Aditivos microbianos

The next stage of analysis was the investigation of associations between the four identified dimensions and the supplementary variables. Although the supplementary variables were found to be significantly associated with dimensions in some cases,

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their correlation with the dimensions (as measured using 𝑐𝑜𝑠2_{) were invariably low} (less than 0.1). Despite this, it may still be possible to extract some potentially useful information from these associations, which may be worthy of further investigation. Sary-Mogol was clearly distinguished from Taldu-Suu on dimension 1, which suggested that dogs from Sary-Mogol tended to be from less livestock-oriented households than those in Taldu-Suu. This feature was evident from personal observation during household visitation. Dogs which tested positive for E. granulosus G1 by PCR had significantly higher scores on dimension 1, which may suggest a direct relationship with households which did not own their own livestock and did not visit Jailoo. One possibility cause of this association is dog type, which will be discussed below in relation to dimension 2. Another possible reason for this association is visitation of Jailoo. Investigation of the potential risk associated with travel to “summer pastures” such as this has produced varied outcomes. A study of E. granulosus in Narenhebuke in Xinjiang, China, suggested that dogs at summer pasture had a lower coproantigen prevalence than those in winter pasture (Wang et al., 2001). However, since these samples were collected at different times of the year, there is a possibility for confounding due to inherent seasonality in infection. Conversely, it has been suggested that summer pasture presents a focus of E. multilocularis transmission in Kazakhstan (Rysmukhambetova et al., 2004). If the risk of canine infection with E. granulosus G1 is reduced when visiting the Jailoo, then those dogs which remain in the villages over the summer period may have a relatively higher prevalence of infection than those which visit Jailoo. Since the life expectancy of E. granulosus can be in the order of 6-20 months (Harris et al., 1980), then it is plausible that worms could still remain at the time of visitation (May). A final possibility is that of socioeconomic status. It has been suggested that travel to Jailoo is not economically feasible for poorer livestock-owning families (Farrington, 2005; Kerven et al., 2012), and a complete lack of ownership of livestock may predominantly identify particularly poor families. Therefore, the identified association may also be representative of socioeconomic factors, which may have an impact upon canine infection.

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Dimension 2 distinguished Kashka’Suu from the other villages, suggesting that dogs from this village were more likely to be described as sheepdogs (rather than guard/pet dogs). As would be expected, sheepdogs were also represented by low scores on dimension 1, but the location of Kashka’Suu on dimension 1 was not noticeably different from the barycentre of this dimension (which therefore suggests that this village had an ‘average’ level of livestock ownership/Jailoo visitation). Another possible explanation for this association with dog types is that houses in Kashka’Suu were generally of a higher build quality than those in other villages, which could mean that guard /pet dogs were not needed for protection of possessions. The variable indicating whether dogs were purged was also associated with this dimension, and suggested that purged dogs were more likely to be identified as sheepdogs. Purging was only conducted in two villages – Taldu-Suu and Kara-Kabak – but selection of dogs was mediated through the local government and private veterinarian, respectively. This association, especially given that these villages did not score highly on dimension 2 per se, possibly suggests a possible selection bias in favour of sheepdogs. This may be due to closer relationships between the veterinarians and sheepdog owners than owners of other dogs, or may indicate relative availability of people when dogs were needed. PCR negativity for both E. granulosus G1 and E. multilocularis were associated with higher scores on dimension 2, suggesting that sheepdogs were less likely to be infected with these species. This is unexpected, and differs from previous studies which have commonly identified sheepdogs or farm dogs as having a higher probability of coproantigen positivity or infection than non-sheepdogs (Moro et al., 1999; Shaikenov et al., 2003; Torgerson et al., 2003c; Buishi et al., 2005b). However, this result does agree with the association between dimension 1 and E. granulosus G1 PCR positivity, since dogs in households which do not own sheep are unlikely to be described as sheepdogs. One possible reason for this association is that sheepdogs are more highly valued than guard/pet dogs, and therefore are better fed. This would also correlate with the high scores on dimension 2 for larger dogs. Another possibility is that sheepdogs may be more commonly in work, herding sheep, and therefore may be less likely to roam through the village in search of food. One other possibility is the

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complex interplay between age and dog type. Dimension 2 identified sheepdogs as well as larger dogs (>20kg). As mentioned above, a previous study in Kazakhstan found that farm dogs had much higher infection pressures for E. granulosus than village dogs (Torgerson et al., 2003c). However, it was suggested that this provoked immunity in these dogs, and resulted in a reduction in worm burdens amongst older individuals. In the absence of immunity (as was suggested for village dogs), the worm burden increased to a plateau as age increased. Although the burdens themselves still appeared to remain higher in farm dogs than village dogs in this case, the possibility of an age-related reduction in burden in the face of high infection pressure cannot be excluded. Further work to characterise age-related trends in prevalence and/or coproantigen levels amongst dogs which visit Jailoo would be worthy of further investigation.

Dimension 3 differentiated dogs from Kara-Kabak from those from the other villages, and suggested that dogs from Kara-Kabak tended to be older dogs in single dog households. This suggests that the replacement rate for dogs in this community was lower than in the others, which may relate to previous culling campaigns. Although no direct questions were asked about previous culling campaigns during this visit, these campaigns were commonly reported in the villages of Sary-Mogol and Taldu-Suu over the period 2012-2013, and in Kashka’Suu in 2014. This result therefore suggests that widespread culling campaigns are not being implemented in Kara-Kabak (and could also indirectly suggest that these campaigns in the other villages ultimately only result in the replacement of culled dogs with new dogs). As low scores on this dimension were also associated with recent praziquantel dosing, this may suggest that praziquantel dosing is predominantly being used in Kara-Kabak rather than culling. The reason for this is unclear. However, one main difference between Kara-Kabak and the other three villages was that there was no resident government veterinarian in this community, although a private veterinarian remained. Culling campaigns appeared to be generally implemented based on governmental advice (Akjol Tagaibekov, personal communication), and therefore the lack of a government veterinarian in the community may be a possible reason for reduced culling in Kara-Kabak. The

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association between this dimension and purged dogs is likely to result from the fact that many of the purge samples were collected from dogs in Kara-Kabak.

Dimension 4 differentiated Taldu-Suu from Kara-Kabak and suggested a possible difference in knowledge of echinococcosis (with associated preventive action), or differences in attitude towards dogs, between these villages. As mentioned above, this may be suggestive of more effective education campaigns in Kara-Kabak than in Taldu-Suu. The finding that Sary-Mogol had a similar (although nonsignificant) positive score to Taldu-Suu and that Kashka’Suu had a similar negative score to Kara- Kabak may be suggestive of differences in educational campaigns between those villages in Alay district and those in Chon-Alay. Kashka’Suu and Kara-Kabak, being located in Chon-Alay, are geographically close to their district centre, Daroot-Korgon (which lies just 50km to the east in the Alay valley), whereas the district centre of Alay district is Gulcha – located in the Alay mountains around 130km to the northwest of Taldu-Suu (and which requires traversing a mountain pass to reach). Education campaigns regarding zoonoses in Kyrgyzstan are largely based on communication between state veterinarians and livestock owners (Stammbach, 2009), and therefore require reciprocal trust and respect (which has been a problem since independence and a loss of control of livestock diseases). The relative isolation of Taldu-Suu (and Sary-Mogol) from their district centres could have repercussions on the implementation and delivery of educational campaigns (which are an important component of any control scheme (Craig and Larrieu, 2006)).

However, an alternative explanation for these differences in dimension 4 may be that people in Kara-Kabak are less involved with looking after their dogs than those in Taldu-Suu. This possibility would be supported by the finding of an association between low values on this dimension and E. granulosus G1 PCR positivity. The correlation coefficient for OD value was -0.14, suggesting that lower scores on this dimension were associated with higher OD values. This finding, combined with the PCR results, may also be suggestive that the causative agent responsible for the coproantigen ELISA results is E. granulosus G1. One possible explanation for this association is that reduced owner involvement with dogs may result in underfeeding

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and therefore increased scavenging behaviour (even though a feature of this dimension was a reduced feeding of offal to dogs). An effective educational campaign leading to these behavioural patterns would be expected to be associated with a reduced, rather than an increased, risk of infection as has been identified in previous studies (Buishi et al., 2005b; Huang et al., 2008). One other possibility worthy of mention is reverse causality. Although canine infection with E. granulosus is asymptomatic and there are no reports of large numbers of human cystic echinococcosis cases in the area, cystic echinococcosis in intermediate hosts would be expected to be identifiable during slaughter (especially amongst the older animals more commonly slaughtered in these areas). Therefore, it is possible higher levels of infection with E. granulosus in the community are in fact the driver for the apparent increased knowledge. However, this is likely to require some degree of education: a study in Morocco found that whilst ruminant cysts were very commonly identified, their association with infection in dogs or humans was invariably unknown (Kachani et al., 2003).