Measles Virus - Morphology, Pathogenesis, Clinical Features, LD & Prophy.

MEASLES VIRUS – MORPHOLOGY, RESISTANCE, PATHOGENESIS, CLINICAL FEATURES, LABORATORY DIAGNOSIS & PROPHYLAXIS

INTRODUCTION TO MEASLES VIRUS

⇒ MEASLES VIRUS is the causative agent of disease Measles, a highly contagious viral infection of the respiratory system.

It had been described by Thomas Sydenham in 1690. Later, in 1954, it was first isolated in monkey and human kidney cells by Enders and Peebles.

Measles virus belongs to the Morbillivirus genus of Paramyxoviridae family.

MORPHOLOGY OF MEASLES VIRUS

⇒ Resembles orthomyxovirus in morphology – Spherical, Enveloped & Pleomorphic virus.

⇒ Size: 120-250 nm in diameter.

MEASLES VIRUS - MEASLES - RESPIRATORY ILLNESS - LUNG DISEASE

The envelope is covered by projections of H (Hemagglutinin) and F (Fusion protein).

Genetic Material:- Linear ssRNA

There is only one serotype of Measles virus.

RESISTANCE SHOWN BY MEASLES VIRUS

The measles virus is labile; readily inactivates by heat, ultraviolet light, ether, and formaldehyde; can be stabilized by MgSO4, so that it resists heating at 50°C for 1 hour.




PATHOGENESIS OF MEASLES VIRUS

The Mumps virus causes the disease mumps, an acute infectious disease characterized by non-suppurative enlargement of the parotid gland and Parotitis.

The virus enters through the Respiratory tract and

through the conjunctiva.

The virus multiplies locally & in the adjoining

lymph nodes.

Then spreads through the bloodstream to

Reticuloendothelial system.

After multiplication, secondary viremia transports the

Virus to the epithelial surfaces.

Koplik’s spots, small bluish-white ulceration, may be seen

on the Buccal mucosa.

The Koplik’s spots contain Giant cells, inclusion bodies,

and virus antigen.

2-4 days later, red maculopapular rashes appear.

CLINICAL FEATURES OF MEASLES

The incubation period of Measles virus is 9-11 days.

The initial signs of the disease include Malaise, Fever, Cough and Nasal Discharge.

After 2-4 days, rashes appear, the 1-2 day before the appearance of rashes, Koplik’s spots develop on Buccal mucosa & occasionally on the conjunctiva.

The red maculopapular rash of measles typically appears on the forehead first & spreads downwards.

LABORATORY DIAGNOSIS OF MEASLES VIRUS

⇒ Specimen: Saliva, Throat secretions, CSF and Urine.

⇒ Direct Demonstration: Giemsa stained smears of nasal secretions can show multinucleated giant cells. Viral antigen can be detected in epithelial cells of respiratory secretions and in urine.

⇒ Isolation of the virus: Virus can be isolated from saliva, Throat swab, CSF or urine by inoculating into Primary monkey Kidney and Amnion cells.

⇒ Serology: Measles-specific IgM antibodies can be detected in serum by ELISA. Hemagglutination Inhibition Test and CFT can also be done.

⇒ PCR: Reverse transcriptase PCR is a sensitive and specific method of diagnosis.

PROPHYLAXIS OF MEASLES VIRUS INFECTION

A live attenuated vaccine is available that can be administered one dose by the subcutaneous route.

It can also be administered in combination as MMR vaccine as a single dose subcutaneously.

This vaccine is given to children aged 12-15 months.

It provides effective protection for more than 20 years.



SAHIL BATRA

Hi, I'm the Founder and Developer of Paramedics World, a blog truly devoted to Paramedics. I am a Medical Lab Tech, a Web Developer and Bibliophiliac. My greatest hobby is to teach and motivate other peoples to do whatever they wanna do in life.

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