Influenza
Introduction: History and Etymology
The word etymology of influenza is of Italian origin- “influenza del freddo” meaning “influence of the cold”. The earlier taboo holds that the virus was ejected by “unfavorable astrological influences”. At an outbreak in Europe, the word was first named influenza as an English word (1743). Other terms use to mean the same disease condition include “epidemic catarrh, grippe”, “Sweat sickness”, and “Spanish fever” The symptoms can be that fatal in children and elderly thereby calling for a medical emergency.
Influenza or Flu is at times mistakenly referred to as the common cold, the severity distinct it from the erroneous synonyms. In certain severe episodes of influenza, pneumonia results as a complication. Influenza can also dissipate gastroenteritis conditions of vomiting and nausea, this is especially found in children. This makes it sometimes to be called “stomach flu” or “24hr influenza” disease. Influenza mode of transmission include through air borne of causative virus from an infected patient or animals during coughing or sneezing. Also air transmission could be through the spraying of virus containing aerosols and droppings from infected poultry. The devastating upsurge of influenza virus among groups is its presence in salivary fluid, nasal secretions and fecal maters with the viability interval of over one week at 36.7 degree Celsius. At 0oC or 32oF, the virus survives over 30 days and lots more at a reduced temperature. The virus is susceptible to killing when disinfectants are used. The virus is yet to show antigenic variant for speedy spread among the people i.e. factors enabling man to man spread is yet unknown.
Epidemiology of Influenza
Citizens of advanced country do have a higher risk owing to their reduced climatic temperature; they are often vaccinated against the causative virus. The commonly administer one is the trivalent vaccine. This trivalent vaccine contains pure and inactivated form of the influenza virus that is prepared from the three available forms known. Two of the strains from Influenza A subtype and one strain extract from influenza B strain. Owing to the swift in the virus change in genomic content per time, old vaccine expires and does not meet the protective action to subside the new trait. Hence, vaccine developed against one strain of influenza virus cold relatively last just for a year and thereby loss its potency. In addition to the treatment is the use of neuraminidase inhibitors, antibiotics.
Symptoms of influenza were first described about 3,000 years ago. A notable outbreak was of 1580 in Asia. In another outbreak, over ten thousand Roman were killed and the Spanish community was almost exterminated. Within the seventeenth and eighteenth centuries in history, influenza caused a major pandemic where a quarter of the infected people died helplessly.
The 1918 Flu pandemic was of H1N1 type A. This particular pandemic has been recorded to memory as similar to medical holocaust against mankind especially resulting in the Black Death. The infection was thought to have caused what is known as a cytokine discharge, this compound the severity of the symptoms. The presentation in 1918 was confusing as some scientist thought of it as other hemorrhagic fever. Of the severity was the hemorrhage from the surface of the skin (mucus membrane). There were bleeding from ear, nose, and petechial hemorrhages of the body skin. Secondary infection was bacterial pneumonia alongside the death as a result of respiratory hemorrhage and oedema. The total death toll in one year pandemic of 1918 was estimated at about 3% to 6% of the global total population. In contrast to the scourge HIV, over 30 million casualties were recorded in the first twenty five weeks of attack while that of HIV recorded the same number of death within the space of twenty five years.
Historical Records of Pandemic Flu Statistics
Pandemic Region
Year
Casualties
Subtype strain
Severity index
Asiatic Flu
1889 to 1890
1 million
H2N2
Unknown
Spanish Flu
1918 to 1920
70million
H1N1
5.0
Asian Flu
1957 to 1958
1.3million
H2N2
2.0
Hong Kong Flu
1968 to 1969
0.8 million
H3N2
2.0
Researchers have also found out that the prevalence of influenza is common in the winter season. The Northern and Southern part of the world geographically experience winter at different times within a year, hence, the presence of two flu seasons each year. Following this discovery, the World Health Organization thereby recommended that the National Influenza Centers are to provide the citizen with twice immunization schedule within a year. Some authors have it that the winter prevalence could be trace to increase in man to man contact since people tend to stay indoor the more in this season. The dried mucus at this season equally substantiates the easy spread of this virus. Additional contributing factors submitted in another research found that the transmission of the virus in dry air and cold environmental temperature (less than 6o C). In the tropics, the peak of spread was in the rainy season.
According to research conducted by Robert Edgar in 1965, he proposed a hypothesis relating the seasonal fluctuation of immune action on the virus to vitamin D seasonal changes. Vitamin D is synthesized beneath the body skin surface exposed to Ultraviolet radiation from the sun. People staying away from the sun during winter suppress the production of vitamin D and hence, the reduced level of immunity. In the research was also found that cod liver oil which contains large Vitamin D could assist in preventing respiratory tract infections as complication of influenza disease.
Microbiology – Strains and subtypes
Influenza is caused by an organism known as influenza virus. It is a RNA virus that belongs to the family of orthomyxoviruses. The five genera of orthomyxoviridea family are “Influenza A, B, C, Isavirus and Thogotovirus”.
It is a serious respiratory disease that affects the epithelial cells of the respiratory cells producing obvious symptoms of sudden chills, prostration, short fever, catarrhal inflammation, headache, and nonproductive cough. The main two forms of existence include influenza A and influenza B. The uncommon one is influenza C. The virus is circular or spherical or sometimes filamentous in shape within an enclosing envelope. While type B is connected to local outbreak of mild cases of influenza disease, influenza A is responsible for a number of world-wide attacks. One of the most popular pandemic caused by influenza virus was recorded in 1918 where there was a record of over thirty millions citizens of the world dropped death. The scientist reports that influenza A virus has a sharp tendency to develop what is called antigenic variants. This occurs haphazardly without a normal pattern that can be predetermined. The characteristic make it such the most dangerous one. The virus surface is characterized by the enveloped content of Hemagglutinatinin and neuraminidase antigens. The body immunity develops antibody to these surface antigens in response to the infection.
Far back in 1957, there was a discovery of major shift in the viral genome’s make up, this led to the discovery of antigenic major shift and the appearance of influenza A2 subtype H2N2, other serotypes will be considered later. This particular antigenic subtype shift is responsible for the global pandemic then. In about 11 years later, there was another pandemic outbreak of influenza virus from Hong Kong. This subtype was discovered to be H3N2. Some minor antigenic shifts have also been reported since then. About ten years ago, avian antigenic strain of H5N1 influenza was discovered to be responsible in human influenza viral disease. This was a major change in the surface antigen of the virus. There was a report of influenza transmission from poultry to man in South East Asia.
Influenza A virus: Has a natural habitat in aquatic birds. Transmission outside this host results in pandemics. This type is the most virulent causing the most severe disease. Different antibody developed to subtypes (serotypes) of Influenza A gave a clue to their discovery viz. H1N1, H2N2, H3N2, H5N1, H7N7, H1N2, H9N2, H7N2, H7N3, and H10N7.
Influenza B virus: Exclusive found almost in human host. It is not in abundance as A. it antigenic shift occur at a slower rate than influenza A having a single serotype.
Influenza C virus: It infects man and pig causing serious sickness and localized epidemics.
Clinical Features Seen in Influenza disease
Influenza virus has an incubation interval of about one to three days. This incubation determines the period between the infection of the virus and the clinically observable manifestation of signs and symptoms of the disease. The attainment of incubation period began with an unexpected fever of low grade causing shivering and overall pains in the limb and joint (myalgia). This does not exclude the presence of headache; there is the presence of sore in the throat, a prolonged unproductive cough that could last for months. The “post-viral syndrome” of influenza includes extended period of debilitation and moment of depression that may take several weeks to subside.
Diagnosing Influenza
People with any chronic disease have a superimposition effect of the disease getting worse off. Other fatal risk factors that could assist the diagnosis include smoking, congestive cardiac failure, emphysema, asthma, et cetera. Symptoms are; Fever, extreme cold, body pains, headache, cough and sneeze, nasal congestion, facial skin hemorrhage, abdominal ache in children. Over 85% of people infected presents with fever, 95% with cough and 80 to 90% with nasal congestion. Fever presentation is a less sensitive presentation. All the three findings are less directly pointing to influenza as a clear cut diagnosis.
Laboratory diagnosis is indicative of influenza in the presence of a fourfold increase in antibody specificity to the virus or an increase in the haemaglutinin antibody when estimated with the period of about 8 to 14 days interval beginning after noticing the symptoms. The virus can also be demonstrated microscopically in the nose and throat fluid extracts.
Treatment
The first advice is to ensure proper and adequate bed rest for the affected patient, ensuring drinking of plenty fluids. Medications recommended include paracetamol or acetaminophen to reduce the pains and muscular aches. Administration of aspirin could potentiate Reye’s syndrome, an additional serious liver disease. The use of antibiotics to treat influenza is only recommended for use in the presence of complications such as pneumonia of bacteria origin. Influenza is caused by virus hence, antibiotics do not directly resolve it. Antiviral drugs used prescribed are basically neuraminidase inhibiting drugs and the M2 inhibitors. Two neuraminidase inhibitors designed to prevent the stop the spread of the virus are oseltamivir and zanamivir. The drugs treat both influenza B and A disease effectively. In addition they abate the symptoms and complication arising from the disease progression. M2 inhibitors include amantadine and rimantadine. They halt the viral genome from infecting the cells. They are used specifically to treat influenza A type. The virus strain H3N2 developed resistance more to M2 inhibitors, found in America Influenza Study, 2005.
Prevention and Control of Influenza
High risk group of patents are considered to be the children and the elderly. Vaccination is strictly advised in this age bracket as they may serve the reservoir for other age group. The commoner source of vaccination requires the culturing of the viral genome in a fertilized poultry egg. The virus is harvested after few days, treated with toxic agent such as detergent to get an inactivated form of the virus which normally serves as the vaccine. Conversely, the virus could be injected live and grown in the egg till its virulence is lost. Albeit, the vaccine effectiveness in either way is dependent of the specified strain action for which it can work against. World Health organization constantly research for any new strains in circulation in a bid to assist the pharmaceutical industries in meeting up the updated demand yearly. In recent time, poultry animals are not exempted from the privilege of vaccine provision. Some of the difficulties encounter is the time ratio of meeting the pertinent need and the virus developing new antigenic breed.
Manufacturing a circulating vaccine could take about six months, this poses economic danger when a mass production cannot treat or provides immunity to the target strain owing to the arrival of new one. So, people can still get vaccinated and suffer influenza. In 2007winter season, CDC did recommend that infants below 60 months should be vaccinated. Most dangerous body reaction to the vaccine is the general allergic reaction to the injection. This should be watched out for and reported immediately.
Since the spread does not exclude air transmission, people should be admonished to always cover their mouth. They should embrace proper hygiene practices; washing hands on a regular basis, covering mouth when sneezing, etc. Exposed surface sanitation should be done regularly with sanitizers such as alcohol. Hospital environments are to use quaternary ammonium groups of compound mixed with alcohol to perform sterilization. Other sterilizing or disinfectant includes the use of halogen-releasing agents such as hypochlorite compound.
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