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Tularemia. This is an infectious disease caused by the organism Francisella tularensis . The disease this organism causes has a large range of hosts, methods of transmission, portals of entry, and clinical syndromes. There are two main types- A and B.
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Tularemia • This is an infectious disease caused by the organism Francisella tularensis. • The disease this organism causes has a large range of hosts, methods of transmission, portals of entry, and clinical syndromes. • There are two main types- A and B. • Type A appears to be more virulent in animals and man. 90% of reported cases in North America are type A. • Type B is less severe and may therefore be less likely to be reported.
Tularemia • Tick-borne tularemia is more common in the spring and early summer among persons who have visited tick-infested areas. • A small wound develops at the site of attachment. • Later, the regional lymph nodes enlarges and becomes tender. • Fever and chills are common. • Serious complications leading to death are rare.
Tularemia Route Syndrome 1. Integumental invasions by arthropod, arthropod bite (ticks), knife, ect. Ulceroglandular, adenopathy proximal to the point of entry. Oculoglandular, cephalic, and cervical nodes involved. 2. Exposure to eye. Typhoidal forms- oral and GI symptoms, stomatitis and pharyngitis. 3. Ingestion All forms may disseminate to the spleen, liver, lungs and pleura. 4. Disseminated
Tularemia • Transmission for this disease is very diverse • Mechanical vectors. Usually this is through either ticks (many species) or deer flies. Mechanical vector means no reactivation period. Sheep and dogs can bring ticks to man. • Tick borne transmission is the most important form in the US. • Tick-borne tularemia is usually type A and has an ulceroglandular presentation.
Tularemia • 2. “Rabbit fever” • As hunting rabbits has become less common, transmission by direct contact with infected game has decreased. • It is advised that hunters avoid rabbits which are sluggish or apathetic. • I personally never understood this recommendation. I think it means that you should not eat rabbits that are slow enough for you to shoot.
Tularemia • 2. “Rabbit fever” • Only in the advanced stages of the disease do the rabbits become lethargic, as such advice to avoid animals with “spots on the liver” may give hunters a false sense of security. • Human infection is usually through direct exposure through wounds or conjunctiva while cleaning and dressing wild game. • The ulceroglandular clinical syndrome is the most common clinical presentation. • Game reservation – cancelled hunt
Tularemia • Transmission cont… 3. Inhalation: This is a problem in Scandinavia. Where voles carrying the bacterium invade hay and create infective dust, which infects the people who breath. This also occurs as laboratory accidents. 4. Water-borne: This is usually type B, it is common in the Russia and associated with small rodents. • Host range: • Incredibly wide - some mammals, birds, and aquatic animals.
Tularemia • Prevention and Control: • Report animal die-offs. • Ectoparasite control of domestic animals. • Avoid ticks. Check yourself for ticks after working with tick-infested domestic animals and after trips to tick-infested areas. • Education of hunters. Use gloves for cleaning game. Cook wild game well before eating. • A vaccine is available in the US for persons at high risk. This vaccine is extensively used in some parts of the world (Russia). • Avoid drinking water directly from “clean” mountain streams.
Q Fever • Agent: • Coxiella burneti • It has a very good viability in the free state. • It is very resistant to desiccation and disintegration. • Extremely infectious!! A single organism can cause disease. • Airborne transmission over long distances is possible. • High potential for use as a biological weapon.
Q Fever • Distribution: • Worldwide in animals and man, the reservoirs are cattle, goats and sheep. • Incidence: • About half of goats and sheep in Michigan show evidence of previous exposure. Cattle and wild animals are also susceptible. • Transmission: • Airborne - this the most common. • Direct contact - with infected animals. Also infected milk, rarely. • Tick transmission • Fomites - contaminated clothing, wool or hair.
Q Fever • Pathology and clinical signs in animals • Classically, Q fever in animals has been reported to be only subclinical. However, recent reports of abortions in goats and sheep have been substantiated. • 1978 - Colorado outbreak of abortions in goats • 1980 - Ontario outbreaks of abortions in goats and sheep herds.
Q Fever • Outbreaks: • Ontario, 1981- Ontario has the first human case ever reported. This coincides with the first reports of outbreaks of goat and sheep abortions. Q fever is now the leading cause of granulomatous hepatitis in the province. • Great Britain, between 1975 and 1981- there were 839 human cases and endocarditis was reported from 11%. • Michigan, 1984 - The first two human cases were reported in southwestern Michigan. None have been reported since.
Q Fever • A case control study among goat owners in two adjacent counties was preformed. • 42% of family members were seropostive. • 13% of community controls were seropostive. • 40% (49/123) of goats were positive. • 44% (10/23) of sheep were positive. • Seropositivity (in people) was statistically associated with number of goat births on the farm, assisting at goat births and the total number of goats on the farm.
Q Fever • In laboratories around the world, there are lots of work-place outbreaks. • Most of these were through airborne exposure and have occurred in both hospital and research laboratories. • Lambing taking place in the basement of research facilities causes the bacteria to become airborne and spread throughout the building. • Germany, 1996 - After a large outdoor lambing, many people in a nearby town were infected with the bacterium.
Q Fever • Diagnosis- This is done through history, serology (CF test), and through isolation of the organism. • Treatment - it responds well to chloramphenicol and tetracycline. • Prevention: • Avoid birthing fluid of ruminants!! • Wear gloves and mask when assisting birthing. • Dispose of placentas and aborted fetus. • Environmental contamination is mainly due to infected placenta and postpartum discharges. • Transmission is mainly through inhalation of Coxiella-laden dust . • Vaccination is possible, but it is not practiced in this country.
Significance for Bioterrorism • Coxiella burnetii is a highly infectious agent that is rather resistant to heat and drying. • It can become airborne and inhaled by humans. • A single C. burnetii organism may cause disease in a susceptible person. • This agent could be developed for use in biological warfare and is considered a potential terrorist threat.
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