Excerpts from Wikipedia.org

Influenza

Influenza, commonly known as flu, is an infectious disease of birds and mammals caused by RNA viruses of the family Orthomyxoviridae (the influenza viruses). The name influenza comes from the Italian: influenza, meaning "influence", (Latin: influentia). In humans, common symptoms of the disease are the chills, then fever, sore throat, muscle pains, severe headache, coughing, weakness and general discomfort. In more serious cases, influenza causes pneumonia, which can be fatal, particularly in young children and the elderly. Although it is sometimes confused with the common cold, influenza is a much more severe disease and is caused by a different type of virus. Influenza can produce nausea and vomiting, especially in children, but these symptoms are more characteristic of the unrelated gastroenteritis, which is sometimes called "stomach flu" or "24-hour flu".

Flu spreads around the world in seasonal epidemics, killing millions of people in pandemic years and hundreds of thousands in non-pandemic years. Three influenza pandemics occurred in the 20th century and killed tens of millions of people, with each of these pandemics being caused by the appearance of a new strain of the virus in humans. Often, these new strains result from the spread of an existing flu virus to humans from other animal species. A deadly avian strain named H5N1 has posed the greatest risk for a new influenza pandemic since it first killed humans in Asia in the 1990s. Fortunately, this virus has not mutated to a form that spreads easily between people.

Influenza reaches peak prevalence in winter, and because the Northern and Southern Hemispheres have winter at different times of the year, there are actually two different flu seasons each year. This is why the World Health Organization (assisted by the National Influenza Centers) makes recommendations for two different vaccine formulations every year; one for the Northern, and one for the Southern Hemisphere.

An alternative hypothesis to explain seasonality in influenza infections is an effect of vitamin D levels on immunity to the virus. This idea was first proposed by Robert Edgar Hope-Simpson in 1965. He proposed that the cause of influenza epidemics during winter may be connected to seasonal fluctuations of vitamin D, which is produced in the skin under the influence of solar (or artificial) UV radiation. This could explain why influenza occurs mostly in winter and during the tropical rainy season, when people stay indoors, away from the sun, and their vitamin D levels fall. Furthermore, some studies have suggested that administering cod liver oil, which contains large amounts of vitamin D, can reduce the incidence of respiratory tract infections

It is not completely clear why outbreaks of the flu occur seasonally rather than uniformly throughout the year. One possible explanation is that, because people are indoors more often during the winter, they are in close contact more often, and this promotes transmission from person to person. Another is that cold temperatures lead to drier air, which may dehydrate mucus, preventing the body from effectively expelling virus particles.

Each year the influenza virus changes and different strains become dominant. Due to the high mutation rate of the virus a particular influenza vaccine formulation usually works for only about a year. The World Health Organization coordinates the contents of the vaccine each year to contain the most likely strains of the virus to attack the next year.

Common Cold

Acute viral nasopharyngitis, or acute coryza, usually known as the common cold, is a highly contagious, viral infectious disease of the upper respiratory system, primarily caused by picornaviruses (including rhinoviruses) or coronaviruses.

Common symptoms are sore throat, runny nose, nasal congestion, sneezing and cough; sometimes accompanied by 'pink eye', muscle aches, fatigue, malaise, headaches, muscle weakness, and/or loss of appetite. Fever and extreme exhaustion are more usual in influenza. The symptoms of a cold usually resolve after about one week, but can last up to 14 days. Symptoms may be more severe in infants and young children. Although the disease is generally mild and self-limiting, patients with common colds often seek professional medical help, use over-the-counter drugs, and may miss school or work days. The annual cumulative societal cost of the common cold in developed countries is considerable in terms of money spent on remedies, and hours of work lost.

The primary method to prevent infection is hand-washing to minimize person-to-person transmission of the virus. There are no antiviral drugs approved to treat or cure the infection. Most available medications are palliative and treat symptoms only. Megadoses of vitamin C, preparations from echinacea, and zinc gluconate have been studied as treatments for the common cold although none has been approved by the Food and Drug Administration or European Medicines Agency.

Smallpox

Smallpox is an infectious disease unique to humans, caused by either of two virus variants named Variola major and Variola minor. The disease is also known by the Latin names Variola or Variola vera, which is a derivative of the Latin varius, meaning spotted, or varus, meaning "pimple". The term "smallpox" was first used in Europe in the 15th century to distinguish variola from the great pox (syphilis).

Smallpox localizes in small blood vessels of the skin and in the mouth and throat. In the skin, this results in a characteristic maculopapular rash, and later, raised fluid-filled blisters. V. major produces a more serious disease and has an overall mortality rate of 30–35%. V. minor causes a milder form of disease (also known as alastrim, cottonpox, milkpox, whitepox, and Cuban itch) which kills ~1% of its victims. Long-term complications of V. major infection include characteristic scars, commonly on the face, which occurred in 65–85% of survivors. Blindness resulting from corneal ulceration and scarring, and limb deformities due to arthritis and osteomyelitis are less common complications, seen in about 2–5% of cases.

Smallpox is believed to have emerged in human populations about 10,000 BC. The disease killed an estimated 400,000 Europeans each year during the 18th century (including five reigning monarchs), and was responsible for a third of all blindness. Between 20 and 60% of all those infected—and over 80% of infected children—died from the disease.

During the 20th century, it is estimated that smallpox was responsible for 300–500 million deaths. As recently as 1967, the World Health Organization (WHO) estimated that 15 million people contracted the disease and that two million died in that year. After successful vaccination campaigns throughout the 19th and 20th centuries, the WHO certified the eradication of smallpox in 1979. To this day, smallpox is the only human infectious disease to have been completely eradicated from nature.

The smallpox vaccine was the first successful vaccine ever to be developed and remains the only FDA approved effective preventive for the deadly smallpox disease. It was first perfected in 1796 by Edward Jenner who acted upon the observation that milkmaids who caught the cowpox virus did not catch smallpox.

In late 2001, the governments of United States and United Kingdom considered stockpiling smallpox vaccines, even while assuring the public that there was no "specific or credible" threat of bioterrorism.

AIDS

Acquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS or Aids) is a set of symptoms and infections resulting from the damage to the human immune system caused by the human immunodeficiency virus (HIV). This condition progressively reduces the effectiveness of the immune system and leaves individuals susceptible to opportunistic infections and tumors. HIV is transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal fluid, preseminal fluid, and breast milk. This transmission can involve anal, vaginal or oral sex, blood transfusion, contaminated hypodermic needles, exchange between mother and baby during pregnancy, childbirth, or breastfeeding, or other exposure to one of the above bodily fluids.

AIDS is now a pandemic. In 2007, an estimated 33.2 million people lived with the disease worldwide, and it killed an estimated 2.1 million people, including 330,000 children. Over three-quarters of these deaths occurred in sub-Saharan Africa, retarding economic growth and destroying human capital. Most researchers believe that HIV originated in sub-Saharan Africa during the twentieth century.

Although treatments for AIDS and HIV can slow the course of the disease, there is currently no vaccine or cure. Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but these drugs are expensive and routine access to antiretroviral medication is not available in all countries. Due to the difficulty in treating HIV infection, preventing infection is a key aim in controlling the AIDS epidemic.

HIV, the infectious agent of AIDS, is thought to have originated in non-human primates in sub-Saharan Africa and transferred to humans during the 20th century. The epidemic officially began on 5 June 1981.

Two species of HIV infect humans: HIV-1 and HIV-2. HIV-2 may have originated from the Sooty Mangabey (Cercocebus atys), an Old World monkey of Guinea-Bissau, Gabon, and Cameroon. HIV-1 is more virulent. It is easily transmitted and is the cause of the majority of HIV infections globally. HIV-2 is less transmittable and is largely confined to West Africa.

* AIDS Origin

* HIV Test

Ebola

Ebola is the common term for a group of viruses belonging to genus Ebola, family Filoviridae, and for the disease which they cause, Ebola hemorrhagic fever. The viruses are characterised by a long, filamentous morphology surrounded by a protein/lipid viral envelope. Ebola viruses are morphologically similar to the Marburg virus, also in the family Filoviridae, and share similar disease symptoms. Each virion contains one minor molecule of linear, single-stranded, negative-sense RNA, totaling 18959 to 18961 nucleotides in length.

The virus is named after the Ebola River Valley in the Democratic Republic of the Congo (formerly Zaïre), near the site of the first recognized outbreak in 1976, in a mission run by Flemish nuns.

The Ebola virus first came to notice in 1976 in outbreaks of Ebola hemorrhagic fever in Zaire and Sudan. The strain of Ebola which broke out in Zaire has one of the highest case fatality rates of any human pathogenic virus, roughly 90%. The strain which broke out later in Sudan has a mortality of approximately 50%. The virus is believed to be initially transmitted to a human via contact with an infected animal host. From the first human infected, the virus is then transmitted by human contact with infected blood and bodily fluids of a diseased person, and by human contact with contaminated medical equipment, such as needles. Both of these infectious mechanisms will occur in clinical (nosocomial) and non-clinical situations. Due to the high fatality rate, the rapidity of demise, and the often remote areas where infections occur, the potential for widespread epidemic outbreaks is considered low.

Ebola is believed to be a zoonotic virus as it is currently devastating the populations of lowland gorillas in Central Africa. As of late 2005, three species of fruit bat were identified as carrying the virus, and did not exhibit symptoms, and are now believed to be the natural host species, or reservoir, of the virus.

Ebola hemorrhagic fever is potentially lethal and encompasses a range of symptoms including fever, vomiting, diarrhea, generalized pain or malaise, and sometimes internal and external bleeding. The cause of death is usually due to hypovolemic shock or organ failure.

Because Ebola is potentially lethal and since no approved vaccine or treatment is available, Ebola is classified as a biosafety level 4 agent, as well as a Category A bioterrorism agent by the Centers for Disease Control and Prevention. It has the potential to be weaponized for use in biological warfare and was investigated for that use by both the Soviet Union and the United States during the Cold War. Its effectiveness as a biological-warfare agent is compromised by its extreme deadliness and its level of contagion: a typical outbreak spreads through a small village or hospital, affects the entire population, and then runs out of potential hosts, burning out before it reaches a larger community. Also important is that none of the strains of Ebola known to cause disease in humans have been found to be airborne; only the strain known as Ebola Reston (after the city of Reston, Virginia where it was first identified in Green Monkeys) is believed to be airborne.

Emergent Viruses

Emergent viruses is a concept based on the fact that through certain selection pressures, viruses can adapt and can emerge as a new disease/pathogenic strain with a new attribute facilitating its pathogenicity in a new field not normally associated with that specific virus. This includes viruses that are the cause of a disease which has notably increased in incidence; this is often a result of a wide variety of causes from both the influence of man and nature. Most emergent viruses can be categorized as zoonotic (an animal disease that can be transmitted to humans), this has the advantage of possibly having several natural reservoirs for the disease.

Examples of Emergent Diseases: Poliomyelitis, SARS and Avian influenza H5N1.

Polio

Poliomyelitis, often called polio or infantile paralysis, is an acute viral infectious disease spread from person to person, primarily via the fecal-oral route. The term derives from the Greek polio (πολίός), meaning "grey", myelon (µυελός), referring to the "spinal cord", and -itis, which denotes inflammation. Although around 90% of polio infections have no symptoms at all, affected individuals can exhibit a range of symptoms if the virus enters the blood stream. In fewer than 1% of cases the virus enters the central nervous system, preferentially infecting and destroying motor neurons, leading to muscle weakness and acute flaccid paralysis. Different types of paralysis may occur, depending on the nerves involved. Spinal polio is the most common form, characterized by asymmetric paralysis that most often involves the legs.

The effects of polio have been known since prehistory; Egyptian paintings and carvings depict otherwise healthy people with withered limbs, and children walking with canes at a young age.

Before the 20th century, polio infections were rarely seen in infants before six months of age, most cases occurring in children six months to four years of age. Poorer sanitation of the time resulted in a constant exposure to the virus, which enhanced a natural immunity within the population. In developed countries during the late 19th and early 20th centuries, improvements were made in community sanitation, including better sewage disposal and clean water supplies. These changes drastically increased the proportion of children and adults at risk of paralytic polio infection, by reducing childhood exposure and immunity to the disease.

Small localized paralytic polio epidemics began to appear in Europe and the United States around 1900. Outbreaks reached pandemic proportions in Europe, North America, Australia, and New Zealand during the first half of the 20th century. By 1950 the peak age incidence of paralytic poliomyelitis in the United States had shifted from infants to children aged five to nine years, when the risk of paralysis is greater; about one-third of the cases were reported in persons over 15 years of age. Accordingly, the rate of paralysis and death due to polio infection also increased during this time.

SARS

Severe acute respiratory syndrome (SARS) is a respiratory disease in humans which is caused by the SARS coronavirus (SARS-CoV). There has been one near pandemic to date, between November 2002 and July 2003, with 8,096 known infected cases and 774 deaths (a case-fatality rate of 9.6%) worldwide.

The epidemic of SARS appears to have originated in Guangdong Province, China in November 2002. The first case of SARS, a farmer, was treated in the First People's Hospital of Foshan. The patient died soon after, and no definite diagnosis was made on his cause of death. Despite taking some action to control it, Chinese government officials did not inform the World Health Organization of the outbreak until February 2003, restricting media coverage in order to preserve public confidence. This lack of openness caused delays in efforts to control the epidemic, resulting in criticism of the People’s Republic of China (PRC) from the international community.

The epidemic reached the public spotlight in February 2003, when an American businessman traveling from China became afflicted with pneumonia-like symptoms while on a flight to Singapore. The plane stopped at Hanoi, Vietnam, where the victim died in The French Hospital of Hanoi. Several of the medical staff who treated him soon developed the same disease despite basic hospital procedures. Italian doctor Carlo Urbani identified the threat and communicated it to WHO and the Vietnamese government; he would later succumb from the disease.

Antibiotics are ineffective as SARS is a viral disease. Treatment of SARS so far has been largely supportive with antipyretics, supplemental oxygen and ventilatory support as needed.

Suspected cases of SARS must be isolated, preferably in negative pressure rooms, with full barrier nursing precautions taken for any necessary contact with these patients.

A 2006 systematic review of all the studies done on the 2003 SARS epidemic found no evidence that antivirals, steroids or other therapies helped patients. A few suggested they caused harm.

Spanish Flu: Street car conductor in Seattle not allowing passengers aboard without a mask in 1918.

The 1918 flu pandemic (commonly referred to as the Spanish flu) was an influenza pandemic that was first found in the United States, appeared in Sierra Leone and France, and then spread to nearly every part of the world. It was caused by an unusually severe and deadly Influenza A virus strain of subtype H1N1. Many of its victims were healthy young adults, in contrast to most influenza outbreaks which predominantly affect juvenile, elderly, or otherwise weakened patients.

The Spanish flu lasted from March 1918 to June 1920, spreading even to the Arctic and remote Pacific islands. It is estimated that anywhere from 20 to 100 million people were killed worldwide, or the approximate equivalent of one third of the population of Europe. This extraordinary toll resulted from the extremely high infection rate of up to 50% and the extreme severity of the symptoms, suspected to be caused by cytokine storms.

In February 1998, a team led by Jeffery Taubenberger of the US Armed Forces Institute of Pathology (AFIP) recovered samples of the 1918 influenza from the frozen corpse of a Native Alaskan woman buried for nearly eight decades in permafrost near Brevig Mission, Alaska. One of the four recovered samples contained viable genetic material of the virus. This sample provided scientists a first-hand opportunity to study the virus, which was inactivated with guanidinium thiocyanate before transport.

* Spanish Flu Research

Exposure to cold weather has not been proven to increase the likelihood of "catching" a cold

Upper respiratory tract infections are the most common infectious diseases among adults and teens, who have two to four respiratory infections annually. Children may have six to ten colds a year (and up to 12 colds a year for school children). In the United States, the incidence of colds is higher in the fall and winter, with most infections occurring between September and April. The seasonality may be due to the start of the school year, or due to people spending more time indoors (thus in closer proximity with each other) increasing the chance of transmission of the virus

Child showing rash due to ordinary-type smallpox

After first contacts with Europeans and Africans, some believe that the death of 90–95% of the native population of the New World was caused by Old World diseases. It is suspected that smallpox was the chief culprit and responsible for killing nearly all of the native inhabitants of the Americas.

Even after the two mighty empires of the Americas were defeated by the virus and disease, smallpox continued its march of death. In 1633 in Plymouth, Massachusetts, the Native Americans were struck by the virus. As it had done elsewhere, the virus wiped out entire population groups of Native Americans. It reached Mohawks in 1634, the Lake Ontario in 1636, and the lands of the Iroquois by 1679. During the 1770s, smallpox killed at least 30% of the West Coast Native Americans. Smallpox epidemic of 1780–1782 brought devastation and drastic depopulation among the Plains Indians.

Philadelphia (video)

Philadelphia is an Academy Award-winning 1993 drama film revolving around HIV/AIDS and homosexuality.

AIDS stigma exists around the world in a variety of ways, including ostracism, rejection, discrimination and avoidance of HIV infected people; compulsory HIV testing without prior consent or protection of confidentiality; violence against HIV infected individuals or people who are perceived to be infected with HIV; and the quarantine of HIV infected individuals. Stigma-related violence or the fear of violence prevents many people from seeking HIV testing, returning for their results, or securing treatment, possibly turning what could be a manageable chronic illness into a death sentence and perpetuating the spread of HIV.

Often, AIDS stigma is expressed in conjunction with one or more other stigmas, particularly those associated with homosexuality, bisexuality, promiscuity, and intravenous drug use.

The Hot Zone by Richard Preston

Outbreak (video)

In the movie Outbreak, the virus looks the same as the Ebola virus. In fact, the entire movie's made up virus "Motaba" is based very closely on Ebola.

Vaccines have been produced for both Ebola and Marburg that were 99% effective in protecting a group of monkeys from the disease. These vaccines are based on either a recombinant Vesicular stomatitis virus or a recombinant Adenovirus carrying the Ebola spikeprotein on its surface. Early human vaccine efforts, like the one at NIAID in 2003, have so far not reported any successes. The biggest problem with the vaccine is that unless the patient is given it near the onset of the virus (1-4 days after the symptoms begin) then there will be too much damage to the human body to repair.

Emergent Virus Infections Factors:

- Population Movements
- Deforestation
- Irrigation
- Urbanization
- Increased long distance air travel
- Increased long distance air travel for livestock
- Migration

An Egyptian stele thought to represent a polio victim, 18th Dynasty (1403–1365 BC)

Following the widespread use of poliovirus vaccine in the mid-1950s, the incidence of poliomyelitis declined dramatically in many industrialized countries. A global effort to eradicate polio began in 1988, led by the World Health Organization, UNICEF, and The Rotary Foundation. These efforts have reduced the number of annual diagnosed cases by 99%; from an estimated 350,000 cases in 1988 to fewer than 2,000 cases in 2006. Should eradication be successful it will represent only the second time mankind has ever completely eliminated a disease. The first such disease was smallpox, which was officially eradicated in 1979.

A SARS-treating hospital in Taiwan.

Both Mainland China and Taiwan were dealing with SARS epidemics at the same time. The People's Republic of China insisted on representing the 23 million Taiwanese people in the WHO by itself and forbid the ROC government's participation.

The ROC claimed that the lack of direct communication with the WHO precluded proper handling of the disease and caused unnecessary deaths on the island.

The ROC further advocated its own seats in WHO and used the case of SARS to illustrate the importance of having Taiwan included in the global health monitoring system. However, the PRC saw this as a politically motivated move towards Taiwanese independence. During the WHO general assembly, the People's Republic of China fiercely snubbed the proposal for Taiwan's participation. Under pressure from the PRC, Taiwan was excluded from several major SARS conferences held by WHO. WHO eventually sent its experts to Taiwan to conduct inspections at the end of the SARS endemic.