The Outbreak of the Novel H1N1 Flu Virus in 2009
Since the dawn of the 20th century, various breeds and mutations of viruses have caused panic to ensue in several countries around the globe. Some of the most popular names that became synonymous to new breeds of illnesses and disease were Anthrax, Mad Cow, and the recent A H1N1. Scientists noted that even the common cold and flu have already transformed due to climate changes, and the advancement of chemicals. Out of all the new breeds of illnesses and viruses that have struck the globe, the Influenza A H1N1 Virus strain had caused much turmoil in both developed and non-developed countries as the H1N1 strain was unlike any form of influenza that can easily be treated by the medications present today. The formation of such new virus paved the concern to many that viruses nowadays are keeping up with change, becoming deadlier and hard to destroy with present medications available.
2009 H1N1 was first detected in the United States in April 2009. This virus was a unique combination of influenza virus genes never previously identified in either animals or people. The virus genes were a combination of genes most closely related to North American swine-lineage H1N1 and Eurasian lineage swine-origin H1N1 influenza viruses. Because of this, initial reports referred to the virus as a swine origin influenza virus. However, investigations of initial human cases did not identify exposures to pigs and quickly it became apparent that this new virus was circulating among humans and not among U.S. pig herds. Infection with this new influenza A virus (then referred to as ‘swine origin influenza A virus’) was first detected in a 10-year-old patient in California on April 15, 2009, who was tested for influenza as part of a clinical study. Laboratory testing at CDC confirmed that this virus was new to humans. Two days later, CDC laboratory testing confirmed a second infection with this virus in another patient, an 8-year-old living in California about 130 miles away from the first patient who was tested as part of an influenza surveillance project. There was no known connection between the two patients. Laboratory analysis at CDC determined that the viruses obtained from these two patients were very similar to each other, and different from any other influenza viruses previously seen either in humans or animals. Testing showed that these two viruses were resistant to the two antiviral drugs amantadine and rimantadine, but susceptible to the antiviral drugs oseltamivir and zanamivir. CDC began an immediate investigation into the situation in coordination with state and local animal and human health officials in California.The cases of 2009 H1N1 flu in California occurred in the context of sporadic reports of human infection with North American-lineage swine influenza viruses in the United States, most often associated with close contact with infected pigs. (During December 2005 – January 2009, 12 cases of human infection with swine influenza were reported; five of these 12 cases occurred in patients who had direct exposure to pigs, six patients reported being near pigs, and the source of infection in one case was unknown). Human-to-human spread swine influenza viruses had been rarely documented and had not been known to result in widespread community outbreaks among people. In mid-April of 2009, however, the detection of two patients infected with swine origin flu viruses 130 miles apart, raised concern that a novel swine-origin influenza virus had made its way into the human population and was spreading among people.
In late April 2009, Mexico became the epicenter of the current influenza pandemic. International cooperation between Mexican, Canadian, and American public health authorities and scientists led to the rapid identification of a novel influenza A (H1N1) virus strain. On April 24th, Mexican authorities instituted aggressive social distancing interventions and began the deployment of antiviral drugs to treat cases and contacts. Within a few days, the virus that was causing the epidemic in Mexico was identified in many other countries worldwide, and on June 11, 2009, the World Health Organization raised the status from epidemic to pandemic. Thus, the first influenza pandemic of the new millennium was officially declared. Since then, and through December 5, 2009, 208 countries have reported cases and over 10,000 deaths have occurred as a consequence of the pandemic. In the first six months of the pandemic, we have learned many important lessons: To begin with, and contrary to what many believed, the first influenza pandemic of the XXI Century started in North America and not in South East Asia and was of swine rather than avian in origin. Influenza pandemics are unpredictable but recurring events that can have severe consequences on human health and economic development. Three criteria must be met for an influenza pandemic to occur. First, a new virus strain to which the vast majority of the population lacks immunity has to appear. Second, the new virus has to cause severe disease in humans, and third, the virus has to be able to easily infect and to be efficiently transmitted between humans. During the past century, there were three major influenza pandemics: in 1918 (H1N1), 1957 (H2N2), and 1968 (H3N2). The most serious influenza pandemic in recent history is the 1918 Spanish flu that killed over 50 million people worldwide. The latter two pandemics were milder than the 1918 one but still resulted in significant mortality, with close to 2 million people dying from the 1957 virus and 1 million from the 1968 virus (Perez-Padilla R, de-la-Rosa-Zamboni D, 2009). Because of the real threat of a new influenza pandemic, international public health agencies called for the development of preparedness plans that would ensure the strengthening of national and global response capacity. As a result, countries began developing pandemic influenza plans in the late 1990's, and many countries had plans in place by 2005. In the United States, the National Strategic Plan for Pandemic Influenza was published in November of 2005 (Gómez-G|$$|Aaomez A, 2009).
In conclusion, within 2 months of its discovery last spring, a novel influenza A (H1N1) virus, currently referred to as 2009 H1N1, caused the first influenza pandemic in decades. The virus has caused disproportionate disease among young people with early reports of virulence similar to that of seasonal influenza. This clinical review provides an update encompassing the virology, epidemiology, clinical manifestations, diagnosis, treatment, and prevention of the 2009 H1N1 virus. Because information about this virus, its prevention, and treatment are rapidly evolving, readers are advised to seek additional information. We performed a literature search of PubMed using the following keywords: H1N1, influenza, vaccine, pregnancy, children, treatment, epidemiology, and review. Studies were selected for inclusion in this review on the basis of their relevance.
Belshe R. The origins of pandemic influenza-lessons from the 1918 virus. N Engl J Med. 2005
CDC. Swine influenza A (H1N1) infection in two children -Southern California, March-April 2009. MMWR—Morb Mortal Wk Rep. 2009
Perez-Padilla R, de-la-Rosa-Zamboni D, Ponce-de-Leon S, et al. Pneumonia and respiratory failure from swine-origin influenza A (H1N1) in Mexico. N Engl J Med. 2009
CDC. Update: Novel influenza A (H1N1) virus infection—Mexico, March-May 2009. MMWR- Morb Mortal Wk Rep. 2009
Gómez-G|$$|Aaomez A, Magaña-Aquino M, García-Sepúlveda C, et al. Severe pneumonia associated with pandemic (H1N1) 2009