Infectious Diseases and their Spread Questions in English

(N/A) Infectious diseases spread through various modes of transmission. These include:
$a)$ Through air: When an infected person sneezes or coughs,they release droplets containing pathogens. These droplets can be inhaled by a healthy person,allowing the microbes to enter a new host.
Examples: $Common$ $cold$,$pneumonia$,and $tuberculosis$.
$b)$ Through water: Consumption of contaminated water can lead to the spread of diseases to many people.
Examples: $Cholera$,$amoebiasis$,and $hepatitis$.
$c)$ Through sexual contact: Certain diseases like $AIDS$ and $syphilis$ are transmitted through sexual contact. Additionally,the $AIDS$ virus can spread through blood transfusion,shared infected syringes,from an infected mother to her baby during pregnancy,or through breastfeeding.
$d)$ Through vectors: Some animals act as intermediaries or vectors. These vectors carry pathogens from an infected person to a healthy person.
Example: $Mosquitoes$ spread the malaria-causing organism in humans while sucking their blood.

(C) The most likely condition to fall sick is $(c)$,when your friend is suffering from measles.
Measles is an infectious viral disease that spreads through droplets released from the nose or throat of an infected person. Being in close contact with a friend suffering from measles increases the risk of exposure to the virus,thereby making you more likely to contract the disease.

(C) Typhoid is a bacterial disease caused by $Salmonella$ $typhi$.
It is not transmitted by a mosquito vector.
It spreads primarily through the consumption of contaminated food and water.

(C) Diseases or conditions like high blood pressure,genetic abnormalities,and blood cancer are non-infectious and cannot be transmitted through contact with an infected person.
Sneezing is a common mechanism for the transmission of pathogens (such as viruses or bacteria) that cause infectious diseases like the common cold,influenza,or tuberculosis.
When an infected person sneezes,they release droplets containing pathogens into the air,which can then be inhaled by a healthy person,leading to infection.
Therefore,sneezing is the correct answer as it is associated with the spread of communicable diseases.

(B) $AIDS$ (Acquired Immuno Deficiency Syndrome) is caused by the $HIV$ virus. It is transmitted through the exchange of bodily fluids such as blood,semen,vaginal fluids,and breast milk. It is also transmitted through unprotected sexual contact and the use of contaminated needles. However,$AIDS$ is not transmitted through casual physical contact such as hugging,shaking hands,or sharing personal items,as the virus does not survive long outside the human body and is not present in sweat or saliva in sufficient quantities to cause infection.

(C) Living in overcrowded and poorly ventilated spaces facilitates the transmission of pathogens through the air. When many people share a small,enclosed space with poor air circulation,droplets containing infectious agents released by an infected person can easily be inhaled by others,thereby increasing the risk of air-borne diseases.

(D) Pneumonia is a respiratory disease caused by bacteria like $Streptococcus \text{ } pneumoniae$. It is primarily transmitted through the air via droplets released when an infected person coughs or sneezes. In contrast, Dengue, Malaria, and Encephalitis are vector-borne diseases transmitted by mosquitoes.

(C) Mosquitoes act as vectors for various serious diseases such as $Malaria$, $Dengue$, and $Chikungunya$. They transmit pathogens from an infected person to a healthy person. Therefore, it is essential to prevent their breeding in our surroundings to maintain public health.

(A) Hepatitis is a viral disease. Hepatitis $A$ and $E$ are primarily transmitted through the consumption of contaminated water and food. Hepatitis $B$,$C$,and $D$ are transmitted through the exchange of infected body fluids,such as blood or sexual contact. Given the options provided,contaminated water is a primary mode of transmission for several types of hepatitis.

(B) Vectors are living organisms that act as carriers of disease-causing pathogens. They transmit infectious agents from an infected individual to a healthy individual without necessarily causing the disease themselves. Common examples include mosquitoes,ticks,and fleas.

(N/A) Pneumonia is an infectious or communicable disease because it spreads from an infected person to a healthy person.
$(b)$ Many skin diseases,such as ringworm,are caused by fungi.
$(c)$ Antibiotics are medicines that specifically target and block biochemical pathways essential for the growth and survival of bacteria.
$(d)$ Living organisms that carry infectious agents from an infected host to a healthy person are known as vectors (e.g.,mosquitoes).

(N/A) Infectious diseases are caused by pathogens (like bacteria, viruses, fungi, or parasites) and can spread from one person to another. Non-infectious diseases are not caused by pathogens and do not spread between individuals.
$(a)$ $AIDS$: Infectious (caused by $HIV$)
$(b)$ Tuberculosis: Infectious (caused by $Mycobacterium$ $\text{tuberculosis}$)
$(c)$ Cholera: Infectious (caused by $Vibrio$ $\text{cholerae}$)
$(d)$ High blood pressure: Non-infectious (lifestyle/genetic factors)
$(e)$ Heart disease: Non-infectious (lifestyle/genetic factors)
$(f)$ Pneumonia: Infectious (caused by bacteria or viruses)
$(g)$ Cancer: Non-infectious (uncontrolled cell division)

(A) Vector-borne diseases are those that are transmitted to humans by vectors such as mosquitoes,ticks,or flies.
Three examples of such diseases are:
$1$. Malaria: Transmitted by the female $Anopheles$ mosquito.
$2$. Dengue: Transmitted by the $Aedes$ $aegypti$ mosquito.
$3$. Chikungunya: Also transmitted by the $Aedes$ mosquito.

(N/A) An infectious disease is a disease caused by pathogens (such as bacteria,viruses,fungi,or parasites) that can spread from an infected person to a healthy person through various modes of transmission like air,water,food,or physical contact.
Example: $Common \ cold$ or $Chickenpox$.

(B) Communicable diseases are those illnesses that can spread from an infected person to a healthy person through various means such as air,water,food,or physical contact.
These diseases are caused by microbial agents like bacteria,viruses,fungi,or parasites.
Because these pathogens can be transmitted from one individual to another,the diseases they cause are termed as communicable or infectious diseases.

(N/A) $(i)$ The disease is $AIDS$ (Acquired Immuno Deficiency Syndrome).
$(ii)$ The pathogen responsible for $AIDS$ is the $Human$ $Immunodeficiency$ $Virus$ $(HIV)$.

(B) In many species of mosquitoes,males feed on fruit juices or plant nectar to obtain carbohydrates for energy. Females also feed on these substances for energy,but they require a blood meal to obtain the proteins and lipids necessary for the development and maturation of their eggs.

(N/A) Encephalitis is primarily caused by a virus. It enters the body through the bite of an infected mosquito.
The virus specifically infects the brain.
Symptoms: If the brain is infected,the following symptoms occur:
- Severe headache
- Vomiting
- Fits (seizures)
- Unconsciousness or confusion.
Prevention: It can be prevented by avoiding mosquito bites,using mosquito nets,and controlling mosquito breeding sites.

(N/A)

Name of disease	Mode of transmission
$(a)$ Syphilis	Sexual contact
$(b)$ Tuberculosis	Air (droplet infection)
$(c)$ Jaundice	Contaminated water
$(d)$ Japanese encephalitis	Mosquito bite (vector-borne)

(N/A) Methods of transmission:
$(i)$ Cholera: It is a water-borne disease transmitted through the consumption of contaminated food or water.
$(ii)$ $AIDS$: It is transmitted through sexual contact with an infected person,sharing infected needles,or blood transfusion.
$(iii)$ Malaria: It is transmitted through the bite of an infected female $Anopheles$ mosquito,which acts as a vector.
$(iv)$ Pneumonia: It is an air-borne disease transmitted through droplets released by an infected person during coughing or sneezing.
$(b)$ If the pathogen targets the liver,the person will suffer from Hepatitis (commonly known as jaundice).

(N/A)

Infectious Diseases	Non-Infectious Diseases
$(i)$ These diseases spread from an infected person to a healthy person.	$(i)$ These diseases do not spread from an infected person to a healthy person.
$(ii)$ These are usually caused by pathogens like bacteria,viruses,fungi,or parasites.	$(ii)$ These are caused by internal factors like genetic disorders,hormonal imbalances,or lifestyle choices.
$(iii)$ These are communicable diseases,e.g.,common cold,influenza,and tuberculosis.	$(iii)$ These are non-communicable diseases,e.g.,diabetes,hypertension,and cancer.

(N/A) Disease: Malaria.
Causative microorganism: $Plasmodium$ (a protozoan).
Mode of transmission: Bite of an infected female $Anopheles$ mosquito.
Symptoms: General weakness,muscular pain,nausea,and high fever accompanied by sweating and shivering.
Prevention and Control: Use mosquito nets and repellents. Spray kerosene or oil on stagnant water to kill mosquito larvae. Avoid the accumulation of stagnant water in the surroundings to prevent mosquito breeding.
Treatment: Antimalarial drugs like quinine (derived from the $Cinchona$ tree) are used for treatment.

(A) Poliomyelitis virus (Polio virus).
$(b)$ Rabies.
$(c)$ Bacteria enters the body via the gastrointestinal tract through contaminated food or water.

(N/A) Dengue virus (Flavivirus)
$(b)$ Aedes mosquito (Vector)
$(c)$ Cholera
$(d)$ $AIDS$
$(e)$ Sexual contact,blood transfusion,or sharing infected needles
$(f)$ Droplet infection (Airborne)

(N/A) Direct contact (e.g.,physical touch or kissing).
$(b)$ By air (e.g.,droplets from coughing or sneezing).
$(c)$ Indirect contact (e.g.,sharing personal items like clothes or utensils).
$(d)$ By food/water (e.g.,contaminated food or water).
$(e)$ Mosquito/insect (e.g.,vector-borne transmission).
$(f)$ Rabid animal (e.g.,animal bite).

(N/A) $(i)$ Transmission by air (airborne disease).
$(ii)$ Transmission by water (waterborne disease).
Both situations describe the spread of communicable diseases.

(N/A) The disease is Rabies (also known as Hydrophobia).
$(b)$ Yes,an anti-rabies vaccine is available for both pre-exposure and post-exposure prophylaxis.
$(c)$ Yes,local authorities implement programs such as the compulsory vaccination of pet dogs,stray dog population control through sterilization ($ABC$ - Animal Birth Control),and public awareness campaigns to prevent the spread of rabies.

(N/A) Cause: $AIDS$ is caused by the $HIV$ ($Human$ $Immunodeficiency$ $Virus$).
Symptoms: The symptoms include significant weight loss,night sweats,loss of appetite,persistent fever,and overall weakness of the body due to a compromised immune system.
Prevention: $AIDS$ can be prevented by avoiding sexual contact with unknown persons,using only sterilized needles and blades,and ensuring that blood used for transfusion is screened and free from $HIV$.

(N/A) The three harmful effects of infectious disease are:
$(a)$ The body functions of the person suffering from the disease are damaged and may never recover completely.
$(b)$ Treatment of the disease takes time,and the person suffering is likely to be bedridden for some time,leading to a loss of productivity.
$(c)$ The infected person serves as a source of infection,which can spread the disease to other healthy individuals in the community.

(N/A)

Disease	Cause and Remedy
$(a)$ Hepatitis	$(i)$ Cause: Hepatitis virus. $(ii)$ Remedy: Avoid contaminated food and water,and get vaccinated for Hepatitis $A$ and $B$.
$(b)$ $AIDS$	$(i)$ Cause: Human Immunodeficiency Virus $(HIV)$. $(ii)$ Remedy: Avoid sharing needles,razors,or blades,and practice safe sexual contact.
$(c)$ Malaria	$(i)$ Cause: Protozoan parasite transmitted by female Anopheles mosquitoes. $(ii)$ Remedy: Maintain hygienic conditions,prevent water stagnation to stop mosquito breeding,and use mosquito repellents or nets.

(N/A) The person is suffering from $AIDS$ (Acquired Immuno Deficiency Syndrome).
The pathogen responsible for this disease is a virus known as $HIV$ (Human Immunodeficiency Virus).
The modes of transmission of $HIV$ are:
$(i)$ Unprotected intimate sexual contact with an infected person.
$(ii)$ Transfusion of contaminated blood or blood products.
$(iii)$ Sharing of contaminated needles,syringes,or razors used by an infected person.

(N/A) Diseases are classified based on whether they can spread from an infected person to a healthy person (communicable) or not (non-communicable).
$(a)$ Cancer: Non-communicable (caused by genetic mutations or environmental factors,not pathogens).
$(b)$ High blood pressure: Non-communicable (a lifestyle or physiological disorder).
$(c)$ Common cold: Communicable (caused by viruses,spreads through droplets).
$(d)$ Diabetes: Non-communicable (a metabolic disorder).
$(e)$ Tuberculosis: Communicable (caused by bacteria,spreads through air).
$(f)$ Night blindness: Non-communicable (caused by Vitamin $A$ deficiency).
$(g)$ $SARS$: Communicable (caused by a virus,spreads through respiratory droplets).
$(h)$ Typhoid: Communicable (caused by bacteria,spreads through contaminated food/water).
$(i)$ Cholera: Communicable (caused by bacteria,spreads through contaminated food/water).
$(j)$ Dengue: Communicable (caused by a virus,transmitted by mosquitoes).

(N/A) Three diseases caused by viruses are:
$(a)$ Influenza
$(b)$ Hepatitis
$(c)$ $AIDS$
Detailed account of $AIDS$ (Acquired Immuno Deficiency Syndrome):
Cause: It is caused by the retrovirus $HIV$ (Human Immuno Deficiency Virus).
Mode of Transmission:
$(i)$ Blood transfusion.
$(ii)$ Unprotected sexual contact.
$(iii)$ Use of contaminated needles and syringes,sharing razors,or piercing instruments.
$(iv)$ From an infected mother to the developing foetus through the placenta.
Symptoms:
$(i)$ Prolonged fever.
$(ii)$ Swollen lymph glands.
$(iii)$ Significant weight loss and loss of appetite.
$(iv)$ Unexplained bleeding.
$(v)$ Decreased count of blood platelets causing haemorrhage.
$(vi)$ Loss of memory and mental ability.
$(vii)$ The patient becomes highly susceptible to opportunistic infections.
Detection:
It is detected using the $ELISA$ test and the Western Blot test.
Prevention:
$(i)$ Practicing safe sex.
$(ii)$ Use of disposable syringes,needles,and fresh razors.
$(iii)$ Mandatory testing of blood before transfusion.
$(iv)$ Public education through $AIDS$ awareness programmes.
$(v)$ Avoiding pregnancy in $HIV$-infected mothers.
Treatment: There is no permanent cure for $AIDS$ so far; only antiretroviral therapy is used to manage the viral load.

(N/A) In $HIV$ infection:
$(i)$ The virus enters the immune system and damages its function by targeting $T-helper$ cells.
$(ii)$ The body can no longer effectively fight off the many minor infections that it encounters every day.
$(iii)$ $A$ very small cold can progress into severe $Pneumonia$,and minor gut infections can lead to major diarrhea with significant blood loss,eventually leading to the death of the patient.

(N/A) The disease is $Rabies$ and it is transmitted by the bite of a rabid dog.
The word 'reservoir' here means that the dog acts as a carrier or a source of the pathogen,which can be transmitted to humans.
The government should take the following steps to prevent the spread of the disease:
$1.$ Provide anti-rabies vaccines to patients who have been bitten.
$2.$ Implement compulsory immunization programs for stray dogs and cats. Pet dogs must also be vaccinated with anti-rabies vaccines.
$3.$ Identify and isolate or eliminate animals showing symptoms of rabies,such as excessive salivation and aggressive behavior.

(N/A) Preventive measures include:
$(i)$ Avoid water logging in and around the house to prevent mosquito breeding.
$(ii)$ Use mosquito nets,repellents,and wear full-sleeved clothing to prevent mosquito bites.
$(b)$ The values displayed by Sana are:
$(i)$ Social responsibility and community service.
$(ii)$ Proactive approach and awareness regarding public health.
$(c)$ $A$ school activity to promote such values could be organizing a 'Cleanliness Drive' or an 'Awareness Campaign' where students visit nearby areas to educate people about the dangers of stagnant water and vector-borne diseases.

(N/A) Acute diseases are those that last for a very short period of time,e.g.,common cold or diarrhoea. Chronic diseases are those that last for a long time,even for a lifetime,e.g.,asthma or elephantiasis.
$(b)$ Diseases that spread by coming in contact with a sick person are called infectious or communicable diseases. These diseases are caused by various pathogens such as viruses,bacteria,fungi,protozoans,and worms.

(N/A) No, all students will not get infected and suffer from the disease because a large inoculum (number of pathogens) is required to transmit the disease.
$(b)$ Two major symptoms of cholera are:
$(i)$ Severe watery diarrhea (often described as rice-water stools).
$(ii)$ Dehydration, which can lead to low blood pressure and muscle cramps.
$(c)$ The different ways of spread of this disease are:
$(i)$ Consumption of contaminated water containing the bacterium $Vibrio$ $\text{cholerae}$.
$(ii)$ Consumption of food contaminated by soiled hands or flies carrying the pathogen.

(N/A) Infectious agents are biological pathogens that cause diseases in hosts. They can be classified into several categories as follows:

Infectious Agents	Diseases Caused
$I$. Viruses	Common cold,influenza,mumps,poliomyelitis,rabies,smallpox,measles,$AIDS$,etc.
$II$. Rickettsiae	Typhus fever,Trench fever.
$III$. Bacteria	Tuberculosis,cholera,tetanus,syphilis,pneumonia,etc.
$IV$. Fungi	Ringworm,athlete's foot.
$V$. Protozoa	Malaria,sleeping sickness,amoebic dysentery,etc.
$VI$. Helminths (Worms)	Filariasis,ascariasis,tapeworm infection,etc.
$VII$. Mites	Scabies.

(N/A) The different means by which infectious diseases spread are:
$(i)$ By direct contact between a healthy and an infected person.
$(ii)$ By indirect contact between a healthy and an infected person.
$(iii)$ Through air (droplets,aerosols).
$(iv)$ Through contaminated food and water.
$(v)$ By vectors such as mosquitoes,flies,and other insects.
$(vi)$ By the bite of a rabid animal (e.g.,dogs,bats).

(A) Pneumonia is a respiratory infection caused by bacteria (such as $Streptococcus$ $\text{pneumoniae}$), viruses, or fungi. It is transmitted through respiratory droplets when an infected person coughs or sneezes, not by mosquitoes.
Malaria is transmitted by the bite of an infected female $Anopheles$ mosquito.
Brain fever (encephalitis) can be transmitted by mosquitoes (e.g., Japanese encephalitis).
Dengue is transmitted by the bite of an infected $Aedes$ mosquito.

(D) Bacterial diseases are caused by pathogenic bacteria.
$1$. Typhoid fever is caused by the bacterium $Salmonella$ $typhi$.
$2$. Cholera is caused by the bacterium $Vibrio$ $cholerae$.
$3$. Tuberculosis $(TB)$ is caused by the bacterium $Mycobacterium$ $tuberculosis$.
$4$. Anthrax is caused by the bacterium $Bacillus$ $anthracis$.
Since all four diseases listed in options $(a)$ and $(b)$ are caused by bacteria, both options are correct. Therefore, the correct answer is $(d)$.

(B) bacterial disease is caused by pathogenic bacteria.
$1$. Cholera is caused by the bacterium $Vibrio cholerae$.
$2$. Anthrax is caused by the bacterium $Bacillus anthracis$.
$3$. Tuberculosis is caused by the bacterium $Mycobacterium tuberculosis$.
$4$. Influenza (commonly known as the flu) is a viral disease caused by the influenza virus.
Therefore, Influenza is not a bacterial disease.

(C) $AIDS$ (Acquired Immuno Deficiency Syndrome) is caused by the $HIV$ virus.
It is transmitted through the exchange of infected body fluids,such as blood,semen,vaginal secretions,and breast milk.
$1$. Sexual contact involves the exchange of body fluids,which can transmit the virus.
$2$. Breast feeding can transmit the virus from an infected mother to her infant.
$3$. Blood transfusion using infected blood is a known mode of transmission.
$4$. Hugs,shaking hands,sharing food,or casual physical contact do not involve the exchange of infected body fluids,therefore $AIDS$ cannot be transmitted through hugs.

(A) $Typhoid$ is a bacterial disease caused by the bacterium $Salmonella$ $typhi$. It is primarily transmitted through the ingestion of contaminated food or water (fecal-oral route),not by mosquitoes.
$Malaria$ is caused by $Plasmodium$ parasites and is transmitted by the bite of an infected female $Anopheles$ mosquito.
$Brain$ $fever$ (often referring to Japanese Encephalitis) is a viral disease transmitted by $Culex$ mosquitoes.
$Dengue$ is a viral disease transmitted by the bite of an infected $Aedes$ $aegypti$ mosquito.
Therefore,$Typhoid$ is the correct answer.

(D) The diseases caused by bacteria are as follows:
$1$. Typhoid is caused by the bacterium $Salmonella \text{ } typhi$.
$2$. Tuberculosis is caused by the bacterium $Mycobacterium \text{ } tuberculosis$.
$3$. Anthrax is caused by the bacterium $Bacillus \text{ } anthracis$.
Since options $A$, $C$, and $D$ are all caused by bacteria, the question implies identifying bacterial diseases. However, if this is a multiple-choice question where only one answer is expected, there is an error in the options provided. Assuming the question asks to identify a bacterial disease from a list where others are not, or if it is a multiple-correct type, all $A$, $C$, and $D$ are correct. Given the standard format, if we must choose one, all listed options except Malaria (which is caused by a protozoan) are bacterial. Therefore, the question is flawed as presented. If we assume the question intended to ask which is $NOT$ bacterial, the answer would be Malaria. If it asks which $IS$ bacterial, $A$, $C$, and $D$ are all correct.

(B) Hepatitis is a viral infection that causes inflammation of the liver.
There are several types of hepatitis viruses,such as Hepatitis $A$,$B$,$C$,$D$,and $E$.
Hepatitis $A$ and $E$ are primarily transmitted through the fecal-oral route,which means they are spread through contaminated water or food.
Since the question asks for the transmission mode of hepatitis viruses in a general context (often referring to Hepatitis $A$ in school-level biology),water is the most appropriate answer among the given choices.

(D) Overcrowded and poorly ventilated living conditions facilitate the rapid spread of infectious pathogens through the air.
When many people share a small,enclosed space with limited air circulation,droplets containing pathogens released by an infected person (through coughing or sneezing) remain suspended in the air for longer periods.
This environment significantly increases the risk of contracting air-borne diseases such as tuberculosis,influenza,or the common cold.
Therefore,the correct option is $D$.

(D) Vectors are living organisms that can transmit infectious pathogens between humans or from animals to humans.
They do not cause the disease themselves but act as carriers (intermediaries) for the pathogens.
For example,the female $Anopheles$ mosquito acts as a vector for the malaria parasite $(Plasmodium)$.
Therefore,option $D$ is the correct definition.

(C) Mosquitoes are considered vectors because they carry disease-causing pathogens from an infected person or animal to a healthy person.
They transmit serious diseases such as $Malaria$,$Dengue$,$Chikungunya$,and $Zika$ virus.
By preventing their breeding,we can significantly reduce the transmission of these infectious diseases in our surroundings.