• Diseases are abnormal conditions that have a specific set of signs and symptoms.
  • Diseases can have an external cause, such as an infection, or an internal cause, such as autoimmune diseases.
  • Types:



A communicable disease is one that is spread from one person to another through a variety of ways that include: contact with blood and bodily fluids; breathing in an airborne virus; or by being bitten by an insect. Ex: HIV, TB, Malaria etc.,


How do these communicable diseases spread?

Some ways in which communicable diseases spread are by:

  1. Physical contact with an infected person, such as through touch (staphylococcus), sexual intercourse (gonorrhea, HIV), fecal/oral transmission (hepatitis A), or droplets (influenza, TB)
  2. Contact with a contaminated surface or object (Norwalk virus), food (salmonella, E. coli), blood (HIV, hepatitis B), or water (cholera);
  3. Bites from insects or animals capable of transmitting the disease (mosquito: malaria and yellow fever; flea: plague); and
  4. Travel through the air, such as tuberculosis or measles.




  • According to WHO, TB is one of the top 10 causes of death worldwide and the leading cause of death from a single infectious agent (ranking above HIV/AIDS).
  • TB is caused by the bacillus Mycobacterium tuberculosis.
  • The disease typically affects the lungs (pulmonary TB) but can also affect other sites (extrapulmonary TB).
  • India’s TB burden is the highest in the world, followed by Indonesia and China.
  • TB is a disease of poverty, and economic distress, vulnerability, marginalization, stigma and discrimination are often faced by people affected by TB (WHO).


Tuberculosis Signs and Symptoms


·         Latent TB doesn’t have symptoms. A skin or blood test can tell if you have it.

·         Signs of active TB disease include: A cough that lasts more than 3 weeks, Chest pain, Coughing up blood, Feeling tired all the time, Night sweats, Chills, Fever, Loss of appetite, Weight loss.

Tuberculosis Treatment


·         TB is curable and preventable.

·         About 85% of people who develop TB disease can be successfully treated with a 6-month drug regimen.

·         Vaccine/drug: BCG living attenuated bacteria, Antibiotics e.g. streptomycin.

Drug-Resistant TB:


·         Multidrug Resistance TB (MDR): It is TB that does not respond to at least isoniazid and rifampicin (2 of the most powerful first-line drugs).

·         Extensively Drug-Resistant Tuberculosis(XDR-TB): It is resistant to at least four of the core anti-TB drugs. It involves multidrug-resistance (MDR-TB), in addition to resistance to any of the fluoroquinolones (such as levofloxacin or moxifloxacin) and at least one of the three injectable second-line drugs (amikacin, capreomycin or kanamycin).

·         Totally Drug-Resistant Tuberculosis(TDR-TB): TB which is resistant to all the first- and second-line TB drugs.





WHO- End TB Strategy:


·         Vision: A world free of TB with zero deaths, disease and suffering due to TB. o It has three high-level, overarching indicators and related targets for 2035:

Ø  95% reduction in the number of TB deaths compared with 2015.

Ø  90% reduction in TB incidence rate compared with 2015.

Ø  Zero the level of catastrophic costs for TB-affected families.

·         Nikshay: Indian government’s web-based TB case monitoring system.

·         TrueNat: is a new molecular test that can diagnose TB in one hour as well as testing for resistance to the drug rifampicin. Developed by an Indian firm MolBio Diagnostics Pvt Ltd & endorsed by the WHO.



Government interventions to eliminate TB:


·         TB Vaccination has been covered under the ‘Universal Immunization Programme’.

·         Revised National TB Control Programme (RNTCP) released ‘National Strategic Plan to end TB’ framework in 2017 for the control and elimination of TB in India by 2025. The RNTCP is being implemented under the umbrella of the National Health Mission.

·         ‘TB Harega Desh Jeetega Campaign’ by the Ministry of Health to improve and expand the reach of TB care services across the country, by 2022.


National Strategic Plan to end TB in India by 2025

  • It provides goals and strategies for the country’s response to the disease during the period 2017-2025.
  • It targets to eliminate TB five years ahead of the global End TB (by 2030) targets under SDGs to attain the vision of a TB-free India.
  • TB elimination has been integrated into the four strategic pillars of “Detect – Treat – Prevent – Build” (DTPB).



  • Loose, watery stools that occur more frequently than usual.
  • It is primarily caused when there is a reduction in the absorption of fluid by intestines or an increase in the secretion of fluid or speedy passage of stool through intestines.
  • Diarrhoea is classified into two types, namely:
    1. Acute diarrhoea: may last for 2 or 3 days, but not more than a week. It is not a life-threatening condition and can be cured by taking relevant medications.
    2. Chronic diarrhoea: may last for 1 or 2 weeks, but it can last much longer. This is usually due to other underlying gastrointestinal diseases.
  • Symptoms: Loose stools, Vomiting, Nausea, Cramps, The feeling of a bowel movement, Abdominal pain, Fever, Bloody stools (rare cases)
  • Treatment: Generally, acute diarrhoea will recede on its own, within 2 to 3 days without any treatment. But it is advised to consult the physician regardless.



  • Anthrax is a serious infectious disease caused by gram-positive, rod-shaped bacteria known as Bacillus anthracis.
  • Anthrax can be found naturally in soil and commonly affects domestic and wild animals around the world.
  • Affects animals such as cattle, sheep, and goats more often than people. People can get anthrax from contact with infected animals, wool, meat, or hides.
  • Spread: It does not spread directly from one infected animal or person to another; it is spread by spores. These spores can be transported by clothing or shoes.
  • Symptoms: People may experience pain in the chest or muscles, Skin blister, dark scab, Ulcers, fever or malaise, respiratory distress or shortness of breath, coughing, headache, itching, nausea, sore throat, or swollen lymph nodes.
  • Treatment: The standard treatment for anthrax is a 60-day course of an antibiotic. Examples include ciprofloxacin (Cipro) or doxycycline (Doryx, Monodox).
  • The anti-anthrax vaccines available in the market generate an immune response against a Bacillus protein-protective antigen– a protein that helps in the transport of bacillus toxins inside the cells.



  • Leprosyis a chronic, curable infectious disease mainly causing skin lesions and nerve damage.
  • Caused by: bacterium Mycobacterium leprae. It mainly affects the skin, eyes, nose and peripheral nerves.
  • Symptoms include light-colored or red skin patches with reduced sensation, numbness and weakness in hands and feet.
  • Mode of Transmission: Mainly by breathing airborne droplets from the affected individuals. It can be contacted at any age.
  • Treatment: Leprosy can be cured with 6-12 months of Multi-Drug Therapy (MDT). Early treatment avoids disability.
  • Rifampicin and clofazimine are now combined with dapsone to treat multi-bacillary leprosy.


Related Information


·         Leprosy is one of the oldest diseases in recorded history, afflicting humanity since time immemorial. A written account of Leprosy date as far back as 600 B.C.

·         Leprosy is also known as Hansen’s Disease.

·         World Leprosy Day is observed on the last Sunday in January every year. Theme (2020): ‘Leprosy isn’t what you think’.

·         The day was chosen by French humanitarian Raoul Follereau in 1953 to coincide with the anniversary of Mahatma Gandhi’s death on 30th January 1948.

Global Leprosy Strategy 2016–2020: Accelerating towards a leprosy-free world


·         Launched the WHO in 2016

·         Aims to reinvigorate efforts to control leprosy and avert disabilities, especially among children still affected by the disease in endemic countries.

·         The strategy emphasizes the need to sustain expertise and increase the number of skilled leprosy staff, improve the participation of affected persons in leprosy services and reduce visible deformities as well as stigmatization associated with the disease.




  • Caused by the Human Immunodeficiency Virus (HIV).
  • HIV is a lentivirus, which is a sub-classification of the retrovirus. It causes the HIV infection which over time leads to AIDS.
  • HIV demolishes a particular type of WBC (White Blood Cells) and the T-helper (CD4) cells.
  • Unlike some other viruses, the human body can’t get rid of HIV completely, even with treatment. So once a person gets HIV, currently, there is no cure for it.


ELISA (Enzyme-Linked Immunosorbent Assay) TEST:


·         ELISA is a test that detects & measures antibodies in the blood.

·         This test can be used to determine antibodies related to certain infectious conditions.

·         Antibodies are proteins that your body produces in response to harmful substances called antigens.

·         An ELISA test may be used to diagnose: HIV, which causes AIDS, Lyme disease, Pernicious anaemia, Rotavirus, Varicella-zoster virus (which causes chickenpox) and shingles Zika virus.

·         ELISA is often used as a screening tool before more in-depth tests are ordered.

·         NOTE: For the 1st time India has developed(by National Institute of Virology, Pune) an indigenous ELISA test for coronavirus.

Highly Active Antiretroviral Therapy (HAART)


·         HAART is a treatment regimen typically comprised of a combination of three or more antiretroviral drugs.

·         HAART may also be called Anti-Retroviral Therapy (ART) or combination antiretroviral therapy (cART).

·         This combination therapy is primarily indicated to treat Human Immunodeficiency Virus Type 1 (HIV-1) infected patients.

·         A key feature of HAART is the co-administration of different drugs that inhibit viral replication by several mechanisms so that propagation of a virus with resistance to a single agent becomes inhibited by the action of the other two agents.

·         NOTE: Though HAART’s primary goal is to reduce the transmission of HIV-1, HAART is also utilized in the treatment of HIV Type-2. But currently, there is no specific guideline of recommendations for HIV-2 treatment. Instead, HIV-2 management is under HIV-1 guidelines with some modifications.



  • It is a highly infectious viral disease which invades the nervous system and can cause irreversible paralysis within hours.
  • There are three individual and immunologically distinct wild poliovirus strains: Wild Poliovirus Type1 (WPV1), Wild Poliovirus Type 2 (WPV2) and Wild Poliovirus Type 3 (WPV3).



Oral polio vaccine: ·         It consists of a mixture of live attenuated strains of polioviruses of three (now only two OPV 1 and OPV 3) different types of serotypes.
Inactivated Poliovirus Vaccine (IPV): ·         This protects people against all three types of poliovirus.

·         IPV does not contain a live virus, so people who receive this vaccine do not shed the virus and cannot infect others and the vaccine cannot cause disease.


Polio Status in India:

  • India launched the Pulse Polio Immunization Programme in 1995 brought down polio cases from 50,000-100,000 each year in the 80s to zero in 2012.
  • In January 2014, India was declared polio-free after three years on zero cases.
  • India introduced the injectable polio vaccine in the Universal Immunization Programme to reduce chances of Vaccine Derived Polio Virus (VDPV), which continues to happen in the country.



  • Public-private partnership to eradicate polio worldwide
  • It has five partners, the WHO, Rotary International, the US Centers for Disease Control and Prevention, UNICEF, Bill & Melinda Gates Foundation and GAVI, the vaccine alliance.



  • Zika is a viral infection spread by Aedes aegypti
  • In most cases, there are no symptoms. In a few cases, Zika can trigger paralysis (Guillain-Barré Syndrome).
  • In pregnant women, it may cause subsequent birth defects. When present, symptoms are mild and last less than a week. They include fever, rash, joint pain and red eyes.
  • There’s no vaccine or specific treatment. Instead, the focus is on relieving symptoms and includes rest, rehydration and acetaminophen for fever and pain.
  • Aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen should be avoided.



  • Dengue is a viral disease transmitted mainly through female mosquitoes of the species Aedes Aegypti, which thrives in tropical climates.
  • Symptoms include high fever, headache, rash and muscle and joint pain.
  • The disease may develop into a life-threatening dengue hemorrhagic fever, resulting in bleeding, low levels of blood platelets and blood plasma leakage.
  • Recently, Spanish health authorities confirmed the world’s first case of dengue being transmitted through sex.
  • Treatment includes fluids and pain relievers. Severe cases require hospital care. Medication example, Analgesic.



  • Japanese encephalitis is a virus spread by the bite of infected mosquitoes. It’s more common in rural and agricultural areas.
  • Caused by a Flavi Virus that affects the membranes around the brain.
  • A major cause of Acute Encephalitis Syndrome (AES) in India transmitted to humans through bites from infected mosquitoes of the Culex species.
  • Treatment involves supportive care. A vaccine is available.
  • JE vaccination is also included under the Universal Immunization Program.



  • A common viral infection that can be deadly, especially in high-risk groups.
  • The flu attacks the lungs, nose and throat. Young children, older adults, pregnant women and people with chronic disease or weak immune systems are at high risk.
  • Symptoms include fever, chills, muscle aches, cough, congestion, runny nose, headaches and fatigue.
  • Treatment: Flu is primarily treated with rest and fluid intake to allow the body to fight the infection on its own.
  • There are four species of Influenza Virus viz. Influenza-A, Influenza-B, Influenza-C, and Influenza-D.
  • Human influenza A and B viruses cause seasonal epidemics of disease (known as the flu season).
  • Influenza type C infections generally cause mild illness and are not thought to cause human flu epidemics.
  • Influenza D viruses primarily affect cattle and are not known to infect or cause illness in people.
  • The common Influenza outbreaks caused by Influenza-A strains include
    1. H1N1 (Swine Flu)
    2. H5N1, H5N8, H2N9 (Bird Flu)



  • Zoonotic virus (it is transmitted from animals to humans)
  • Transmission: Nipah virus can be transmitted to humans from animals (such as bats or pigs), or contaminated foods and can also be transmitted directly from human-to-human.
  • Symptoms: (similar to that of influenza) fever, muscle pain, and respiratory problems.
  • Inflammation of the brain causing disorientation.
  • There are currently no drugs or vaccines specific for Nipah virus infection.



  • Coronaviruses are a large family of viruses that circulate among a range of animals, such as bats, cats, and birds.
  • The virus causes respiratory and gastrointestinal symptoms in humans with infectious diseases ranging from the common cold to more severe diseases such as Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS) and CoVID-19.



  • The SARS coronavirus is thought to have evolved from bats to civet cats to humans in the Guangdong province of southern China in 2002.
  • The MERS coronavirus evolved from bats to camels to humans in Saudi Arabia in 2012.
  • The CoVID-19 virus was first identified in Wuhan (Hubei province), China in 2019


Coronavirus Disease 2019 (COVID-19)

  • COVID-19 is an infectious disease caused by a newly discovered coronavirus. COVID-19 is a Zoonotic disease.
  • Symptoms: mild to moderate respiratory illness and recover without requiring special treatment. Older people and those with underlying medical problems like cardiovascular disease, diabetes, chronic respiratory disease, and cancer are more likely to develop serious illness. (WHO)
  • Vaccine: Currently under development. Few approved drugs include Pfizer (USA), Covaxin, Covishield (India).



  • Hepatitis refers to an inflammatory condition of the liver.
  • It’s commonly caused by a viral infection, but there are other possible causes of hepatitis. These include autoimmune hepatitis and hepatitis that occurs as a secondary result of medications, drugs, toxins, and alcohol.
  • Hepatitis Types:
  • Hepatitis B and C can cause chronic hepatitis and are responsible for 96% of overall hepatitis mortality.
  • Hepatitis A and E usually cause acute hepatitis.
  • Note: Hepatitis D infections occur only in those who are infected with Hepatitis B Virus.
  • There are vaccines to prevent Hepatitis A, B and E. However, there is no vaccine for Hepatitis C.
  • Nobel Prize for Medicine or Physiology, 2020 for the discovery of the Hepatitis C virusHarvey J Alter, Charles M Rice and Michael Houghton.


National Viral Hepatitis Control Program

  • It aims to reduce morbidity and mortality due to viral hepatitis.
  • Vision: Ending viral hepatitis as a public health threat by 2030 in the country.



  • Also called Ebola Hemorrhagic Fever, caused by Ebola virus that causes severe bleeding, organ failure and can lead to death.
  • Humans may spread the virus to other humans through contact with bodily fluids such as blood.
  • Initial symptoms include fever, headache, muscle pain and chills. Later, a person may experience internal bleeding resulting in vomiting or coughing blood.
  • Treatment is supportive hospital care like oxygen therapy, IV fluids.
  • Medication: Blood transfusion.




  • Malaria is a disease caused by a plasmodium parasite, transmitted by the bite of infected female Anopheles
  • Symptoms are chills, fever and sweating, usually occurring a few weeks after being bitten.
  • Treatment includes antimalarial drugs.



  • World’s first vaccine against a parasitic disease: Mosquirix
  • Recently, Algeria and Argentina have been officially recognized by the WHO as malaria-free.
  • WHO’s E-2020 initiative: It is part of the Global Technical Strategy for Malaria 2016-2030 endorsed by WHO which aimed to dramatically lower (or eliminate) the global malaria burden over these 15 years.



  • It is a neglected tropical disease affecting almost 100 countries including India, caused by infection with Leishmania parasites.
  • Also known as Dumdum fever. It spread through sandfly bites.
  • Symptoms: some people have no symptoms. For others, symptoms may include fever, weight loss and swelling of the spleen or liver.
  • There are three types of leishmaniasis:
    1. Visceral leishmaniasis, which affects multiple organs and is the most serious form of the disease.
    2. Cutaneous leishmaniasis, which causes skin sores and is the most common form.
    3. Mucocutaneousleishmaniasis, which causes skin and mucosal lesions.
  • Visceral leishmaniasis which is commonly known as Kala-azar in India is fatal in over 95% of the cases if left untreated. This type of leishmaniasis affects the internal organs, usually the spleen, liver and bone marrow.
  • Medication exists to kill the parasites. If left untreated, severe cases are typically fatal.



  • NCDs also known as chronic diseases tend to be of long duration and are the result of a combination of genetic, physiological, environmental and behaviours factors.
  • The main types of NCDs are:
  • Cardiovascular diseases (like heart attacks and stroke),
  • Cancers,
  • Chronic respiratory diseases (such as chronic obstructive pulmonary disease and asthma)
  • NCDs disproportionately affect people in low and middle-income countries where more than three-quarters of global NCD deaths occur – WHO


NCDs and India:

  • According to Indian Council of Medical Research (ICMR) report titled “India: Health of the Nation’s States”:
    1. Contribution of NCDs to total death in the Country was 61.8% in 2016, as compared to 37.9% in 1990.
    2. In the States of Kerala, Goa and Tamil Nadu, due to epidemiological transition, fewer deaths are recorded for Communicable, maternal, neonatal and nutritional diseases, thereby raising the share of NCDs in total deaths.
    3. Risk factors for NCDs inter alia include ageing, unhealthy diet, lack of physical activity, high blood pressure, high blood sugar, high cholesterol and overweight.
  • According to ‘National Non-communicable Disease Monitoring Survey (NNMS):
    1. Two in five adults have three or more risk factors for NCDs in India.
    2. Overweight or obese: More than 1 in every 4 adults and 6.2% of adolescents
    3. Raised blood pressure: Almost 3 out of 10 adults
    4. Raised blood glucose:3%.
    5. Insufficient physical activity: More than 2 in 5 adults and 1 in 4 adolescents.
    6. One in every three adults and more than one-fourth proportion of men used any form of tobacco and consumed alcohol in the past 12 months respectively.



Universal Immunization Programme (UIP):


·         One of the largest public health programs in the world started in 1985 in a phased manner.

·         India’s Universal Immunization Programme (UIP) provide free vaccines against 12 life-threatening diseases, to 26 million children annually.

·         The UIP provides life-saving vaccines to all children across the country free of cost to protect them against- Tuberculosis, Diphtheria, Pertussis, Tetanus, Polio, Hepatitis B, Pneumonia and Meningitis due to Haemophiles Influenzae type b(Hib), Measles, Rubella, Japanese Encephalitis (JE) and Rotavirus diarrhea.

Mission Indradhanush:


·         Launched by Ministry of Health and Family Welfare, GOI on Dec 25, 2014.

·         Aims to fully immunize more than 89 lakh children who are either unvaccinated or partially vaccinated under UIP by 2020.

·         It targets children under 2 years of age and pregnant women for immunization.

·         It provides Vaccination against 12 Vaccine-preventable diseases (VPD).

·         Earlier the increase in full immunization coverage was 1% per year which has increased to 6.7% per year.

·         Intensified Mission Indradhanush (IMI) was launched on Oct 8, 2017, to improve immunization coverage and to ensure full immunization to more than 90% by Dec 2018.

Ayushman Bharat:


Flagship initiative for comprehensive need-based health care service.

Two-pronged approach: – Creation of health and wellness centers, Pradhan mantra Jan Arogya Yojana (PMJAY).

1.      Wellness centers will provide comprehensive primary health care, covering both maternal and child health services and non-communicable diseases, including free essential drugs and diagnostic services.

2.      PMJAY: provides insurance of 5 lakh per family for secondary and tertiary care to beneficiaries identified by the latest Socio-Economic Caste Census, 2011(SECC-2011) data.


The insurance cost is shared by the centre and states in the ratio of 60:40.

National Health Agency has been constituted as an Autonomous entity for effective implementation of PMJAY.