wnf zoonoses
DESCRIPTION
5th year 2nd semesterZoonosesTRANSCRIPT
Dr. Heba AhmedSunday, 17th, April, 2011
IntroductionWNV is a mosquito-borne flavivirus originally
isolated from the blood of a febrile woman in the West Nile province in Uganda.
Neuro-invasiveness is a common feature of flavivirus infections
EtiologyThe virus belongs to Family Flaviridae and
genus FlavivirusSingle stranded positive sense RNA virusPhylogenetic studies revealed the existence
of two main lineages1- Lineage I2- Lineage II
Animal ReservoirAvian species and wild birdsReptilesEquinesOther animals: bats, cats, dogs, camels,
rabbits, squirrels and chipmunks
Insect vectorMosquitoes: 43 speciesCulexTicks
Transmission in humans
Transmission in humansMosquito bitesBlood transfusionTransplantationBreast feedingIntrauterine transmission
OccurrenceBefore 1994, outbreaks of West Nile fever
were sporadic and occurred primarily in the Mediterranean region, Africa and east Europe.
Since 1994, outbreaks have occurred with higher incidence of severe human disease
Since 1999, the disease has spread rapidly to the western hemisphere, including USA, Canada, Mexico, Central and South America
OccurrenceIn Egypt:WNV was first recognized in Egypt in 1950s where a sero-
survey revealed that 22% of children and 61% of adults had antibodies to WNV
In 1968, a study in Alexandria showed that 14.6% of children admitted to a hospital with a febrile illness had WNV
In 1989, a seroprevalence study in Nile Delta showed only 3% prevalence of WNV in school children
In 1999, a study showed that WNV was widely distributed in Egypt
In 2010, a study revealed that WNV was actively circulating in different areas in Egypt (humans, birds and mosquitoes)
Clinical Picture In HumansMost individuals are asymptomatic Symptoms may develop in 20-40% of people with
West Nile virus infectionLess than 1% of infected individuals develop
severe neuroinvasive syndromes:1- West Nile meningitis2- West Nile encephalitis3- Acute flaccid paralysis
Prevention and Control1- Surveillance:ImportanceMethods2- Vaccination:A- An inactivated vaccine B- Chimeric vaccinesC- Kunjin vaccine3- Vector Control
IntroductionToxoplasmosis is a protozoan
disease of warm blooded animals including humans
Worldwide distributed
EtiologyToxoplasma gondiiObligate intracellular parasiteToxoPlasmaDifferent strains
EtiologyToxoplasma gondiiHas three forms:1- Oocyst2- Tachyzoites3- Tissue cyst
Etiology1- Oocyst
Etiology2- Tachyzoites
Etiology3- Tissue cyst
Reservoir1- Definitive host: Cats2- Intermediate host:PigsSheepGoatsCattlePoultryRodentsHumans
OccurrenceOne-third of the world population is infected
What are the reasons of the high environmental contamination with the oocysts?
Transmission cycle
Clinical manifistaion1- Acute infection in immunocompetentsMainly asymptomaticSigns: Localized or generalized lymphadenopathy Low grade of fever Lethargy Headache Most symptoms resolve in few weeks
Clinical manifistaion2- Occular toxoplasmosis
Headlight in the fog appearance
Blurred vision
Photophobia
Clinical manifistaion3- Infection of immunocompromised
patientsMainly due to recurrence of chronic infectionSigns: CNS abnormalities Chorioretinitis Dyspenia Diarrhea
Clinical manifistaion4- Infection during pregnancy and congenital
toxoplasmosisIn pregnancyCongenital: Manifested directly after birth or many years later Hydrocephalus Microcephalus Chorioretinitis Blindness Epilepsy Mental retardation
Prevention and control1- TreatmentCombination of pyrimethamine, sulfadiazine
and folinic acid for 4-6 weeksSpiramycin2- VaccinationAnimal vaccine: TOXOVAX®
Vaccine candidates (SAG1 antigen)3- Hygienic measures