Newcastle disease (ND) is an infectious viral disease of birds and has been considered as one of the most significant diseases of poultry and other avian species around the globe (Aldous and Alexander 2001). The disease is endemic in Pakistan and causes major economic losses to poultry industry each year (Rehman H et al. 2013). Although incidence of ND in broiler and layers remains higher during the course of year, it reaches its plateau during seasonal stress (January-February and June-July). One report shows that during September 2011 - January 2012, the diseases has killed 45 million birds and resulted into a loss of approximately 65 million US $ to the country (Anonymous). ND virus (NDV) is an enveloped, single stranded RNA virus and grouped into the genus Avulavirus within family Paramyxoviridae(Calibeo-Hayes et al. 2003). Isolates of NDV may be categorized into three main pathotypes (lentogenic, mesogenic and velogenic) depending upon the severity of disease in chickens (Seal et al. 2000).
NDV is most commonly transmitted through fecal-oral and respiratory route provided that birds are in close contact (Alexander 1988). Infected birds excrete large amount of virus in their feces (Calibeo-Hayes et al. 2003). Virus is present in most tissue secretions of acutely infected birds even 24 hours prior to appearance of clinical signs. Under certain conditions, NDV can survive up to 20 days in fecal material (anonymous) and presence of organic matter might enhance the virus survival rates (Clarke et al. 1956). In order to control the spread of disease, decontaminate the infected premises is of prime importance. Strict biosecurity measures in conjunction with mass vaccination programs are also employed for the control of the disease. In past few decades, implementation of extensive vaccination programs in commercial poultry has reduced the
Introduction
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disease incidence to some extent in Pakistan. However, this might also led to the generation of novel genotypes under high immune pressure(Miller et al. 2009). Disinfection of farm premises plays significant role to break the disease cycle of microbial pathogens(Fawzia1 et al. 2013). Such procedures gain more significance on the farms that experience disease outbreaks. Dry cleaning, burning and fumigation followed by chemical disinfection is routinely practiced in Pakistan. Although, physical method are helpful to reduce the pathogen load on farm premises but complete disinfection cannot be achieved without the use of chemical disinfectants. Commercial disinfectants employed in Pakistan are grouped into oxidizing agents, aldehydes, quaternary ammonium compounds, and phenolic preparations. The products containing these ingredients are available either alone or various combinations under different brand names. (Stringfellow et al. 2009).
All of the disinfectants do vary in their disinfection power but to achieve proper disinfectants appropriate interaction time is necessary. Under clean conditions such interaction time is low but longer contact times are needed in presence of organic matter. Some studies show that environmental temperature influences the interaction time of disinfects with matter/surfaces to achieve proper disinfection. In case of chlorine disinfection of adenovirus inactivation time was increased 2-3 times when temperature was lowered to an extent of 10°C (Clarke et al. 1956). Similarly, virucidal activity of some disinfectants including aldehyde, chlorine and iodine compounds against infectious bursaI disease virus (IBDV) was also decreased at lower temperatures (Benton et al. 1967).