In just a few years, West Nile virus has gone from an obscure, isolated ailment to a growing threat in much of the United States.

abc news (James Gathany, CDC/Reuters)

In the early 1960s, some scientists declared victory on many diseases and stated that the world will be free of infectious disease threats in the foreseeable future. In 1968, the U.S. Surgeon General urged the medical community to turn its focus away from infectious diseases and focus on chronic diseases, such as heart disease.

They were pretty much wrong.

Today, infectious diseases are the second leading cause of mortality worldwide and the leading cause of mortality in people from birth to 29 years of age. The “matrix” of infectious diseases, or the leading infectious diseases worldwide, includes respiratory diseases, HIV/AIDS, diarrheal diseases, tuberculosis and malaria, SARS, Influenza virus H5N1, also known as "bird flu",and Influenza virus H1N1 also known as swing flu.

Flu Viruses/Virus Types - Influenza viruses are classified as type A, B, or C based upon their protein composition. Type A viruses are found in many kinds of animals, including ducks, chickens, pigs, and whales, and also humans. The type B virus widely circulates in humans. Type C has been found in humans, pigs, and dogs and causes mild respiratory infections, but does not spark epidemics.

Type A influenza is perhaps the most dangerous of the three. It is believed responsible for the global outbreaks of 1918, 1957, and 1968. Type A viruses are subdivided into groups based on two surface proteins, H and N (H stands for the protein hemagglutinin,.N stands the protein neuraminidase. These are proteins found on the surface of the virus). Scientists have characterized 16 H subtypes and 9 N subtypes.

Swine Influenza A (H1N1) Virus is a new type A influenza virus causing illness in people. This new virus was first detected in people in the United States in April 2009. This virus is spreading from person-to-person worldwide, probably in much the same way that regular seasonal influenza viruses spread. On June 11, 2009, the World Health Organization (WHO) signaled that a pandemic of 2009 H1N1 flu was underway.

Why is 2009 H1N1 virus sometimes called “swine flu”? This virus was originally referred to as “swine flu” because laboratory testing showed that many of the genes in this new virus were very similar to influenza viruses that normally occur in pigs (swine) in North America. But further study has shown that this new virus is very different from what normally circulates in North American pigs. It has two genes from flu viruses that normally circulate in pigs in Europe and Asia and bird (avian) genes and human genes. Scientists call this a "quadruple reassortant" virus.

Avian Influenza A (H5N1) Virus - Influenza A (H5N1) virus – also called “H5N1 virus” – is an influenza A virus subtype that occurs mainly in birds, is highly contagious among birds, and can be deadly to them. H5N1 virus does not usually infect people, but infections with these viruses have occurred in humans. Most of these cases have resulted from people having direct or close contact with H5N1-infected poultry or H5N1-contaminated surfaces.

Since November 2003, nearly 400 cases of human infection with highly pathogenic avian influenza A (H5N1) viruses have been reported by more than a dozen countries in Asia, Africa, the Pacific, Europe and the Near East. Highly pathogenic avian influenza A (H5N1) viruses have never been detected among wild birds, domestic poultry, or people in the United States.

The variola virus is responsible for causing smallpox . It is an enveloped DNA virus.

How to handle Biological Agent threats

vaccination, smallpox killed up to 500 million people.

In 1980, the same year that the World Health Assembly announced smallpox had been eradicated and recommended that vaccination rograms cease, the Soviet Union launched a program to mass-produce the virus as a bioweapon. Russia may still maintain a research program to produce virulent and contagious strains, ostensibly as a defensive measure.

The only confirmed repositories of smallpox are at the Centers for Disease Control and Prevention in Washington D.C. and at the Institute of Virus Preparations in Moscow, but Iraq and North Korea are suspected to have stocks. Smallpox has no natural reservoirs other than humans. While the chance of terrorists obtaining smallpox is remote, it is considered a grave bioterrorism threat because the disease is highly contagious and deadly. The most lethal natural form of smallpox, caused by the Variola major virus, has a fatality rate of roughly 30%.

In addition, the incidence of many diseases widely presumed to be under control such as Cholera, Dengue, Yellow Fever, and TB has increased in many areas or spread to new regions. We need to find solutions to the use and misuse of antimicrobial drugs that increases the emergence of these drug-resistant pathogens. As their numbers increase, drugs used in the treatment of common infections are becoming increasingly ineffective and the anti-microbial treatment options available to Health care workers declines.

Antibiotic use or misuse?

Antibiotics work only against infections that are caused by bacteria. These drugs are not effective at all against most viral infections. This is why your doctor will not always prescribe an antibiotic if you have an infection. Some antibiotics are effective against only certain types of bacteria; others can effectively fight a wide range of bacteria. Bacterial infections include strep throat, most (but not all) ear infections, and some sinus, bladder, and lung infections. Most common infections (such as, colds, bronchitis, and sore throats) are caused by viruses.

Antibiotics should not be used for these viral infections because they don’t help, they may cause side effects, and overuse of antibiotics contributes to the growing problem of bacterial resistance. Antibiotics also kill naturally occurring bacteria that are needed by the body; these “good” bacteria are then replaced by bacteria that can cause diarrhea or yeast infections. If you experience any side effects when you are taking an antibiotic, you should call your doctor.

Viruses can become resistant to anti-viral medications (Cold or Flu? Bio 113 page)

Bacteria can become resistant to an antibiotic that was previously effective. Resistance is most likely to develop after long-term treatment with an antibiotic or with antibiotics that kill a wide variety of bacteria. Resistance is a growing problem, and there is concern that some types of infections will eventually not be treatable with antibiotics. This resistance is ascribed to overuse of antibiotics, especially for common viral infections.

It is very important that antibiotics be taken as prescribed. Antibiotics should only be used when prescribed by your doctor. You should never take antibiotics given to you by someone else or prescribed for a previous illness. This is a serious business and can help prevent the development of antibiotic resistant bacteria in the future. Remember it could one of your children that contracts a strain of antibiotic resistant bacteria

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