Rickettsia prowazekii is an obligate intracellular bacteria that inhabit the cytosol of its host. It is mostly known for infecting humans with the disease epidemic Typhus. R. Prowazekii is a gram negative, aerobic bacteria that have had a recent loss of abilities that has caused an evolutionary genome reduction. These lost functions include encoding enzymes for the synthesis of amino acids, sugar metabolism, nucleotides, and lipids. However this species still has unique features due to their strict intracellular lifestyle, adaptability between invertebrate and vertebrate, and finicky requirements for growth. Although the disease is not as prominent as it was in the early to mid-1900’s few cases have been reported within the U.S. and many places…show more content… Rickettsial infections are caused by exposure to vectors, or an organism that transmits disease that can be through a bite that are infected. With R. prowazekii the infection spreads most commonly in overcrowded and unsanitary conditions through body lice (Pediculus humanus corporis) and it has also been found in another strain through flying squirrels in the U.S. and their squirrel fleas (Orchopeas howardi) Lice feed on their human host’s blood 4-6 times a day sucking up 1 µL each time. This easily causes lice to receive Rickettsia infection from its host as well as transmit it to its host through its bite. Lice infected with the bacteria also can expose a human to its disease through its own feces within 3 days of the infection. Its feces can contaminate the blood from an open wound on the scalp of a human host after they scratch the irritating itch the bite causes. Once a human is infected, one of the first onset symptoms they will experience is a fever. This raise in temperature is not favored by the body louse which then forces them to leave its host. This need to relocate is the main cause for Typhus epidemics within overcrowded populations. The contact to another human would also have to be very close due to the restriction of the louse’s…show more content… prowazekii is an obligate intracellular bacteria; it can only grow within the cell. This allows the bacteria to have a barrier between itself and the host’s immune responses and to access their nutrients. Through phagocytosis the Rickettsia genus enters the host cell through clathrin (protein that has a major function in forming coated vesicles) coated pits. However, R. prowazekii is different and instead uses cell lysis to leave and then infect nearby cells due to it lacking gene that encodes Rick A (protein that maintains the rearrangement of the cytoskeleton of actin). This heavy cell lysis is too much for the infected louse which causes them to die within 2 weeks after initial infection. Even after a person is treated for Typhus and survives R. prowazekii can isolate itself within the body and can stay there for the rest of the person’s lifetime. This means the bacteria can remain dormant but still infect human hosts. This latent infection can cause Brill-Zinsser disease, a form of Typhus that is nowhere near as lethal; but this serves a source for R. prowazekii making these infected hosts serve as reservoirs to the
