Animal Waste, Water Quality and Human Health

140Animal Waste, Water Quality and Human Healthand between humans and pigs is eliminated from most developed countries but is amajor problem in many developing countries. Tapeworm eggs can survive in soiland water and one of the consistent risk factors is drinking surface water (Cao et al.1997). However, the extent of waterborne transmission is unclear.Another crucial difference is that in developing countries most of the populationdrinks untreated water (including surface water) and even when treated water isavailable, breakdowns in treatment are common. Crypto. parvum is a highprofile waterborne zoonosis partly because it is not eliminated by typical watertreatments used in developed countries: in developing countries, all waterbornezoonoses, rather than just a few, risk escaping treatment.Low- and middle-income countries also differ in their proportion of susceptiblehosts: infants and children are a higher proportion of the population and a largeproportion of the global HIV-AIDS burden is borne by these countries: thiswould be expected to increase the relative importance of zoonoses associatedwith immuno-suppression such as listeriosis. Different socio-cultural practicesalso influence the presence and prevalence of pathogens. For example, inEthiopia meat is commonly eaten raw resulting in high levels of Cysticercusbovis infection. At the same time, not all characteristics of developing countryfarms are risk enhancing. The small number of animals kept and lack of verticalintegration decrease opportunities for microbial spread and because value chainsare short and comprise numerous actors, failure is both less likely and of lessimpact when it occurs. Moreover, many indigenous farming and food-handlingpractices are risk mitigating (Grace et al. 2008).Finally, most poor countries are tropical countries where the disease ecosystemis very different from the temperate and wealthy countries beyond the tropics ofCapricorn and Cancer. In most tropical countries, there is no distinct cold seasonwhere freezing temperatures can kill off bacteria in soil and water. The hot,humid conditions that prevail are more conducive to growth and survival ofmany pathogens and vectors and some water-associated zoonoses (e.g.schistosomiasis) are only found in tropical areas.Low- and middle income countries not only have different priorities in terms ofwaterborne zoonoses, they also have different challenges in managing them.Control of waterborne zoonoses at farm level in developing countries isconstrained by structure, lack of awareness, inadequate services, and incentivefailures. Small farmers are numerous, poor, and lack infrastructure; compared tothe average farmer, they are more likely to be female, illiterate, non-participantsin farmer associations, and remote from veterinary services (Grace et al. 2008).These structural factors will obviously make control on farms difficult.Compounding this, public veterinary services in developing countries are oftenunder-resourced and dysfunctional while private veterinary services have yet to