Communicable and Non-communicable Diseases

A disease is an illness. A person is said to be diseased or ill if he or she is physically, emotionally and socially unfit or not healthy. Each disease can be classified into the two categories of communicable and non-communicable diseases. Communicable diseases are those which can be transmitted via touch, sharing of body fluids etc. while non-communicable diseases cannot spread from one person to another by such means.

Communicable Diseases

We have often heard elders ask us to avoid contact with people who have cough or cold. In case we come in contact with them, we are asked to clean our hands with soap, wash our face and clear our nasal passage. Cough and cold is an allergic reaction to a foreign body in our system. The foreign body may be pathogenic or dust. Cold is caused by a virus called Rhino virus. It has more than thousand different strains, each capable of infecting the human body. To avoid the entrance of this virus in our system, we avoid contact with body fluids of the infected person.

Causal Factors of CD

The term infectivity describes the ability of an organism to enter, survive and multiply in the host, while the infectiousness of a disease indicates the comparative ease with which the disease is transmitted to other hosts. A wide variety of microbes is present in nature though all of them are not capable of causing diseases in a healthy human body. Few of them cause infection by the interplay between their genome and the defense of the host that they infect. These pathogenic microbes are divided into two categories- primary pathogens and opportunistic pathogens.

  • Primary Pathogens: these cause diseases as a result of their presence in the human body. The extent of the disease depends on their inherent virulence or disease causing capacity. Most of these pathogens are specific to humans and affect them only as a part of their reproduction cycle. Some others can be obtained via exposure to infected animals too.
  • Opportunistic Pathogens: these microbes can cause disease only in patients whose immune response is suppressed. They may be introduced to the body via surgical wounds, environmental exposure or may already be present in the body in the gastrointestinal or upper respiratory tract. These cause infection only when the host’s defenses are depressed. This depression may be caused due to trauma, intake of immune-suppressant drugs (such as are used during cancer treatment), exposure to ionizing radiation or being pre-infected by an immune system attacking pathogen such as HIV.

Transmission of CD

Transmission of a communicable disease can take place via various means. Respiratory diseases and meningitis are caused by being exposed to aerosolized droplets of infected body fluid released by sneezing, coughing, spitting, talking, kissing and singing. Gastrointestinal diseases are caused by consumption of contaminated food and water. Sexually transmitted diseases are transmitted via direct exchange of body fluids during sexual activity. Disease may also spread by coming in contact with an inanimate object like a coin which was exposed to the infected person’s body fluid. At times, transmission requires the aide of vectors. These vectors are biological. In such cases, the pathogen completes a phase of its life inside the body of the vector before being communicable diseasestransmitted to the host. Inside the vector, the microbe does not cause infection or harm while in the host, it reproduces and causes infection.

Major CD events of the world

‘Typhoid Mary’ a.k.a. Mary Mallon, a cook by profession was an asymptomatic carrier of typhoid disease. Over the course of her career, through her cooking she unknowingly infected 53 people of whom 3 died.

The Plague of Justinian killed about 55% of the European population while the Black Death killed almost 25 million people (world population at that time was only 500 million).

Till 1918, one in six deaths in France was caused by Tuberculosis. In the same year, the Spanish flu also created massive number of deaths. Today influenza kills 0.25 to 0.5 million people each year.

Smallpox killed an estimated 60 million Europeans during the 18th century (approximately 400,000 per year). Up to 30% of those infected including 80% of the children less than 5 years of age died from the disease and one-third of the survivors went blind.
The following is a table showing worldwide mortality rate caused due to infectious diseases.

mortality rate caused due to infectious diseases.

Diagnosis of Communicable diseases

CDs are diagnosed by a preliminary examination and a record of the patient’s medical history. This is performed by a medical specialist. Further, microbes from body fluids of the patient (including blood and urine) are separated and examined via various techniques. Also, techniques such as PET scans and MRI scans can be useful for judging the amount of internal damage caused to a person’s body by the growth of pathogen within it.

Non-communicable Diseases

A non-communicable disease cannot be transmitted from one person to another via direct or vector contact. These diseases may be of chronic nature or cause rapid deaths as in strokes. They include heart illnesses, cataract, autoimmune disorders, some cancers, osteoporosis etc.. Though most NCDs are chronic, all chronic diseases (such as HIV-AIDS) are not NCDs. They are mostly a product of the person’s lifestyle. Maximum deaths are caused by NCDs worldwide. In 2008, 63% of the global death rate was contributed to by these. It is estimated that by 2030, number of deaths due to these diseases will increase to 52 million per year.

Common Non-communicable disease

Cancer is the most common NCD which causes maximum number of deaths in the world. It is the rapid proliferation of a tissue to form a tumor such that it might not be healthy for the body to have it. There are over 200 different types of cancer. Depending on the stage of detection, cancer may or may not be treated. Some cancers can even be treated in the last stage of detection. Main aim for medical professionals is to provide care and quality of life to patients.

Cardiovascular diseases are always of research interest in biomedical sciences. It has been established that there is a direct link between consumption of fast food and this diseases. Many fast food chains have responded to this study positively and have introduced healthier items on their menu.

Diabetes mellitus  is also a growing NCD which is largely preventable but not easily curable. With proper exercise, nutritious diet and cautious maintenance of blood sugar levels (euglycemia), diabetes can be avoided. Insulin medication is given for type 1 diabetes. Type 2 will require oral medication though insulin may be given too.

Chronic Kidney Disease (CKD), cardiovascular diseases and diabetes occur in close association due to common causal and risk factors. CKD is not currently on the list of WHO’s NCD protection drive but it should be added soon due to its associates. Hypertension is a common cause and result of all three.

Causal Factors of NCD

Causal and risk factors include a person’s background and lifestyle i.e. genetics, sex, unhealthy diet, smoking, physical inactivity, hypertension, obesity etc.. Environment may also be held responsible for the occurrence of many diseases due to pollutants present in them which may cause occupational diseases too. Genetic disorders are inherited from parents to progeny or offspring. They may be chromosomal anomalies or mutations (Down syndrome, Hemophilia).

Prevention and Precautions

All communicable and non-communicable diseases can be avoided by using the following as precautionary measures,

  • Maintain complete hygiene of self and surroundings.
  • Eat a healthy and nutritious diet.
  • Avoid smoking and other narcotics.
  • Avoid drinking alcohol.
  • Exercise regularly.
  • Maintain an optimistic self and be productive.
  • Keep yourself abreast on all common illnesses.
  • Go for regular medical check-ups.
  • Avoid contact with people infected with communicable diseases.