If it's listeria you want to avoid, don't eat cheese. Or peanut butter. Or anything, really. http://www.myfoodpoisoninglawyer.com/category/listeria-ou...
The sad fact is, ALL foods are exposed to viruses: Spinach to eColi, canteloupes to salmonella, unpastuerized apple juice to eColi, cheese to listeria, eggs to salmonella.
For lunch meats: I personally ate them, all the time. I avoided ones with nitrites/nitrates (Boars Head is a good brand) because I know for certain nitrites are bad. I don't know if either the tomato, lettuce, sandwich meat or cheese on the sandwich will make me sick however, so I gambled with all of it.
For the long winded Dr answer, which was very interesting in pointing out that Fifth disease is more fatal to fetuses than Lysteria, here you go:
We wish to thank Dr Khatter and Ms Taylor and Dr Galanis for their interest in our Motherisk Update ‘Foodborne illnesses in pregnancy” in CFP in April 2010.
We believe that some of their recommendations are not evidence-based. We concur that it is important for pregnant women to be very careful in regards to consuming foods. However, despite their impressions, we did not make contradictory statements, as will be clearly shown here.
Despite the increased relative risk for pregnant women contracting Listeria, the absolute risk is extremely low and avoiding deli meats altogether does appear to be rather punitive. A risk assessment of Listeria monocytogenes in ready-to-eat foods conducted by the FDA/Center for Food Safety and Applied Nutrition and USDA/Food Safety and Inspection Service estimated the risk of developing listeriosis to be 1.2 x 10-5 (95% CI: 3.2 x 10-6 to 1.4 x 10-5) and 2.0 x 10-7 (95% CI: 4.8 x 10-11 to 5.3 x 10-6) per serving of deli meat and soft cheese, respectively, in the perinatal population. Taking the reciprocal of these values, the model estimates one case of listeriosis in 83000 servings of deli meat or 5 million servings of soft cheese consumed by a pregnant woman, which is a minimal risk (1).
To put this in perspective, for a woman who is less than 20 weeks of gestation, a conservative estimate of the risk of fetal loss following contact with an individual in the contagious stage of fifth disease (parvovirus B19 infection) is 1.8 x 10-3. This calculation uses the lower estimates of the proportion of the population that is not immune (35%), chance of maternal infection (20% in a daycare/school setting), and rate of vertical transmission (17%), and an estimated 14.8% rate of spontaneous loss of fetuses affected by parvovirus B19 before 20 weeks of gestation. For a woman who acquires the infection after 20 weeks of gestation, the estimated risk of fetal loss is lower (2.7 x 10-4), but still one order of magnitude higher than the risk of developing listeriosis following consumption of a single serving of deli meat. However, most government agencies do not recommend that pregnant women should routinely be excluded from a workplace where an outbreak of fifth disease is occurring (2).
We strongly believe that women should be informed of the nature and magnitude of the risks associated with the consumption of deli meats and soft cheeses. The decision to consume or avoid these foods should be made by her, based on this information, thus allowing her to make an informed decision. Subsequently, if she chooses not to avoid them, she should be advised on how she can minimize her exposure (and thus, her risk). Factors that determine exposure include amount and frequency of consumption, duration of refrigerated storage before consumption, and temperature at which the food is stored. We acknowledge that L. monocytogenes – unlike most bacterial pathogens – is able to grow at refrigeration temperatures (i.e., 4°C). However, growth at 4° is slow and limiting the duration of storage will limit bacterial growth.3
Therefore, she should be advised to: (1) limit the amount and frequency of consumption; (2) limit the duration of storage by choosing the freshest foods (i.e., those dated as close to the manufacture/packaging date as possible) and consuming them in a timely manner; (3) ensure that foods are kept at the correct temperature (less than 4°C) at all times including transport from the retail outlet to the home.
References 1.http://www.fda.gov/Food/ScienceResearch/ResearchAreas/Ris...) 2.(http://www.sogc.org/guidelines/public/119E-CPG-September2...; http://www.cdc.gov/ncidod/dvrd/revb/respiratory/B19&p...; Gillespie SM, et al. JAMA. 1990 Apr 18;263(15):2061-5; ACOG Practice Bulletin #20) 3.(http://fsrio.nal.usda.gov/document_fsheet.php?product_id=156; http://fsrio.nal.usda.gov/document_fsheet.php?product_id=221