About Dhanya V C

Dhanya (M.Sc) is a Senior Research Fellow at the Indian Veterinary Research Institute. A member of the FMD Virus Vaccine Production Unit, she specializes in Medical Microbiology, Biochemistry, Physiology, and Molecular Biology. She has over three years of professional experience.

HIV Test Options – Tips For Diagnosing The Disease

Many people who have been infected with HIV display no signs and symptoms of the infection. The only way to confirm an HIV infection is by doing an HIV test. HIV testing can be done in Sexual health clinics (Genito Urinary Medicine Clinics), contraception and young people’s clinics, or antenatal clinics for pregnant women. Continue reading

The Symptoms of HIV Infection – The Top Danger Signs

The Human Immunodeficiency Virus (HIV) infection may go unnoticed, either because it is devoid of symptoms or shows only a mild, flu-like infection in the early stages. HIV patients may also feel sick for some time and then appear to have recovered completely. It is only when the HIV infection progresses to AIDS (Acquired ImmunoDeficiency Syndrome), the patient develops life-threatening signs that are confirmed symptoms of HIV. Continue reading

Is HIV Treatment Possible? – A Look At The Options In Hand

The Food and Drug Administration has approved antiretroviral therapy as the recommended treatment for the Human Immunodeficiency Virus (HIV) infection. The HIV treatment aims to fight HIV and the complications this virus creates by reducing the viral load in the body, stopping viral replication (multiplication), and restoring the immune functions of the body. Continue reading

The Causes of Influenza – The Primary Causes Explained

Influenza, commonly known as the flu, is an airborne respiratory infection. The causes of influenza are various strains of the influenza virus, which belongs to the family Orthomyxoviridae. These strains are created as the main virus shows high rates of mutations and changes its structure frequently. Humans do not have immunity to the new strains (similar viruses with minor differences) that emerge through such mutations. As a result these recurring processes create pandemics, in which the infection spreads rapidly across continents in a short span of time, causing several deaths and requiring the  hospitalization of many people.

causes of influenza

The type A influenza virus is one of the prime causes of influenza infection.

Causes Of Influenza – The Influenza Virus

The influenza virus is grouped into 3 types – A, B, and C, based on the protein and nucleic acid composition of the virus. Human infection is caused most frequently by the Influenza A type of virus. There are also reports of infection caused by the type B virus, but infection by the type C virus is rare.

Influenza viruses are RNA viruses because their genetic material is RNA. The virus has two protein spikes termed Haemagglutinin (HA) and Neuraminidase (NA). HA plays a major role in the attachment of the virus to human respiratory cells, while NA influences the progression of the infection. 16 HA and 9 NA have been identified till date.

Based on the nature of the HA and NA spikes, influenza viruses are again grouped into various sub types such as H1N1 (Swine Flu), H3N2 (Seasonal Flu), and H5N1 (Bird Flu).

what causes influenza

The reassortment of the influenza virus is what causes influenza in its various forms. The 2009 swine flu pandemic is one such example.

The Source Of The Infection

Wild aquatic birds such as ducks and shore birds are collectively the primary reservoir of the influenza virus. Such birds shed the virus in their excreta, which then acts as the source of infection.The flu virus may mutate and readily jump to species like domestic poultry or swine. The influenza viruses that infect birds and those that infect humans are both capable of infecting pigs. This leads to the mixing up of both the distinct strains, causing an emergence of a new influenza virus which can spread from pigs to humans. This came true during the 2009 H1N1 pandemic, where the pigs acted as the mixing bowl for influenza virus reassortment (mixing up of genes).

The influenza infection is airborne. The virus is transmitted from one person to another  through the air. When an infected individual coughs, sneezes, talks, or spits, the respiratory droplets that carry the virus are exposed to the environment. These viruses then enter the body of another individual through his nose or mouth. Airborne infections can even spread to persons standing up to 6 feet away.

Indirect transmission can also occur in rare cases, when a person’s nose or mouth gets infected by his hands that have already been in contact with contaminated surfaces.

How The Infection Occurs

Once the virus enters a person’s body through his nose, it attaches to the host’s respiratory epithelial cells with the help of the surface protein Haemagglutinin (HA). The virus then travels down the respiratory tract causing much internal damage and finally infects the person’s lungs, leading to pneumonia and bronchitis.

The Life Cycle Of The Influenza Virus Within The Body

Once inside the cells, the influenza virus takes over the host’s body to replicate and produce more viral particles to spread the infection further.

A person infected with influenza sheds the causative virus in his respiratory secretions even before the flu symptoms have manifested. In children, the shedding of the virus can continue for up to 7 days or more.

The Causes Of Influenza – How To Keep The Infection From Spreading

what causes flu

Wear a mask to protect yourself from the influenza virus, which is what causes flu.

If you’ve been infected with influenza, you should take extra care to ensure that you do not unwittingly spread the infection to others. Here are some precautionary measures you can take:

  • Cover your nose and mouth while coughing or sneezing, or wear a mask to cover your nose and mouth at all times during the infection
  • Stay away from your workplace and do not attend any public gatherings when you’re down with the flu. If your child has influenza, do not send him to school or out to play with other kids
  • Wash your hands vigorously with soap and water or with alcohol based hand rubs.

Influenza can cause serious complications and even turn fatal when not diagnosed and treated on time. For this reason, it’s important for you to protect yourself and your family from the causes of influenza, at least by getting the flu vaccine and maintaining high levels of hygiene and sanitation.

The Influenza Vaccine – A Detailed Look at the Preventive Measure

Influenza is an infectious viral disease that can quickly turn complicated, and even fatal. The Advisory Committee on Immunization Practices (ACIP) recommends that the annual influenza vaccine be administered to all people above the age of 6 months. The vaccination should be scheduled before the arrival of the flu season so that there is sufficient time for the body to develop protective antibodies to fight against this dangerous condition. Annual vaccination is the mainstay of preventive measures against influenza.

influenza vaccine

The Live Attenuated Influenza Vaccine comes in the form of a nasal spray.

The Types Of Influenza Vaccine

The Food and Drug Administration (FDA) has licensed two influenza vaccines for use.

  1. The Flu shot (Trivalent Inactivated Influenza Vaccine / TIV)
  2. A Nasal Spray (Live Attenuated Influenza Vaccine / LAIV)

The influenza vaccine is an injectable vaccine that contains a strain of a dead flu virus and it can be administered to anybody older than 6 months. The second type of vaccine contains a live strain of the weakened flu virus (attenuated flu virus) in the form of a nasal spray. It is approved for individuals ranging from 2 years to 49 years of age, except pregnant women. Fluzone, an intradermal influenza vaccine is recommended for adults in the age group of 18 to 64 years.

Within two weeks of vaccination, the body develops antibodies to fight against the flu virus.

The Dosage, Administration, And The Storage Of The Influenza Vaccine

Except the intradermal vaccine, Fluzone, other TIVs should be injected intramuscularly, usually in the arms, and given in one or two doses. The first dose should be given as soon as the vaccine becomes available, to prime the immune system. The second dose, which is administered about four weeks or 28 days after the first dose provides the real protection. TIV is available under different trade names such as Flublok, Flulaval, Fluvirin, Fluarix, Agriflu, Afluria. LIAV is available under the trade name Flumist.

The TIV (injectable) and LIAV (nasal spray) vaccines should be stored at temperatures between 2°C and 8°C, and should not be frozen. LAIV also contains the same formulations as TIV, but is given intranasally. This vaccine is available in a prefilled single-use sprayer container with 0.2 ml of the vaccine. Approximately half of the container (0.1 ml) is administered into one nostril and the second half into the other nostril keeping the recipient in an upright position.

Influenza Vaccine Formulations

The 2012-2013 flu vaccine gives protection against the Influenza A H1N1 2009 pandemic virus, Influenza A H3N2 seasonal strain, and the Influenza type B virus. It is a trivalent (working against three viruses) vaccine formulation.

Influenza viruses undergo constant changes in their structure, as a result of which no vaccine can provide protection from this infection for long. Every year, the World Health Organization (WHO) revises and modifies the formulation of the influenza vaccine according to the influenza virus strain that is circulating in a given geographic area in the specified flu season.

Vaccines should be administered before the flu season, which may start as early as October and reach its peak activity in February. You can get the flu shot administered in clinics, health departments, or pharmacies.

The influenza vaccine is highly recommended for individuals who come under the high risk group, as they are prone to develop serious health conditions related to influenza.

Who Should Be Vaccinated

  • Young children in the age group of 6 months to 5 years of age
  • Adults older than 50 years of age
  • Individuals having health conditions like asthma, diabetes, lung or heart disease, neurologic or hematologic illnesses, or hypertension
  • Individuals with any immuno-compromised condition like pregnancy or HIV infection
  • Those who are taking immunosuppressive drugs
  • Health care workers like laboratory personnel, doctors, and nurses
  • Obese individuals with a Body Mass Index (BMI) of greater than 40
  • Patients undergoing aspirin therapy, who might develop complications due to a flu infection
  • Caretakers of patients having the influenza infection, and others who are in close contact with these patients

Who Should Not Be Vaccinated?

  • Children younger than 6 months old
  • People who are allergic to eggs
  • People who have a history of severe reactions to the influenza vaccine
  • Individuals who suffer from a condition called the Guillian Barré Syndrome, acquired from a  previous influenza vaccination
  • Individuals with a moderate or severe case of the flu, with or without fever
flu shot

Babies under six months of age should not be given the flu shot.

As the influenza vaccine can cause complications when administered to certain people, it is advisable to screen individuals before administering the vaccine, to ensure that the vaccine will not cause the person any harm.

Influenza Vaccine Side Effects

Even though seasonal flu vaccines have very good track records for safety, they can cause adverse effects in some cases. In many cases, mild side effects like nausea, headaches, redness and swelling at the injection site, fever, a runny nose, and muscle aches are observed.

In rare cases, serious adverse reactions like fainting, difficulty in breathing, paleness, and behavioral changes are also reported. If such reactions are observed, the patient should immediately be taken to the doctor. It is a myth that one can get the flu by vaccination, because the viruses in the vaccine are inactivated ones that cannot initiate infection inside the human body.

Getting influenza vaccine shots annually reduces the chances of infection to 60 %, protects you from severe flu-related complications including death, and also reduces the spread of the infection to others. It is considered the best defense against the flu infection.

Flu Symptoms in Children – Identifying the Danger Signs

Flu symptoms in children are commonly exhibited during winter, as this is a communicable condition that spreads rapidly, especially among children.

The Reasons Behind Flu Symptoms In Children

School-going children are at high risk of contracting flu as their immune systems (the defense mechanisms of their bodies) are not fully developed. The infection spreads when they mingle with their already-infected classmates, without taking the necessary precautions. Flu symptoms in children typically begin with high fever (sometimes rising above 103 F or 39.4 °C) and are accompanied by chills.

flu symptoms in children

Flu symptoms in children mainly arise due to their underdeveloped immune systems.

About 20000 children of age 5 are hospitalized in the US every year for flu complications.

Common Flu Symptoms In Children (Above 5 Years Of Age)

Apart from the high fever and chills mentioned above, flu comes with symptoms like dry cough, sore throat, headache, fatigue or tiredness, runny nose, and muscle and joint pain. Nausea, diarrhea, and vomiting are also frequently observed.

In addition to these typical flu symptoms in children, some danger signs may be visible, indicating an emergency. They are:

  • Fever
  • Rash
  • Fast breathing
  • Bluish discoloration of the skin
  • A return of symptoms that seemed to have disappeared
  • Irritability
  • Decrease water intake

Common Flu Symptoms In Children (Below 5 Years Of Age)

Children younger than 5 years of age face a high risk of developing complications, including febrile seizures, when infected with the flu. Asthma, diabetes and any other underlying medical conditions also worsen during flu infection.

In younger children (6 months – 5 years of age), the influenza infection pattern resembles the patterns of infections like croup, bronchitis, and pneumonia.

Danger signs in infants include:

  • Lack of tears
  • Less wet diapers than usual
  • Poor intake of food

In infants, there is a danger that signs may go unnoticed, as they are often non-specific.

If the condition is not treated on time, influenza can induce serious complications and turn deadly, even in the healthiest of children. For this reason, parents are advised to pay close attention to flu symptoms in children and consult a doctor immediately in case they notice any.

The Different Types Of Flu – A Quick Look At The Types

Flu, the short form of Influenza (the virus that causes the flu), is one of the most common infections of the respiratory tract (nose, throat, and lungs). There are different types of flu, and some variants like swine flu and bird flu have been featured prominently in the media due to their sudden outbreaks.

types of flu

You can get vaccinated against different types of flu, to protect yourself from the infection.

The symptoms of flu include cough, sore throat, and fever, and the condition can spread easily from one person to another through air. The severity of the disease may range from mild to severe, and the illness sometimes might even lead to the death of the individual.

The Different Types Of Flu – How It Is Classified

Flu, swine flu, bird flu, or seasonal flu are the variations of this disease that you are sure to be familiar with. The Influenza virus can be classified based on the nucleic acid (RNA) and protein (on its outer coat) composition as Type A, B, and C.

Influenza has two protein spikes haemagglutinin (HA) and neuraminidase (NA) in its outer coat and these form the basis for its further classification (into subtypes) as H1N1 or H3N2 etc.

Given below are the three common types of influenza, and how they can distinguished from one another.

Influenza Type A Virus

Type A influenza viruses are the most virulent (extremely infectious) among the three and cause severe disease. Wild aquatic birds are the natural hosts. The virus can also be found in humans, ducks, chickens, pigs, and whales. It causes global outbreaks and was responsible for the 1918, 1957, 1968, and 2009 pandemics (outbreak of global proportions).


Type A viruses have 16 HA (H1-H16) and 9 NA (N1–N9) subtypes that can occur in different combinations and evolve into new strains. For example, the influenza virus that caused the recent 2009 pandemic was H1N1 (Swine Flu). H stands for HA and N for NA and H1N1 is a subtype of the Influenza Type A virus.

Other examples of Type A Influenza viruses are:

• H1N1–1918 1918 (Spanish Flu)

• H2N2 – 1957 (Asian Flu)

• H3N2 – 1968 (Hong Kong Flu)

• H5N1 – 2004 (Bird Flu)

H7N7, H1N2, H9N2, H7N2, H7N3, H10N7 are other Type A viruses. Only H1, H2, H3, N1, and N2 combinations have infected humans till date, but studies have shown that even H7, H9, and H5 combinations can affect humans.

All possible combinations of surface proteins can infect birds. When a subtype that causes an outbreak in birds emerges, it can colloquially obtain the name Bird Flu. Similarly, the types of flu that target swine are commonly christened swine flu.

Influenza type A viruses are unique because they can change their structure very rapidly (high rate of mutation) and can emerge into new viral strains (same but slightly different organisms), bypassing the immune system’s defence mechanism and causing devastating pandemics.

In short, humans are not entirely protected against the new emerging subtypes of Influenza A viruses, and the chances of acquiring an infection are still high.

different types of flu

Bird flu, one of the different types of flu, is caused by the Type A H5N1 virus.

Influenza Type B Virus

Type B viruses are mostly found in humans, but are less common than Type A viruses. These viruses can also infect seal and ferrets.

Among the types of flu, type B viruses cause local epidemics but not pandemics. They also don’t have subtypes like type A viruses. Although these viruses can sometimes cause severe illness, their mutation rate is slow and for this reason, immunity against this type is usually acquired in early life itself. However, there is no long lasting protection against such infections.

Influenza Type C Virus

Influenza Type C viruses are found in humans, pigs, and dogs. These viruses are less common and cause mild cold-like illness.

Structural Differences Between The Types Of Flu

Basically, the three types of flu have almost similar structures – so much so that it’s hard to distinguish between type A and B viruses even with an electron microscope. Some notable differences between the types have been given below.


Type A: Has three membrane proteins, namely HA, NA, and M2, a matrix protein M1, ribonucleoprotein core (with PA, PB1 and PB2), and NEP/ NS2 proteins.

Type B: Has four envelope proteins HA, NA, NB, and BM2.

Type C: Has HEF protein (haemagglutinin-esterase-fusion protein), which has the functions of HA and NA. It has CM2 as the viral envelop protein.

Ribonucleic Acid (RNA)

Type A: RNA has 8 segments

Type B: RNA has 8 segments

Type C: RNA has 7 segments

People often get confused and use the term “flu” for any respiratory illness that is caused by a virus. By learning about the types of flu, you’ll find it easier to identify the type of infection and choose the relevant treatment.

Spotting Amoebic Dysentery Symptoms – Signs To Watch Out For

Amoebic dysentery (Amoebiasis) is an infection of the large intestine that is caused primarily by a single celled protozoan parasite (amoeba), Entamoeba histolytica. This infection is characterized by amoebic dysentery symptoms, which range from general weakness to stomach ache and severe diarrhea.

dysentery symptoms

Ingestion of contaminated water is one of the most common dysentery symptoms.

Over time, the infection worsens and patients usually pass stool that is laced with blood and mucus, with other complications like mild fever and abdominal pain. The infection is mainly acquired through the ingestion of food or water that’s contaminated with the causative organism. The disease presents itself as mild or often asymptomatic (without any symptoms) in a majority of the cases. If dysentery diagnosis and treatment are not done at the right time, the condition can turn life threatening and in about 20 % of the cases, it does.

Once the organism invades the intestine, amoebic dysentery symptoms appear after an incubation period of 7 to 28 days. This may vary from a few days to even months.

The Two Stages Of Amoebic Dysentery Symptoms

Mild Amoebic Dysentery Symptoms

Most affected individuals start experiencing certain mild amoebic dysentery symptoms during the early stages of the disease. It is important that these signs are noted immediately, so that you can consult a physician at the earliest possible instance.

The early symptoms of amoebiasis include:

  • Nausea
  • Loose stools
  • Stomach pain
  • Loose bowel movements with rectal pain
  • Stomach cramping
  • Lack of appetite
  • General weakness

Severe Amoebic Dysentery Symptoms

Blood and mucus (pus) stained feces is an indication of severe amoebic dysentery. This symptom is presented when the parasite multiplies enough to cause ulcers or localized lesions in the large intestine.

The organism may break through the intestinal wall, causing amoebic colitis (inflammation of the colon). Severe disease is associated with abdominal pain and massive diarrhea, with the constant loss of fluid inevitably leading to dehydration. Patient may need to relieve their bowels 10 – 20 times, and streaks of blood will be visibly present in such stool. Other symptoms at this stage include:

  • Fatigue
  • Excessive gas and abdominal bloating (flatulence)
  • Weight loss
  • Anemia
  • Foul smelling stool
  • Intermittent diarrhea and constipation
  • Indigestion
  • Abdominal swelling and tenderness
  • Rectal bleeding
  • Localized perforation
  • Appendicitis
symptoms of dysentery

Appendicitis is one of the symptoms of dysentery. It occurs in severe cases of the infection.

Extra Intestinal Amoebic Dysentery Symptoms

In rare cases, the causative organisms invade the blood and are carried to other organs of the body, leading to the formation of abscesses (swollen areas within body tissue, containing an accumulation of pus). Such abscesses mainly occur in the liver but may also extend to adjacent areas like the cardiac region. Brain abscesses and genitourinary diseases may also result due to complications.

Symptoms at this later phase include:

  • Fever
  • Chills
  • Nausea
  • Vomiting
  • Weight loss
  • Dry painful cough
  • Pain in the upper right part of the abdomen
  • Hepatomegaly (enlarged liver)
  • Jaundice

Amoebic dysentery symptoms are easy to miss during the early stages. For this reason, it’s doubly important to consult a physician immediately once the primary symptoms manifest.

Are You Prone To Amoebic Dysentery Symptoms?

Amoebic dysentery symptoms are commonly noted in certain regions, and there are many risk factors associated with the disease. People who can contract the disease are:

  • HIV/ AIDS patients
  • Post-transplant patients
  • Travelers who visit developing countries or tropical regions, where amoebic dysentery is prevalent
  • Mentally challenged individuals with poor personal hygiene
  • Underdeveloped or developing countries, where proper sanitary measures are inadequate
  • Heterosexuals/Homosexuals who practice anal intercourse
  • The use of corticosteroid medication
  • Malnutrition
  • Cancer
  • Alcoholism

The disease is communicable as long as the organism is excreted in the feces of infected individuals. Some chronic carriers often act as potential dysentery causes by excreting the organism for years without showing any clinical symptoms otherwise. Usually, it is amoebic dysentery symptoms that dictate how critical the case is and what form of amoebic dysentery treatment is ideal for that particular case.