Cronobacter Support
07-13-2009, 09:34 AM
5. EXPOSURE ASSESSMENT
5.1 EXPOSURE TO INFANT FORMULA/BREASTFEEDING RATES
It is impossible to estimate on a global basis the percentage of all infants who receive one of the products under consideration. This is due, on the one hand to the variable rates of breastfeeding in different populations and, on the other hand to the availability of the products in different parts of the world.
Exclusive breastfeeding rates differ from one country to the next. In Scandinavian countries, for example, 95% of babies are breastfed shortly after birth with almost 75% of those still being breastfed at 6 months of age. In other European countries, initial breastfeeding rates are below 30%, decreasing to almost no exclusive breastfeeding at 6 months. Available data on rates and exclusivity of breastfeeding from Australia in 1995 (Donath and Amir, 2000) and from Germany in 1997/98 (Kersting and Dulon, 2002) allow an estimate of the percentage of infants at different ages exposed to infant formula (Table 1).
Infant formula may be a direct source, an indirect source (contributing to a reservoir of E. sakazakii in the environment), and/or a vehicle for E. sakazakii-induced illness; it may also be neither the source nor the vehicle for E. sakazakii-induced illness. The meeting considered, on the basis of the information available, that in between 50 and 80% of cases, powdered infant formula is both the vehicle and the source (direct or indirect) of E. sakazakii-induced illness. To estimate a range of the proportion of cases due to powdered infant formula versus some other source, the meeting considered data from the United States in 2003 (C. Braden, personal communication, 2004). For sporadic cases of E. sakazakii sepsis and meningitis, six out of seven cases had exposure to powdered infant formula; the exposure was unclear in the remaining case. Thus, for at least 85% of these cases, powdered infant formula was a potential source. A review of 48 E. sakazakii cases in English language literature since 1961 revealed that at least 25 cases (52%) were directly linked to powdered infant formula.
Table 1. Estimated percentage of (healthy term) infants exposed to powdered infant formula or follow-up formula in Australia and Germany.
Age...............Australia, 1995...........................Germany, 1997/98
.....................(Donath and Amir, 2000)............(Kersting and Dulon, 2002)
.....................n = 2 874...................................n = 1 717
1 month........29%.................................. .........-
2 months.......-................................................42 %
3 months.......40%.................................. ........-
4 months.......-................................................51 %
6 months.......57%.................................. ........61%
Reconstituted powdered infant formula is probably a common vehicle in transmitting Salmonella to infants, given its major role in the infant diet, but contamination of formula is more likely to occur from the preparer or preparation environment than from the manufacturing process. Infrequent occurrence of intrinsic contamination of powdered infant formula does occur and has resulted in outbreaks of illness, but this appears to be rare. Thus, the meeting considered that most cases of salmonellosis amongst infants were probably not caused by intrinsic contamination of powdered infant formula. Disease caused by contamination of powdered infant formula by rare serotypes is more likely to be detected. As stated above (section 2.1.2), it would be difficult to detect outbreaks or specific sources of salmonellosis due to common serotypes within the higher incidence of background illness.
5.2 DEVELOPING COUNTRIES
There is a dearth of information on contamination of powdered infant formula sold in developing countries, and there has also been no surveillance on the disease burden resulting from consumption of contaminated powdered infant formula in developing countries. However, even if there have been no studies on whether the product used in developing countries is contaminated, the potential risks of contamination cannot be ruled out given that reports from different developed countries have shown that some batches of powdered infant formula are contaminated. Many developing countries import powdered infant formula from processing plants in a few countries, for example Bangladesh. The incidence and levels of E. sakazakii are likely to be the same as in products evaluated in exporting countries of origin and reported in published surveys. The levels should remain stable during transport and distribution.
In many developing countries, the proportion of special subpopulations consisting of low-birthweight infants and infants of HIV-infected mothers is higher than in developed countries; therefore, the use of powdered infant formula in these circumstances may be increasing. The basis of the higher demand for powdered infant formula is the recommendation for infants of HIV-positive mothers that – where replacement feeding is acceptable, feasible, affordable, sustainable and safe – all breastfeeding be avoided. (WHO, 2001). Human milk fortifiers are required to compensate the nutritional needs of very low-birth-weight infants. In circumstances when the mother cannot breastfeed or chooses not to breastfeed for any reason, special powdered infant formula may be required for feeding of low-birth-weight infants. Therefore, well-controlled studies need to be conducted to assess the extent of risk associated with contaminated powdered infant formula for infants in developing countries.
5.3 MICROBIAL ASPECTS OF MANUFACTURE AND USE OF POWDERED INFANT FORMULA
According to industry experts from the United States and Europe, powdered infant formula can be manufactured in different ways. A flow chart of the production and use of powdered infant formula highlights a number of points at which this product may be subject to microbial contamination (Figure 2). (attached)
Figure 2 (attached). Flow chart for the production and use of powdered infant formula. The heat step during wet blending is assumed to effectively eliminate Enterobacteriaceae.
* = potential sites for environmental contamination.
Posted from ftp.fao.org/docrep/fao/007/y5502e/y5502e00.pdf
5.1 EXPOSURE TO INFANT FORMULA/BREASTFEEDING RATES
It is impossible to estimate on a global basis the percentage of all infants who receive one of the products under consideration. This is due, on the one hand to the variable rates of breastfeeding in different populations and, on the other hand to the availability of the products in different parts of the world.
Exclusive breastfeeding rates differ from one country to the next. In Scandinavian countries, for example, 95% of babies are breastfed shortly after birth with almost 75% of those still being breastfed at 6 months of age. In other European countries, initial breastfeeding rates are below 30%, decreasing to almost no exclusive breastfeeding at 6 months. Available data on rates and exclusivity of breastfeeding from Australia in 1995 (Donath and Amir, 2000) and from Germany in 1997/98 (Kersting and Dulon, 2002) allow an estimate of the percentage of infants at different ages exposed to infant formula (Table 1).
Infant formula may be a direct source, an indirect source (contributing to a reservoir of E. sakazakii in the environment), and/or a vehicle for E. sakazakii-induced illness; it may also be neither the source nor the vehicle for E. sakazakii-induced illness. The meeting considered, on the basis of the information available, that in between 50 and 80% of cases, powdered infant formula is both the vehicle and the source (direct or indirect) of E. sakazakii-induced illness. To estimate a range of the proportion of cases due to powdered infant formula versus some other source, the meeting considered data from the United States in 2003 (C. Braden, personal communication, 2004). For sporadic cases of E. sakazakii sepsis and meningitis, six out of seven cases had exposure to powdered infant formula; the exposure was unclear in the remaining case. Thus, for at least 85% of these cases, powdered infant formula was a potential source. A review of 48 E. sakazakii cases in English language literature since 1961 revealed that at least 25 cases (52%) were directly linked to powdered infant formula.
Table 1. Estimated percentage of (healthy term) infants exposed to powdered infant formula or follow-up formula in Australia and Germany.
Age...............Australia, 1995...........................Germany, 1997/98
.....................(Donath and Amir, 2000)............(Kersting and Dulon, 2002)
.....................n = 2 874...................................n = 1 717
1 month........29%.................................. .........-
2 months.......-................................................42 %
3 months.......40%.................................. ........-
4 months.......-................................................51 %
6 months.......57%.................................. ........61%
Reconstituted powdered infant formula is probably a common vehicle in transmitting Salmonella to infants, given its major role in the infant diet, but contamination of formula is more likely to occur from the preparer or preparation environment than from the manufacturing process. Infrequent occurrence of intrinsic contamination of powdered infant formula does occur and has resulted in outbreaks of illness, but this appears to be rare. Thus, the meeting considered that most cases of salmonellosis amongst infants were probably not caused by intrinsic contamination of powdered infant formula. Disease caused by contamination of powdered infant formula by rare serotypes is more likely to be detected. As stated above (section 2.1.2), it would be difficult to detect outbreaks or specific sources of salmonellosis due to common serotypes within the higher incidence of background illness.
5.2 DEVELOPING COUNTRIES
There is a dearth of information on contamination of powdered infant formula sold in developing countries, and there has also been no surveillance on the disease burden resulting from consumption of contaminated powdered infant formula in developing countries. However, even if there have been no studies on whether the product used in developing countries is contaminated, the potential risks of contamination cannot be ruled out given that reports from different developed countries have shown that some batches of powdered infant formula are contaminated. Many developing countries import powdered infant formula from processing plants in a few countries, for example Bangladesh. The incidence and levels of E. sakazakii are likely to be the same as in products evaluated in exporting countries of origin and reported in published surveys. The levels should remain stable during transport and distribution.
In many developing countries, the proportion of special subpopulations consisting of low-birthweight infants and infants of HIV-infected mothers is higher than in developed countries; therefore, the use of powdered infant formula in these circumstances may be increasing. The basis of the higher demand for powdered infant formula is the recommendation for infants of HIV-positive mothers that – where replacement feeding is acceptable, feasible, affordable, sustainable and safe – all breastfeeding be avoided. (WHO, 2001). Human milk fortifiers are required to compensate the nutritional needs of very low-birth-weight infants. In circumstances when the mother cannot breastfeed or chooses not to breastfeed for any reason, special powdered infant formula may be required for feeding of low-birth-weight infants. Therefore, well-controlled studies need to be conducted to assess the extent of risk associated with contaminated powdered infant formula for infants in developing countries.
5.3 MICROBIAL ASPECTS OF MANUFACTURE AND USE OF POWDERED INFANT FORMULA
According to industry experts from the United States and Europe, powdered infant formula can be manufactured in different ways. A flow chart of the production and use of powdered infant formula highlights a number of points at which this product may be subject to microbial contamination (Figure 2). (attached)
Figure 2 (attached). Flow chart for the production and use of powdered infant formula. The heat step during wet blending is assumed to effectively eliminate Enterobacteriaceae.
* = potential sites for environmental contamination.
Posted from ftp.fao.org/docrep/fao/007/y5502e/y5502e00.pdf