta wall. On its own, this

parasite may have little veterinary importance, but in combination with the multiple parasitic infections that many cattle harbour in the region, the cumulative effects may be significant. Previous authors have speculated that O. armillata adult worms buy Galunisertib to be the cause of aneurysmal cardio-vascular disturbances ( Nelson, 1970) and aortopathy ( Zak, 1975). The skin-dwelling Mf of O. armillata may be

uniformly distributed throughout the skin ( Wahl et al., 1994) or, as reported in other studies ( Elbihari and Hussein, 1976 and Atta el Mannan et al., 1984), agglomerate in the region of the hump. This may reflect variation in biting behaviours of the vector in different areas and/or the possibility of different vectors distributed across the parasite’s wide geographic range. O. ochengi Mf were located in greatest abundance ventrally, which accords with the preferred feeding site of its vector ( Wahl and Renz, 1991). In the current study, the hump appeared to be the site most favoured by O. gutturosa, as reported previously ( Elbihari through and Hussein, 1978). Although not significant in this study, a similar reduction in the density of O. armillata Mf within the epidermis of older cattle has been previously observed ( Atta el Mannan et al., 1984). This trend may be due

to an increase in old, less fecund or dead, calcified worms in older cattle ( Trees et al., 1992); and/or a degree of immunity in hyper-endemic areas may be acquired, which has been found to occur against O. ochengi Mf ( Trees et al., 1992). Younger cattle, having had less exposure to the biting vectors, would be expected to have a lower prevalence of infection than the high level (100%) found in this study. Further investigation is required to establish the identity of the biological vector for O. armillata, and how it is so highly successful in transmitting the infection. This study provides the first evidence that O. armillata contains the endosymbiotic bacterium, Wolbachia. If, as previously supposed, the neutrophil chemotactic activity in filarial nematodes is largely dependent on the presence of Wolbachia ( Nfon et al., 2006), the cellular response to adult O. armillata worms should primarily consist of these cells. However, in contrast to O. ochengi, a heavy concentration of neutrophils around adult worms was not observed.