Effect of vegetated filter strips on transport and deposition rates of Escherichia coli in overland flow in the eastern escarpments of the Mau Forest, Njoro River Watershed, Kenya.

The fate and transport of Escherichia coli (E. coli) in lotic waters through vegetated filter strips (VFSs) was evaluated in a field model pasture, utilizing VFSMOD Windows along with direct pathogen testing. This study assessed effects of VFS on transport and deposition rates of E. coli in lotic overland flow waters. The VFS measured 44 m long by 40 m wide, covering an area of 1584 m2 and land slope of 15 %. Cowpat was applied onto the model pasture and washed by overland flow into the VFS. The 4-methylumbelliferyl ß-D-glucuronide substrate confirmed the identity of E. coli prior to cowpat application and after isolating them from soil using centrifugation and membrane filtration techniques. Napier grass root system recorded the highest recovery rates of E. coli at 99.9 % along the length of VFS III. This efficiency reduced significantly (p < 0.05; df = 29) to 95 % in Kikuyu grass and 75 % in Couch grass-Buffer grass. The data demonstrated similarity in transport of manure-borne E. coli and organic carbon (OC) through all the simulated VFS. These results indicated that OC could be used as a true natural tracer of manure-borne E. coli, a pollution indicator organism of lentic and lotic surface waters provided the OC release kinetics from cowpat were similar to that of E. coli kinetics. Thus, efficient filtering to reduce E. coli concentrations and load in overland flows requires managing combined grass species, agro-pastoral systems models and dispersed or preferential flows to enhance surface water quality standards.

Composition and design of vegetative filter strips instrumental in improving water quality by mass reduction of suspended sediment, nutrients and Escherichia coli in overland flows in eastern escarpment of Mau Forest, Njoro River Watershed, Kenya.

This study assessed the effect of vegetative filter strip (VFS) in removal of suspended sediment (SS), total nitrogen, total phosphorus and Escherichia coli (E. coli) in overland flow to improve receiving water quality standards. Four and half kilograms of cowpat manure was applied to the model pasture 14 m beyond the edge of vegetated filter strip (VFS) comprising 10-m Napier grass draining into 20-m Kikuyu grass (VFS II), 10-m Kikuyu grass draining into 20-m Napier grass (VFS III) and native grass mixture of Couch-Buffel (VFS I-control). Overland flow water samples were collected from the sites at positions 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25 and 30 m along the length of VFSs. E. coli removal by Napier grass VFS was on the order of log unit, which provided an important level of protection and reduced surface-flow concentrations of E. coli to below the 200 (CFU 100 mL-1) recommended water quality standards, but not for nutrients and SS. The Napier grass showed highest efficiency (99.6 %), thus outperforming both Kikuyu grass (85.8 %) and Couch-Buffel grasses VFS (67.9 ± 4.2 %) in removing E. coli from overland flow. The low-level efficiency of native Couch-Buffel grasses in reducing E. coli in overland flow was because of preferential flow. Composition and design of VFS was instrumental and could be applied with a high potential of contracting the uncertainty in improving water quality standards through mass reduction of SS, nutrients and E. coli load in watersheds.

Peptic ulcer and its course in cirrhosis: an endoscopic and clinical prospective study.

The epidemiological and clinical characteristics of peptic ulcer were studied in 324 of 368 consecutive patients with cirrhosis of the liver during a mean period of 1.2 (+/- 0.61) years. Peptic ulcer prevalence rates in patients with cirrhosis were as follows: point prevalence 11.7%, period prevalence 15.1%, and life-time prevalence 24.2%. The annual incidence rate observed in 140 patients with cirrhosis undergoing endoscopic follow up was 4.3%. Ulcers were asymptomatic in more than 70% of patients. The peptic ulcer complication rate at entry was 20% in the whole group and 40% in those who had not a previous diagnosis of peptic ulcer when admitted to the study. Peptic ulcer was more frequent among HBsAg+ cirrhotics (p = 0.05). Patients with more severely decompensated cirrhosis also had a higher frequency of asymptomatic ulcers (p = 0.04), gastric ulcers (p = 0.01) and asymptomatic gastric ulcers (p = 0.005). After diagnosis, during endoscopic follow up, gastric ulcer in patients with cirrhosis tended to heal slowly and recurred with higher frequency than in controls without cirrhosis (p = 0.04). Seventy-nine per cent of peptic ulcer recurrences were asymptomatic in patients with cirrhosis. There were no complications during the follow-up period: this could be due to the regular timing of endoscopy, which permitted early detection and treatment of the recurrences, thus preventing further complications.