Measles-Red measles, Rubeola
spread by respiratory droplets;very contagious. No reservoir other than human. need dense poplation to sustain continuous chain of infections leading to an epidemic. kills babies and young kids; 7th most frequent cause of death in those age groups worldwide.
Measles symptoms and pathology
virus first invades mucosal lining of respiratory tract; this is followed by viremia.Incubation time is 2 weeks,sore throat, dry cough,headache,conjunctivitis,lymphadenitis,and fever. oral lesions are first to show up and called kopliks's spots. A red maculopapular rash appears,first on head,then trunk and extremities. the rash coalesces into red patches that fade to brown.
Complications of measles : Laryngitis
bronchopneumonia, bronchitis,bacterial secondary infections like ototis media,sinus infection. death is 1/500 in children.
Complication of measles:SSPE
subacute sclerosing panencephalitis. Progressive neurological degeneration of the cerebal cortex, whitematter and brain stem=>occurs in 1/million measles cases,mostly in children and adolescents. it brings profound retardation start with a decline in memory, judgement, and motor activity. leads to coma and death in months or years.
Measles vaccine has been very effective
at limiting cases and complications in usa.
Rabies Bullet shape
caused by the bullet shaped rhabdovirus. Helical with spikes on envelope.
it is a zoonosis found worlwide in various mamals such as skunks,foxes, racoon,wolves,bats,badgers,sometimes dogs and cats. Characterized by fatal meningoencephalitis.
Rabies pathology and symptoms
virus multiplies one week at bite site.Virus enters sensory nerve endings goes to spinal cord then brain.Brain to eyes heart,skin andor mouth where it replicates in salicary glands and ends up in saliva.
Rabies pathology and symptoms :incubation
the total incubation periodcan last for 1-2 months or a year. Depends on the portal of entry and the dose received.Prodromal symptoms include anorexia , nausea, headache,fatigue.
Rabies stages of infection are
incubation,prodromal,acute,or acme,Neurological encephalitis,coma,death.
There are two forms of rabies the acute stage can take: Furious Rabies
agitation,disorentation,seizures,twitching ,spasm in neck and pharynx.Pain on swallowing so that even sight of liquid brings on hydrophobia.
There are two forms of rabies the acute stage can take;Dumb form
Dumb form patient is paralyzed,disorentated,and stuporus. Both forms lead to coma & death from cardiac or respiratory arrest.Very few people are known to have survived rabies without treatment.
Problems with Rabies diagnosis: difficult to diagnose
if the contact with the animal is not clearly defined,or when symptoms are delayed.
problems with rabies diagnosis:symptoms of
anxiety,agitation,and depression, resemble psychoneurosis or even spasms of the pharynx, like tetanus. Encephalitis,convulsions,and paralysis mimic other viral infections. lab diagnosis to find negri bodies inclusion in cells of infectd nervous tissue.
Epidemiology,Treatment, Prevention:before exposure
control of reservoir animal population. Vaccine incorporated in bait placed in habitat of wild reservoir species like skunksand racoons .pre exposure vaccine available.
Epidemiology,Treatment, Prevention:after exposure
assess animal if domestic animal, quarantine 10 days to observe; Examine brain samples. Treat bite wound wash ,debride, and treat with antiseptic.Recieve passive vaccine.
Rabies Vaccine:post exposure
immunization in both passive and active:wound is infused w/human rabies Ig (HRIG)given intramuscular. manufactured b plasmapheresis of hyperimmunized volunteers.manufactured quanity of HRIG falls short worldwide requirements;not available in many developing countries. Equine rabies immune globin(ERIG) or purified fractions of ERIG have been used effectively in some developing countries.
Rabies Vaccine:post exposure,(HDCV)
Human diploid cell vaccine is given simultaneously. new genetically engineered vaccine,made with inactivated virus that carries the gene for rabies surface antigen.Produced in cultures of normal human diploid cells.
Rabies Vaccine:pre exposure
consist of series of three injections with human diploid cell rabies vaccine(HDCV) or purified chick embryo cell (PCEC) vaccine. Older vaccine involved shots given on 1st,3rd,7th,14th,28th,60th days after exposure,with 2 boosters.
Rubella- German Measles;teratogenic
teratogenic-causes birth defects in prenatal rubella(congenital) rubella. Mom can transmit virus even if she is asymptomatic.
Rubella German Measle-Disrupts/damage
damage disrupts development of germ layers in 1st trimester. Cataracts,spontaneous abortion,cardiac anomalles,ocular lesions,deafness,mental //physical retardation. Thromocytopenic purpura which is hemorrhage into tissue due to low platelet count.Infant can develop diabetes thyroiditis or encephalitis. Less dramatic symptoms are anemia,hepatitis,pneumonia,carditis,bone infections.
PostNatal Rubella Infection:Develops
develops in children and adults.Transmitted by respiratory droplets.
PostNatal Rubella Infection : Incubate
incubates 2-3 weeks, during which virus multiplies in respiratory epitheliun gets into lymph tissue,enters bloodstream and invades organs. Half of infections are asymptomatic.Early symptoms include malaise,mild fever,sore throat, swollen lymph glands.Then a rash of pink macules and papules first on face,then trunk and extremeties:rash takes about three days.Adults have joint pain usually instead of rash.
PostNatal Rubella Infection : disease& immunity
The disease is usually mild and results in long-lasting immunity. Symptoms mimc other diseases;diagnose by serological testing and isolation of virus.An attenuated virus vaccine is part of MMR;given at 15 months old.
Arboviral fevers (arthropod-borne) Enveloped with a single strand (+) RNA genome
Spead by arthropod vectors.Over 400 vertebraes arthropods.Nonselective bloodsuckers sread these viruses,like mosquitos ,ticks,flies,gnats. Mostly cause fever,some cause encephalitis,some are life threating hemorrhagec fever.
Influence of the Vector
life span of vector,food and breeding sites,temperature& humidity influence vector population.Peak incidence of disease spirng and early fall when vector is actively feeding and breeding. Warm blooded reservoirs maintain virus during cold or dry season.
Transmission occurs when humans happen to go into the habitat of the reservoir and vector. Arthropod
The arthropod vector lives in habitat separate from humans and spread the virus among wild warm blooded animals and to its own offspring. Humans intrude into the cycle by contact upon a vector in the wild.
Who is at risk for arbovirus?
millions of people get arboviruses each year, thousands of them die. Native peoples have some immunity ,while travelers and the military are at special risk. Knowing about travel & possible contact with vector is important.
Arbovirus Treatment and Control: treatment
Treaatment consists of support measures to control fever, convulsions,dehydration,shock and edema.
Arbovirus Treatment and Control: Vaccines
some vaccines are available.Yellow fever vaccine is a live attenuated form that is required for travel in tropics in some areas. WEE & EEE vaccines given to veterinarians,stockmen,horses,lab workers.
Arbovirus Treatment and Control: control measures
Control measures aimed at arthropod vectors include mosquito abatement, elimination of breeding sites,insecticides. These are effective in urban setting, but difficult in woodlands.
Distribution of Important Arboviruses in the U.S: (EEE)
Eastern Equire Encephalitis Virus (ALPHA VIRUS).
Distribution Of Important Arboviruses in U .S. (Bunyavirus)
California serogroup virus (bunyavirus)
Distribution of Important Arbovirus in U.S. (WEE)
Wes.tern Equine Encephalitis virus (alphavirus)
Distribution of Importaant Arbovirus in U.S. (st. louis E V)
St. Louis encephalitis virus (Flavivirus)
Distribution of Important Arbovirus in U.S. (WNV)
West nile Virus (FLavivirus).
(WEE) and EEE Transmission and Symptoms part 1
Mortality low ~4-7%, 500 cases ea.yr. under 700 confirmed since 1964 U.S.,Some case are asymptomatic.Syptoms manifest 5-10 days after bite of infected mosquito.Headache with mild fever.Severe symptoms=sudden hi fever,headache,droesiness,irrability,nausea, vomiting followed by confusion, weakness and coma. Infants suffer from seizure.
WEE and (EEE )Transmission and symptoms part 2
Horses are primary reservoir,very seriuos disease:fatality rate approaching 70%.Rare in U.S. 7 cases a yr, Major symptoms =fever,chills,listlessness,myalgia,encephalitis. Survivors have permanent disabilites.Many propagated between birds and mosquitos,but ocassionally a human,horse, or attle snake(emu/ostrich) can get infected. No human vaccine, but there is one for horses.
EEE cause horse Mortality :Reservoirs
Reservoirs include songbirds,bluejays,chickadee,cardinal,and others:they do not have symptoms.
EEE causes horse Mortality: Symptoms horse
Horse develops symptoms within 5 days and will die within 48-72 hours after first symptoms. Symptoms include=fever,sleepy appearance, erratic behavior, weak and staggering gait,loss of coordination, muscle twitches of the head,neck shoulder, flank ,and seizures.
Bunyaviruses (california serotype Group) that are Arbovirus-borne( Negative strand DNA virues)
-strandDNA virus significant cause of encephalitis.Probaly most prevalent mosquito-borne disease after ST. Loius encephalitis in USA. Cases occur in the summer months infection subclinical or results in mild febrile illness.Occurs in children .Prognosis is good;complete recovery is the rule & residua are rare.
A BUNYAVIRUS also causes Hantavirus Pulmonary Syndrome (not arboviral)
Long tailed deer mice shed virus in their urine and feces and people inhale aerosoles.First appeared 1993 four corners healthy young adults.
Fever,muscle aches and respiratory distress.Then dramatic worsening 70%died in 5-6daysfrom catastrophic lung failure.Capillaries leakage caused fluidto fill lungs air space.Nov. 93 ;45 cases in 12 staes,27 died.Hantavirus sin nombre. Other strains cause kidney diseases.
ST. Louis Encephalitis Virus (SLE)
A flavivirus( Positive-sense ssRNA,enveloped,icosahedral)
Present in all u.s.a. but reported by central states. maintained in nature by bird- mosquito cycle but only causes disease in humans. Infections subclinical, if symptoms develop-fever, chills,myalgia & headache.More serious cases encephalitis and aseptic meningitis.
West Nile Virus
A flavivirus IWNV) is largest single cause of death ever to hit Ca. bird populations,killed millions of individuals from hundreds of different species. Incubates 2-8 days in humans.
West Nile Encephalitis
Introduced in U.S. 1998, WNV has spread south and west ward at alarming pace.15,700 human cases & 650 fatalities as of Sept,24,2004.
West Nile Encephalitis: (20% develop WNv)
Approximately 20% of cases develop West nile fever.Symptoms include fever,headache ,tiredness,and body aches.some with skin rash (on trunk of body) and swollen lymph glands.Can last from few days to several weeks.
West Nile Encephalitis (30% symptomatic)
Almost 30% of symptomatic human West nile cases develop a more serious form of neuroinvassive disease.Characterized by headache, hi fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis.
Dengue Fever & Dengue Hemorrhagic Fever (Flavivirus) transmitted
transmitted by Aedes Aegypti mosquito.:active during the daytime so not controlled by bed netts.new research using bacterium, wolbachia pipientis, to infect mosquitos preventing virus from replicating in mosquito.
Dengue Fever & Dengue Hemorrhagic Fever (flavivirus) Associated epidemics
Associated with epidemics, globally there are 50-100 million cases of DF and DHF /year. Average fatality rate is 5%. Kills about 12,500 people per year.
Symptoms of Dengue Fever (infects WBC)
Virus infects WBC:s and lymphatics,then enters circulation.
Symptoms of Dengue Fever (febrile phase)
Febrile Phase is- Sudden on set fever,chills, myalgia, arthralgias,rash,vomiting diarrhea. also Leucopenia,thrombocytopenia, hemorrhagic manifestation.
Symptoms of Dengue Fever (critical phase)
Critical phase (DHF). Vascular damage, internal shock and organ damage.
Dengue Fever & DHF (infected Again!)
Different serotypes make it possilbe to get disease again. Second infection increases risk of Dengue Hemorragic Fever.
Dengue fever & DHF ( Hypothesis)
Poorly understood but best hypothesis so far : antibodies produced against Dengue 1 do not work as well on the new Dengue 2 virus (poorly bind). D1 antibodies for complexes with the still-infectious D2 virus. Complexes readily engulfed by macrphages,transport virus back to lymph nodes ,virus replicates. this causes a more severe infection because more virions are transported to the lymph node.
Yellow fever,another flavivirus
Vector = aedes aegypticus mosquito. 3-5 days incubation, mild chills & fever, severe symptoms are bleeding into skin, tachycardia, headache, backpain, extreme prostration, nausea, vomiting Jaundice and hepatitis appears after 2-3 days of generalized symptoms.
Yellow Fever continued patient thinks they are better.
After 3rd day symptoms recede and pt's think they are better but symptoms return more severe includes brain disfunction decreased urination, delirium, seizures, coma.Finals stages=severe hemorrhage, Coffee grind vomit with blood key symptom.During epidemics it has a 85% mortality rate.
The yellow fever Vaccine
live attenuated virus 90% have immune response with1 dose. confers immunity for 10 years,cannot be given if allergic to eggs, risk of neurological disease ,encephalitis and mltiple organ failure especially in those over 60.
causes 10-15% of common colds in adults ,cause pneumonia and intestinal infections, named due to spikes looks like sun's corona.
Sars identified as type of coronavirus. thought to originate in civet cats in china.now believed to come from bats,dna in bats faces 90% similar sars dna sequence.Characterized by hi fever ,muscle aches ,dry cough, headache, shortness of breath, pneumonia.
Picornaviridae:Rhinovirus (20-25% common cold)
100 different serotypes identified and more evolving so you can get colds again and aga Prevalent Oct. thru April in northern hemisphere. Only in Humans.
Rhinoviruses; Picornaviridae-- transmitted
Transmitted hand to hand and by formites, not so much by droplet(wash hands often) Sneezing,runny nose, congestion, sore throat,fever,headache. Discomforts associated with interferons , no cure, don't take antibiotics. Major host defense is IgA in nasal mucosa; the protective effects last about 1 1/2 years.