OSHA defines an excavation as any man-made cut, cavity, trench, or depression in the earths surface formed by earth removal. A trench is defined as a narrow underground excavation that is deeper than it is wide, and is no wider than 15 feet (4.5 meters). Dangers of Trenching and Excavation. Cave-ins pose the greatest risk and are much more likely than other excavationrelated accidents to result in worker fatalities.
How long does a typhoid shot last?   According to the CDC website, a booster dose is needed every 2 years for people who remain at risk.. The oral (live) vaccine lasts 5 years before another dose is neededâ¦.
However, excessive inoculum of infection from food sources can overcome this immunity. Thus, typhoid can recur in future, either after years or if the infective dose in food is very high. The child does not need any typhoid vaccination for a period of about 2-3 years if he had confirmed typhoid fever. Rarely, some subjects can become carriers after antibiotic dose (for example cefixime); it is difficult to predict this possibility in an individual child.