MMG301 1st Edition Lecture 36Outline of Last Lecture I. Direct contact diseasesOutline of Current Lecture II. Vector transmitted diseasesIII. Soil borne diseasesCurrent LectureZoonosis: disease found primarily in animals but transmissible to humans-Transmission usually by direct contact or respiratory-Enzootic infectious diseases are found only in animal populations (usually at constant low levels)-Significant increases in infectious disease prevalence within animal populations is epizootic (the animal equivalent of epidemics in humans)-Rabies: -Infections agent: Rabies virus-Transmission: Bites from infected animal, but respiratory also possible (virus in saliva)-Infects: Spinal cord, brain stem, and cerebellum-Incubation period: 1-2 weeks in animals; several to 9 months in humans-Fatality rates: Nearly 100% fatal in most mammals if not treated – is claimed by some tobe the most lethal of all infectious diseases; over 55,000 deaths worldwide each year-Treatment: Usually involves “live attenuated vaccine” (live but weakened viruses) plus anti-rabies immunoglobulin (nearly 100% effective)-Diagnosis: Negri bodies in brain samples from animals; microscopic examination of tissues using fluorescent antibodiesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-Hantavirus: -Infectious agent: hantavirus; related to hemorrhagic fever viruses such as Ebola & Lassa viruses-Transmission: Deer mouse host; inhalation of dried airborne fecal material from infected animal-Diseases: Severe cases can lead to hantavirus pulmonary syndrome: fever, muscle aches, decreased blood platelets, lungs fill with fluid-West Nile Virus (mosquito vector)-Identified in Uganda in 1937; Egypt in 1950; US in 1999-Humans, horses, and birds are affected (birds are reservoirs (“corvids”-ravens, crows, bluejays))-Birds are the major reservoirs – over 130 species can be hosts-Human mortality 2-3%; up to 40% for horses (but vaccine effective)-About 80% of human infections are asymptomatic-20% develop West Nile fever – in rare cases, this can lead to serious complications such as encephalitis.-cycles between birds and mosquitos to spread, in some cases the mosquito can go to horse or human (called dead end hosts)-Rickettsial Diseases (spread by ticks, lice, fleas): -Rocky Mountain spotted fever-Ehrlichiosis-Typhus-Q fever-Rickettsias are intracellular parasites (bacteria), mainly infecting mammals-Transmission: from vector bite-Treatment: antibiotics-Rocky Mountain spotted fever: Rickettsia rickettsii-A zoonotic disease – humans are accidental hosts-3-12 day incubation in host-fever, headache, and eventually severe rash and diarrhea, vomiting-Ehrlichiosis and Anaplasmosis -Can infect many mammals; zoonotic transmission to humans by tick vector-Initially appears as flu-like symptoms, but can become life-threatening in some cases-Caused by members of Ehrlichia and Anaplasma: infect white blood cells of host-Typhus: (Rickettsia prowazekii) note: not typhoid fever-Humans are the only known host-Human-to-human transmission by common body or head lice-Sometimes called “war fever”; associated with large-scale military campaigns – killed more WW1 soldiers than fighting; 3 million died in Russia 1914-1917-Q-fever: caused by Coxiella burnetii-Usual animal→animal or animal→human transmission by inhalation or contact with urine, feces, milk, or other fluids from infected animal-rarely transmitted by
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