(C) (< 1) (258 - Park 22nd)AEDES AEGYPTI INDEX: This is a house index and is defined as "the percentage of houses and their premises in a limited well-defined area, showing actual breading of Aedes - aegypti larvae"* This index should not be more than 1 percent in towns and seaports in endemic areas to ensure freedom from yellow fever.* Airports and seaports are kept free from the breeding of insect vectors over an area extending at least 400 meters** around their perimeters.* The "aedes aegypti index" is kept below 1 **YELLOW - FEVER* It is a exotic zoonotic disease in India.* Causative agent - Group B Arbovirus (Flavivirus fibricus) (Togavirus family)* Reservoir - Monkey in forest areas and Man in urban area.* Vector - Aedes aegypti* Incubation Period - Intrinsic 3-6 days, Extrinsic 8-12 days.* Immunity - One attack confers life long Immunity. Infants bom of immune mothers have antibodies up to 6 months of life.* Clinical features - Haemorrhagic fever (black vomit, epistaxis, malena) with severe hepatic and renal manifestations. Spectrum of disease varies from clinically indeterminate to severe cases.* Case fatality rate - May reach 80% in severe cases.* Period of communicability: Blood of patients is infective during the first 3 to 4 days of illness.* Vaccine - 17 D vaccine Live attenuaed, Freeze dried. Immunity apperrs on 7th day and lasts >35 years. Rapid immunization of population at risk is the most effective control strategy.* International certificate of vaccination - Valid 10 days after date of vaccination and extends up to 10 years. WHO recommends re-vaccination after 10 years.* All travellers (including infants) exposed to risk of yellow fever or passing through endemic zones of yellow fever must poses a valid International certificate of vaccination.* Quarantine - A traveller without a valid international certificate of vaccination' is placed on quarantine in a mosquito proof ward for 6 days.