This is the VOA Special English Health Report.

Here is a common situation: Aperson gets sick with a high temperature, muscle pain and a cough.The person goes to a doctor to ask for some antibiotics to treat theinfection. The doctor says the person has influenza which is causedby a virus. Antibiotics are not effective against viruses. They onlytreat infections caused by bacteria. But there are newer kinds ofmedicines known as antivirals.

A case of the flu usually lasts a week or two. Scientists at theUnited States Centers for Disease Control say early antiviraltreatment can shorten that time by about one day. But they say forthis to happen, people must take the medicine within the first twodays of sickness.

Four antiviral drugs are approved for use against influenza inthe United States. They mainly fight infections in the breathingsystem. Each drug has possible side effects. In the United States, aperson must have an order from a doctor to receive these medicines.

Scientists say two of the four drugs are effective against theinfection caused by the type A influenza virus. They are noteffective against influenza type B. The other two drugs can treatboth. One of these antiviral medicines, called oseltamivir, can alsohelp prevent influenza.

Viruses invade cells and copy the genetic material inside inorder to reproduce. Some antivirals work by preventing this process.Or they may interfere with the ability of the virus to connectitself to the cell. Other antiviral drugs prevent the virus fromdestroying the protective protein around a cell.

The first antiviral drugs were created in the nineteen-sixties. Anumber of new antivirals were in common use by thenineteen-nineties. Progress in the engineering of genes and thescience of molecular biology made these new medicines possible. Somehave helped patients suffering from diseases like hepatitis B in theliver. Other kinds of antiviral drugs are able to suppress H-I-V,the virus that causes AIDS, so a person lives longer.

Antibiotics are made from bacteria. The drugs contain organismsthat damage the cells of other microbes that cause sickness. TheBritish doctor Alexander Fleming discovered what is generallyaccepted as the first antibiotic, penicillin. That was innineteen-twenty-eight. Penicillin did not come into common use,however, until the nineteen-forties.

This VOA Special English Health Report was written by JerilynWatson.