Batch solar disinfection (SODIS) inactivation kinetics are reported for suspensions in water of Campylobacter jejuni, Yersinia enterocolitica, enteropathogenic Escherichia coli, Staphylococcus epidermidis, and endospores of Bacillus subtilis, exposed to strong natural sunlight in Spain and Bolivia. The exposure time required for complete inactivation (at least 4-log-unit reduction and below the limit of detection, 17 CFU/ml) under conditions of strong natural sunlight (maximum global irradiance, ϳ1,050 W m ؊2 ؎ 10 W m ؊2 ) was as follows: C. jejuni, 20 min; S. epidermidis, 45 min; enteropathogenic E. coli, 90 min; Y. enterocolitica, 150 min. Following incomplete inactivation of B. subtilis endospores after the first day, reexposure of these samples on the following day found that 4% (standard error, 3%) of the endospores remained viable after a cumulative exposure time of 16 h of strong natural sunlight. SODIS is shown to be effective against the vegetative cells of a number of emerging waterborne pathogens; however, bacterial species which are spore forming may survive this intervention process.
Aim: To determine whether batch solar disinfection (SODIS) can be used to inactivate oocysts of Cryptosporidium parvum and cysts of Giardia muris in experimentally contaminated water.
Methods and Results: Suspensions of oocysts and cysts were exposed to simulated global solar irradiation of 830 W m−2 for different exposure times at a constant temperature of 40°C. Infectivity tests were carried out using CD‐1 suckling mice in the Cryptosporidium experiments and newly weaned CD‐1 mice in the Giardia experiments. Exposure times of ≥10 h (total optical dose c. 30 kJ) rendered C. parvum oocysts noninfective. Giardia muris cysts were rendered completely noninfective within 4 h (total optical dose >12 kJ). Scanning electron microscopy and viability (4′,6‐diamidino‐2‐phenylindole/propidium iodide fluorogenic dyes and excystation) studies on oocysts of C. parvum suggest that inactivation is caused by damage to the oocyst wall.
Conclusions: Results show that cysts of G. muris and oocysts of C. parvum are rendered completely noninfective after batch SODIS exposures of 4 and 10 h (respectively) and is also likely to be effective against waterborne cysts of Giardia lamblia.
Significance and Impact of the Study: These results demonstrate that SODIS is an appropriate household water treatment technology for use as an emergency intervention in aftermath of natural or man‐made disasters against not only bacterial but also protozoan pathogens.
Hospital-acquired infections (HAI) are defined as infections that are neither present nor incubating when a patient enters the hospital (Bourn, 2000). Their effects vary from discomfort to prolonged or permanent disability and they may contribute directly or substantially to a patient’s death. HAI’s are estimated to cost the National Health Service (NHS) in England £1 billion annually (Bourn, 2000) with as many as 5,000 patients dying as a result of acquiring such an infection (Anon, 2001). Not all hospital-acquired infections are preventable but Infection Control Teams believe that they could be reduced by at least 15%, with yearly savings of £150 million (Anon, 2001). Central intravascular catheters have been found to be a common source of infection. Catheters can become infected via a number of different routes with the infection proliferating in multiple areas along the catheter surface. It has been reported that over 40% of the identified micro-organisms causing hospital-acquired infection were Staphylococci, an organism that is typically found on the natural skin flora (Bourn, 2000).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.