Presentation deals with the virus associated with the disease, host, epidemiology, transmission, life cycle of the virus, diagnosis and treatment for chickengunya.

1. Pallavi Rane
NIPER-Ahmedabad

2. Definition
• Chikungunya is a relatively rare form of viral fever
caused by an alphavirus that is spread by mosquito
bites from Aedes species.
• Synonyms are
 CHIKV Fever
 Buggy Creek virus infection
 Knuckle fever
 Me Tri virus infection
 Semliki Forest virus infection

3. What is this virus ?
• Causative agent is an RNA – VIRUS
• Class – Arbor Virus (Arthropod Borne)
• Family – Togaviridae
• Genus – Alpha Virus
• Species – Aedes aegypti, Aedes albopictus

4. Vector
• It is transmitted by Aedes species
• Mosquitoes - Aedes aegypti, Aedes albopictus
• Aggressive day time Bite
• Major period of activity – sunrise and sunset

5. Aedes Mosquitoes
• Household container breeders
• Breeds in
– clean water
– In all stored water for drinking, washing and bathing
– Rainwater collected in unused materials like coconut
shells, mud pots, plastic cups, tyres etc

6. HOST
• Man
• The main virus reservoirs are monkeys, but other
primates, mammals and birds can also be affected
Host

8. Transmission
• This virus is transmitted only by mosquitoes
• The mosquito picks up the virus from an infected
person during the viraemic period – within five days
from the day of starting of symptoms
• An infected mosquito will remain infected all its life
span and can transmit the virus each time it bites
• An infected person cannot spread the infection
directly to other persons

9. Life Cycle of Virus

10. Alphavirus
enter target
cells by
endocytosis
the acidic
environment of
the endosome
triggers
conformational
in the viral
envelope
expose the E1
peptide which
mediates virus–
host cell
membrane
fusion.
cytoplasmic
delivery of
the core and
release of the
viral genome
Two precursors of
non-structural
proteins (nsPs) are
translated from the
viral mRNA, and
cleavage of these
precursors generates
nsP1–nsP4
. The assembled
alphavirus
pcomplex, which
synthesizes a full-
length negative-
strand RNA
intermediate.
This serves as the
template for the
synthesis of both
subgenomic (26S)
and genomic (49S)
RNAs
subgenomic RNA drives
the expression of the
C–pE2–6K–E1
polyprotein precursor,
which is processed by
an autoproteolytic
serine protease
The capsid (C) is
released, and the
pE2 and E1
glycoproteins are
generated by
further processing
pE2 and E1 associate in
the Golgi and are
exported to the plasma
article, with an
icosahedral core, buds
at the cell membrane

11. • Fever Which Can Reach 39°C, (102.2 °F)
• Petechial or Maculopapular Rash Usually Involving the
Limbs and Trunk
• Arthralgia or Arthritis Affecting Multiple Joints Which
Can Be Debilitating.
• Headache, Conjunctival Injection and Slight
Photophobia.
• Sudden onset of fever, chills
• Headache, nausea, vomiting, abdominal pain
• Low back pain and rash
Symptoms

12. Diagnosis Of Chickengunya
RT-PCR
• Viral RNA can be easily detected by reverse transcriptase-
polymerase chain reaction (RT-PCR) in serum specimens
obtained from patients during the acute phase of infection.
• Chikungunya infections cause high levels of viremia ,which
typically last for 4–6 days after the onset of illness.
• RT-PCR can therefore easily been done within the first 7
days.
• RT–PCR products from clinical samples may also be used
for genotyping of the virus, allowing comparisons with virus
samples from various geographical sources.
• PCR results can be available within one to two days.

13. ELISA
• Enzyme-linked immunosorbent assays (ELISA) detect
both anti-CHIKV immunoglobulin (Ig) M and IgG
antibodies from either acute- or convalescent-phase
samples.
• Serological diagnosis requires a larger amount of blood
than the other methods.
• ELISA results require 2–3 days and the test is quite
specific with very little cross reactivity with related
alphaviruses.
• Testing of samples from imported cases found that
chikungunya-specific IgM antibodies develop rapidly
within a few days after illness onset and persist for
several months.

14. PRNT
• Plaque reduction neutralization tests (PRNT) are very
useful because they are quite specific for
alphaviruses and are the gold standard for
confirmation of serologic test results.
• The major drawback to PRNT is that it requires the
use of live virus.
• The test must be carried out in Biosafety level 3
laboratories (BSL-3) that requires special laboratory
containment equipments.

15. Treatment
Currently, no specific treatment for chikungunya is
available. Supportive care is recommended.
Nonsteroidal anti-inflammatory drugs such as
• naproxen,
• non-aspirin analgesics such as paracetamol
(acetaminophen) and
• fluids for symptomatic treatment.

17. Corticosteroids, but not recommended during the
acute phase of disease, as they may cause
immunosuppression and worsen infection.
Passive immunotherapy involves administration of
anti-CHIKV hyperimmune human intravenous
antibodies (immunoglobulins) to those exposed to a
high risk of chikungunya infection.
No antiviral treatment for chikungunya virus is
currently available, though testing has shown several
medications to be effective in vitro.

18. Chronic arthritis
• In those who have more than two weeks of arthritis,
ribavirin may be useful.
• The effect of chloroquine is not clear.It does not
appear to help acute disease, but tentative evidence
indicates it might help those with chronic arthritis.
• Steroids do not appear to be an effective treatment.
• NSAIDs and simple analgesics can be used to provide
partial symptom relief in most cases.
• Methotrexate a drug used in the treatment of
rheumatoid arthritis, has been shown to have
benefit in treating inflammatory polyarthritis
resulting from chikungunya, though the drug
mechanism for improving viral arthritis is unclear.

19. Vaccines
• Currently, no approved vaccines are available.
• A phase-II vaccine trial used a live, attenuated virus, to
develop viral resistance in 98% of those tested after 28 days
and 85% still showed resistance after one year.
• Alternative vaccine strategies have been developed, and
show efficacy in mouse models, but have so far not reached
clinical trials.
• In August 2014 researchers at the National Institute of
Allergy and Infectious Diseases in the USA were testing an
experimental vaccine.
• Even with a vaccine, mosquito population control and bite
prevention will be necessary to control chikungunya
disease.

20. Prevention
• Elimination of stagnant water at home, schools and
work place to avoid breeding of mosquitoes.
• Using mosquito screens or nets in non – Air-
conditioned rooms.
• Wearing the long sleeved clothes like long trousers of a
light shade for protection against mosquitoes.
• Properly covering all water tanks so that mosquitoes
cannot get in.
• Getting rid of any container capable of retaining water
in the outdoor surroundings (used tyres, food cans,
garbage, saucers under flower pots, etc)

21. Control
• Aedes species is the main target of control.
• Source reduction of breeding sites of mosquitoes.
• Requires community involvement to keep the
water storage containers free of mosquitoes
• Eliminate other breeding places in and around
houses
• Biological control: Introduction of larvivorous fish,
namely Gambusia in water tanks and other water
sources

22. Antimosquito Measures
• The organophosphorous insecticide ABATE is being
used in a large scale
• ABATE can prevent breeding upto 3 months when
applied to sand granules
• It does not affect man or the taste of water.
• Aerosol spray of ultra low volume [ULV] of
MALATHION or SUMITHION 250 ml/hectare is
effective in interrupting transmission and stopping
epidemics.

23. • Chikungunya, centre for disease control, january
2013,northern territory government,
www.Nt.Gov.Au/health
• Olivier schwartz et.Al., Biology and pathogenesis of
Chikungunya virus, Nature reviews-microbiology,
volume 8, July 2010, 491-500.

24. Thank You