Introduction to Human Diseases for RRB Exams
Welcome, aspiring railway professionals! As you gear up for the highly competitive RRB NTPC and Group D exams, a thorough preparation strategy is your key to success. The General Awareness section, a crucial component of these exams, often includes a significant number of questions from General Science. Within this, Biology holds a special place, and one of the most frequently tested topics is 'Human Diseases'.
Understanding human diseases, their causes, symptoms, and prevention is not just essential for scoring marks but also for building general awareness about health and well-being. This topic might seem vast, but with a structured approach, you can easily master it. This comprehensive guide is designed to break down the complexities of human diseases into simple, understandable concepts, complete with examples, tables, and practice questions tailored for your RRB exam preparation.
Topic Weightage and Importance
In the General Awareness section of RRB NTPC (CBT-1 & CBT-2) and RRB Group D, General Science questions are a certainty. Biology, in particular, contributes a substantial number of these questions. Based on the analysis of previous years' question papers, you can expect around 2 to 4 questions directly or indirectly related to Human Diseases.
These questions can be about:
- The causative agent (pathogen) of a disease (e.g., virus, bacteria, protozoa).
- The vector that spreads the disease (e.g., mosquito, fly).
- Diseases caused by vitamin or mineral deficiencies.
- Vaccines and their corresponding diseases.
- Common names vs. scientific names of diseases or pathogens.
Given that these questions are often factual and direct, a solid understanding of this topic can fetch you easy and valuable marks, potentially making a significant difference in your overall score and rank.
Key Concepts: Understanding Human Diseases
To master this topic, we first need to understand the basic terminology and classification of diseases.
What is a Disease?
According to the World Health Organization (WHO), health is a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity. A disease is a condition that impairs the normal functioning of the body, either physically or mentally. It is often associated with specific symptoms and signs.
- Pathogen: A disease-causing microorganism, such as a bacterium, virus, fungus, or protozoan.
- Vector: An organism, typically an insect, that transmits a disease or parasite from one animal or plant to another. For example, the female Anopheles mosquito is a vector for malaria.
Classification of Diseases
Diseases are broadly classified into two main types: Congenital and Acquired.
- Congenital Diseases: These are diseases present from birth. They are caused by genetic abnormalities or metabolic disorders. Examples include Haemophilia, Colour Blindness, and Sickle-cell anaemia.
- Acquired Diseases: These are diseases that develop after birth. They are further divided into two categories:
A. Communicable (Infectious) Diseases
These diseases are caused by pathogens and can spread from an infected person to a healthy person through air, water, food, or physical contact. These are the most commonly asked types in RRB exams.
B. Non-Communicable (Non-Infectious) Diseases
These diseases are not caused by pathogens and do not spread from one person to another. They are often caused by lifestyle factors, environmental factors, genetic predispositions, or deficiencies. Examples include Cancer, Diabetes, Hypertension, and deficiency diseases like Scurvy or Goitre.
Detailed Look at Major Communicable Diseases
The following tables provide a structured overview of important communicable diseases, their causative agents, and other relevant details. This is the most crucial section to memorize.
1. Viral Diseases
| Disease | Causative Virus | Mode of Transmission | Affected Body Part/Symptoms |
|---|---|---|---|
| AIDS (Acquired Immuno Deficiency Syndrome) | Human Immunodeficiency Virus (HIV) | Sexual contact, infected blood transfusion, use of infected needles | Immune system (WBCs) |
| Dengue Fever | Dengue virus (Arbovirus) | Bite of Aedes aegypti mosquito | Severe headache, pain behind eyes, muscle and joint pains |
| Polio | Poliovirus | Contaminated food and water | Nervous system, paralysis of limbs |
| Influenza (Flu) | Myxovirus | Air droplets (sneezing, coughing) | Respiratory system |
| Chicken Pox | Varicella-zoster virus | Direct contact, air droplets | Skin (rashes all over the body) |
| Measles | Morbillivirus | Air droplets | Skin (reddish eruptions), respiratory tract |
| Rabies (Hydrophobia) | Rhabdovirus | Bite of an infected animal (dog, monkey) | Nervous system, severe headache, high fever, fear of water |
| Hepatitis | Hepatitis Virus (A, B, C, etc.) | Contaminated food/water (A, E), infected blood/body fluids (B, C, D) | Liver (Jaundice is a major symptom) |
2. Bacterial Diseases
| Disease | Causative Bacterium | Mode of Transmission | Affected Body Part/Symptoms |
|---|---|---|---|
| Typhoid | Salmonella typhi | Contaminated food and water | Intestines, high fever (Widal Test is used for diagnosis) |
| Cholera | Vibrio cholerae | Contaminated food and water | Intestines, severe diarrhoea and vomiting |
| Tuberculosis (TB) | Mycobacterium tuberculosis | Air droplets (coughing, sneezing) | Lungs, persistent cough, chest pain |
| Tetanus (Lockjaw) | Clostridium tetani | Wound contamination with soil, dust, or rust | Nervous system, muscle spasms, jaw stiffness |
| Diphtheria | Corynebacterium diphtheriae | Air droplets | Throat, respiratory tract (difficulty in breathing) |
| Pneumonia | Streptococcus pneumoniae | Air droplets | Lungs (alveoli get filled with fluid) |
| Plague | Yersinia pestis | Bite of infected rat fleas | Lymph nodes, lungs (Bubonic Plague) |
3. Protozoan Diseases
| Disease | Causative Protozoan | Vector | Affected Body Part/Symptoms |
|---|---|---|---|
| Malaria | Plasmodium species | Female Anopheles mosquito | Liver, Red Blood Cells (RBCs), high fever with chills |
| Amoebiasis (Amoebic Dysentery) | Entamoeba histolytica | Housefly (mechanical carrier) | Large intestine, stools with excess mucus and blood clots |
| Kala-azar | Leishmania donovani | Sandfly | Spleen, liver, bone marrow; high fever |
| Sleeping Sickness | Trypanosoma | Tsetse fly | Brain, nervous system; fever, severe drowsiness |
A Brief Look at Non-Communicable Diseases
- Deficiency Diseases: Caused by the lack of essential nutrients. Examples: Night blindness (Vitamin A), Scurvy (Vitamin C), Rickets (Vitamin D), Beriberi (Vitamin B1), Goitre (Iodine), Anaemia (Iron).
- Cancer: Uncontrolled growth of abnormal cells in the body. The study of cancer is called Oncology.
- Diabetes: A metabolic disorder where the body has high blood sugar levels, either because insulin production is inadequate, or because the body's cells do not respond properly to insulin.
Solved Examples (Step-by-Step)
Let's apply our knowledge to some exam-style questions.
Example 1:
Question: Which of the following diseases is caused by a protozoan?
(a) Typhoid
(b) Common Cold
(c) Malaria
(d) AIDS
Solution:
- Step 1: Analyze the options. We need to identify the causative agent for each disease.
- Step 2: Recall the information.
- Typhoid is caused by the bacterium Salmonella typhi.
- Common Cold is caused by a Rhinovirus.
- Malaria is caused by the protozoan Plasmodium.
- AIDS is caused by the Human Immunodeficiency Virus (HIV).
- Step 3: Conclude the answer. Based on the analysis, Malaria is the only disease in the list caused by a protozoan.
- Correct Answer: (c) Malaria
Example 2:
Question: The Widal test is used for the diagnosis of which disease?
(a) Tuberculosis
(b) Typhoid
(c) Cholera
(d) Plague
Solution:
- Step 1: Understand the question. The question asks for the disease associated with a specific diagnostic test, the Widal test.
- Step 2: Access your memory. This is a fact-based question. From our study, we know that the Widal test is the confirmatory test for Typhoid fever, which detects antibodies against the Salmonella typhi bacterium.
- Step 3: Confirm the answer. The Widal test is specifically for Typhoid.
- Correct Answer: (b) Typhoid
Example 3:
Question: Dengue fever is transmitted by the bite of which mosquito?
(a) Female Anopheles
(b) Culex
(c) Aedes aegypti
(d) All of the above
Solution:
- Step 1: Identify the core question. The question is about the vector of Dengue fever.
- Step 2: Differentiate between vectors. It's important not to confuse the vectors for different diseases.
- Female Anopheles is the vector for Malaria.
- Aedes aegypti is the vector for Dengue, Chikungunya, and Zika virus.
- Culex mosquito is a vector for Japanese encephalitis.
- Step 3: Select the correct vector. The Aedes aegypti mosquito is responsible for transmitting the Dengue virus.
- Correct Answer: (c) Aedes aegypti
Common Mistakes to Avoid
- Confusing Pathogen and Vector: A very common mistake is mixing up the disease-causing organism (pathogen) with the carrier (vector). For example, remember that Plasmodium (a protozoan) causes malaria, while the Female Anopheles mosquito is just the vector that transmits it.
- Mixing Up Viral and Bacterial Diseases: Many aspirants get confused between diseases caused by viruses and bacteria. Create separate lists or use mnemonics to remember them distinctly. For example, Typhoid and TB are bacterial, while Polio and Measles are viral.
- Forgetting Deficiency Diseases: While focusing on infectious diseases, don't forget to study diseases caused by the deficiency of vitamins and minerals. Questions on Scurvy (Vit C), Goitre (Iodine), and Anaemia (Iron) are very common.
- Ignoring Vaccines: Be aware of common vaccines. For example, the BCG (Bacillus Calmette-Guérin) vaccine is for Tuberculosis, and the DPT vaccine is for Diphtheria, Pertussis, and Tetanus.
- Neglecting Scientific Names: While you may not need to know all of them, being familiar with the scientific names of common pathogens (like Salmonella typhi for Typhoid) can give you an edge.
Practice Questions with Solutions
Test your knowledge with these practice questions.
Q1. Ringworm is a common skin infection caused by a ________.
(a) Bacterium
(b) Virus
(c) Fungus
(d) Protozoan
Q2. The disease 'Goitre' is caused by the deficiency of which of the following?
(a) Vitamin D
(b) Iron
(c) Iodine
(d) Vitamin A
Q3. Which of the following diseases is also known as 'Lockjaw'?
(a) Rabies
(b) Tetanus
(c) Diphtheria
(d) Pneumonia
Q4. BCG vaccine is administered to provide immunity against which disease?
(a) Polio
(b) Diphtheria
(c) Cholera
(d) Tuberculosis
Q5. Kala-azar is transmitted by the bite of which of the following?
(a) Tsetse fly
(b) Sandfly
(c) Aedes mosquito
(d) Housefly
Q6. Which of the following is NOT a viral disease?
(a) Chicken Pox
(b) Hepatitis
(c) Cholera
(d) Dengue
Q7. Which body organ is primarily affected by Jaundice (a symptom of Hepatitis)?
(a) Lungs
(b) Kidneys
(c) Brain
(d) Liver
Solutions
A1. (c) Fungus. Ringworm, despite its name, is not caused by a worm but by a type of fungus that lives on the skin.
A2. (c) Iodine. Iodine is essential for the thyroid gland to produce thyroxine hormone. Its deficiency leads to the enlargement of the thyroid gland, known as Goitre.
A3. (b) Tetanus. Tetanus is called 'Lockjaw' because the infection often causes muscle spasms, beginning in the jaw, which prevents the mouth from opening.
A4. (d) Tuberculosis. The BCG (Bacillus Calmette-Guérin) vaccine is the primary vaccine used worldwide to prevent Tuberculosis (TB).
A5. (b) Sandfly. Kala-azar is a protozoan disease caused by Leishmania donovani and is transmitted by the bite of an infected sandfly.
A6. (c) Cholera. Cholera is a bacterial disease caused by Vibrio cholerae. Chicken Pox, Hepatitis, and Dengue are all caused by viruses.
A7. (d) Liver. Jaundice is a condition where the skin and whites of the eyes turn yellow. It is caused by a high level of bilirubin in the blood, which often indicates a problem with the liver, as seen in Hepatitis.
Frequently Asked Questions (FAQs)
- Q1: What is the difference between a communicable and a non-communicable disease?
- A communicable (or infectious) disease is caused by a pathogen and can be transmitted from one person to another (e.g., Influenza, TB). A non-communicable disease is not caused by a pathogen and cannot be transmitted between people (e.g., Diabetes, Cancer, Goitre).
- Q2: How are questions on Human Diseases typically framed in RRB exams?
- RRB exams usually ask direct, fact-based questions in a multiple-choice format. You might be asked to match a disease with its cause (virus/bacteria), identify the vector, name the deficiency that causes a particular disease, or identify the purpose of a vaccine.
- Q3: Is it necessary to remember the scientific names of all pathogens?
- While it's not necessary to memorize every single one, knowing the scientific names for the most common and serious diseases (like Salmonella typhi for Typhoid, Vibrio cholerae for Cholera, and Plasmodium for Malaria) is highly recommended as questions are sometimes asked on them.
- Q4: What is the best way to revise the topic of Human Diseases?
- The most effective revision technique is to use the tables provided in this guide. Create flashcards with the disease on one side and its key details (pathogen, vector, symptoms) on the other. Regularly solving quizzes and previous year question papers is also crucial to solidify your knowledge and understand the exam pattern.
Conclusion and Final Tips
Mastering the topic of Human Diseases is an achievable goal that will pay rich dividends in your RRB NTPC and Group D exams. The key lies in structured learning and consistent revision. Focus on understanding the classification of diseases, and then meticulously memorize the details in the tables—pathogens, vectors, and affected body parts.
Here are some final tips:
- Use Mnemonics: Create simple, catchy phrases to remember lists of viral or bacterial diseases.
- Revise Regularly: Spend 15-20 minutes every few days revising the tables. Spaced repetition is more effective than cramming.
- Solve PYQs: Practice questions from previous years' papers to get a feel for the real exam and identify high-frequency sub-topics.
- Stay Healthy: As you study diseases, remember to take care of your own health. A healthy mind resides in a healthy body.
With dedicated effort and the right strategy, you can confidently tackle any question from this topic and move one step closer to securing your dream job in the Indian Railways. Keep learning and stay motivated!
