Yellow fever, Japanese encephalitis, and Kyasanur forest disease (KFD) are zoonotic mosquito-borne viral diseases. Yellow fever virus infects monkeys and humans in tropical Africa and South America and is transmitted by Aedes mosquitoes. Japanese encephalitis virus infects pigs and birds and is transmitted to humans by Culex mosquitoes. KFD virus infects monkeys and rodents in parts of India and is transmitted to humans by ticks. These diseases cause fever and neurological symptoms and can be fatal, with thousands of cases reported annually worldwide. Vaccination is the primary preventive measure for yellow fever.

1. Yellow fever , Japanese encephalitis
&
KFD( Kyasanur forest
disease )
Bikash Gyawali
Mph, B.Sc optometry

2. Contents
 Introduction
 Case definition
 Epidemiological determinants ( Risk factors, Agent /Host )
 Indian scenario ( appearance/condition of disease)
 Clinical features
 Distribution
 Mode of transmission ( incubation period)
 Control & preventation

3. Yellow Fever ()
 Zoonotic disease caused by an arbovirus
 Affects monkeys and vertebrates (in tropical America &
Africa)
 Transmitted to human by culicine
mosquitoes
Clinical features – viral hemorrhagic fever ( e.g. dengue,
lassa fever)and further characterized by
more sever hepatic and renal involvement

4. Epidemiology
RESERVOIR
 Reservoir- Nonhuman and human primates
 In urban areas of endemic countries, the reservoirs are
humans and Aedes mosquitoes
 In forest areas, vertebrates other than humans (mainly
monkeys and possibly marsupials) and forest
mosquitoes are the reservoir
AGENT
 Causative agent- Flavivirus - formerly classified as
a Group B Arbo-virus - member of the Togavirus family

5. Contd.
TRANSMISSION
 Transmitted to humans by the bites of
infectedaedes and haemogogus mosquitoes
Epidemiology
 Between August 1 and November 9, 1793, approximately 11,000
people contracted yellow fever in the US
 Of that number, 5,000 people, 10 percent of the city’s population,
died
 There are an estimated 2,00,000 cases of yellow fever, causing
30, 000 deaths, worldwide each year, with 90% occurring in
Africa (WHO)

7. Treatment
 There is no specific treatment for yellow fever. Treatment is
symptomatic, aimed at reducing the symptoms for the comfort
of the patient.
 Vaccination is the most important preventive measure against
yellow fever.
 Note: India is not a yellow fever endemic area

8. Japanese encephalitis (JE)-
 Mosquito – borne encephalitis caused by group B arbovirus
( Flavivirus)
 Transmitted by culicine mosquitoes
 Zoonotic disease , i.e. infecting mainly animals(horse, pigs)
and incidentally man

9. Cont.
• OCCURRENCE – occurring throughout most of Asia
and parts of the western Pacific
- JE virus has not been detected in
Africa, Europe, or the Americas
• RESERVOIR - Pigs and various wild birds transmitted to
new animal hosts and occasionally
humans by mosquitoes of the genus Culex
• AGENT - Flavivirus- belongs to family Flaviviridae

10. Cont.
 TRANSMISSION - bite of infected Culex species mosquitoes
- virus is maintained in a cycle
between mosquitoes and vertebrate hosts,
primarily pigs and wading birds
 JE virus transmission occurs primarily in rural agricultural
areas, often associated with rice production and flooding
irrigation

11. Epidemiology
 Occurrence - Areas with temperate climates (including China,
Japan, South Korea, Nepal, northern Vietnam, and northern
India- warm weather after the monsoons begin
 JE - cases 50,000
- deaths 15,000 (annually worldwide)
 In endemic areas, the highest age-specific attack rates occur in
children of 3 to 6 years of age

12. Cont.
 1871: Summer-fall encephalitis outbreaks suggestive of JE
were recorded in Japan from 1871
 1924: Agent from human brain tissue isolated in rabbits,
following massive epidemic in Japan with > 6000 cases

13. Cont.
Source: Directorate of National Vector Borne Disease Control Programmed ,India

15. KFD( Kyasanur forest disease )
 Causes - Kyasanur Forest disease virus (KFDV)
 Family - Flaviviridae- common targets among monkeys
are langur
 KFDV was identified in 1957 - isolated from a sick monkey
from Kyasanur Forest in Karnataka (formerly Mysore) State,
India
 Cases- 400-500 humans per year have been
 reported

16. Epidemiology
 During 2012–2013, KFD infection was reported from other
districts and states in India:
 Chamarajanagara District, Karnataka State
 Nilgiri District, Tamil Nadu State and
 Waynad District, Kerala State
 Morbidity rate of 2-10%, and affects 100-500 people annually

18. Epidemiology
• Occurrence -
• Reservoir- Hard ticks (Hemaphysalis spinigera) and once
infected, remain so for life
• Transmission- Rodents, shrews, and monkeys are common
hosts for KFDV after being bitten by an infected tick or
contact to human
• No person-to-person transmission has been described
• Temporal pattern – From December to May

19. Incidence of KFD in Karnataka State, India, through
March 24, 2012
Year
Total
village
Total
cases
Hospitalized
case
Confirmed
Cases*
Confirmed
deaths
NHP
Death
NHP cases
conformed
2003 218 953 725 306 11 132 11
2004 121 568 311 153 5 86 8
2005 179 661 521 63 7 53 4
2006 123 354 246 99 2 54 3
2007 23 76 30 14 0 19 0
2008 29 112 31 36 0 23 0
2009 57 179 139 64 1 72 1
2010 3 5 0 0 0 28 0
2011 20 41 17 19 1 35 4
2012 141 314 294 69 1 27 2
Total 917 3263 2314 823 28 529 33

20. Thank you