Measles, Rabies and Japanese encephalitis

1. VIRAL INFECTIONS
MEASLES RABIES JAPANESE ENCEPHALITIS
ANANYA. M
II MSc BIOLOGY

2. VIRAL INFECTION
• Viral infections are any illness you get from a virus.
• If it is a viral illness then typically it’s symptoms are shorter lasting.
• The classic symptoms include fever, sore throat, running nose, cough, nasal congestion and
body pain.
• Medicine that treat viral infections is called an antiviral
• These medicines usually stop a virus from making copies of itself and also stop from going
into or leaving a cell. It target the virus not the host cell.

3. MEASLES
• Highly contagious skin disease that is epidemic through out the world.
• Incubation period :- 10-12 days.
• Symptoms:- Fever, runny nose, cough and swollen weepy eyes.
• Very rarely Measles reactivation is observed after 2-10 years and form a disease called SSPE( Subacute
Sclerosing Pan Encephalitis).
• Causative virus known as Measles virus.
• Measles virus is an enveloped RNA virus.
• There is 2 biologically active projections from the envelope. They are H and F spikes. H for viral
attachment and cause Haemaglutination , F spike is responsible for fusion.
• It can be inactivated by heat, UV –rays, ether and also with the action of formaldehyde .

4. STRUCTURE OF MEASLES VIRUS

5. PATHOGENESIS
• The virus is acquired through the respiratory route and conjunctiva
• It primarily replicates in the upper respiratory epithelium, then spreads to lymphoid tissues and
spreads through out the body.
• Mucous membrane involvement is responsible for an important diagnostic sign koplicks spot( small
bluish white ulceration on the buccal mucosa).
• Damage to the respiratory mucous membrane leads to secondary bacterial infections.
• The skin rash of measles results from the cytopathic effects of measles virus replication in skin vascular
endothelial cells and cellular immune response against the viral antigen in the skin.

6. LABORATORY DIAGNOSIS
• Primary diagnosis is with the help of koplicks spot formation.
• Virus can be recorded from throat/nasopharyngeal swab, urine and whole blood. Primary cultures of
human embryonic kidney cell and monkey kidney cells are more sensitive for virus isolation.
• Specimens should be fixed with formalin and stained with Haemotoxylin and Eosin. Characteristic giant
cells containing eosinophilic intranuclear and intracytoplasmic inclusions are observed in cell cultures.
• Antigens can be detected with immunofluorescence technique. Immuno enzyme staining increases the
sensitivity of the test.

7. KOPLICK SPOT

8. CONTROL
• Measles infection can be prevented by active immunisation programs using live, disabled virus vaccines.
• Pre –school children are vaccinated to protect them from measles.
• Children are too young to be vaccinated.
• The vaccine is now usually given as part of MMR vaccine. It usually given in two doses.
• Plan of vaccination:-Vaccine is administrated after 9&16 month from birth.
• Quarantine of patients for 5-10 days.

9. RABIES
• Acute or fatal encephalitis.
• It is a Madman disease, the reason is that ,with a rare exception, all the people who are bitten by a
rabid animal get rabies.
• An important zoonotic infection.
• The virus spreads to man when the infected animal bites human being.
• Man is a dead end of the infection.
• It is an epidemic disease.

10. PATHOGENESIS
• After deposition, rabies virus attaches to nicotinic acetylcholine
receptors of tissue cells.
• Rabies virus may enter the peripheral nervous system directly and
migrates to the brain, causing the symptoms of encephalitis.
• Characteristic inclusion bodies called Negri bodies , are formed at
the site of viral replication in the brain but the cells are not lysed.
• The immune response of the host probably plays an important
role in pathogenesis since the viral antigens are expresses on the
surface of the infected cells.

11. LAB DIAGNOSIS
• Saliva/sputum, skin biopsy, hair follicle, cerebrospinal fluid, blood, corneal swab, urine and brain are
used for the clinical diagnosis of rabies.
• Methods used in the diagnosis of rabies in laboratories are,
1. Negri body examination
2. Fluorescent antibody test
3. Complement fixation test
4. ELISA
5. Immuno peroxidase test
6. Haemagglutination test

12. TREATMENT
• Management of wounds reduce the risk of rabies in man.
• The dog bite area is washed with soap. 1% cetrimonium bromide is applied as antiseptic along with
antirabies serum.
• Post exposure immunization reduces the multiplication of rabies virus in infected man. Immunization
must be started at the earliest to ensure that the individual will be protected before the rabies virus
invades central nervous system.
• Two types of agents are employed to confer immunity to an individual who has been exposed to rabies
virus. They are Antirabies serum/rabies immunoglobulin and antirabies vaccine :-HDCV , Human Diploid
Cell Vaccine.

13. JAPANESE ENCEPHALITIS
• An infection found in Asia and the west Pacific that can cause brain swelling.
• Japanese encephalitis is a virus spread by the bite of Infected mosquitoes.
• It is more common in rural and agricultural areas.
• Extremely rare, fewer than 5000 cases per year (India).
• In general Arbovirus causes encephalitis, means inflammation of the brain.
Alpha virus, Flavi virus and Bunya virus may cause Encephalitis in human.
• The disease are named after their ecological distribution.
:- Japanese Encephalitis (Japan & India), Culex- Mosquito borne.
California Encephalitis (California), Aedis –Mosquito borne
Russian spring Encephalitis (Russia), Ixodes – Tick borne.

15. PATHOGENESIS
• Pathogenesis of Encephalitis is not well studied.
• The virus enters the human body through mosquito or tick bite.
• The Japanese encephalitis virus (JEV) attaches to host cell membranes.
• Initially propagating at the site of the bite and nearly lymph nodes.
• After the entry, the virus multiplies in non- nueral tissue and is present in the blood 3 days before first
sign of involvements of CNS.
• Then the virus multiplies in the brain cells, destroys the cell and hence encephalitis become apparent.

16. LAB DIAGNOSIS
1. Recovery of virus from cerebrospinal fluid (CSF).
2. Inoculation of serum with intracerebral inoculation of sucking mice.
3. Neutralizing haemagglutination –inhibiting antibodies are detected within a few days after infection. CF
antibodies appear later.
4. Patients with JE virus IgM antibodies, confirmatory neutralizing antibody testing should be performed.
5. In fatal cases, nucleic acid amplification, histopathology with immunohistochemistry and virus culture
of autopsy tissue can also be useful.

17. TREATMENT
• There is no specific treatment.
• Vector control and immunization are found to be effective in the control of disease caused by Arbo
virus.
• The best way to prevent JEV infection is to be protect yourself from mosquito bites.
• Use insect repellent.
• Wear long-sleeved shirts and pants.
• Get vaccinated before travelling, if vaccination is recommended for you.

18. THANK YOU