Chlorine inactivation of coliphage MS2 on strawberries by industrial-scale water washing units

Fruits and vegetables (produce) intended for minimal processing are often rinsed or washed in water. Chlorine and other sanitizers are used during washing to inactivate produce spoilage microbes, but such procedures may also inactivate pathogens epidemiologically linked to produce, such as hepatitis A virus (HAV). However, no information exists on the efficacy of chlorinated wash water to inactivate HAV and other viruses on produce in actual practice, because of obvious safety concerns. In contrast, coliphage MS2 (a bacterial virus) is commonly used as a surrogate for some pathogenic viruses and may be safely used in field studies. In the present investigation, strawberries seeded with MS2 were passed through industrial-scale water washing units operated with or without added sodium hypochlorite. MS2 on strawberries was inactivated by 68%, 92% and 96% at free chlorine (FC) concentrations of < or = 2, 20 and 200 ppm in wash water, respectively. MS2 was detected in wash water containing < or = 2 ppm FC in one trial, but was not detected in water containing 20 or 200 ppm FC. The presence and absence of MS2 in wash water containing various levels of FC highlight the importance of controlling sanitizer levels to prevent viral cross contamination of strawberries.

Chlorine disinfection of produce to inactivate hepatitis A virus and coliphage MS2

Disinfection of produce is principally used to inactivate spoilage microbes and may also reduce the risk of consumer exposure to enteric pathogens. However, the rate and extent of enteric virus inactivation by free chlorine on produce has not been adequately characterized. Experiments were performed to determine the kinetics of free chlorine inactivation of hepatitis A virus (HAV) and the indicator virus coliphage MS2 on strawberries (SBs), cherry tomatoes (CTs), and head lettuce (HL). The oxidant demand of these produce items also was determined. When produce items were exposed to approximately 20 parts per million (ppm) solution of free chlorine for 5-10 min, HAV and MS2 were inactivated by 90-99% and in some cases virus inactivation was > or =99%. Exposure of strawberries to approximately 200 ppm free chlorine resulted in more rapid and extensive inactivation of both viruses. The produce items tested in this study exhibited a demand for chlorine which varied by produce type, and chlorine residuals declined over time. These results demonstrate the potential for chlorine to reduce the levels of infectious viruses on different produce types, but adequate contact time and chlorine residual are required to achieve maximum virus inactivation. The difference in chlorine demand between SBs, CTs, and HL suggests that varying disinfection practices are needed for the wide variety of processed fruits and vegetables. The inactivation kinetics of MS2 and HAV were similar, suggesting that MS2 and perhaps other similar bacterial viruses may be used as process indicators and surrogates for determining the disinfection efficacy of produce in the laboratory or in actual practice.

Photoinactivation of hepatitis A virus by synthetic porphyrins

Porphyrins are photosensitizers and may be applicable in situations where viral inactivation is required, as for in vitro inactivation of nonenveloped viruses in blood components or in other aqueous media. No study has examined the efficacy of porphyrin inactivation on human pathogens such as hepatitis A virus (HAV) in plasma or other liquids. Experiments were conducted to evaluate the effect of synthetic porphyrins on HAV in porphyrin-containing human plasma and phosphate-buffered saline exposed to long-wavelength (365 nm) UV light. Inactivation of bacteriophage MS2 (MS2) also was determined in some trials. Solutions containing cationic, anionic or amphiphilic porphyrins irradiated with an average light dose of 4.3 J/cm(2) for 90 min resulted in >3 log(10) (>99.9%) to >4 log(10) (>99.99%) inactivation of both HAV and MS2. Viral inactivation may have been greater than observed because the limits of detection of the assay had been reached. Under ambient lighting conditions, none of the porphyrins was mutagenic in the Ames assay and only the congener with the longest chain-length, tetrakis (N-[n-hexadecyl]-4-pyridiniumyl) porphyrin, was appreciably toxic to mammalian cells. Disinfection by photoactivated synthetic porphyrins therefore can offer an effective and relatively safe approach to removal of nonenveloped viruses from aqueous media.

Fecal contamination of agricultural soils before and after hurricane-associated flooding in North Carolina

Hurricane Floyd and other storms in 1999 caused widespread and extensive flooding of eastern North Carolina and environmental contamination with fecal wastes from municipal wastewater and livestock operations. Because wastewater contains high levels of pathogenic micro-organisms, principal health risks to humans from flooding are consumption of crops grown in fecally contaminated soil and ingestion of contaminated water. Flood waters polluted with microbial and other contaminants also may be detrimental to the health of livestock and plant crops. In the present study, agricultural soils impacted by flood waters were analyzed for bacterial and viral indicators of fecal contamination. Total coliforms, fecal coliforms, Escherichia coli, spores of Clostridium perfringens, and both male specific (F+) and somatic coliphages were recovered from soil and assayed in liquid culture media. A number of samples were positive for the presence of fecal coliforms, E. coli, and coliphages, indicating the presence of human or animal feces. Most samples were positive for total coliforms, and almost all samples contained high levels of Cl. perfringens spores. The levels of Cl. perfringens spores were significantly (P < 0.001) higher in flooded soil (post-Hurricane Floyd) compared to pre-flood soil. Persistent fecal contamination of soil, as demonstrated by the high levels of Cl. perfringens spores, suggests the need for additional or alternative measures to protect crop-growing areas, including prospective microbiological monitoring and improved protection of watersheds from incidents capable of releasing fecal material.

Adolescent femicide: a population-based study

BACKGROUND

Homicide is the third leading cause of deaths for girls aged 11 to 14 years and the second leading cause of death for girls aged 15 to 18 years. However, few studies examine the contextual issues of adolescent femicide, especially among 11- to 14-year-old victims.

OBJECTIVES

To obtain quantitative and contextual information about adolescent femicide, and to compare the context of femicide in younger vs older adolescents.

METHODS

Data from the North Carolina medical examiner were analyzed for all 11- to 18-year-old female homicide victims during 1990 to 1995. Police interviews were conducted for 1993 to 1995 cases to determine context, the relationship of victim and perpetrator, and criminal histories.

RESULTS

There were 90 victims; 63 were aged 15 to 18 years, 55 were killed with firearms, and 40 were behind in school. Of 37 femicides for which law enforcement interviews were conducted, the most common contexts were altercation (n = 9), broken or desired relationship (n = 8), reckless behavior with a firearm (n = 6), retaliation (n = 5), and drug related (n = 3). Most perpetrators were men (89%; n = 33), were older than their victims (mean age difference, 8 years), and had criminal records (59%; n = 21). Seventy-eight percent of victims (n = 29) were killed by an acquaintance or intimate partner.

CONCLUSIONS

Femicide contexts differed by age. Younger adolescents (aged 11-14 years) were more likely to be killed by a family member in the context of an argument than by an intimate partner or acquaintance in the context of a broken relationship or reckless behavior with a firearm. Many victims were engaged in high-risk behaviors, including dropping out of school, running away from home, using drugs, and dating much older men with criminal records. Intervention specialists targeting high-risk female adolescents should be aware that this population may also be at increased risk of femicide.