Abidelfatah M. Nasser

Prevalence and fate of hepatitis a virus in water

Abstract Hepatitis A virus (HAV) is a major waterborne disease agent with worldwide distribution. The main transmission route of HAV is direct person‐to‐person contact. However, hepatitis A (HA) outbreaks associated with the consumption and use of fecally contaminated water were reported from many countries. Studies on the environmental behavior of HAV were feasible only after developing techniques for its cultivation and enumeration in tissue culture. This study reviews data on the extent of HAV prevalence and persistence in the environment and water. HA is highly prevalent in low socioeconomic populations as determined by seroepidemiologic studies. HAV is excreted for long periods by infected individuals, but it is also shed by healthy persons. HAV has been detected in concentrated wastewater and natural waters. However, in most cases the natural waters were monitored for the presence of HAV after the occurrence of HA outbreak. HAV persists for months at temperatures below 10°C and for at least 1 month ...

Detection of Aeromonas and microbiological indicators in fish marketed in Israel

This study was conducted to determine the microbial and enteric virus quality of fresh fish sold on the open market in Israel. Three species of fish were studied: bottom feeders carp and tilapia, which tolerate heavy organic loads, and trout growing in high quality fresh water. Samples of liver, spleen, skin and muscle were assayed for Aeromonas, E. coli and F+ coliphages; digestive tract (DT) samples were assayed also for enteric viruses. The highest concentration of microorganisms was found in carp followed by tilapia and trout. Aeromonas was highest in the DT and lowest in muscle. E. coli and F+ coliphages were not detected in trout tissue other than skin. Enteric viruses were detected only in the DT of the carp (15%), indicating the presence of wastewater of human origin in the growth ponds. The results show that the degree of contamination reflected the quality of water in which the fish were grown. Caution in handling and preparing fish is recommended to avoid cross‐contamination of other tissues by...

Removal of indicator microorganisms and enteroviruses from wastewater in a single cell stabilization pond

A study was performed to evaluate the removal efficiency of bacterial indicators, F+bacteriophages and enteroviruses, in a single‐cell stabilization pond with a design hydraulic detention time of six to ten days. The performance of the stabilization pond was also evacuated by measuring the pH, conductivity and the level of dissolved oxygen in the influent and effluent. A dye tracer study indicated that 5% of the pond influent reached the ponds outlet within 16 h, indicating severe short‐circuiting in the pond. The removal of the indicator microorganisms ranged between 90.7 to 96.6% in the stabilization pond. Average concentration of F. coliform, enterococci and F+bacteriophage in the ponds effluent was 2.1 X 104, 1.2 X 102 and 1.6 X 102 cfu or pfu/ml‐1, respectively. The microbial quality of the effluents obtained does not meet the WHO recommended guidelines for effluents reuse for unrestricted crop irrigation. Uncontrolled discharge of these low quality effluents may result in the contamination of natu...

Detection of F+ bacteriophage in large volumes of water by a membrane filter method (MFM)

In recent years, F + bacteriophages were proposed by several researchers as an alternative to fecal coliforms to signal the presence of fecal pollution in water sources. The sample volume which can be monitored for the presence of bacteriophages by the conventional methods is limited to 1-10 ml. This study was conducted to test the feasibility of detecting and enumerating F + bacteriophages in large volumes of water by an MFM. A recovery of up to 100% was observed for MS2 coliphage when the pH of the water samples was adjusted to 3.5. The presence of humic acid in the water interfered with the adsorption of phages to the membrane filter. F + bacteriophages were detected in 11 out of 50(22%) water samples collected from swimming pools in Jerusalem. Total coliform were detected in only 2 out of the 50 (4%) samples. Both indicator microorganisms were detected in only one sample, suggesting the lack of correlation between their presence. The results of this study demonstrated that the MFM is a sensitive assay for detecting low concentrations of F + bacteriophages in large volumes of water.

Active microbial decontamination of tilapia fish

Fish grown in contaminated ponds can be exposed to a variety of human pathogenic microorganisms which may accumulate in its tissues. This study was conducted in order to examine the efficiency of changing the water, in the holding tanks, to reduce the level of microorganisms in various fish tissues. Fish contamination was accomplished by seeding 109, 1011 1010cfu or pfu ml‐1 of E.coli, MS2 coliphage and poliovirus 1, respectively, into 1001 of water. These microorganisms were tested in the skin, muscle, liver, spleen and the digestive tract (DT). A single inoculation of the test microorganisms was followed by 3–24 water changes (tank volumes) and compared with self‐purification (control) experiments without changing the water. The highest levels of microorganisms were found in the DT, 6 h after inoculation for E.coli and 12 h after inoculation for MS2 and poliovirus 1. Lower levels of the microorganisms were found in the spleen, liver and on the skin and none were detected in the muscle. In the decontamin...