Listeria Monocytogens: A Case Study

2.6.1 Global epidemiology of Listeria monocytogens

The illness Listeriosis is an advancing infection of major public health significance worldwide due to the occurrence of its foodborne outbreaks and significant risk of mortality and morbidity. According to Weinstein and Bronze (2015), the overall mortality rate of L monocytogenes infection is 20-30%. Human listeriosis is mainly acquired through ingestion of contaminated food; Other modes of transmission include the transmission of the infection from mother to child transplacentally or through an infected birth canal and cross-infection in neonatal nurseries (Farber et al., 1992; Colodner et al, 2003). According to Howard (2007), listeriosis was found to be highest in infants 60 years of age.

It reported 34 cases in pregnant women and 7 cases in non-pregnant adults over a period of 6 months. Another was recorded in the year 1998 and 1999 which was also traced in hot dogs (Montville and Matthews, 2005). A total of 12 people were killed and 79 people fell ill in 17 states in the 1998 and 1999 outbreak. According to Jay (2005) the 1985 outbreak of listeriosis which occurred at southern California in contaminated Mexican-style cheese has brought new alteration to the syndrome. He further stated that at least 86 cases of listeriosis were traced to several brands of commercially produced Mexican-style cheese. 58 of the cases were among mother-infant pairs and 16 were non perinatal. There were 29 deaths; 8 neonates and 13 still-borns and 8 non-neonates. The bacteria entered the product by cross contamination of raw milk through faulty equipment. In addition to what Jay (2005) stated, Montville and Matthews (2002) also made mention of the fact that almost one third of the people infected died. Inadequate pasteurization of milk and mixing of raw milk with pasteurized milk caused the

2000) as well as its occurrence in coleslaw (Edna,2012). Furthermore, the event of the ailment in traditional processed fish has been accounted for whereby its prevalence in market was high (40-80) % (Bomfeh, 2011)

2.8 Methods of detecting Listeria monocytogenes

The many-sided features of Listeria monocytogenes allow the microorganism to survive and multiply in different food matrices even under harsh and adverse conditions. Therefore, there is the need to detect and trace this pathogen along the entire food supply chain using various methods (Zunabovic et al., 2010). These methods should meet government, scientific and industrial party requirements and should fulfill several guidelines. Some methods used in the detection of Listeria spp. include the cultural based technique and the immunological method.

2.1.1 Cultural based