What Is The Influenza Virus?

The influenza virus is a serious respiratory illness, which can cause complications that lead to hospitalizations and even death if it is not treated in time. It is produced by the virus of the Orthomyxoviridae family and was the cause of various pandemics. Let’s know a little about its history.

What is the influenza virus?

During the First World War, the appearance of a pandemic was known, this currently, it is called as the influenza or Spanish flu. The number of deaths at this time from the epidemic was quite devastating, that according to data from the Chilean Journal of Infectology, it is estimated that the influenza epidemic was responsible for 20 to 40 million deaths in less than a year, it is even calculated that a fifth of the world’s population was infected.

Its origin is directly related to a disease in pigs or farm animals, described by an inspector of the US Animal Industry Bureau in 1918, but it would not be valid until 1928, when Dr. Richard Shope of the Department of Comparative Pathology of the Rockefeller Institute in Princeton, was the first that could demonstrate a viral etiology of swine flu.

Influenza virus subtypes

The influenza virus circulates in various parts of the world, such as China, where the origin of the viruses that caused pandemics of H2N2 influenza in 1957, H3N2 influenza in 1968 and the re-emergence of H1N1 in 1977 was evidenced. In current years, outbreaks of H5N1 and H9N2 avian influenza have occurred in people in Hong Kong, so it is important to know the subtypes of influenza that exist:

H5N1 influenza

Last November 1997, 18 confirmed cases of H5N1 occurred in Hong Kong. This epidemic was followed by other epidemics such as avian H5N1, in chicken farms. The outbreak was not controlled until 2001, and a new case was confirmed in 2003. It is considered a highly aggressive strain with significant epidemiological repercussions.

H9N2 influenza

After the H5N1 epidemic in Hong Kong, epidemiological surveillance was strengthened in the province where the virus appeared. This led to the isolation of nine human samples of influenza A H9N2 virus between July and September 1998. Then in March 1999, H9N2 was isolated from two other Hong Kong patients, but the disease was mild and transmission between Humans.

H1N2 influenza

At the beginning of 2002, the new H1N2 influenza virus appeared, which was isolated from patients with influenza in England, mainly affecting young children. This virus originated from the genetic rearrangement of circulating strains of influenza A H1N1 and H3N2.

H7N7 influenza

At the end of February 2003, a fatal case occurred, in which 82 people mostly developed symptoms of conjunctivitis and only 7 had respiratory symptoms, known as the H7N7 Influenza virus.

Vaccination

The production of the anti-influenza vaccine has presented several challenges for the pharmaceutical vaccine manufacturing industries, due to controls for the possible appearance of adverse effects. Therefore, every year an effort is made between different countries to maintain an epidemiological alert, study the antigenic variations of circulating viruses and thus develop an appropriate vaccine. The vaccine is recommended by ACIP experts in the following cases:

• People over 65 years of age.
• Children older than 6 months.
• Children older than 6 months or adults with chronic metabolic diseases including diabetes, kidney failure, hemoglobinopathies or immunosuppression.
• People who live or are in continuous contact with high-risk patients.
• Personnel who work in nursing homes or handle patients considered as high risk.

Vaccine effectiveness

The effectiveness of vaccination can vary from person to person. The effectiveness of the influenza vaccine changes year after year depending on the degree of antigenic similarity of the vaccine strains (chosen 9 to 10 months prior to the epidemic period) and the strains that circulate during the period to be prevented.

In a study that was carried out, according to the Journal of the National University of Colombia School of Medicine, the efficacy was higher for the H3N2 subtype, this due to the genetic identity of the vaccine strain and the strain causing the epidemic outbreak. On the other hand, the vaccine is less effective in preventing the disease, however, the vaccine reduces the severity of major symptoms.

Flu symptoms

This respiratory disease is widely contagious, so parents should be especially attentive to the symptoms that the little one presents. This virus is characterized by starting suddenly and may present some or all of these symptoms:

• Fever.
• Cough.
• Sore throat.
• Runny nose or stuffy nose.
• Muscle and body aches.
• Headaches.
• Fatigue.

The influenza virus can appear suddenly, it is really dangerous and contagious, so when symptoms appear, parents should be vigilant and go to a specialist promptly.