WATER BUGS   Leave a comment

 

DEFINITION: any of various hemipteran insects that live in fresh waters, including the back swimmers and the water boatmen.

Even though they breathe air, several kinds of insects can also live underwater and are able to fly, crawl, or swim at will. Called water bugs, such insects belong to the order of true bugs Hemiptera.

One of the most common water bugs is the water boatman, the only water bug that can take flight directly from the water. It usually stays anchored to the bottom feeding on algae and organic debris and keeps a supply of air stored under its wings.

The back swimmer is named for its habit of rowing itself through the water upside down. It stores air in two grooves on its under surface. Each of its three pairs of legs serves a different purpose. The front pair captures small creatures for food; the middle pair holds on to objects; and the long, flat hind pair, fringed with stiff hairs, acts as oars that row with powerful sweeping strokes. Before it can take flight, the back swimmer must crawl onto the land, turn over, and wait for its wings to dry.

The grasping forelegs of the water scorpion resemble scorpion claws, and its scorpion like tail is used as a breathing tube. It seldom swims, preferring to hunt for small fish and insects from a fixed station. A bubble of air trapped underneath sensory hairs on its abdomen imparts stimuli that tell the bug whether it is walking down deeper into the water or heading upward.

The water strider, or pond skater, has a long narrow body and six spidery legs. Unlike the other water bugs, it never ventures underwater. Its underside is covered with a water-repellent coat of hair that keeps it afloat. Its middle legs propel it across the surface, its hind legs act as rudders and brakes, and its short forelegs are used exclusively for catching prey.

American cockroach (or water bug), insect (Periplaneta americana) of the family Blattidae.

The giant water bug is the largest species and can grow up to 4 inches (10 centimetres) long. These bugs have two retractable appendages that, when held together, form a breathing tube. The bugs are strong flyers and formidable hunters. They paralyse their prey by injecting a poison through the beak, and in this manner they can overpower fish twice their own size. The American cockroach (Periplaneta americana), a large insect in the order Orthoptera, is often called water bug.

Water boatmen belong to the family Corixidae; back swimmers, Notonectidae; water scorpions, Nepidae; water striders, Gerridae; giant water bugs, Belostomatidae.

Posted 2012/05/16 by Stelios in Education

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VIRUSES   Leave a comment

DEFINITION:1 orig., venom, as of a snake 2 a) any of a kingdom (Virus) of prokaryotes, usually ultra microscopic, that consist of nucleic acid, either RNA or DNA, within a case of protein: they infect animals, plants, and bacteria and can reproduce only within living cells so that they are considered as being either living organisms or inert chemicals b) a disease caused by a virus 3 anything that corrupts or poisons the mind or character; evil or harmful influence 4 an unauthorized, disruptive set of instructions placed in a computer program, that leaves copies of itself in other programs and disks.

1981: US AIDS diagnosed. A new fatal, infectious disease was diagnosed in 1981. Called Acquired Immunodeficiency Syndrome (AIDS), it began appearing in major cities among homosexual men and intravenous drug users. Other high-risk groups were haemophiliacs and other recipients of blood or blood products, babies born of AIDS-infected women, bisexual men, and prostitutes and their customers. AIDS was soon recognized as a worldwide health emergency: a fatal disease with no known cure that quickly became an epidemic. It was especially widespread in Africa, the apparent land of its origin.

By 1983 the virus that causes the disease had been isolated. Some medicines, notably AZT (azidothymidine), slowed the disease’s progress for a few months or more; but the spread of AIDS continued relentlessly, with more than 3,000 new cases being reported each month by 1991.

The federal government had committed more than 1.6 billion dollars to research, while the homosexual community and other special interest groups sought more federal funding and greater assistance from the health insurance industry. Educational programs on safe sexual practices, such as the use of condoms, seemed the best means of slowing the epidemic. Meanwhile, more than 70,000 persons in the United States had died from AIDS by the end of the decade.

1981: WORLD AIDS identified. A strange, new, and deadly disease made its appearance in 1980. Physicians in such large cities as Los Angeles, New York, and San Francisco noticed that homosexual men were dying from rare lung infections or from a cancer known as Kaposi’s sarcoma. By 1981 the disease was identified and given a name: AIDS, or acquired immunodeficiency syndrome.

The virus that causes AIDS, human immunodeficiency virus (HIV), was identified by Dr. Luc Montagnier of the Pasteur Institute in Paris in research done during the years 1981-84. The results of Dr. Montagnier’s studies were released in 1984. Since its discovery, AIDS has become one of the world’s major health problems. Within certain populations it has become an epidemic: male homosexuals, haemophiliacs, and intravenous drug users in the United States, for example, and heterosexual men and women in Sub-Saharan Africa. Many people were infected through blood transfusions before HIV screening was introduced. An individual infected with the virus may not show the symptoms of AIDS for several years, but the condition is eventually fatal.

The search for a successful vaccine was pursued in laboratories around the world, with no success by the early 1990s. Meanwhile, the disease continued to spread to different parts of the world. Already rife in the United States, Europe, and sub-Saharan Africa by the mid-1980s, it quickly spread to Central and East Asia. The disease also began to spread to larger portions of the heterosexual community throughout the world.

The composition of a virus is relatively simple, and its size is extremely small. It cannot even properly be called an organism because it is unable to carry on life processes outside a living cell of an animal, plant, or bacteria. Yet its method of entering and “enslaving” a living cell is so ingenious that the virus is humankind’s deadliest enemy and resists the most advanced efforts of modern science to eliminate it.

Millions of people throughout the world suffer each year from viral diseases such as polio, measles, chicken pox, mumps, acquired immunodeficiency syndrome (AIDS), and the common cold. Viruses also produce such illnesses as foot-and-mouth disease in livestock, distemper in dogs, panleukopenia in cats, and hog cholera. The viruses that infect bacteria are called bacteriophages.

Structure and Composition

Nucleic acid, any of substances comprising genetic material of living cells; divided into two classes: RNA (ribonucleic acid) and DNA (deoxyribonucleic acid); directs protein synthesis and is vehicle for transmission of genetic information from parent to offspring.

Viruses are exceedingly small; they range in size from about 0.02 to 0.25 micron in diameter (1 micron = 0.000039 inch). By contrast, the smallest bacteria are about 0.4 micron in size. As observed with an electron microscope, some viruses are rod-shaped, others are roughly spherical, and still others have complex shapes consisting of a multi sided “head” and a cylindrical “tail.” A virus consists of a core of nucleic acid surrounded by a protein coat called a capsid; some viruses also have an outer envelope composed of fatty materials and proteins. The nucleic-acid core is the essential part of the virus it carries the virus’s genes. The core consists of either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), substances that are essential to the transmission of hereditary information. The protein capsid protects the nucleic acid and may contain molecules that enable the virus to enter the host cell that is, the living cell infected by the virus.

Cycle and Patterns of Infection

Outside of a living cell, a virus is a dormant particle. It exhibits none of the characteristics generally associated with life namely, reproduction and metabolic processes such as growth and assimilation of food. Unlike bacteria and other micro-organisms, viruses remain dormant in body fluids. Thus, great numbers of viruses may be present in a body and yet not produce a disease because they have not invaded the body’s cells. Once inside a host cell, however, the virus becomes an active entity capable of taking over the infected cell’s metabolic machinery. The cellular metabolism becomes so altered that it helps to produce thousands of new viruses.

The virus’s developmental cycle begins when it succeeds in introducing its nucleic acid, and in some cases its protein coat, into a host cell. Bacteriophages attach to the surface of the bacterium and then penetrate the rigid cell wall, transmitting the viral nucleic acid into the host. Animal viruses enter host cells by a process called endocytosis. Plant viruses enter through wounds in the cell’s outer coverings through abrasions made by wind, for example, or through punctures made by insects.

Virion, an entire virus particle the extracellular infective form of a virus consisting of an outer protein shell (capsid) and an inner core of nucleic acid (either ribonucleic or deoxyribonucleic acid); in some, the capsid further enveloped by a fatty membrane.

Once inside the host cell, the virus’s genes usually direct the cell’s production of new viral protein and nucleic acid. These components are then assembled into new, complete, infective virus particles called virions, which are then discharged from the host cell to infect other cells.

In the case of bacteriophages, the new virions are usually released by bursting the host cell a process called lysing, which kills the cell. Sometimes, however, bacteriophages form a stable association with the host cell. The virus’s genes are incorporated into the host cell’s genes, replicate as the cell’s genes replicate, and when the cell divides, the viral genes are passed on to the two new cells.

In such cases no virions are produced, and the infecting virus seems to disappear. Its genes, however, are being passed on to each new generation of cells that stem from the original host cell. These cells remain healthy and continue to grow unless, as happens occasionally, something triggers the latent viral genes to become active. When this happens, the normal cycle of viral infection results: the viral genes direct viral replication, the host cell bursts, and the new virions are released. This pattern of infection is called lysogeny.

Closely related to lysogeny is the process known as transduction, whereby a virus carries bacterial genes from one host to another. This transduction process occurs when genes from the original host become incorporated into a virion that subsequently infects another bacterium.

Viral infections of plant and animal cells resemble those of bacterial cells in many ways. The release of new virions from plant and animal cells does not, however, always involve the bursting of the host cell as it does in bacteria. Particularly among animal viruses, the new virions may be released by budding off from the cell membrane, a process that does not necessarily kill the host cell.

In general, a viral infection produces one of four effects in a plant or animal cell: in apparent effect, in which the virus remains dormant in the host cell; cytopathic effect, in which the cell dies; hyperplastic effect, in which the cell is stimulated to divide before its death; and cell transformation, in which the cell is stimulated to divide, take on abnormal growth patterns, and become cancerous.

Cold sore (or fever blister, or Herpes simplex), a virus infection of the borders of the mouth, lips and nose, or genitals; marked by watery blisters; may be due to illness, emotional upset, or other stress.

Viral infections in animals can be localized or can spread to various parts of the body. Some animal viruses produce latent infections: the virus remains dormant much of the time but becomes active periodically. This is the case with the herpes simplex viruses that cause cold sores.

Natural Defences, Immunization, Treatment

Fever, a condition in which the body temperature rises above normal.

Animals have a number of natural defences that may be triggered by a viral infection. Fever is a general response; many viruses are inactivated at temperatures just slightly above the host’s normal body temperature. Another general response of infected animal cells is the secretion of a protein called interferon. Interferon inhibits the reproduction of viruses in non infected cells.

Fever and interferon production are general responses to infection by any virus. In addition, humans and other vertebrates can mount an immunological attack against a specific virus. The immune system produces antibodies and sensitized cells that are tailor-made to neutralize the infecting virus. These immune defenders circulate through the body long after the virus has been neutralized, thereby providing long-term protection against reinfection by that virus.

Such long-term immunity is the basis for active immunization against viral diseases. A weakened or inactivated strain of an infectious virus is introduced into the body. This virus does not provoke an active disease state, but it does stimulate the production of immune cells and antibodies, which then protect against subsequent infection by the virulent form of the virus.

Active immunizations are routine for such viral diseases as measles, mumps, poliomyelitis, and rubella. In contrast, passive immunization is the injection of antibodies from the serum of an individual who has already been exposed to the virus. Passive immunization is used to give short-term protection to individuals who have been exposed to such viral diseases as measles and hepatitis. It is useful only if provided soon after exposure, before the virus has become widely disseminated in the body.

The treatment of an established viral infection usually is restricted to relieving specific symptoms. There are few drugs that can be used to combat a virus directly. The reason for this is that viruses use the machinery of living cells for reproduction. Consequently, drugs that inhibit viral development also inhibit the functions of the host cell. Nonetheless, a small number of antiviral drugs are available for specific infections.

The most successful controls over viral diseases are epidemiological. For example, large-scale active immunization programs can break the chain of transmission of a viral disease. Worldwide immunization is credited with the eradication of smallpox, once one of the most feared viral diseases. Because many viruses are carried from host to host by insects or contaminated food, insect control and hygienic food handling can help eliminate a virus from specific populations.

History of Virus Research

Historic descriptions of viral diseases date back as far as the 10th century BC. The concept of the virus, however, was not established until the last decade of the 19th century, when several researchers obtained evidence that agents far smaller than bacteria were capable of causing infectious diseases.

Mosaic disease, highly infectious virus disease affecting many plants including cucumber, potato, tomato, bean, and turnip; dwarfs growth and mottles leaves.

The existence of viruses was finally proved when bacteriophages were discovered by independent researchers in 1915 and 1917. The question of whether viruses are actually micro-organisms (similar to very tiny bacteria) was resolved in 1935, when the virus responsible for causing mosaic disease in tobacco was isolated and crystallized; the fact that it could be crystallized proved that the virus was not a cellular organism.

Bacteriophages are a valuable research tool for molecular biologists. Studies of bacteriophages have helped to illuminate such basic biological processes as genetic recombination, nucleic-acid replication, and protein synthesis.

COCKROACHES   Leave a comment

 

DEFINITION: any of an order (Blattaria) of insects with long antennae and a flat, soft body: some species are common household pests.

The cockroach is considered one of the most obnoxious of household pests. This brown or black insect can be found in houses, apartment and office buildings, ships, trains, and air planes in many parts of the world. Domestic cockroaches, which are also called roaches, have a disagreeable odour They live in warm, dark areas. Their broad, flat bodies permit them to crawl in narrow cracks and along pipes. They hide in the daytime, coming out at night to feed. The diet of the cockroach, which includes both plant and animal products, ranges from food, paper, clothing, and books to dead insects. Although cockroaches can be difficult to eliminate entirely, a variety of common poisons and traps are effective in controlling their numbers. Cockroaches are believed to be able to transmit several different human diseases.

Cockroaches are among the oldest living insects. Fossil cockroaches that resemble today’s species are commonly found in Coal Age deposits from more than 320 million years ago. About 3,500 species have been identified. Although the most notable varieties are those that infest households in the temperate regions, most species are tropical. Some reach lengths of several inches, and many are colourful Several species of woodland cockroaches are found in temperate regions. These live amid decaying wood and other vegetation and do not enter houses.

The cockroach has long, powerful legs and can run very fast. Long antennae on the head are used for feeling in dark places. Most species have two pairs of wings that are larger in the males. The female cockroach carries her eggs in a leathery capsule called an ootheca that protrudes from the rear of the abdomen. Females of some common species lay 16 to 45 eggs at a time. The eggs take from 4 to 12 weeks to hatch. After the female deposits an egg case, soft, white young called nymphs emerge. After exposure to air, the nymphs harden and turn brown.

The scientific name of the German cockroach is Blattella germanica. A common household pest, it is light-brown with two dark stripes on the thorax segment just behind the head. Because it is only about half an inch (12 millimetres) long, it can easily enter or be transported into homes. Abundant around the water pipes of the Croton Aqueduct in New York City, this cockroach became known as the Croton bug.

American cockroach (or water bug), insect (Periplaneta americana) of the family Blattidae.

The American cockroach (Periplaneta americana), also called water bug, is 1.2 to 2 inches (30 to 50 millimetres) long, reddish brown, and lives outdoors or in dark, heated indoor areas, for example in basements and furnace rooms. The American cockroach, a native of tropical and subtropical America, has well-developed wings and can fly long distances.

Cockroaches belong to the order Orthoptera and to the family Blattidae. They are closely related to the grasshoppers, katydids, and crickets.

Posted 2012/05/09 by Stelios in Education

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SEXUALLY TRANSMITTED DISEASES (Part 1 of 2)   Leave a comment

1981: AIDS diagnosed. A new fatal, infectious disease was diagnosed in 1981. Called Acquired Immunodeficiency Syndrome (AIDS), it began appearing in major cities among homosexual men and intravenous drug users. Other high-risk groups were haemophiliacs and other recipients of blood or blood products, babies born of AIDS-infected women, bisexual men, and prostitutes and their customers. AIDS was soon recognized as a worldwide health emergency: a fatal disease with no known cure that quickly became an epidemic. It was especially widespread in Africa, the apparent land of its origin.

By 1983 the virus that causes the disease had been isolated. Some medicines, notably AZT (azidothymidine), slowed the disease’s progress for a few months or more; but the spread of AIDS continued relentlessly, with more than 3,000 new cases being reported each month by 1991.

The federal government had committed more than 1.6 billion dollars to research, while the homosexual community and other special interest groups sought more federal funding and greater assistance from the health insurance industry. Educational programs on safe sexual practices, such as the use of condoms, seemed the best means of slowing the epidemic. Meanwhile, more than 70,000 persons in the United States had died from AIDS by the end of the decade.

1981: AIDS identified. A strange, new, and deadly disease made its appearance in 1980. Physicians in such large cities as Los Angeles, New York, and San Francisco noticed that homosexual men were dying from rare lung infections or from a cancer known as Kaposi’s sarcoma. By 1981 the disease was identified and given a name: AIDS, or acquired immunodeficiency syndrome.

The virus that causes AIDS, human immunodeficiency virus (HIV), was identified by Dr. Luc Montagnier of the Pasteur Institute in Paris in research done during the years 1981-84. The results of Dr. Montagnier’s studies were released in 1984. Since its discovery, AIDS has become one of the world’s major health problems. Within certain populations it has become an epidemic: male homosexuals, haemophiliacs, and intravenous drug users in the United States, for example, and heterosexual men and women in Sub-Saharan Africa. Many people were infected through blood transfusions before HIV screening was introduced. An individual infected with the virus may not show the symptoms of AIDS for several years, but the condition is eventually fatal.

The search for a successful vaccine was pursued in laboratories around the world, with no success by the early 1990s. Meanwhile, the disease continued to spread to different parts of the world. Already rife in the United States, Europe, and sub-Saharan Africa by the mid-1980s, it quickly spread to Central and East Asia. The disease also began to spread to larger portions of the heterosexual community throughout the world.

Dec. 1, 1993: AIDS awareness day. The sixth annual World AIDS Day was celebrated in many countries. The commemoration was started in 1988 by the World Health Organization. The day was partly a memorial for those who had died from AIDS (acquired immunodeficiency syndrome). Although the growth of the epidemic had peaked in the United States in the early 1990s, the disease was still spreading rapidly in Africa and parts of Asia. No cure had yet been found, nor was there a successful vaccine to protect against contracting the disease.

Dec. 1, 1993: AIDS awareness day. The sixth annual World AIDS Day was celebrated in many countries. The commemoration was started in 1988 by the World Health Organization. The day was partly a memorial for those who had died from AIDS. Although the growth of the epidemic had peaked in the United States in the early 1990s, the disease was still spreading rapidly in Africa and parts of Asia. No cure had yet been found, nor was there a successful vaccine to protect against contracting the disease.

April 7, 1994: Failure of AZT. A team of British and French medical researchers reported that AZT, a drug often used to fight AIDS, does not slow the onset of the disease in persons who have the HIV virus. Published in the journal Lancet as the Concorde Report, the document stated that AZT does prolong the lives of patients who have developed AIDS, but it does not impede the progression of HIV into full-blown AIDS. The report was based on tests conducted on HIV-infected patients in Ireland, France, and the United Kingdom.

Diseases that can be passed between people during sexual contact have plagued humankind throughout history. Until recently such a disease was called venereal disease, or VD. The preferred term now is sexually transmitted disease, or STD. The two main venereal diseases in the United States have traditionally been gonorrhoea and syphilis. Scientists now know that many other diseases can be passed during sex. More than 30 STDs have been identified.

AIDS (acquired immunodeficiency syndrome), incurable disease caused by a virus that damages the human body’s immune system; believed to be transmitted through sexual contacts, blood transfusions, or contaminated needles used for intravenous drug injections; often fatal; high percentage of victims are homosexuals or drug abusers.

The names of such STDs as acquired immunodeficiency syndrome (AIDS) and gonorrhoea are known to most people; however, other STDs such as trichomoniasis and genital candidiasis may not be as familiar. Some STDs affect only a few people or do not cause life-threatening problems. Other STDs, such as gonorrhoea and chlamydial infections, affect many people or cause severe health damage.

STDs are a major health problem throughout the world. In the United States STDs strike an estimated 20 million people each year, or an average of one person every 1.5 seconds. About one half of STD patients are under the age of 25. Nearly 2.5 million teenagers are infected with an STD each year.

Pelvic inflammatory disease (PID), general, acute inflammation of the pelvic cavity in women.

Sterility, in biology, the inability to produce offspring; one cause is the production of non functioning sex cells.

The health problems caused by STDs seem endless. The diseases can cause arthritis, sterility, nervous system damage, heart disease, and death. Women and infants suffer the most damage from STDs. For example, each year more than 1 million women suffer from pelvic inflammatory disease resulting from gonorrhoeal or chlamydial infections. About 200,000 of these women become sterile each year. More than 300,000 babies are injured or die each year from STDs.

Transmission

Mucous membrane (or mucosa), membrane that secretes mucus and lines the mouth, nose, throat, windpipe, lungs, eyelids, and the alimentary canal.

STDs are caused by a variety of organisms that include bacteria, protozoa, viruses, and very small insects such as Phthirus pubis, or pubic lice. These organisms usually live in the warm and moist parts of the body called mucous membranes. The penis, vagina, rectum, mouth, and eyes have mucous membranes. These organisms usually invade a person through the mucous membranes during sexual contact. Some STDs are passed by deep kissing or skin-to-skin contact, though these transmission methods are not common.

Anyone can get an STD regardless of age, sex, race, social class, or whether the person is heterosexual, homosexual, or bisexual. Exposure to STD organisms results from participating in certain sexual or drug-use behaviours

People with many sexual partners have the greatest risk of contracting an STD. The risk increases with each new partner. The risk is even greater if any of the partners have several sex partners.

It is virtually impossible to get an STD from such things as door knobs, toilet seats, drinking glasses, or whirlpool baths. Light and air destroy STD organisms very quickly. Some STDs such as gonorrhoea, syphilis, and genital herpes are practically always spread by sexual contact. Such diseases as AIDS, hepatitis, and pediculosis pubis, however, can sometimes be acquired through non-sexual means. AIDS and some forms of hepatitis can be acquired from infected blood in intravenous drug needles and syringes. Pubic lice can be picked up from contaminated clothing or bedding that is infected with the lice or their eggs.

Most STDs can also be passed during pregnancy or birth from an infected woman to her baby. Women can develop some infections in the vagina without having sex. It is possible but not common for those infections to be passed to others during sex. Other vaginal infections are sexually transmitted, but the woman’s sex partners may not have symptoms.

Prevention

Most people have heard some information about STDs. In recent years public awareness has increased. The media have developed greater coverage of STDs, and more schools teach about STDs. There are news items on television and in newspapers and magazines about AIDS almost daily. This increased discussion has alerted people to how widespread STDs are, to STD health dangers, and to methods of preventing STDs. Hence, many people have become more cautious.

Medical personnel and public health officials believe that education is the key to controlling the spread of STDs. STDs are dangerous. Further medical advances may bring improved modes of treatment, but avoiding infection in the first place is vital. The actions of individual persons are the most important factors in halting the spread of these diseases. Many health educators emphasize the idea that the wisest teaching approach is to motivate people to practice responsible STD-preventive behaviour, such as sexual abstinence and sexual fidelity.

Communication between partners. Among people who are mature enough to have a sexual relationship, one of the most important things to do is communicate. A person should feel free to discuss concerns about getting an STD. The conversation can be started by one partner stating that he or she cares about the health and well-being of both persons. Persons deciding to have sex with a new partner should discuss ways of protecting each other.

SEXUALLY TRANSMITTED DISEASES (Part 2 of 2)   2 comments

Sexual precautions. Naturally, the most certain way to avoid an STD is to avoid sexual contact with infected persons. One sure way to do that is by sexual abstinence, meaning not having sex with anyone. Sexual abstinence in young adults is a normal and healthy choice.

The next most certain way of avoiding an STD is by practising sexual fidelity. It is nearly impossible for two people having a long-term, faithful relationship to get an STD. This is true unless one partner is infected at the start of the relationship or uses intravenous drugs and shares needles or syringes. Moreover, it is not always possible to know whether one’s partner is sexually faithful.

Condom (or rubber), device to prevent conception and disease.

Persons having sex outside a long-term, sexually faithful relationship should avoid exposure to certain body fluids. This suggestion also applies to those who are not sure whether their partner is infected with an STD. The person should not allow blood, semen, or vaginal secretions to touch the genitals, mouth, or anus. The proper use of latex condoms is one good way to prevent body fluids from entering one’s body. Although condoms made of animal membranes may protect against some STDs, they do not always protect against viral STDs, such as AIDS and herpes. Hence, the latex condom, or rubber, should be used. The latex condom, which is designed to protect both sexes, should be used during sex. The latex condom can greatly reduce the chances of getting an STD, though it is not 100-percent effective.

Using a contraceptive foam, cream, or jelly along with a latex condom may also help prevent STDs. Spermicides containing nonoxynol-9, which can kill most bacteria and viruses, are recommended. Other birth-control methods, such as birth control pills, do not provide protection from STDs.

Symptoms

Persons having sex should be alert for the symptoms of STDs. This is especially true for those having sex with a person other than a long-term, faithful partner. Any unusual or unexplained changes in the health of persons who engage in sex with different partners may indicate an STD. Of course, the changes may be caused by other diseases. STD symptoms may appear anywhere on the body, but usually they occur in the genital area. The major STD symptoms are: (1) genital discharge, (2) abdominal pain, (3) pain during urination, (4) skin changes, and (5) genital itching. Symptoms of infection with the AIDS virus include fatigue, fever, loss of appetite, weight loss, diarrhoea, night sweats, and swollen lymph glands.

Some STDs do not produce any symptoms until the disease is advanced. Often the symptoms are hidden, especially in females. For some STDs, the symptoms disappear without treatment, but the infection persists. All STDs, however, can be passed when the symptoms are not present. Persons suspecting that they have an STD should stop having sex, go to a doctor, and encourage their partners to go to a doctor. There may be no permanent health damage if the STD is treated early.

Treatment

Persons who think they might have an STD should not try to diagnose or treat themselves. Only a doctor or other trained health professional can do those things. STD treatment is available from STD clinics in health departments, private doctors, family-planning clinics, and hospitals. A person can call the local health department to learn where STD treatment is given in his or her city. In every state, minors can get STD treatment without parental consent. Services are confidential. No one will know that a person has been to a clinic or a doctor unless the person tells others. If money is a problem, a person should still seek proper treatment. Most clinics will treat people without charge or for a small fee.

When seeing a doctor, the person should inform the physician why an STD is suspected. An STD examination is not the same as a routine check-up Special tests are performed to find out if the person has an STD. Usually a small sample of blood is taken from the patient’s arm. Also, fluid is often taken from the genitals or other exposed areas with a cotton-tipped swab.

Sometimes a doctor can tell right away if a person has an STD. Otherwise the doctor must wait for several days before the test results are known. Treatment, however, may begin on the first visit. Except for AIDS, genital herpes, and viral hepatitis, most STDs can be cured easily and quickly. Not all STDs are treated in the same way. Prescription drugs, shots, or creams may be used. The drugs or medicine should be taken exactly as directed by the doctor. A person should never take someone else’s medicine. Serious side effects could occur and the infection could be covered up but not cured.

Persons with an STD should be sure that their partners receive medical care so they do not become seriously ill. Also, treatment of the partner will keep the person from getting reinfected if sex with that partner resumes. One of the best ways to be sure a partner gets treatment is to take the person to the doctor or health department and to do so without delay. The partner can be told in person or over the phone that he or she might be infected with a sexually transmitted disease. A doctor or STD case specialist can help notify a partner confidentially.

Advances in Research

Despite the advances of medical science, the accurate diagnosis and effective treatment of a few STDs continue to remain serious problems. Much current STD research centres on these two areas, as well as on attempts to develop STD vaccines. Some progress has been made in these areas. For example, chlamydial infections, which have been difficult to diagnose, can be discovered more rapidly with a recently developed test. Also, a more effective treatment for genital herpes has been found. Even though herpes is not cured, these new medicines can relieve pain, shorten the time of blisters, and decrease the number of outbreaks of blisters. Scientists have also developed safer and improved treatment for genital warts.

In recent years, types of gonorrhoea that cannot be cured with penicillin or other antibiotics have emerged. This has greatly concerned public-health officials, who fear that the new strains could become widespread. However, scientists have been able to discover alternative drugs to treat the newer strains.

AIDS (acquired immunodeficiency syndrome), incurable disease caused by a virus that damages the human body’s immune system; believed to be transmitted through sexual contacts, blood transfusions, or contaminated needles used for intravenous drug injections; often fatal; high percentage of victims are homosexuals or drug abusers.

Much research is being done on ways to better diagnose and treat AIDS. While it is possible to detect AIDS virus antibodies, scientists are trying to develop a test that would detect the actual virus. Experimental vaccines are also being developed.

The ideal way to stop the spread of STDs would be through vaccines. Despite major attempts to develop STD vaccines, especially for AIDS, only hepatitis A and hepatitis B can currently be prevented with vaccines. These very effective vaccines prevent people from becoming infected with hepatitis A or hepatitis B no matter how they are exposed to it.

Someday, perhaps, the number of STD cases can be greatly decreased. Better tests, more effective drugs, and vaccines can help control STDs. In the meantime, the damage caused by STDs can be reduced by persons being responsible for their own health and the health of any sex partner. The preventive efforts of individual persons is the best way of stopping the spread of STDs.

Assisted by William L. Yarber.

BIBLIOGRAPHY FOR SEXUALLY TRANSMITTED DISEASES

Jackson, Bernard. What Doctors Can’t Heal (Strictly Honest, 1993).

Jackson, James. Wellness (Dushkin Pub, 1992).

McCauslin, Mark. Sexually Transmitted Diseases (Macmillan Child Group, 1992).

Mandel, Bea, and Mandel, Byron. Play Safe: How to Avoid Getting Sexually Transmitted Diseases, 2nd ed. (Center for Health Information, 1986).

Meltzer, A.S. The ABC’s of S.T.D. A Guide to Sexually Transmitted Diseases (Eden, 1983).

Yarber, W.L. STD: A Guide for Today’s Young Adults (American Alliance Publishers, 1985).

Posted 2012/05/05 by Stelios in Education

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MAYFLIES   Leave a comment

DEFINITION: 1 any of an order (Ephemeroptera) of delicate, soft-bodied insects with gauzy wings held vertically when at rest: in the adult stage, it lives only hours or a few days, but the aquatic larval stage may last for several years 2 an angler’s artificial fly made to resemble this insect.

The delicate-winged mayflies with their long threadlike tails appear suddenly in great swarms in the late spring or early summer and live just long enough to mate and reproduce. They are called mayflies, shad flies, day flies, or ephemera. Once it was thought that they lived only a single day, but more careful study has shown that they may remain alive somewhat longer.

The eggs are laid in fresh water, and the young are called naiads or nymphs. They spend from a few weeks to a year (rarely to four years) swimming about or crawling on the bottom, feeding on tiny animals and vegetable life. They may moult as many as 60 times. The young pass through a winged pre adult stage, when they are called subimagos. They rise to the water surface enveloped in an air bubble, emerge, and fly to a nearby bush or tree. The only insects to moult after their wings become functional, the pre adults shed their skins again, and the full imago, or adult, emerges. During this final stage, the mayfly is unable to eat either solid or liquid food.

Mating takes place soon after the adult appears, and often the males will “dance” in large swarms to attract the females. The male dies as soon as fertilization has been completed. The female dies after she has laid her eggs, almost immediately after mating.

The scientific name of the mayfly order is Ephemeroptera. Mayflies are the oldest of the winged insects to survive to the present day.

Posted 2012/05/03 by Stelios in Education

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Magic JOHNSON   Leave a comment

AIDS (acquired immunodeficiency syndrome), incurable disease caused by a virus that damages the human body’s immune system; believed to be transmitted through sexual contacts, blood transfusions, or contaminated needles used for intravenous drug injections; often fatal; high percentage of victims are homosexuals or drug abusers.

The sports world was stunned on Nov. 7, 1991, when superstar Magic Johnson announced his immediate retirement from professional basketball because he was infected with the virus that causes AIDS (acquired immunodeficiency syndrome). The athlete who, according to one characterization, could “take only three shots and still dominate a game” was slam-dunking a message to defeat HIV ignorance.

Earvin Johnson, Jr., was born in Lansing, Mich., on Aug. 14, 1959, the sixth of ten children. He got his start playing basketball on the playgrounds of Lansing. As a senior he led the Everett High School team to the Michigan Class A championship. After a particularly amazing display of basketball skill, during which he scored 36 points, grabbed 18 rebounds, and had 16 assists, a Lansing sports writer christened him Magic.

The home town Michigan State University wooed the All-Stater in 1977. Johnson’s talents led the Spartans to the 1979 NCAA championship during his sophomore year, after which he decided to turn pro.

The 6-foot, 9-inch point guard was drafted by the Los Angeles Lakers in 1979. In his 12 years with the Lakers, the team won five NBA championships (1980, 1982, 1985, 1987, and 1988). He was chosen play-off MVP three times (1980, 1982, and 1987) and was the first rookie to be so named. He was the league’s MVP three times (1987, 1989, and 1990), and he was chosen for the 1992 Olympic basketball team. His 9,921 career assists were the most in NBA history.

With his dazzling smile, style, and blind passes, Johnson was among those credited with professional basketball’s surge in popularity in the 1980s. As one of the greatest and most popular players in the history of the NBA, he promised to use his public prominence as a spokesman in the fight against AIDS. He counselled young people to abstain from sex or practice safe sex and warned that contracting HIV “can happen to anybody, even Magic Johnson.”

Posted 2012/05/01 by Stelios in Education

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