Rickettsia Rickettsii
James Crocker
Rickettsia rickettsii The cause of Rocky Mountain Spotted Fever is Rickettsia rickettsii. These organisms are tiny, Gram-negative, non-motile coccbicilli. It is an obligate intracellular bacterium. Rickettsia rickettsii can sometimes be identified early in an infection demonstrating the organisms in biopsies, small pieces of tissue that are removes surgically, of skin lesions. Rocky Mountain Spotted Fever was first discovered in the Rocky mountains, therefore the name was attached. The disease is representative of a larger group of serious diseases that occur throughout the world, transmitted by certain species of ticks, lice or mites. The incubation period is from 4-8 days. The initial symptoms of Rocky Mountain Spotted Fever are a sudden headache, pain in the muscles and joints and fever. In a few days a rash with light pink spots appears on the palms of the hands, wrist and ankles, and the soles of the feet. The rash can then spread up the arms and legs to the trunk of the body and become hemorrhagic. Bleeding may also come from other sites of the body such as the mouth and nose. As the disease process continues it can involve the heart, kidneys and other body tissues resulting in a drop in blood pressure leading to shock and even death without proper treatment. The vector that carries the Rickettsia rickettsii is a tick. The bite is not usually felt and therefore may go unnoticed; however the tick may stay attached to the body for hours while feeding on the capillary blood supply. The rickettsii may not be immediately released from the saliva of the tick; this may take four to six hours. Once the bacterium is inside the cell they leave their phagosome and multiply in the cytoplasm and nucleus. Early in the infection the bacteria enter and leave fingerlike host cell cytoplasm projection that eventually damages the cell membrane. The worst part of the disease is the release of endotoxin into the blood stream from the rickettsial cell
Rickettsia rickettsii The cause of Rocky Mountain Spotted Fever is Rickettsia rickettsii. These organisms are tiny, Gram-negative, non-motile coccbicilli. It is an obligate intracellular bacterium. Rickettsia rickettsii can sometimes be identified early in an infection demonstrating the organisms in biopsies, small pieces of tissue that are removes surgically, of skin lesions. Rocky Mountain Spotted Fever was first discovered in the Rocky mountains, therefore the name was attached. The disease is representative of a larger group of serious diseases that occur throughout the world, transmitted by certain species of ticks, lice or mites. The incubation period is from 4-8 days. The initial symptoms of Rocky Mountain Spotted Fever are a sudden headache, pain in the muscles and joints and fever. In a few days a rash with light pink spots appears on the palms of the hands, wrist and ankles, and the soles of the feet. The rash can then spread up the arms and legs to the trunk of the body and become hemorrhagic. Bleeding may also come from other sites of the body such as the mouth and nose. As the disease process continues it can involve the heart, kidneys and other body tissues resulting in a drop in blood pressure leading to shock and even death without proper treatment. The vector that carries the Rickettsia rickettsii is a tick. The bite is not usually felt and therefore may go unnoticed; however the tick may stay attached to the body for hours while feeding on the capillary blood supply. The rickettsii may not be immediately released from the saliva of the tick; this may take four to six hours. Once the bacterium is inside the cell they leave their phagosome and multiply in the cytoplasm and nucleus. Early in the infection the bacteria enter and leave fingerlike host cell cytoplasm projection that eventually damages the cell membrane. The worst part of the disease is the release of endotoxin into the blood stream from the rickettsial cell
References: DOI: www.textbookofbacteriology.net Nester. , Anderson, , & Roberts, (2012). Microbiology a human prospective. (7th ed., pp. 529-531). New York, NY: McGraw Hill.