Plague S l i d Plague e 1 S In today’s presentation we will cover information regarding the organism l Overview that causes plague and its epidemiology. We will also talk about the i • Organism history of the disease, how it is transmitted, species that it affects, and • History clinical signs seen in humans and animals. Finally, we will address d • Epidemiology prevention and control measures that can be taken. e • Transmission • Disease in Humans • Disease in Animals Image: Plague, although of great historical importance, is still of concern 2 • Prevention and Control in some parts of the world, as reflected in this Newsweek cover from October 10, 1994. This story covered the outbreak of plague in India. Center for Food Security and Public Health, Iowa State University, 2011 S l i d The Organism e 3 S Yersinia pestis, the causative agent of plague, is a pleomorphic, gram l Yersinia pestis negative coccobacillus in the family Enterobacteriaceae. It is an aerobic, i • Family Enterobacteriaceae facultatively anaerobic, and facultatively intracellular pathogen. Only one – Gram negative serotype is recognized. Y. pestis can be divided into three biovars: d – Pleomorphic coccobacillus – Aerobic, facultatively anaerobic, Antiqua, Medievalis, and Orientalis. Yersinia pestis has multiple plasmids e facultatively intracellular (110 and 9.5 kbp plasmids) and virulence factors (F1, Murine exotoxin, • One serotype – Three biovars LPS endotoxin, coagulase, pesticin, plasminogen activator). 4 • Multiple plasmids and virulence factors Center for Food Security and Public Health, Iowa State University, 2011 S Yersinia pestis is easily destroyed by sunlight and drying. However, it can l Yersinia pestis survive briefly in the soil and longer in frozen or soft tissues. i • Destroyed by Additionally, it can survive for up to one hour (depending on conditions) – Sunlight when released into air. This could increase its threat and aid in its d – Desiccation dispersal as a potential bioterrorism weapon. e • Survival – 1 hour in air – Briefly in soil Image: Wayson stain of blood shows the characteristic bipolar “safety 5 – 1 week in soft tissue – Years when frozen pin” appearance of Yersinia pestis. From CDC. Center for Food Security and Public Health, Iowa State University, 2011 Center for Food Security and Public Health, Iowa State University, 2011 1 Plague S l i d History e 6 S Plague has played a long and important role throughout history. It has l History caused several pandemics and epidemics which have led to large numbers i • 540-590 AD: Justinian’s pandemic of deaths. Justinian’s Constantinople pandemic lasted from 540 AD to – 10,000 deaths per day 590 AD and resulted in approximately 10,000 deaths per day at its height. d – Fall of the Roman Empire Plague also contributed greatly to the fall of the Roman Empire. In the e • 1346~1400: Black Death pandemic – Quarantine 14th century, plague was carried from outbreaks in India and China to – 1/3 of European population died Italy by merchants returning home. During this time, Venice instituted a 7 – Fall of the feudal system 40-day period of detainment for docking ships, which gave us what is • 1665: Great Plague of London now known as “quarantine.” Despite these efforts, plague quickly spread Center for Food Security and Public Health, Iowa State University, 2011 throughout all of Europe. Over 1/3 of the European population died during the “Black Death pandemic.” The decline in population aided in the fall of the feudal system of government. Another important plague epidemic occurred in 1665. Although limited to England, it killed approximately 100,000 (of the 500,000) inhabitants of London. During this outbreak, some modern public health practices were initiated (i.e., disease reporting, closing up of homes). S It is thought that this nursery rhyme has origins from plague. “Ring” l refers to an early clinical sign that appears on the skin (perhaps the ulcer i that commonly appears around a flea bite wound infected with Y. pestis); “Ring Around The Rosy “a pocket full of posies” refers to the use of flower petals as a means of d A Pocket Full Of Posies warding off the stench and infection of a plague victim; “ashes, ashes” e Ashes, Ashes refers to dust to dust; and “all fall down” refers to victims who were All Fall Down” falling down dead. 8 Center for Food Security and Public Health, Iowa State University, 2011 S The causative agent of plague was first isolated following an 1894 l Discovery outbreak in Hong Kong. Alexandre Yersin, an unknown bacteriologist, i • 1894: Hong Kong isolated a gram negative organism while celebrated Japanese scientists • Alexandre Yersin isolated a gram positive organism. In 1896, Yersin developed an d – Identified Gram antiserum that saved the life of an 18 year-old Chinese student. e negative bacillus • 1896 Eventually, it was accepted that Yersin had found the agent (a gram – Developed negative bacillus) responsible for plague. antiserum 9 Image: Dr. Alexandre Yersin in Front of the National Quarantine Station, Center for Food Security and Public Health, Iowa State University, 2011 Shanghai Station, 1936. This was the laboratory building in Shanghai, China where Dr. Yersin first isolated and described in detail, Pasteurella pestis, the old term used for Yersinia pestis. From CDC. Center for Food Security and Public Health, Iowa State University, 2011 2 Plague S The U.S. has not been immune to the influence of plague. In the late l History: U.S. 1800s, plague was first identified in Hawaii. Later, ships brought rats i • 1899: Hawaii carrying plague to the western U.S., and indigenous, wild rodents became – From ship rats to sylvatic rodents infected. Currently, plague is permanently and enzootically established in d – Spread throughout the western U.S. the southwestern U.S. The last documented person-to-person transmission e • 1924: Los Angeles – Last person-to-person case of plague occurred during the 1924 outbreak in Los Angeles, California. – 32 pneumonic cases; 31 deaths During this outbreak, 32 pneumonic cases were reported with 31 resulting 1 • Currently established in southwest in death. 0 Center for Food Security and Public Health, Iowa State University, 2011 S Plague is a disease that the CDC Division of Quarantine are empowered l Plague as a Disease to apprehend, detain, medically examine or conditionally release a i suspect having this illness. Plague in humans is a reportable disease, and in many states plague in animals is also reportable. The U.S. Public d Health Service requires that all cases of suspected plague be reported e immediately to local and state health departments and that the diagnosis • CDC Division of Quarantine • Reportable disease in the U.S. be confirmed by CDC. As required by the International Health 1 • All U.S. cases reported to the WHO Regulations, CDC reports all U.S. plague cases to the World Health 1 Organization. Center for Food Security and Public Health, Iowa State University, 2011 S l i d Transmission e 1 2 S Transmission can occur via three main routes, however, flea bites are l Transmission most common. Direct transmission can occur between animals or animals i • Flea bite and people. Y. pestis is present in tissues, draining lesions, and some body • Direct animal contact fluids (depending on the form of the disease); these bacteria can be d – Tissues, body fluids, scratches, bites transmitted through mucous membranes and broken skin. People (hunters e – Enters through break in skin • Aerosol especially) can be directly infected by handling the tissues of infected • Human cases animals. Plague has also been transmitted by bites or scratches of infected 1 – April through November animals, but this is rare. People or animals with the pneumonic form of 3 – Increased activity of fleas and hosts plague may transmit Y. pestis in respiratory droplets. In humans, Center for Food Security and Public Health, Iowa State University, 2011 transmission by inhalation is most common in crowded, poorly ventilated conditions. Y. pestis can be transmitted on fomites at least for short periods; however, its long-term survival in the environment, particularly in soil, is still poorly understood. Human cases of plague typically occur in April through November, when fleas and their hosts are most active and people are more likely to be outdoors. Center for Food Security and Public Health, Iowa State University, 2011 3 Plague S More than 30 species of fleas are capable of transmitting Y. pestis, but l Flea Vectors they vary in their efficiency as vectors. Fleas (order Siphonaptera) are i • Can live off host for months able to live off their host for weeks to months. Host specificity of fleas • Many species can serve as vector varies, and most fleas will feed temporarily on other host(s). The flea d • Oropsylla montana most often responsible for human cases, Oropsylla montana (ground e – Rock squirrels, California ground squirrels, prairie dogs squirrel flea), is commonly found on rock squirrels, California ground – Most important flea vector in U.S. squirrels, and prairie dogs. It is the most important flea vector in the U.S. 1 • Xenopsylla cheopis and will readily feed on humans when its normal host is absent, unlike – Epidemics in Asia, Africa, South America 4 most prairie dog fleas. Xenopsylla cheopis (oriental rat flea) is the Center for Food Security and Public Health, Iowa State University, 2011 primary vector of plague in most large plague epidemics in Asia, Africa, and South America. S Successful transmission from the flea depends upon ambient temperature, l Flea Transmission because temperature affects the degree of blood clotting in the gut of the • 27°C (80°F) flea. After a flea takes a blood meal from a host, the blood enters the i o o – Blood clots in gut of flea flea’s stomach.