Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Neonatal infection wikipedia , lookup
Infection control wikipedia , lookup
Human microbiota wikipedia , lookup
African trypanosomiasis wikipedia , lookup
Sociality and disease transmission wikipedia , lookup
Hospital-acquired infection wikipedia , lookup
Germ theory of disease wikipedia , lookup
Transmission (medicine) wikipedia , lookup
Bubonic Plague By Prayas Patel Outline 1. General information 2. Etiological agent and vector 3. Transmission 4. Human plague infections Plague 1.Caused by Yersinia pestis. 2.Bacteria transmitted by: • Bites from fleas (usually Xenopsylla cheopis) • Handling an infected animal (rarely) History Pandemic of the mid-14th century was just 1 of 3 pandemics of the plague thus far (Kosoy 2004). US and Global Incidence 1. Plague has not been eradicated. 2. Cases globally: 1,000 – 2,000 a year 3. Cases in US.: 10 – 15 a year Figure 1. Reported cases of human plague by counties in the US between the years 1970-1997 produced by the CDC. Figure 2. Countries with reported human plague infections between the years 1970-1998 and the distribution of animals infected with the plague bacterium around the world produced by the CDC. Outline 1. General information 2. Etiological agent and vector 3. Transmission 4. Human plague infections Etiology Yersinia pestis 1. Classified in the family Enterobacteriaceae. 2. Evolved from a clone of Yersinia pseudotuberculosis (Achtman 14047). Yersinia pestis 1.Coccobacillus 2.Gram-negative 3.Facultative anaerobe Biovars Y. pestis has 3 biovars (Achtman et al. 1999) Biovar – “a strain of a strain” 3 Biovars (Perry 1997) • Antigua – 6th century • Medievalis – 14th century • Orientalis – 20th/21st century Virulence Virulence factors • Biofilms (Darby 2008) • Interference of inflammatory response (Sun et al. 2007) • Induce immunodeficiency (Bi et al. 2008) Reservoirs 1. Most common reservoirs are wild rodents. 2. These would include Rattus species Rock squirrel • California ground squirrel • • 3. EVEN the soil (Infectious Disease Society of America) Xenopsylla cheopis Figure 3. A Xenopsylla cheopis. X. cheopis 1. Ectoparasite 2. Found worldwide with a host (typically a species of Rattus). •Most commonly in tropical and subtropical climates. X. cheopis feeding 1. X. cheopis feeds from the blood vessel of its host. • Injects salvia to prevent clotting (Andersen et al. 2007). 2. Proventriculus is a valve-like organ between esophagus and stomach. 3. Both sexes can transmit infection. Y. pestis’ impact on flea Bacteria may occasionally block the flea’s digestive tract. Blockage is caused by biofilms (Perry 1997). Process aids in spread of disease. Y. pestis’ impact on flea To feed again, the flea must remove the blockage. By removing the blockage the flea may inadvertently spread the infection. Outline 1. General information 2. Etiological agent and vector 3. Transmission 4. Human plague infections Transmission 1. Bites from infected fleas 2. The bacterium can enter through breaks in the skin. Transmission (continued) 1. Contact with plague infected animal’s carcass. 2. Plague may be spread through the air by an animal with pneumonic plague. Figure 5. The various cycles the bubonic plague circulates in and the modes of transmission between organisms with the infection. Humans as “hosts” Humans are NOT the primary host of Y. pestis. They are INCIDENTAL hosts (Infectious Disease Society of America 2009). Human bubonic plague Bubonic plague occurrence in humans is related to: (Infectious Disease Society of America 2009) Percentage of hosts killed by infection Amount of human exposure to rodents Human to Human Transmission Found ONLY in pneumonic plague. Droplets expelled may contain bacteria. Outline 1.General information 2.Etiological agent and vector 3.Transmission 4.Human plague infections Disease Progression The bacteria enters into the body Bacteria spreads to lymph tissue The bacteria may also spread to infect the lungs (pneumonic plague). Signs and Symptoms • Fever, chills, headache • Painful, warm, and swollen lymph node Called a bubo (Bubonic plague) • Death caused by endotoxic shock. Bubo Figure 6. A bubo on the thigh of a person infected with Y. pestis. Treatment 1. The best courses of treatment are the antibiotics Gentamicin or Streptomycin. 2. Vaccines were developed but were ineffective. Review 1. General information 2. Etiological agent and vector 3. Transmission 4. Human plague infections Literature Cited Achtman, M., K. Zurth, G. Morelli, G. Torrea, A. Guiyoule, and E. Carniel. 1999. Yersinia pestis, the cause of plague, is a recently emerged clone of Yersinia pseudotuberculosis. Proceedings of the National Academy of Sciences of the United States of America 96:14043-14048. Andersen, J. F., B. J. Hinnebusch, D. A. Lucas, T. P. Conrads, T. D. Veenstra, V. M. Pham, and J. M. Ribeiro. 2007. An insight into the sialome of the oriental rat flea Xenopsylla cheopis. BMC Genomics 8:102-110. Bi, Y., Z. Du, Y. Han, Z. Guo, Y. Tan, Z. Zhu, and R. Yang. 2008. Yersinia pestis and host macrophages: immunodeficiency of mouse macrophage induced by YscW. Journal of the British Society for Immunology 126:141-153. Center for Disease Control. 2007. Plague. Accessed online at http://www.cdc.gov/ncidod/dvbid/plague/index.htm. Darby, C. 2008. Uniquely insidious: Yersinia pestis biofilms. Trends in Microbiology 16:158-164. Literature Cited (continued) Infectious Disease Society of America. 2009. Plague: Current, comprehensive information on pathogenesis, microbiology, epidemiology, diagnosis, and treatment. Accessed online at http://www.cidrap.umn.edu/idsa/bt/plague/biofacts/plaguefactshe et.html Kosoy, M. K. and K. L. Gage. 2004. Natural history of plague: perspectives from more than a century of research. Annual Review of Entomology 50:505-528. Perry, R. D. and J. D. Fetherston. 1997. Yersinia pestis – Etiologic agent of plague. Clinical Microbiology Review 10:35-66. Sun, P., J. E. Tropea, B. P. Austin, S. Cherry, and D. S. Waugh. 2007. Structural characterization of the Yersinia pestis Type III secretion system needle protein YscF in complex with its heterodimeric chaperone YscE/YscG. Journal of Molecular Biology 377:819-830.