(half-hour at a temperature that causes first and second degree burns in humans in ten seconds) Acidic pH conditions Presence of anti-microbial surfactants such as sodium dodecyl sulfate and lipid solvents Exposure to disinfectants: B-propiolactone, formalin, and iodine compounds Ordinary levels of chlorine in tap water kill H5N1 in public water systems. To kill avian flu viruses, H5N1 "can remain infectious in municipal landfills for almost 2 years. [...] The two factors that most reduced influenza survival times were elevated temperature and acidic or alkaline pH." Avian flu in birds According to Avian Influenza by Timm C. Harder and Ortrud Werner: Following an incubation period of usually a few days (but rarely up to 21 days), depending upon the characteristics of the isolate, the dose of inoculum, the species, and age of the bird, the clinical presentation of avian influenza in birds is variable and symptoms are fairly unspecific. Therefore, a diagnosis solely based on the clinical presentation is impossible. The symptoms following infection with low pathogenic AIV may be as discrete as ruffled feathers, transient reductions in egg production or weight loss combined with a slight respiratory disease. Some LP strains such as certain Asian H9N2 lineages, adapted to efficient replication in poultry, may cause more prominent signs and also significant mortality. In its highly pathogenic form, the illness in chickens and turkeys is characterised by a sudden onset of severe symptoms and a mortality that can approach 100% within 48 hours. The current method of prevention in animal populations is to destroy infected animals, as well as animals suspected of being infected. In southeast Asia, millions of domestic birds have been slaughtered to prevent the spread of the virus. Poultry farming practices There have been a number of farming practices that have changed in response to outbreaks of the H5N1 virus, including: vaccinating poultry against bird flu vaccinating poultry workers against human flu limiting travel in areas where H5N1 is found increasing farm hygiene reducing contact between livestock and wild birds reducing open-air wet markets limiting workers contact with cock fighting reducing purchases of live fowl improving veterinary vaccine availability and cost. For example, after nearly two years of using mainly culling to control the virus, the Vietnamese government in 2005 adopted a combination of mass poultry vaccination, disinfecting, culling, information campaigns and bans on live poultry in cities. Dealing with outbreaks The majority of H5N1 flu cases