5 Deadliest Viral Infections of the Decade



Viruses are a worldwide menace causing vast number of infections and deaths. The viral infections spread through various modes while direct person-to-person spread remains the worst kind. According to some experts, ‘viruses’ occupy the twilight zone separating the living from the non-living. Viral diseases range from minor ailments like common cold to horrifying diseases like HIV, Rabies, Dengue and Influenza. I will be describing the world’s deadliest viral infections in brief and the common problems associated with them.


Viruses are very different organisms alive on the planet. Every living organism has a proper cellular structure and a nucleic acid (DNA or RNA) in the center which is regulated by certain kind of chemical signals called ‘Enzymes’. This nucleic acid is the main center for multiplication of the cell. Viruses lack Enzymes which is needed for their multiplication; which means that they are devoid of normal process of multiplying themselves on their own. Thus, they do not divide like Bacteria, hence they are unaffected by antibacterial antibiotics and cause severe viral infections.

How do viruses multiply?

Because they lack bio-synthetic enzymes for their multiplication, they depend upon the synthetic machinery of the host (organism they infect) for its multiplication.


Viruses as described, do not multiply of their own due to lack of bio-synthetic machinery in them. Thus they invade the host cell through any of the routes: Blood contact, body fluid contact, Droplet infection, entry through alimentary canal (gut), etc. when they reach their target areas they utilize the host synthetic machinery for their multiplication causing severe viral infections. At this point of time the patient (host) remains asymptomatic. Once a threshold quantity is reached by multiplication, the viruses invade the tissues where they challenge the immunity of the host (patient). Some viral infections cause a suppression of the immune response. Individuals with deficient cellular immunity show a heightened susceptibility to infection by viral infections.


The severity of these viral infections is a total menace. This causes abrupt infectious disease of the lungs which may range from sporadic (single cases) to a mass epidemic (involving a major area) or even a pandemic (involving a subcontinent or a big portion of the entire world). This virus is capable of producing wide variety of lung infections due to its ever changing genetic nature called as ‘Antigenic Variation’ in Microbiology world. This is very similar to ‘Variation’ described in one of my earlier post named ‘7 Secrets of Cancer.’ It causes all kinds of ‘Flu’ infections namely; Common Flu, Bird Flu, Swine Flu, SARS, etc. This is due to its various serotypes capable of undergoing variation in their genetic sequence and returning back to infect with a new serotype unaffected by previous Anti-Influenza drugs. It is essential to differentiate Common cold from Influenza infection as latter is lethal.





This virus multiplies rapidly inside the body and presents mainly as severe lung infection. The major complications produced by this infection are: Pneumonia, Heart failure (CHF) and Encephalitis (Brain tissue infection). Though these complications do not arise commonly in healthy subjects, but the infection is aggravated in presence of underlying problems (pre-existing lung infections, heart problems) and extremes of age (newborn, geriatric age group).

Oseltamivir and Zanamivir are the latest drugs being used for the prevention and treatment of severe Influenza viral infections.


Swine-Flu-PreventionKEY POINTS:

  • Persistent cough, uneasiness in chest, high grade fever and severe malaise and body ache is a sign of high probability of Influenza infection. Immediately consult your Physician in case of arising symptoms of these viral infections. Patients of extremes of age should consider these symptoms as the alarming.
  • When clinically suspected, treatment should not be withheld while awaiting for the test results.
  • Oseltamivir is associated with neurologic side-effects in children.
  • Super infection with bacteria can result in severe Pneumonia.
  • Co-administration of Aspirin can result in Reye’s Syndromme, a fatal complication.


This remains the most deadliest infectious organism alive on the planet and consequently the most serve of all viral infections. The Rabies virus is present in the saliva of dogs, cats, jackals, wolves, foxes, vampire bats and similar species. No human-to-human transmission is noted till now. Patients present with Hydrophobia, Agitation, Insomnia, Depression, Painful spasms of throat and bizarre behaviour. Rabies virus multiplies in the muscles, spreading to the adjacent nerves, travelling in the spinal cord to infect the brain. Death mainly occurs due to complications leading to respiratory arrest.


Current method of prevention and treatment of Rabies viral infections is of two kinds:

  • Pre-Exposure Vaccination – This vaccination is done prior to the bite of the rabid animal.
  • Post- Exposure Vaccination – This vaccination is carried out after the bite of a rabid animal. This is the main treatment of Rabies when exposed to the bite of such infected animal.



  • It is one of the most deadliest virus living on the planet with a very few survivors.
  • It multiplies in the muscles and infects the nerves and brain tissue, thus giving rise to both- Neurological and Psychological symptoms.
  • The only way of prevention and cure is Vaccination which are available in multiple vaccination schedules.
  • Apart from dogs; cats, jackals, foxes and bats also contains Rabies virus in their saliva.



Ebola virus causes haemorrhagic fever and is similar to Marburg virus. This virus is called ‘Ebola’ after the Ebola river in Sudan and Zaire in Africa where the first cases were noticed in 1976. Three years later, in 1979, this viral infections re-emerged in Sudan with serial person to person spread. Case fatalities have varied between 40% to 90% in the previous outbreaks, thus depicting its aggression. The virus is transmitted from the wild animals to humans and spreads by human to human transmission. The symptoms are similar to Influenza infection along with vomiting, diarrhoea and rash. Liver and Kidney functions deteriorate rapidly leading to both internal and external bleeding.


No FDA approved vaccine or anti-viral drug is available for the treatment of Ebola infection. Only supportive care and maintaining basic sanitation care is the mainstay of the treatment. In 2014, Ebola epidemic was the largest in the history affecting many countries in West Africa infecting approximately over 25,000 new cases causing over 10,000 deaths.

who factsheet


  • This is also one of the deadly viruses that cause haemorrhagic fever.
  • The symptoms are similar to Influenza viral infections, but the fatalities are extremely high during the epidemics.
  • There is no known specific treatment. Only treatment is supportive care.


HIV is most searched viral infections on the internet today. The reason behind this is the awareness in the community regarding the disease which was brought by NACO, an NGO fighting for the rights of the patients suffering from HIV/ AIDS. The emergence and pandemic spread of AIDS have posed the greatest challenge to public health in modern times. This disease was first spotted in 1981 in USA when these patients were reported to have an outbreak of two very rare diseases called- Pneumocystic carinii Pneumonia and Kaposi’s Sarcoma. They appeared to have lost their immune competence, rendering them vulnerable to opportunistic infections (Infections that progress due to extremely weak immunity). This virus typically affects the CD4+ cells which are believed to trigger the immune response. Thus, indicating that it directly suppresses the immune system making the patients prone for the other bacterial and viral infections.


HIV is transmitted by contact of blood and body fluids (serum, amniotic fluid, semen, etc.). HIV is primarily a sexually transmitted disease, but other modes of transmission need to be checked. Blood transfusion, Organ and Tissue donation of infected person has the highest chance of infection per exposure. Mother to baby transmission through placenta or through breast milk later carries a high risk of infection to the baby. Similarly, needle sharing by the drug addicts and needle-stick injuries in health care providers impose additional challenge.

What is the difference between HIV+ and AIDS?

Well, to begin with, HIV (Human Immunodeficiency Virus) Positive generally refers to the presence of HIV infection in an individual, while AIDS (Acquired Immunodeficiency Syndrome) is a complex presentation of symptoms which the patient presents in a full blown HIV infection, also called as ARC (AIDS Related Complex). This ARC consists of patients suffering from unexplained fever, fatigue, persistent diarrhea and marked weight loss. Other opportunistic fungal and viral infections present cause severe illness in the AIDS patient and is the end-stage disease.


The diagnosis of HIV infection is a two-step process: ELISA for screening and Western Blot Test as the confirmatory test.  The approaches of treatment of AIDS is a multi-tier therapy which includes: General management of symptomatic problems, preventive therapies against opportunistic infections, Anti-HIV drugs and Immuno-restorative methods.


  • HIV is merely presence of viral infections in the body may or may not be associated with the symptoms of AIDS. This may happen for years when it emerges out as a full blown AIDS in the patient.
  • The HIV is transmitted through three modes: Sexual contact, contact of infected body fluids and mother to baby transmission.
  • HIV infection weakens the immunity thus making the patient prone for opportunistic infections.
  • AIDS is an end-stage disease characterized by severe debility due to multiple infections.


This virus causes severe hemorrhagic fever with kidney failure. It is spread by rodents that shed the virus in their saliva and urine; human gets infected by inhaling the aerosols of these infected fluids. The infection starts with fever, malaise, body ache and gastrointestinal symptoms, rapidly progressing to lung involvement and in severe cases death!


There is no specific cure or treatment of Hanta viral infections. The only treatment remains supportive care. In the early course of this disease the clinical picture is similar to Influenza infection. The only differentiating feature is the history of potential rural rodent exposure.

Haemorrhagic fever with renal syndrome is another severity of the Hanta viral infections. This carries an additional risk of developing Acute Shock and Acute Kidney Failure, leading to sudden death. The treatment is generally supportive. The death rate remains high despite of Critical Care ranging from 20% to 60% in the infected cases.


  • This is a disease transmitted by rodents involving lungs and kidneys leading to rapid lung disease and kidney failure with a high death rate.
  • There is no specific treatment to Hanta virus infection. Only possibility is the supportive care.
  • The clinical picture may mimic infection of Influenza virus.

All the above described viral infections are the most deadliest ones producing millions of infections and causing thousands of deaths worldwide. Keep up with the basic sanitation methods and practice safe sex. Blood transfusion is one major cause of viral infections transmission from donor to the recipient. Spread the awareness, live long and live happy!

Dr Navneet Goyal

Dr Navneet Goyal is an Anesthesiologist Doctor, Internet Entreprenuer, Self-taught Marketer, SEO and a Growth Hacker! He has also learnt Web Designing, Lead Management, Digital Marketing & Financial Planning through various resources. His goal is to enhance the current Education model into a Motivational Driven Self Learning Platform.