Why We Need to Get a Flu Shot Every Year

Waaiz Alam Saad
Freshman
School of Life Sciences
Independent University, Bangladesh

April 13th, 2017

Influenza, which is often referred to as the "flu", is a viral respiratory disease which can cause severe complications and can even lead to death. Every year the influenza outbreak can seriously affect the population. The threat is especially high for children younger than 2 years, adults aged 50 years or older, pregnant women and also people with medical conditions.  The virus has the ability to spread rapidly between workplaces, homes, businesses and schools. Infection can result from inhalation of infected air, direct contact or by coming in contact with contaminated objects.

According to WHO, influenza occurs globally with an annual strike rate estimated at 5%-10% in adults and 20%-30% in children. Therefore, the best method to reduce chances of getting infected is to get vaccinated annually. The vaccine is a biological preparation which contains a dead or weakened strain of a pathogen or its toxin. The body produces defensive proteins called antibodies, which recognize and kill pathogens based on antigens (unique proteins or other molecules) found on or within the pathogen. The body retains memory of the pathogen, and is able to produce antibodies against the actual live pathogen if or when it is encountered.

Mortality from seasonal influenza and pneumonia, a common secondary infection from the flu, 2010-14. CDC

Each year, new vaccines need to be developed for influenza because these viruses are continuously changing and evolving. There are proteins on the surface of the virus called hemagglutinin (HA) and neuraminidase (NA). Our immune system identifies these proteins that are on the viral surface, and generates and produces antibodies against these proteins. The structures of the viral proteins are determined by genes. The genetic code of influenza changes or mutates frequently as it is very prone to copying errors when the viruses reproduce. If, for instance, there is a change in the gene encoding the HA protein, HA might change shape, and then antibodies that normally bind to the previous version of HA will no longer be able to. This would allow the newly mutated virus to evade the immune system. Mistakes or mutations occur randomly, so these changes occur slowly over time in a process known as antigenic drift. The consequence of this is that the virus eventually evolves resistance to any antibody that is common in a population.

Finding the ideal vaccine formula is therefore difficult. Vaccines are developed after careful surveillance and prediction of which strains will be common, and be likely to have an adverse impact, in the next year. Since the virus mutates rapidly, the effectiveness of vaccines can vary; they have been shown to decrease the danger of flu by about 50% to 60% among the overall population during times when most current flu viruses are same as the vaccine viruses. That may not seem like a lot, but if large percentage of the general population is protected by the vaccine, vulnerable individuals are less likely to come into intact with infected individuals. Vaccination therefore protects not only the vaccinated individual, but also others in the population; this is known as herd immunity. This is especially important for individuals who are at higher risk of acquiring severe flu, such as children, the aged, and people with certain chronic health conditions.

Saad is a Freshman at the School of Life Sciences. He plans to work in drug and vaccine development, and towards the improvement of diagnostic tools for infectious diseases.

What Is Dengue Anyway?

Samara Tawziat Choudhury
Sophomore
School of Life Sciences
Independent University, Bangladesh

March 30th, 2017

Every year from the month of July to October my mother goes berserk. She forces me to drink milk and eat eggs and vegetables every day. Now, you may ask - what could possibly push a mother to force feed her 20-year-old? The answer, for reasons I will explain, is dengue. In Bangladesh, at least 700 people are affected by dengue each year. We all have a general idea of what dengue is. A type of severe fever caused by mosquitoes that can, in many cases, lead to death. Well, today I would like to talk about all things dengue.

First and foremost, let us clarify something. It’s not the mosquito that causes the disease. It just acts as a vector, or in simpler words, carries the disease from one individual to another. What causes the disease is a virus known as dengue. Most of us have heard about viruses. But how many of us actually know what a virus is? A virus is a microorganism. Don’t get scared reading the name. It only sounds hard. Its meaning is actually pretty straightforward. “Micro” because it is so small we couldn’t possibly see it without a microscope. And “organism” because even though it is way too tiny for us to even imagine it, it is still very much a living thing.

Aedes aegypti after a blood meal. CDC

Now that we know what causes dengue, let us get back to the involvement of mosquitoes. It is actually a sort of a cycle. A mosquito bites a person infected with dengue and while sucking in the individual’s blood, the virus is also taken up by the mosquito. Many of us don’t know the mechanism of a mosquito bite. A mosquito actually pushes in two needle-like tubes into its victim’s blood vessels through their skin. One tube releases mosquito saliva that makes sure the blood does not clot, so that it can be quickly sucked in by the other tube. An infected mosquito can pass on the virus to a healthy individual through its saliva, and the virus replicates inside the individual. Then another mosquito may bite this person and thus, the cycle continues.

Not all mosquitoes cause dengue. The virus is primarily carried by mosquitoes of the Aedes aegypti species. It can be recognized by the black and white stripes throughout its surface. The symptoms of dengue include sudden, high fever, severe headaches, pain behind the eyes, severe joint and muscle pain, fatigue, nausea, vomiting and a skin rash, which appear two to five days after the onset of fever. In severe cases of dengue, especially with the onset of dengue hemorrhagic fever, the symptoms can also include bleeding or bruising under the skin, cold or clammy skin, nosebleeds, and large drops in blood pressure. This is where it gets serious, and without immediate medical attention, can be fatal.

Finally, I would like to go back to the months I mentioned in the beginning. Mosquitoes tend to lay their eggs in stagnant water because the eggs require water to hatch. In Bangladesh, the months from July to October are usually categorized as the rainy season. In these months, flooding may occur and drainage systems may get all clogged up, providing mosquitoes with the perfect breeding grounds to lay their eggs. Therefore, it is important that dirty water bodies are cleaned out regularly. Also, we should make it a habit to use mosquito repellents and mosquito nets to reduce chances of getting bitten by an infected mosquito. And, in the end, if you want to have a strong immune system to fight the dengue virus, it may not be a bad idea to take my mother’s number one advice- eat healthy as this would better prepare your body to fight infection in the event that it occurs.

Samara dreams of curing diseases and working for the WHO. She also loves to cook, and has a weird wish to be buried in a library so that her soul can read books for eternity.

How Smallpox Was Conquered

Farina Afrin Malik

Freshman

School of Life Sciences

Independent University, Bangladesh

March 23rd, 2017

From the day we are born and sometimes prior to birth, we humans have had one constant companion: disease. However for as long as disease has existed so has our ability to survive despite them. Over the centuries, by sheer perseverance humans have discovered many ways of treating these diseases. We have made great advancements in our methods of treatment and have attained means of curing and preventing innumerable diseases. One such illness that we have actually managed to successfully eradicate is smallpox.

Smallpox is known to be caused by a virulent form of the Variola virus. The symptoms of this disease include small rash-like bumps forming all over the body. Some may confuse smallpox to be chickenpox, as their symptoms are quite similar, but their most distinct difference would be the fatality rate. Smallpox had a 30% death rate, unlike chickenpox which has a less than 1% mortality rate. Smallpox also often resulted in lifelong scarring and disfiguration whereas chickenpox causes mild scarring which would heal with time. 

Public domain

An 18^th century English scientist, Edward Jenner, was the mastermind behind the vaccine; he discovered that milkmaids who were infected with a milder disease called cowpox (a viral disease which commonly occurs in cows) did not suffer from smallpox. He transferred some of the fluid found in the pustules in the skin from the cowpox-infected person to a healthy individual, and later challenged him with smallpox. The disease was effectively prevented, suggesting that exposure to cowpox had somehow made the individual immune to, or protected against smallpox. Edward Jenner coined the term vaccinia to denote cowpox, and this became the origin for the term vaccine.

Since Jenner lived in a time with much more lax ethical standards in society, he was able to carry out human testing. Today however, animal testing of some form is carried out before human trials since it is considered unethical and risky to test on humans first. 

Jenner's original discovery led to the development and standardization of a commercial vaccine against smallpox. To continue the work started by Jenner, many individuals all over the world collaborated to establish The Smallpox Eradication Programme that began its work in 1966. One of their main techniques that helped in conquering this disease was the “ring vaccination” method. This particular form of vaccination involved administering the vaccine to all the individuals living in a radius surrounding an infected person so that the disease would not spread beyond this area. Infected and exposed individuals were isolated or quarantined to minimize spread.

As part of the worldwide eradication effort, the exact same methods of treatment were conducted in Bangladesh during the 1970s, by the American doctor, D.A. Henderson who traveled across the country examining every case of smallpox and preventing it from being spread to neighboring villages. Once all individuals had been vaccinated, he offered rewards to anyone who could bring forth a patient who had acquired smallpox. Near the end of the decade, the disease was declared by the WHO (World Health Organization) to have been successfully eradicated. 

From this success we can gather that with large-scale collaborative effort, it may be possible to replicate this for other pathogens. It is also quite likely that it may happen sooner than we expect, as recent updates state that polio and measles are on the road to eradication as well.

Farina is a Freshman at IUB who aspires to be a biomedical scientist. In her free time, she enjoys delving into the sciences of baking and imaginative fiction.

Revisiting the 2009 Swine Flu Pandemic

Amira Mohammed Ali
Senior
School of Life Sciences
Independent University, Bangladesh

23rd March, 2017

Influenza, commonly known as the "flu", is a disease caused by the influenza virus. The virus is known for its ability to cause pandemics, in which cases of the disease spread across multiple continent. The 1918 Spanish flu pandemic is estimated to have killed up to 50 million people. The virus has resulted in a few more pandemics since then, notably the 1957 pandemic that claimed around 4 million lives worldwide, and most recently the 2009 swine flu pandemic. Influenza virus has several subtypes, and is known to frequently produce new strains. It not only also has the ability to adapt through mutations or random changes in its genetic code, but can also exchange genes with other strains of influenza in cases where two or more strains infect the same individual. Seasonal influenza is very common and occurs every winter throughout the globe, and the new strains we see every year occur mostly as a result of accumulating mutations. The other mechanism of variation, in which exchange of genes can create new, unpredictable strains, resulted in the 2009 H1N1 pandemic strain which had never infected humans before. It was derived from an animal influenza strain, and different from the seasonal H1N1 strains that normally affect humans.

The first infection with this new strain is believed to have occurred in March 2009 in Mexico. Immediately after the first case, suddenly a number of these new H1N1 infection cases were rushed into many clinics across the country. The outbreak received increasing attention as the infection started to spread out to the northern parts of America. The CDC (Center for Disease Control) collected patient samples from infected people, and confirmed the emergence of the new strain. After few weeks of initial emergence of the new virus, it spread to 74 countries causing 29000 cases. The WHO (World Health Organization) declared it a global pandemic. The number of infected patients increased steeply as the winter approached globally.

Intensity map of confirmed cases of 2009 swine-derived H1N1 influenza. Public domain

To tackle the infection, a huge number of antiviral drugs, Oseltamivir and Zanamivir, were released to treat the patients. When existing drug supplies were insufficient and sometimes ineffective in meeting the rapidly increasing demand for treatment, the FDA (Food and Drug Administration) issued emergency use of previously unapproved antivirals and diagnostic tests for the H1N1 strain. Other measures were taken at that time to halt the spread, e.g. by monitoring airports.

After these efforts, the pandemic started to decline from May 2010 and in August 2010, the WHO declared that it was over. Even though the pandemic was over, it had taken more than 18,000 lives (laboratory confirmed) and made many more people sick globally. The WHO then declared a post-pandemic period where people received help to overcome the difficulties they had gone through. To help prevent any such pandemic in the future, the US government and private manufacturers have developed a vaccine in the form of injections (flu shots) and nasal spray, for swine-derived H1N1 influenza virus.

Amira is a wanderer and tries to understand the wonders of life. She wishes to have a lab of her own one day where she will unravel the mystery of life.