Quick Diagnosis for Early Treatment

Dec. 12, 2014

By Medical Discovery News

Quick Diagnosis for Early Treatment

The time it takes to test for the cause of an infection ranges from minutes to weeks. A new generation of biosensors may change that, as they are being developed to identify the viral, bacterial, or fungal origin of an illness within a few hours, allowing physicians to begin the correct treatment sooner.

Many infections have symptoms that resemble the flu, such as HIV, the fungal infection coccidioidomycosis, Ebola, and even anthrax. This makes it very difficult to make a diagnosis. The emergence of new microbial pathogens such as SARS and MERS and bacterial resistance to antibiotics only adds to the fight against infectious agents. Scientists like Louis Pasteur and Robert Koch developed the traditional method for diagnosing infectious disease about 150 years ago, and modern methods have improved their discoveries.

Viruses, bacteria, and fungi have genetic information contained in DNA, RNA, or both. Each strand of DNA or RNA is made of four kinds of building blocks called nucleotides: adenine (A), cytosine (C), guanine (G), and thymine (T) in DNA or uracil (U) in RNA. Every species has a unique genetic code as seen in its arrangement of nucleotides, and by unlocking that code scientists can determine their identity. Each of the nucleotides has a different molecular weight, so the number of each nucleotide in a strand of DNA or RNA can be determined by measuring it on a device called a mass spectrometer. This can identify a microbial pathogen faster than the traditional culturing method, and can also identify those that can’t be grown in a lab.

However, the massive amount of DNA and RNA in a patient’s own cells complicates things. To tackle this problem, inventors of the new biosensor have coupled a mass spectrometer with polymerase chain reaction (PCR) to amplify any piece of genetic information that matches a known sequence from a pathogen. The sensor can then detect a very broad array of potential pathogens simultaneously.

Scientists have been very careful in selecting the unique genetic regions of various pathogens for this test. Once the PCR is used to amplify pieces of potential pathogens in the sample, the mass spectrometer spits out a series of numbers that can be cross-referenced to a database of over 1,000 pathogens that cause human disease in just a few hours.

For example, two children were hospitalized with flu-like symptoms in Southern California in 2009. They tested positive for the flu virus, but doctors did not know which strain of the flu they had. The new sensor analyzed their samples and revealed that both children were infected with H1N1, otherwise known as swine flu, which was not circulating at that time. H1N1 became a pandemic strain with cases all around the world.

This new technology represents a universal pathogen detector, capable of identifying the organism responsible for a person’s illness in just a few hours. Networking the detectors between hospitals and health departments would quickly identify outbreaks and possibly save lives.

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When An Epidemic Becomes a Pandemic

By Medical Discovery News

July 7, 2012

For at least thousands of years, people have suffered flu epidemics and pandemics.  In 412 B.C., Hippocrates described what was likely an influenza epidemic in Ancient Greece. The term influenza comes from 15th century Italy, when people believed stars influenced the illness because it always came in cycles. Soon after, in 1580, the first clear account of a flu pandemic was written. From that point on, records show flu pandemics have been recurring every one to three decades somewhere in the world.

So what is the difference between an epidemic and pandemic? Flu epidemics occur every year because each year the virus comes back just slightly different. In a flu pandemic, a much larger geographic area is affected, sometimes worldwide, when a new strain of the virus infects people for the first time and everyone is susceptible.

The World Health Organization has defined three phases of pandemics. The first, or earliest, is called the Inter-Pandemic period. During this time, no new influenza viruses are detected in humans, but new flu viruses could be circulating in animal populations.

The next level is the Pandemic Alert period. Here, the flu virus is infecting humans but is either incapable or has limited ability for human-to-human transmission. The last is the Pandemic period where there’s widespread and rapid transmission in human populations.

The potential for a flu virus to be capable of causing pandemics lays in its ability to infect many different species including horses, pigs, and birds. As various strains of the flu virus spread from species to species, multiple viruses can infect the same animal, allowing the viruses to exchange genetic information and create a new virus. Once it can infect and efficiently transmit between humans, a pandemic starts.

The annual flu epidemic sickens 20 percent of America’s population and kills 40,000 people, creating a $10 billion loss in productivity and medical costs. Imagine the cost of a pandemic.  The largest recorded was the 1918 Spanish flu pandemic, which killed 675,000 people in America and 20 to 40 million people worldwide.

Today, health officials worry about avian flu (H5N1) and whether, or more likely when, this flu strain will start a new pandemic. The H5N1 virus was first recognized in Hong Kong in 1997.  Since then it has spread extensively throughout Asia and can now be found in the Middle East, Africa, and Europe. The virus is in the Pandemic Alert period with no means yet for extensive human-to-human transmission. As of spring 2012, approximately 600 people have been diagnosed with H5N1 and the mortality rate is an alarming 60 percent.

In order to understand how this virus may attain efficient transmission between people, American and Dutch scientists created a transmissible H5N1 in the lab. The controversial study could help other scientists create a vaccine for when an avian flu pandemic occurs. But others fear this research could provide a “blueprint” for terrorists to create a potential biological weapon.

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