VIRAL DISEASES

VIRAL DISEASES

MUMPS

Caused by a virus : Paramyxovirus.

Characterized by painful swelling of the salivary glands (particularly the parotid gland) accompanied with high fever. Due to this, the movement of the jaw becomes very difficult. In adults, the gonads (both testes and ovaries) may also become inflammed.

0ASLES

 Caused by the virus, rubeola virus, 10-12 days incubation period. At the end of this period, the buccal and respiratory passage (mucous membranes) show signs of inflammation. There is a loss of appetite and eruption occurs on the skin.

CHICKEN POX

By vericella-zoster virus, highly contagious, generally in children less than 10 yrs.

POLIOMYELITIS

 Causedby the smallest known virus, enterovirus.

•    The virus occurs only in man and it enters the body through contaminated food and water. It multiplies in the cells of intestinal wall and then the infection spreads through the blood stream and lymphatic system.

•    The virus mainly attacks the C.N.S. and destroy the cells of the dorsal horn of spinal cord. This results in the atrophy of the muscles of arms and legs as these muscles do not get the nerve impulses.

•    It usually leads to paralysis.

INFLUENZA (or FLU)

•    Influenza is an acute respiratory tract infection caused by influenza virus. Influenza viruses are classified within the family Orthomyxoviridae.

•    It spreads mainly from person to person by droplet infection or droplet nuclei created by sneezing, coughing or talking.

•    Influenza causes inflammation of upper respiratory tract, nose, throat and eyes.

COMMON COLD

•    Caused by rhinovirus ('rhino' means nose) which belongs to picornavirus group.

•    The viruses are transmitted through droplet nuclei, pharyngeal and nasal secretions.

•   Symptoms include headache, watery eyes, sneezing, excessive nasal secretions and
cough.

RABIES (Hydrophobia)

•   Caused by RNA virus called Rabies virus. The virus is neutrotrophic, i. e., damages motor

neurons of brain.

•   Rabies affects all warm blooded animals and is exclusively transmitted by the bites of

carnivores.

•     It leads to encephalitis, fear of water (hence called hydrophobia), high fever, severe headache, spasm of throat and chest leading to death.

•     Vaccine against rabies was developed by Louis Pasteur.

HEPATITIS

•   Hepatitis is the viral infection of liver. It is accompanied by loss of appetite, nausea,
whitish stool, but orange brown urine and jaundice which occur due to bilirubin
released from damaged liver cells.

•   Hepatitis is of two types :
(i) Hepatitis A (epidemic jaundice) : Caused by hepatitis A virus (HAV). It is

transmitted from person to person by faecal-oral route. It is benign and usually

not fatal, (ii) Hepatitis B (Serum hepatitis): Caused by hepatitis B virus (HBV). It is transmitted by transfusion of contaminated blood and blood products. It may be chronic and is fatal

DENGUE FEVER

•     It is an acute tropical frequently epidemic viral disease of humans which is caused bv RNA containing dengue virus. It is transmitted by the bite of female tiger mosquito Aedes aegypti during day time.

•     Two types of dengue fever are :

(i) Classical dengue fever : More severe in adults and characterised by mild conjunctivitis, high fever, backache, retro-orbital pain (pain behind the eye ball) etc.

(ii) Dengue haemorrhagic fever : Fatal form with nausea, headache, vomitting abdominal pain, etc.

YELLOW FEVER

•     Caused by arbovirus. It is a haemorrhagic disease transmitted by the infected Aedes aegypti.

Symptoms are headache, fever, vomitting, rupture of veins in kidneys, spleen, liver, etc. In severe cases, the skin of the sufferer becomes yellow from jaundice, hence the name yellow fever