Communicable Diseases — REET Notes
This page covers, for REET Level 2 (Maths-Science), the types of communicable diseases, their pathogens, how they spread and how to prevent them. REET 2024 asked direct questions on identifying sexually transmitted diseases and matching diseases to their pathogens, so every disease here is explained with its pathogen and mode of transmission in clear tables that are easy to revise.
- 2 questions in REET 2024
- Class 6-8 level
- 9 min read
How this topic is asked in REET
REET 2024 had two kinds of questions from this topic — one asked which disease is NOT a sexually transmitted disease (STD) (answer: TB), and the other asked students to match filariasis, amoebiasis, pneumonia and the common cold to their correct pathogens (Wuchereria, Entamoeba, Haemophilus, Rhinovirus). This shows that disease-pathogen matching and identifying the mode of transmission are the most common question types here, and more than one detail about the same disease (pathogen, transmission, prevention) is often asked together.
What Are Communicable Diseases
Communicable diseases are diseases caused by disease-causing microorganisms (bacteria, viruses, fungi, protozoa or worms) that can spread from an infected person or source to another healthy person. In contrast, non-communicable diseases (such as diabetes, high blood pressure) do not spread from one person to another and are usually caused by lifestyle or genetic factors.
Diseases that last only a short time are called acute diseases, such as the common cold; diseases that persist for a long time are called chronic diseases, such as tuberculosis (TB). Acute diseases affect health immediately but resolve quickly, while chronic diseases weaken the body gradually and take a long time to treat. The common cold, which clears up on its own, is a typical acute disease, whereas tuberculosis, which weakens the body gradually and needs prolonged treatment, is a typical chronic disease — matching the very distinction between acute and chronic illness described here.
Types of Pathogens and Example Diseases
| Pathogen Type | Example Diseases |
|---|---|
| Bacteria | Tuberculosis (TB), cholera, typhoid |
| Virus | Common cold, influenza, dengue, AIDS |
| Protozoa | Malaria, kala-azar, amoebiasis |
| Fungi | Ringworm, skin infections |
| Worms | Filariasis (elephantiasis), intestinal worm infections |
Note that the same disease (such as pneumonia) can sometimes be caused by more than one type of pathogen, so pay close attention to the specific pathogen named in the question.
Major Diseases and Their Pathogens (Matching)
| Disease | Pathogen |
|---|---|
| Filariasis (elephantiasis) | Wuchereria bancrofti (worm) |
| Amoebiasis | Entamoeba histolytica (protozoan) |
| Pneumonia | Haemophilus influenzae / Streptococcus pneumoniae (bacteria) |
| Common cold | Rhinovirus (virus) |
| Malaria | Plasmodium (protozoan, via the female Anopheles mosquito) |
REET 2024 asked exactly this kind of matching question, so this table is very useful to revise and can even be gone over right before the exam.
How Diseases Spread (Transmission)
| Route | Example Diseases |
|---|---|
| Air/respiratory droplets | Common cold, tuberculosis, influenza |
| Contaminated water/food | Cholera, typhoid |
| Vectors (such as mosquitoes) | Malaria, dengue, filariasis |
| Direct/sexual contact | Gonorrhoea, syphilis, AIDS |
| Animal bites/scratches | Rabies (from the bite or scratch of a rabid dog or other infected animal) |
General Principles of Preventing Communicable Diseases
There are two main ways to prevent communicable diseases — general hygiene measures and specific protection. General hygiene includes drinking clean water, washing hands, covering the mouth while coughing or sneezing, and keeping the surroundings clean — these steps significantly cut the chances of many diseases spreading.
Vaccination is the most effective form of specific protection, where a weakened or inactive form of the pathogen is introduced into the body so the immune system is pre-trained against that disease. In India, children are routinely given vaccines such as BCG for protection against TB and OPV for protection against polio, under the regular immunisation programme. For vector-borne diseases (such as malaria, dengue), preventing mosquito breeding — such as not letting water collect around the house and using mosquito nets — is considered the most effective measure. Taken together, hygiene lowers the chance of a pathogen reaching a person in the first place, vaccination prepares the immune system in advance for a specific pathogen, and controlling mosquito breeding removes the vector that would otherwise carry diseases like malaria and dengue from one person to another.
Sexually Transmitted Diseases (STDs)
- Examples
- Gonorrhoea, syphilis, genital herpes, AIDS (HIV)
- Note
- Tuberculosis (TB) is not a sexually transmitted disease — it is caused by bacteria and spreads mainly through the air (coughing/sneezing)
- Prevention
- Safe sexual practices and avoiding infected blood are the main basis of STD prevention
- Role of awareness
- Providing correct, scientific information at the school level helps clear rumours and misconceptions
- Mode of infection
- Most STDs spread through direct physical/sexual contact with an infected person or through infected blood, not through air or food
- Caution for the exam
- REET often adds an unrelated disease (such as TB) to the options and asks 'which one is NOT an STD,' so memorise the list well
How to Teach This in Class
Classroom activity
Have students list habits such as handwashing, drinking clean water and using mosquito nets, and discuss which diseases each habit prevents; make a 'hygiene checklist' poster with the class and put it up.
Teaching aid
Show a mosquito net, a container of clean water and a mask, or pictures of them, and compare vector-borne, waterborne and airborne diseases. If possible, show a sample immunisation card to explain which vaccines are given in childhood.
Common misconception
Students often think all communicable diseases spread only by touch, or that every fever is the same disease. Clarify that air, contaminated water/food, vectors (mosquitoes) and direct contact are four separate routes, and that each disease has its own pathogen and prevention method suited to its route. For instance, a waterborne disease like cholera or typhoid needs clean drinking water and food for prevention, while a vector-borne disease like malaria or dengue needs mosquito control — treating every disease with the same precaution misses this distinction.
Assessment idea
Build a four-column table (airborne/waterborne/vector-borne/contact-borne) in class and have students place different diseases in the correct column, along with one prevention measure for each.
Memory trick
Remember pathogens in order of size — worm (the largest, such as filariasis) → protozoan (such as malaria, amoebiasis) → bacteria (such as typhoid, TB) → virus (the smallest, such as the common cold). This order reduces confusion in matching-type questions, since the exam often mixes pathogens of different sizes in the same question.
Questions Asked in REET 2024 (With Solutions)
Question 140
Which is not an example of sexually transmitted disease ?
- Aगोनोरिया
- Bसिफिलिस
- Cजननिक परिसर्प
- Dटी. बी.
Explanation
गोनोरिया, सिफिलिस और जननिक परिसर्प (genital herpes) यौन संपर्क से फैलने वाले यौन संचारित रोग (STD) हैं। टी.बी. (क्षय रोग) Mycobacterium tuberculosis जीवाणु से होता है और मुख्यतः संक्रमित व्यक्ति के खाँसने-छींकने से हवा द्वारा फैलता है, इसलिए यह यौन संचारित रोग नहीं है।
Question 147
Match the following : 1. Elephantiasis — a. Rhino virus 2. Amoebiasis — b. Haemophillus influenzae 3. Pneumonia — c. W. Bancrofti 4. Common cold — d. A. Histolytica Codes (1 2 3 4) :
- Ad c a b
- Bc d b a
- Ca b c d
- Db a d c
Explanation
हस्तिपाद (फाइलेरिया) का रोगजनक कृमि वुचेरेरिया बैंक्रोफटाई (W. bancrofti) है → c; अमीबता (amoebiasis) एंटअमीबा हिस्टोलिटिका (E. histolytica) से होती है → d; न्यूमोनिया हीमोफिलस इंफ्लुएँजी (तथा स्ट्रेप्टोकोकस न्यूमोनी) जीवाणु से होता है → b; सामान्य जुकाम राइनोवायरस से होता है → a। अतः सही क्रम c, d, b, a अर्थात् विकल्प (B) है।
Practice Questions
Question 1
Microorganisms that cause communicable diseases are called —
- Aपोषक
- Bरोगजनक (Pathogen)
- Cउत्प्रेरक
- Dएंजाइम
Explanation
Microorganisms that cause disease (bacteria, viruses, and so on) are called pathogens.
Question 2
Tuberculosis (TB) is caused by which type of pathogen?
- Aविषाणु
- Bजीवाणु
- Cकवक
- Dप्रोटोज़ोआ
Explanation
Tuberculosis (TB) is caused by the bacterium Mycobacterium tuberculosis.
Question 3
The common cold is caused by which pathogen?
- AHIV
- Bराइनोवायरस
- Cवुचेरेरिया बैंक्रोफ्टाई
- Dएंटअमीबा हिस्टोलिटिका
Explanation
The common cold is caused by the virus Rhinovirus.
Question 4
Malaria is spread by —
- Aमादा एनाफिलीज़ मच्छर
- Bदूषित जल
- Cसीधा स्पर्श
- Dदूषित भोजन
Explanation
Malaria is caused by the protozoan Plasmodium, which spreads through the bite of the female Anopheles mosquito.
Question 5
Which of the following is NOT a sexually transmitted disease (STD)?
- Aगोनोरिया
- Bसिफलिस
- Cक्षय रोग (TB)
- Dजननिक परिसर्प
Explanation
TB is caused by bacteria and spreads mainly through the air, so it is not a sexually transmitted disease; gonorrhoea, syphilis and genital herpes are STDs.
Question 6
The pathogen causing filariasis (elephantiasis) is —
- Aएंटअमीबा हिस्टोलिटिका
- Bवुचेरेरिया बैंक्रोफ्टाई
- Cराइनोवायरस
- Dप्लाज़्मोडियम
Explanation
The pathogen for filariasis (elephantiasis) is the worm Wuchereria bancrofti.
Question 7
Amoebiasis is caused by which pathogen?
- Aवुचेरेरिया बैंक्रोफ्टाई
- Bहीमोफिलस इन्फ्लुएंजी
- Cएंटअमीबा हिस्टोलिटिका
- Dराइनोवायरस
Explanation
Amoebiasis is caused by the protozoan Entamoeba histolytica.
Question 8
The most suitable activity for teaching modes of transmission of communicable diseases in class is —
- Aकेवल परिभाषा रटवाना
- Bरोगों को वायुजनित/जलजनित/वाहकजनित/संपर्कजनित तालिका में वर्गीकृत करवाना
- Cविषय पर कोई गतिविधि न करना
- Dकेवल पाठ्यपुस्तक पढ़कर सुनाना
Explanation
A classification activity helps students understand different transmission routes in a hands-on, practical way.
Question 9
A common misconception among students is that all communicable diseases spread only by touch. The correct way to clear this is —
- Aइसे नज़रअंदाज़ करना
- Bवायु, जल, वाहक व संपर्क जैसे विभिन्न संचरण-माध्यमों को उदाहरण सहित स्पष्ट करना
- Cकेवल एक माध्यम पढ़ाना
- Dविद्यार्थियों को स्वयं शोध करने देना
Explanation
Explaining different transmission routes — air, water, vectors and contact — with examples helps students understand that diseases spread in more ways than just touch.
Question 10
Diseases like cholera and typhoid mainly spread through —
- Aवायु द्वारा
- Bदूषित जल/भोजन द्वारा
- Cमच्छर द्वारा
- Dसीधे यौन संपर्क द्वारा
Explanation
Cholera and typhoid are bacterial diseases that spread mainly through contaminated water or food.
Frequently Asked Questions
How many questions come from communicable diseases in REET?+
REET 2024 had 2 questions from this topic — one on identifying an STD and one on disease-pathogen matching.
Which pathogen causes filariasis (elephantiasis)?+
Filariasis is caused by a worm called Wuchereria bancrofti, which spreads through the bite of the Culex mosquito.
Is tuberculosis (TB) a sexually transmitted disease?+
No, TB is not a sexually transmitted disease. It is caused by bacteria and spreads mainly through the air (coughing/sneezing), so it is not included in the STD list.
How does malaria spread?+
Malaria is caused by a protozoan called Plasmodium, which spreads from an infected person to a healthy person through the bite of the female Anopheles mosquito. Preventing mosquito breeding — for example, not letting water collect around the house and using mosquito nets — is considered the most effective way to cut the risk of catching it.
How does vaccination help prevent communicable diseases?+
Vaccination introduces a weakened or inactive pathogen into the body, so the immune system learns to recognise that disease in advance and can respond quickly on real infection — such as BCG for TB prevention and OPV for polio prevention.
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Change Log
- 17 September 2026 — English page published — mirrors the fact-checked Hindi page, independently bilingual-accuracy checked