pabilities, and training and auditing programs. Challenges include harmonization of regulations establishing upper lev­els of intake of nutrients and other substances (Bennett and Klich, 2003), and improving food safety without creating barriers for poor producers and consumers.
       Heavy metal contamination in soils affects the quality and safety of foods. For example, rice grains can accumu­late cadmium (Cd) from Cd-contaminated soils, thereby exposing consumers to serious health consequences from consumption of locally produced rice (Chaney et al., 2004). Undernourished populations  are particularly at risk,  as iron and zinc deficiencies can cause increases in Cd absorp­tion from the food supply (Anderson et al., 2004). While increased soil pH or maintaining soil flooding until grain maturation can reduce Cd levels in rice grains, yields can be affected (Chaney et al., 2004). Bioremediation with selected ecotypes of Thlaspi caerulescens, a hyperaccumulator of Cd, could effectively reduce levels in contaminated soil (Chaney et al., 2000). However, these wild ecotypes of T. caerule­scens need to be improved for commercialization before practical applications of this technology would be available (Chaney et al., 2004).

6.7.3 Reduce factors that facilitate the emergence and reemergence of human and animal diseases
Communicable diseases are the primary cause for variations in life expectancy across countries (Pitcher et al., 2008). AKST is important for three broad categories of infectious diseases: diseases whose incidence is affected by agricultural systems and practices (e.g., malaria and bovine spongiform encephalopathy), foodborne zoonotic diseases, and epidem­ic zoonotic disease (e.g., avian influenza). For example, the expansion of irrigated agriculture, as a result of the need to further intensify food production and to better control wa­ter supplies under increased climate variability and change, is expected to contribute to an increased incidence of ma­laria in some areas and the rapidly increasing demand for livestock products could increase the likelihood of BSE to spread more widely.
        The geographic range and incidence of many human and animal diseases are influenced by the drivers of AKST. Currently,  204 infectious  diseases  are considered to  be emerging; 29 in livestock and 175 in humans (Taylor et al., 2001). Of these, 75% are zoonotic (diseases transmitted be­tween animals and humans). The number of emerging plant, animal, and human diseases will increase in the future, with pathogens that infect more than one host species more likely to emerge than single-host species (Taylor et al., 2001). Fac­tors driving disease emergence include intensification of crop and livestock systems, economic factors (e.g., expansion of international trade), social factors (changing diets and life­styles) demographic factors (e.g., population growth), envi­ronmental factors (e.g., land use change and global climate change), and microbial evolution. Most of the factors that contributed to disease emergence will continue, if not in­tensify, this century (IOM, 1992). The increase in disease emergence will affect both high- and low-income countries.
       Serious socioeconomic impacts can occur when diseases spread widely within human or animal populations, or when they spill over from animal reservoirs to human hosts

(Cleaveland et al., 2001). Animal diseases not only affect animal and human health and welfare, they also influence perceptions of food safety, result in trade restrictions, ad­versely affect rural incomes and livelihoods, adversely affect non-livestock rural industries, have detrimental environ­mental effects, and adversely affect national economies for countries heavily dependent on agriculture Even small-scale animal disease outbreaks can have major economic impacts in pastoral communities (Rweyemamu et al., 2006).

6.7.3.1 On-farm options
The adoption integrated vector and pest management at the farm level, have been tested for reducing the persistence of human and animal diseases. These include environmental modification, such as filling and draining small water bod­ies, environmental manipulation, such as alternative wet­ting and drying of rice fields, and reducing contacts between vectors and humans, such as using cattle in some regions to divert malaria mosquitoes from people (Mutero et al., 2004; Mutero et al., 2006).
        Specific farming practices can facilitate infectious dis­ease emergence and reduce the incidence of certain diseases, such as malaria, in endemic regions (van der Hoek, 2004). However, the relationships between agriculture and infec­tious disease are not always straightforward. For example, whereas rice irrigation increases breeding grounds for the mosquito that carries malaria, in some regions the preva­lence of malaria in irrigated villages is lower than in sur­rounding villages because better socioeconomic conditions allow greater use of antimalarials and bed nets (Ijumba et al., 2002) and/or because the mosquito vector tends to pref­erentially feed on cattle (Mutero et al., 2004). However, in other regions, intensification of irrigated rice reduces the capacity of women to manage malaria episodes among chil­dren, leading to a higher prevalence of malaria (De Plaen et al., 2004). Therefore, greater understanding is needed of the ecosystem and socioeconomic consequences of changes in agricultural systems and practices, and how these factors interact to alter disease risk.
        In areas affected by high rates of HIV/AIDS, labor-saving agricultural technologies and systems are needed to support sustainable livelihoods. Ensuring access to diverse diets can also reduce the adverse impacts of disease on liveli­hoods and health. Agroforestry interventions, in particular, can improve communities' long-term resilience against HIV/ AIDS and other external shocks in ways that agricultural interventions alone cannot (Gari, 2002).
        In  addition,  improved  agricultural  information  and knowledge  exchange   between  experienced   farmers   and youth and widows is needed (Peter et. al., 2002). Agrofor­estry technology can respond to the cash, labor and short­ages confronted by AIDS-affected communities, both in the short term and in the long term. Medicinal plants and trees often provide the only source of symptomatic relief avail­able to the poor. Future agroforestry programs and forest policies in general should be reviewed to assess their effects on key determinants of HIV vulnerability (Villarreal et al., 2006). Using less labor intensive crops that need fewer in­puts can help households allocate labor more efficiently in food producing activities (Ngwira et al., 2001). While di-