Hepatitis : A Serious Health Risk

Hepatitis is an inflammation of the liver. It may be due to viral infection, toxic agents on drugs. It is characterized by jaundice, abdominal pain, liver enlargement, fatigue and some times fever.
There are various types of Hepatitis.

HEPATITIS --- A
Hepatitis A is transmitted by contact with faces from infected individuals. It is caused by non-enveloped RNA virus.

HEPATITIS --- B (serum hepatitis is caused by unusual DNA virus.

The causative agent of hepatitis B, contains a small, circular molecule of partly, but not completely, double standard DNA. The viral genome encodes two kind of proteins, a core protein and a surface protein, as well as DNA polymerase.

The amount of genetic information in the hepatitis B viral genome-359 nucleotides-is less than that of any other pathogen, except of the viroids.

The hepatitis B virus poses a serious public health problem, particularly among Asian, Africans, and male homosexuals. It often persists in carriers without causing any symptoms, but it may still be highly infections. People infected early in life often become carriers, and it is estimated that there are about 200 million such carriers worldwide. Since most of these people are not recognized as carriers, there is a real possibility of the frequent transmission of Hepatitis through skin contacts, blood transfusion, and similar medical procedures.

HEPATITIS --- C
Hepatitis C pass through blood from mother to child during pregnancy and afterward by sexual contact.

Prevention

The reduction in the spread of HIV could be brought about by the use if clean needles and sterile syringes by drug addicts.
Education about the disease has an important part to play particularly in reassuring the public about the real risk. There is no evidence that infection can occur by droplet infection through the nose or mouth, or by casual contact such as shaking hands etc.

Control and Treatment Of AIDS

An enormous international effort is being made to devise methods of treating and preventing the diseases. There are two lines of research, one into developing drugs which can be used to cure the disease, and one into developing a vaccine, Both approaches are at an early stage and require heavy financial investment. In the short-term the aim is to develop drugs to inactivate the virus, by blocking the pathogen's metabolism.

The best known drug used by 1987 was azidothymidine or zidovudine (formerly known as AZT) which slows progression of the disease and can attack the virus even in the brain (a major reservoir of infection) other drugs are being examined such as Ribavarrin a drug used to treat other viral infection which has been found to suppose the AIDS virus under laboratory conditions. Submarine, an anti parasitic drug has also shown encouraging results inhibiting viral reproduction in host.

Human Immune Deficiency Virus (HIV)

A RETROVIRUS AIDS--Symptoms, Transmission and its control

In HIV, the infections agent that causes AIDS, the glyco-proteins of the envelope enable the virus to bind to specific receptors on the surface of certain white blood cells, although there are two RNA molecules. They are identical, not complementary strands.
Acquired Immune Deficiency Symptoms (AIDS ) is a disorder which impairs the body's lymphocyte cell T4 immune system in humans, in that the virus replicates within the T4 or helper cell. Thus these cells can no longer help or induce other T cell, called Killers, to fight invaders. The body's immune system breaks down, leaving the patient exposed to a variety of diseases.

It is important to realize, however, that infection with the virus (HIV) does not necessarily result in AIDS. As with other diseases, some people remain symptoms less and are therefore termed carriers.

Plant Diseases

We have already discussed one of the best known plant diseases called tobacco mosaic virus. Plant viruses can stunt any plant growth and diminish crop yields. There are two major routes by which a plant viral disease can spread either by Horizontal Transmission or Vertical Transmission. In the first, a plant is infected from an external source of virus through injured parts or through insects. In the second, a plant inherits a viral infection from a parent. Agriculturists have not yet devised cure for most viral diseases of plants. Therefore, their efforts have focused largely on reducing the incidence and transmission of such diseases and on breeding genetic varieties of crop plants that are relatively resistant to certain viruses.

Viral Diseases ( Transmission / Spread and Control )

1. Animal Diseases: Several of the animal viruses cause important diseases. Poliomyelitis cause by polio-virus was a wide spread, cropping disease through the first half of the twentieth century. Although poliomyelitis is now largely under control by vaccination in the industrialized countries, it remains a serious and common disease in the tropics and elsewhere in the less developed parts of the world. Colds are viral infection of the upper respiratory tract. About one third of all colds are caused by the rhino-viruses which are unenveloped plus-strand RNA viruses. There are dozens of different strains of clod-causing rhino-viruses alone, each of them with different properties and none conferring cross-immunity to the others. More than 200 of viruses that cause colds have been identified, which makes the development of appropriate immunization methods very difficult, if not impossible.

Bacteriophage

They are among the most complex viruses. Each of them is made up of at least five separate proteins; these make up the head, the tail core, the molecules of the capsid, the base -plate of the tail, and the tail fibers. A long DNA molecule is coiled within the head.
One the basis of morphology viruses are classified into rod shaped (T.M.V), spherical (Polio-virus) and tadpole like bacteriophage viruses etc.

Classification of Virus

Viruses are generally classified on the basis of morphology and nucleic acid. they contain. On the basis of morphology, viruses are classified into rod-shaped (T.M.V), spherical (Polio virus) and tadpole ( Bacteriophage ). The nucleic acid present may be DNA or RNA which may be naked enveloped or complex. Recently, viruses are classified on the pattern to their diversity. The diversity of the viruses is great and is almost certainly related to their modes of origin. To provide a systematic idea of some of this diversity, we will discuss the viruses under eight main headings.

Structure of Viruses

They appear like little spheres of golf-balls, rod shaped, like tadpoles and may be polyhedral.

Viruses may consists of Viral-Genomes, Capsids, Envelopes and Tail-Fibers. Their Genomes (set of genes) may consists of a single or several molecules of DNA or RNA. The smallest viruses have only four genes while the largest have several hundreds.

The protein coat that encloses that virul genome is called a Capsid. It may be of different shapes. Capsid is made up of protein subunits called Capsomeres. The number of capsomeres is characteristic of a particular virus.

Some viruses have accessory structures called viral-envelops that help them infect their hosts. They are membranous cloaking their capsids. Bacteriophages have tail piece with Tail Fibers.

Characteristics of Virus

Viruses are non cellular parasitic entities. They cannot line and reproduce outside of living cells since they lack the machinery to do so by themselves. They range in size from 20nm to 250nm.
Viruses are either virulent, destroying the cell in which they occur or temperature, becoming integrated into their host genomes and remaining stable there for long periods of time.
The adhesion properties of viruses are determined by those of the proteins that make up their coats and envelops. The simplest viruses use the enzymes of the host cell for both their protein synthesis and gene replication; the more complex ones contains up to 200 genes and are capable of synthesizing through their host may structural proteins and enzymes.

AIDS is caused by HIV ( Human Immunodeficiency Virus ), which possesses a Glycoprotein on its surface that penetrates the cell membrane, sheds its protective coat and reproduce.

Viruses

The word VIRUS is derived from a Latin word meaning "Poison". This use of word goes back to many hundreds of years, long before anyone really knew what a virus was, or that it even existed as we know it today.It was generally believed that these "Viruses". or Poisons, were carried in the air and could cause many unexplained diseases.

By the late 19th century pioneer biologists had demonstrated that many diseases of man and other organism were caused by bacteria. Some diseases puzzled them. Once such disease was found to occur in tobacco plants. It causes the leaves to winkle and become mottled. The mottled effect has the appearance of a mosaic. and the disease was called Tobacco Mosaic Disease.