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