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Part Three


Health is a state of complete physical, mental and social well – being and not merely the absence of disease or infirmity.

-World Health Organization

Chapter – 4

Preventing Infections 

Infections are caused by microorganisms – including bacteria, viruses, and protozoa (worms) – that can invade the body and multiply inside.  Out immune system attacks them with white blood cells and antibodies.  The symptoms we have from infections – such as fever, pain and redness, swelling – are the result of immune – system response.

The steps you need to take to prevent an infection depend on how the infection is spread.

Food borne illnesses

Unsafe food, (containing harmful bacteria, viruses, parasites or chemical substances), causes more than 200 diseases (WHO) – ranging from diarrhea to cancer.  It is estimated that one in ten people in the world – fall ill after eating contaminated food. Diarrheal diseases are the most common illnesses resulting from consumption of contaminated food.

  • Bacteria
  • Salmonella, Campylobacter and E-coli are the moist common bacteria that infect millions of people. They cause nausea, vomiting, diarrhea, abdominal pain and fever.  Salmonella comes from raw egg, poultry and other products of animal origin.  Campylobacter infections are mainly caused by raw milk, raw or under cooked poultry and contaminated drinking water. E.coli is associated with unpasteurized milk, contaminated water, under cooked meat and fresh fruits and vegetables.  coliis found in human and animal feces and urine.
  • Listeria

Listeria is found in unpasteurized dairy products.  Listeria infection leads to abortion in pregnant women or death of new born babies.

  • Vibrio Cholera

Cholera bacteria infect people through contaminated water or food.  Symptoms include abdominal pain, vomiting and profuse watery diarrhea, which may lead to severe dehydration and death.

  • Viruses

Norovirus, Rotavirus, Norwalk virus and other viruses can cause nausea, explosive vomiting, watery diarrhea and abdominal pain.  Hepatitis A can cause jaundice and liver disease.  These viruses typically spread through raw or under cooked food.  Infected food handlers are often the source of food contamination.

  • Parasites

Some parasites such as Entamoeba histolytica (amoeba) or Giardia enter the food chain via water or soil and can contaminate fresh produce.  Tape worm, round worm may infect through water, or fresh produce or direct contact.

Rotavirus and E-coli are the two most common agents of diarrhea in developing countries.


  • Safe drinking water.
  • Improved sanitation – no outdoor defecation.
  • Hand washing with soap and water – before handling food.
  • Drinking and eating only pasteurized milk products.
  • Eating well cooked food – especial meat and poultry.
  • Washing fruits thoroughly before eating.
  • Washing vegetables well and cooking them well.
  • Refrigerating leftover food promptly. Bacteria can grow quickly at room temperature.

 Common Cold and Flu 

The Common Cold

Sneezing, a scratchy throat, a running nose – everyone is familiar with the first signs of a cold.  Most colds are mild, lasting from one to two weeks.  Children have six to ten cold a year on average.  One reason colds are so common in children is that they are often in close contact with other children in a day care centers and schools.  On average, people older than 60 have fewer cold a year, because of their immunity.  In most countries, most colds occur during the fall and winter.

More than 200 different viruses are known to cause common cold.  Colds always spread from one person to another.  You cannot get cold from exposure to cold weather or from bathing in cold water.  Some research suggests that psychological stress and allergy of the nose and throat can increase the risk for cold.

There is no treatment for cold.  If you treat it will last 7 days and if you do not it will last for a week (it is a common saying among doctors).


Here are some steps you can take to avoid getting cold or passing a cold to others.

  • Wash your hands often with soap and water. When water is not available, use an alcohol based hand sanitizer.
  • Keep your hands away from your eyes, mouth and nose.
  • If you have cold, avoid getting close to people.
  • If you sneeze or cough, cover your nose and mouth, and then wash your hands.

Influenza (Flu)

Influenza or flu for short is a very contagious infection that causes high fever, chills, a dry cough, sore throat, running or stuffy nose, headache, muscle aches, and extreme fatigue.  The flu is more severe and long-lasting than a cold.  It can belife-threatening in infants, older adults and people with respiratory problems such as asthma or chronic bronchitis (COPD).

Flu Types

There are two main types of influenza (flu) virus: Type A and B.  The influenza A and B viruses that routinely spread in people are responsible for seasonal flu epidemics each year.  There are also many subtypes of A and B viruses causing flu.  The viruses also change from year to year – hence some year flu shots are not as effective as they should be.

Influenza Symptoms

The flu is different from cold.  The flu usually comes on suddenly. People who have the flu often feel some or all of these symptoms.

  • Fever or feverish / chills
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Muscle or body aches
  • Headache
  • Fatigue (tiredness)
  • Some people may have vomiting and diarrhea, though this is more common in children than adults.

It is important to note that not everyone with flu will have a fever.

Flu Complications

Most people with flu will recover in a few days to less than two weeks.  Some people can develop complications (such as pneumonia), and some of which can be life – threatening and result in death.  Pneumonia, bronchitis, sinus and ear infections are examples of complications from flu.  The flu can make chronic health problems worse.  For example, people with asthma may experience asthma attacks while they have flu.  People with chronic congestive heart failure may experience worsening of this condition that is triggered by the flu.  Older people, infants and people with certain chronic medical conditions (such as asthma, diabetes, or heart disease) can develop serious flu – related complication and can die from it.


Flu viruses are spread mainly by droplets made when people with flu cough, sneeze or talk.  The droplets can go up to 6 feet.  To avoid flu:

  • Stay away from sick people and stay home if sick.
  • Wash your hands often with soap and water or sanitizer.
  • Keep your hands away from your nose, mouth and eyes if you have flu.
  • If you sneeze or cough, cover your mouth and wash your hands.


Flu viruses change from year to year, which is why you need to take your flu shot every year.  To give your body time to build up immunity, take your flu shot between September and mid-November, before flu season starts.  Side effects from flu shots are mild – soreness, redness, or swelling of the site of the shot.  You should not get the vaccination if you are highly allergic to egg or latex (components of the vaccine).


Pneumonia is an infection of the lungs that can cause mild to severe illness in people of all ages.  It is the leading cause of death in children younger than 5 years of age worldwide.  However, these infections can be prevented with vaccines and can usually be treated with drugs.  Common signs of pneumonia include cough, fever, and difficulty in breathing.  You are more likely to become ill with pneumonia if you smoke or have underlying medical conditions, such as diabetes or heart disease.

Common Causes of Pneumonia

Pneumonia can be caused by viruses, bacteria, and fungi. Common causes of viral pneumonia are influenza and respiratory syncytial virus (RSV).Common cause of bacterial pneumonia is streptococcus pneumoniae.  Pneumonia can also be caused as a result of being on ventilator (respirator – or breathing machine).  This is known as ventilator – associated pneumonia.  Whooping cough, measles, hemophilus, and chickenpox can cause pneumonia in children and lead to death especially among under nourished children.


There are several vaccines that prevent infection by bacteria or viruses that may cause pneumonia.  These are:

  • Pneumococcal
  • HemophilusInfluenza types type-b (Hib)
  • Pertussis (whooping cough)
  • Varicella (Chicken pox)
  • Measles
  • Influenza (Flu)

People older than 65 should get pneumococcal vaccine (once only) and yearly flu shots.  All children should be vaccinated against Hemophilus Influenza (Hib), whooping cough, chickenpox and measles. 


Malaria is a life-threatening disease that is transmitted to people through the bites of infected female mosquitoes.  About 3.2 billion people-almost half of the world’s population – are at risk of malaria.  Young children, pregnant women and non-immune travelers from malaria free areas are particularly vulnerable to the disease.  Malaria is preventable and curable.

Causative Agent

Malaria is caused by Plasmodium parasites.  The parasites are spread to people though the bites of infected female Anopheles mosquitoes, called “malaria vectors”.  There are five parasites species that cause malaria in humans.  Two of these species – P. falciparum and P. Vivax – pose the greatest threat.  P. falciparum is the most prevalent in African continent.  It is responsible for most malaria – related death globally.

  1. Vivax has a wider distribution and predominates in many countries outside of Africa – Asia. SE. Asia, South America.


Malaria is an acute febrile illness.  Symptoms appear 7-15 days after the infective mosquito bite.  The first symptoms – fever, headache, chills and vomiting – may be mild and difficult to recognize as malaria.  If not treated within 24 hours, P. falciparum malaria can progress to severe illness, often leading to death.  Children with severe malaria frequently develop severe anemia and / or breathing difficulty.  In adults, multi-organ involvement is also frequent.  Multi-organs failure from malaria can lead to death.

Who is at risk?

In 2015, approximately 3-2 billion people – nearly half of the world’s population – were at risk of malaria.  Most malaria cases and deaths occur in sub-Saharan Africa.  However, people inAsia, Latin America, and to a lesser extent the Middle East and parts of Europe are also at risk (WHO).


Mosquitoes control is the way to prevent and reduce malaria transmission.

Insecticide – treated mosquito nets (ITNs).  Long-lasting insecticidal nets (LLIN) are the preferred form of mosquito nets that should be used by all at risk.

Indoor spraying

Indoor residual spraying with insecticides is powerful way to rapidly reduce malaria transmission.  Its full potential is realized when at least 80% of houses in targeted areas are sprayed.  Indoor spraying is effective for 3-6 months.

Antimalarial Medicines

Antimalarial medicines can be used to prevent malaria.  For travelers, malaria can be prevented through chemoprophylaxis (medicine), which suppresses the blood stage of malaria infections, thereby preventing disease.

Many parts of the world, sub-Sahara Africa and India, mosquitoes are being resistance to insecticides.  The use of 2 different insecticides in treating mosquito net is being recommended for these areas.

Diagnosis and Treatment

Early diagnosis and treatment of malaria reduces disease and prevents death.  It also contributes to reducing malaria transmission.  Resistance to anti-malarial medicines is a recurring problem.

Vaccine against malaria

There are currently no licensed vaccines against malaria or any other human parasite.  One research vaccine against P. falciparum is being evaluated in a large clinical trial in 7 African countries.  It seems to be working.


Tuberculosis (TB) is a top infectious disease killer worldwide.  In 2014, close to 10 million people fell ill with TB and 1.5 million died from the disease.  Over 95% of TB deaths occur in low – and middle – income countries.  TB is the leading killer of HIV – positive people.

Tuberculosis (TB) is caused by bacteria (Mycobacterium tuberculosis) that most often affect the lungs.  TB is curable and preventable.

How does TB spread?

TB is spread from person to person though the air.  When people with lung TB cough, sneeze or spit, they propel the TB germs into the air.  A person needs to inhale only a few of these germs to become infected.  People infected with TB bacteria have a 10% life time risk of falling ill.  However, persons with compromised immune systems, such as HIV/AIDS, malnutrition or diabetes, or smokers, have much higher risk of falling ill.  People with active TB can infect 10-15 other people though close contact over the course of a year.

About one-third of the world’s population has latent TB, which means; they have the TB bacteria but are not (yet) ill.  They cannot transmit the disease.

Who is most at risk?

  • People who are immune compromised like HIV/AIDS.
  • All households’ members and co-workers of a TB patient.
  • Children, especially malnourished one.
  • Tobacco smokers
  • People with diabetes.

Symptoms and diagnosis

  • Cough with sputum and blood at times.
  • Chest pains
  • Weakness
  • Weight loss
  • Fever and night sweats

A trained laboratory technician can look at the sputum samples under a microscope to see TB bacteria and can make the diagnosis.  Chest x-ray can also help in the diagnosis.  The diagnosis can be made within 24 hours, but this test does not detect numerous cases of less infectious forms of TB.  Tuberculosis is particularly difficult to diagnose in children.


TB is a treatable and curable disease.  Active non drug resistant TB is treated with a standard 6 months course of 4 drugs.  The vast majority of TB cases can be cured when medicines are provided freely and taken properly.  Disease caused by standard drug resistance TB bacteria (MDR-TB) is treatable and curable by using a second line of drug.

Sexually Transmitted Disease (STDS)

Sexually transmitted diseases or infections (STD or STI) are contagious infections that can be passed from person to person through sexual intercourse or other sexual contact, including oral and anal sex.  Many of the organisms that transmit STDs can live on the penis, vagina, anus, mouth, and nearby skin surfaces.  Some STDs can also be transmitted through non sexual contact with infected tissues or fluids, such as infected blood.  For example, intravenous drug users can acquire HIV or hepatitis B from sharing needles.  HIV and hepatitis B can also be transmitted from the mother to a fetus during pregnancy.

Causative Agents

More than 30 different bacteria, viruses and parasites are known to be transmitted through sexual contact.  Of these 8 infections, 4 are curable: syphilis, gonorrhea, chlamydia and trichomoniasis.  The other 4 are viral infections and are not curable: hepatitis B, herpes simplex virus (HSV or herpes), human papilloma virus (HPV) and HIV. Symptoms or disease due to the incurable viral infections can be reduced or modified through treatment.


A person can have STDS without having obvious symptoms of disease.  Common symptoms of STDS are:

  • Vaginal discharge.
  • Urethral discharge or burning in men
  • Genital ulcers
  • Abdominal pain


STDs can have serious consequences beyond the immediate impact of the infection itself.

  • Mother to child transmission can result in still birth, premature birth, new born death, infection and congenital deformities.
  • STDs can increase the risk of HIV infections.
  • STDs such gonorrhea and chlamydia are major causes of pelvic inflammatory disease (PID) and infertility in women.
  • Human papilloma virus (HPV) infection causes cervical cancer – and death in women and mouth and throat cancer in both men and women.


  • Don’t have multiple sex partners. Having multiple sex partners exponentially raises your risk of STDs.
  • Use condom (male or female) from start to finish of sexual activity.
  • Don’t have sex with intravenous drug users – risk of hepatitis B and HIV are very high.
  • Be in a committed relationship and know the STD status of your partner.
  • Take precaution during pregnancy.
  • Tests for STDs are inexpensive and are easily available. Effective treatment is currently available for several STDs. If in doubt get tested.

You cannot avoid STDs by washing your genital area, urinating, or douching after sex.  Keep in mind that you can still acquire and transmit STDs, even if you use a condom, because a condom does not cover the surrounding skin areas.


Human Immunodeficiency Virus (HIV) causes AIDS (Acquired Immuno Deficiency Syndrome). HIV virus attacks the cells of the immune system, leaving a person vulnerable to life-threatening infections and cancers.  Without treatment, AIDS is usually fatal.  HIV continues to be a major global public health issue, having claimed 1.6 million lives in 2014.


HIV can be transmitted via the exchange of a variety of body fluids from infected individuals, such as blood, semen and vaginal secretions and breast milk. Individuals cannot become infected though ordinary day to day contact such as kissing, hugging or shaking hands. 

Risk Factors

Behaviors and conditions that put individuals at greater risk of contracting HIV include:

  • Having unprotected oral or vaginal or anal sex.
  • Having STDs such as syphilis, herpes, gonorrhea, and chlamydia.
  • Sharing contaminated needles, syringes.
  • Receiving unsafe injections, blood transfusions, medical procedures that involve unsterile cutting or piercing.
  • Experiencing accidental needle stick injuries – including among health workers.


Most individuals develop antibodies to HIV within 28 days but antibodies may not be detectable early after infection.  HIV infections can be detected with great accuracy after 28 days.


Individuals can reduce the risk of HIV infection by limiting exposure to risk factors.

  • Male and Female Condom use. Male latex condoms have 85% or greater protective effect against HIV and other STDs.
  • Testing and counseling for HIV and STDs.

Testing for HIV and other STDs is strongly advised for all people exposed to any of the risk factors.  By getting tested people learn their own status and seek necessary treatments.  TB is the most common presenting illness among people with HIV.  Early detection of TB and prompt treatment for both (TB + HIV) will save life.

  • Male Circumcision

Medical male circumcision, when safely done, reduces the risk HIV infection in men by 60%.

  • Antiretroviral treatments(ART) use for prevention

Pre-exposure prophylaxis (PREP) is the use of ART drugs within 72 hours of exposure to HIV in order to prevent infection.  It works.

  • Elimination of mother-to-child transmission of HIV

The transmission of HIV from an HIV-positive mother to her child during pregnancy, labor, delivery or breastfeeding is called vertical transmission or mother-to-child transmission (MTCT).  Mother to child transmissioncan be prevented if both the mother and the child are treated with ART.

  • Safe needle use

People who inject drugs (addicted drug users) can take precautions against becoming infected with HIV by using sterile needles and syringes.

Between 2000 and 2015, new HIV infections have fallen by 35% and AIDS – related death have fallen by 24%.


A number of viruses can cause hepatitis.  Hepatitis is an inflammation of the liver. 

Hepatitis – B

Hepatitis B is a viral infection that attacks the liver and can cause both acute and chronic liver disease.  The virus is transmitted through contact with the blood or other body fluids of an infected person.  It is a major global health problem.  It can cause chronic infection and puts people at high risk of death from liver failure and liver cancer.  An effective vaccine against hepatitis B has been available since 1982.


The hepatitis B virus can survive outside the body for at least 7 days.  The incubation period of hepatitis B virus is 75 days on average, but can vary from 30 to 180 days.  The virus may be detected within 30 to 60 days after infection.  Hepatitis B is transmitted the following ways:

  • Mother to child at birth.
  • Expose to infected blood – blood transfusion.
  • Various body fluids – blood, saliva, menstrual, vaginal, and semen (sexual).
  • Use of infected needles, syringes and unsterilized medical instruments.
  • Infection can occur during medical, surgical, dental procedures, tattooing or razors.


In many cases, a hepatitis B infection produces no symptom.  However, some people have acute illness with symptoms that last several weeks.  They can include jaundice (yellow discoloration of skin and eyes), feeling tired, loss of appetite, nausea, abdominal discomfort, dark urine, gray – colored stools, and joint pain.  More than 90% of healthy adults who are infected with the hepatitis B virus will recover naturally from the virus within the first year.


It is not possible to differentiate hepatitis B infection from other forms of hepatitis.  However a number of blood tests are available to diagnose and monitor people with hepatitis B.  They can be used to distinguish between acute and chronic infections.


There is no specific treatment for acute hepatitis B.  Chronic hepatitis B infection can be treated with antiviral drugs.  Treatment can slow the progression of liver damage (cirrhosis), reduce incidence of liver cancer and improve survival.  However, in most people, the treatment does not cure hepatitis B infection.  The treatment is life-long and very expensive.

Prevention – Vaccination

The most effective way to prevent hepatitis B is to have the hepatitis B vaccination.  The three-dose vaccine is 95% effective in preventing infection and the development of chronic liver disease and liver cancer due to hepatitis B.  The vaccination is recommended for all infants and children, and adults who are at risk (such as health care workers) for hepatitis B infection. Using latex condoms correctly and consistently may help reduce the risk of transmission during sexual activity.

Hepatitis A

Hepatitis A is viral liver disease that can cause mild to severe liver disease.   The hepatitis A virus is transmitted through ingestion of contaminated food and water or through direct contact with an infected person.  Most people recover fully from hepatitis A.  Unlike hepatitis B and C, hepatitis A infection does not cause chronic liver disease and rarely fatal.  The disease is common in all the developing countries.


The hepatitis A virus is transmitted primarily by the fecal-oral route; that is when an uninfected person ingests food or water that has been contaminated with the faces of an infected person.  Water borne out breaks, though frequent, are usually associated with sewage – contaminated or inadequately treated water.  The virus can also be transmitted through close physical contact with an infectious person.  Casual contact among people does not spread the virus.


The incubation period (that is the time between the infection and the start of the symptom) of hepatitis A is usually 14-28 days.  Symptoms of hepatitis A range from mild to severe, and can include fever, malaise, loss of appetite, nausea, abdominal discomfort, jaundice (a yellowing of the skin and whites of the eyes and dark – colored urine.  Not everyone who is infected will have all of the symptoms.  Infected children under 6 years of age do not usually experience noticeable symptoms, and only 10% develop jaundice. 

Who is at risk?

Anyone who has not been vaccinated or previously infected can contract hepatitis A.  Risk factors include:

  • Poor sanitation;
  • Lack of safe water;
  • Living in a household with an infected person;
  • Being sexual partner of someone with acute hepatitis A infection;
  • Travelling to areas where hepatitis A is common;
  • Being a child or worker in a day care center.


Cases of hepatitis A are not medically distinguishable from other types of acute viral hepatitis.  Diagnosis can be made by detection of hepatitis antibodies in the blood.


The spread of hepatitis A can be reduced by:

  • Adequate supply of safe drinking water.
  • Proper disposal of sewage within communities and
  • Personal hygiene such as regular hand-washing with uncontaminated water.


Several hepatitis A vaccines are available.  The two-shot vaccination against hepatitis A is quite effective.  All people at risk or all people travelling to countries where hepatitis A is common should get the vaccine.

Hepatitis C, D and E

Hepatitis C is spread through blood and blood products and contaminated needles.  The majority of people with acute hepatitis C are without symptoms.  The hepatitis D virus survives and multiplies by attaching itself to the hepatitis B virus. It is common in drug users. Hepatitis E is a food – borne virus similar to hepatitis A.  It is common in Asia and South America.


Saheb Sahu, M.D., F.A.A.P., MPH.


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