Increased prevalence of indicator and pathogenic bacteria in Vembanadu Lake: a function of salt water regulator, along south west coast of India

Prevalence of faecal indicator bacteria, Escherichia coli and pathogenic bacteria, Vibrio cholerae, Vibrio parahaemolyticus and Salmonella were analysed in Vembanadu lake (98350N 768250E), along south west coast of India for a period of one year from ten stations on the southern and northern sides of a salt water regulator constructed in Vembanadu Lake in order to prevent incursion of seawater during certain periods of the year. While the northern side of the lake has a connection to the sea, the southern side is enclosed when the salt water regulator is closed. The results revealed the water body is polluted with high faecal coliform bacteria with mean MPN value ranging from 1718-7706/100 ml. E. coli, V. cholerae, V. parahaemolyticus and Salmonella serotypes such as S. paratyphi A, B, C and S. newport were isolated and this is the first report on the isolation of these Salmonella serovars from this lake. E. coli showed highest percentage of incidence (85.6–86.7%) followed by Salmonella (42–57%), V. choleare (40–45%) and V. parahaemolyticus (31.5–32%). The increased prevalence of indicator and pathogenic bacteria in the enclosed southern part of Vembanadu Lake may be resulting from the altered flow patterns due to the salt water regulator.

Influence of a Salt Water Regulator on the Survival Response of Salmonella Paratyphi in Vembanadu Lake: India

Contamination of environmental water by pathogenic microorganisms and subsequent infections originated from such sources during different contact and non- contact recreational activities are a major public health problem worldwide particularly in developing countries. The main pathogen frequently associated with enteric infection in developing countries are Salmonella enterica serovar typhi and paratyphi. Although the natural habitat of Salmonella is the gastrointestinal tract of animals, it find its way into natural water through faecal contamination and are frequently identified from various aquatic environments (Baudart et al., 2000; Dionisio et al., 2000; Martinez -Urtaza et al., 2004., Abhirosh et al., 2008). Typhoid fever caused by S. enterica serotype typhi and paratyphi are a common infectious disease occurring in all the parts of the world with its highest endemicity in certain parts of Asia, Africa, Latin America and in the Indian subcontinent with an estimated incidence of 33 million cases each year with significant morbidity and mortality (Threlfall, 2002). In most cases the disease is transmitted by polluted water (Girard et al., 2006) because of the poor hygienic conditions, inadequate clean water supplies and sewage treatment facilities. However in developed countries the disease is mainly associated with food (Bell et al., 2002) especially shellfish (Heinitz et al., 2000

Diversity of Bacillus And Actinomycetes in the water and sediment samples from Kumarakom region of Vembanadu lake

Diversity of different groups of Bacillus and Actinomycetes in the water and sediment samples from kumarakom estuary was analysed to find out potential strains for further application. Bacillus genera was identified and grouped into five phenogroups .Phenogroups show differences in the shape of the spore,position of the spore,and swelling of the sporangium.Ability of the isolates to elaborate various hydrolytic enzymes and their ability to reduce nitrate and ferment various carbohydrate sources were also studied.

Potential Exposure Risk Associated with the High Prevalence and Survival of Indicator and Pathogenic Bacteria in the Sediment of Vembanadu Lake, India

Prevalence of faecal coliform bacteria and the survival of Escherichia coli, Vibrio parahaemolyticus and Salmonella paratyphi were studied in the water and sediment from Vembanadu Lake in the presence and absence of protozoan predators. The density of faecal coliform bacteria ranged between mean MPN value 5080–9000/100 ml in water and 110,000–988,000/1 g in sediment (p <0.01), which was 110 times greater than in overlying water. The laboratory microcosm studies revealed that E. coli, V. parahaemolyticus and S. paratyphi showed significantly higher survival (p <0.05) potential in sediment than in overlying water both in the presence and absence of protozoan predators. The results indicate that Vembanadu Lake sediment constitutes a reservoir of pathogenic bacteria and exhibits potential health hazard from possible resuspension and subsequent ingestion during recreational activities. Therefore, assessment of bacterial concentration in freshwater lake sediments used for contact and non-contact recreation is of considerable significance for the proper assessment of microbial pollution of the overlying water and the management and protection of related health risk at specific recreational sites. In addition, assessment of the bacterial concentration in sediments can be used as a relatively stable indicator of long-term mean bacterial concentration in the water column above.