Disease Vectors and Pathogens

Mosquito-borne diseases or mosquito-borne illness are disease caused by bacterial, viruses or parasites transmitted by mosquitoes. They can transmit disease without being affected themselves. Mosquito vectored diseases include protozoan diseases, i.e., malaria, filarial diseases, and viruses such as dengue, encephalitis and yellow fever. 

Some infectious diseases can be passed from person to person. Some are transmitted by bites from insects or animals. And others are acquired by ingesting contaminated food or water or being exposed to organisms in the environment. Therefore, (d) is the correct answer.

Vector borne diseases are illnesses caused by an infectious microbe that is transmitted to vertebrates by another animal, usually an arthropod. This second animal is called a vector for the disease. There are a large number of viral, bacterial and parasitic diseases that can be transmitted by insect vectors. The most common vectors are blood sucking insects such as mosquitoes, fleas, lice, biting flies, bugs, lice, helminths and ticks. Most common vector borne diseases affecting people and their vectors are: malaria -anopheles mosquitoes, dengue and chikungunya - aedes mosquitoes, Leishmaniasis (kala azar) - sandflies, trypanosomiasis (gambia fever) - flies and bugs, filariasis - mosquitoes, encephalitis - mosquitoes and ticks, yellow fever - mosquito, plague - flies, lyme disease - ticks etc.

Air, water and soil are carriers of infectious organisms. Soil can cause contamination of plants and infect them and hence, the human. Air is the most common carriers of pathogens around us. Therefore, (d) is the correct answer.

There are numerous ways through which infections can be transmitted. Coughing by the infected person can cause transfer as the organisms coming out are inhaled by the healthy person. No use of proper sanitization can also cause transmission of diseases. Therefore, (b) is the correct answer.

Encephalitis is the disorder in which there is inflammation of the meninges of the brain. This disease may be caused due to bacterial or viral infection and is transmitted by the vector which is the Culex mosquito. Malaria is a disorder which is caused by the protozoan Plasmodium vivax. The disease is transmitted by the Anopheles mosquito. 

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• A disease vector is an agent who carries and transmits an infectious pathogen into another living organism.
• Female Anopheles mosquito serves as vector for malaria.
• Musa(house fly)serves as a vector for at least 65 diseases to humans, including typhoid fever, dysentery, cholera, poliomyelitis, yaws, anthrax, tularemia, leprosy, and tuberculosis.
• Culex mosquito serves as a vector for arbovirus infections such as West Nile virus, Japanese encephalitis, or St. Louis encephalitis, but also filariasis.
• Hence Vectors are Anopheles, Musca, and Culex.
• So, the correct answer is 'Anopheles, Musca, and Culex'.

Droplet infection is an infection transmitted from one individual to another by droplets of moisture expelled from the upper respiratory tract through sneezing or coughing. Direct transmission occurs when there is physical contact between an infected person and a susceptible person. Droplet infection is a mode of direct transmission in which the infection is transmitted by coughing, sneezing.

• Diseases transmitted by mosquitoes include: malaria, dengue,Yellow fever,Elephantiasis West Nile virus, chikungunya, filariasis, tularemia, dirofilariasis, Japanese encephalitis, Saint Louis encephalitis, Western equine encephalitis, Eastern equine encephalitis, Venezuelan equine encephalitis, Ross River fever, Barmah Forest fever, La Crosse encephalitis, and Zika fever,as well as newly detected Keystone virus and Rift Valley fever.
• Out of pneumonia, gangrene, yellow fever, dengue fever, malaria and elephantiasis, mosquitoes transmit 4 diseases they are Yellow fever, dengue, malaria, and elephantiasis.
  
• So, the correct answer is '4'.

• African trypanosomiasis, also known as sleeping sickness, is an insect-borne parasitic disease of humans and other animals. It is caused by protozoa of the species Trypanosoma brucei. It is transmitted by the bite of an infected tsetse fly which acts as a vector.
  
• Malaria is a mosquito-borne infectious disease affecting humans and other animals caused by Plasmodium species. The disease is most commonly transmitted by an infected female Anopheles mosquito which acts as a vector.
  
• Kala-azar is a disease caused by protozoan parasites belonging to genus Leishmania. The disease is transmitted by insects which act as vectors such as sand fly.

• Malaria is caused by a one-celled parasite called a Plasmodium. Female Anopheles mosquitoes pick up the parasite from infected people when they bite to obtain blood needed to nurture their eggs. Inside the mosquito, the parasites reproduce and develop.
• In Filariasis, mosquitoes can transmit the parasite, depending on the geographic area. In Africa, the most common vector is Anopheles. During a meal, an infected mosquito introduces third-stage filarial larvae onto the skin of the human host, where they penetrate into the wound. 
• Hence, Plasmodium ovale and Wuchereria bancrofti human parasites require mosquito to complete their life cycle.
• So, the correct answer is 'Plasmodium ovale and Wuchereria bancrofti'

• Obligate anaerobes are poisoned by oxygen, so they gather at the bottom of the tube where the oxygen concentration is lowest. example: Entamoeba histolytica.
• Facultative anaerobes can grow with or without oxygen because they can metabolise energy aerobically or anaerobically. Example: Ascaris lumoricoides. 
• Polyembryony is the phenomenon of two or more embryos developing from a single fertilized egg. Due to the embryos resulting from the same egg, the embryos are identical to one another but are genetically diverse from the parents. An example is Fasciola hepatica.
• Reservoir host is the host of an infection in which the infectious agent multiplies and/or develops, and on which the agent depends for survival in nature; the host is essential for the maintenance of the infection during times when the active transmission is not occurring. Examples of the reservoir host include  humans, animals, and the environment
• Biological vectors, such as mosquitoes and ticks may carry pathogens that can multiply within their bodies and be delivered to new hosts, usually by biting.
• So, the correct answer is 'a-v,b-iii,c-i,d-ii,e-iv'.

A fomite is any nonliving object or substance capable of carrying infectious organisms, such as viruses or bacteria, and hence transferring them from one individual to another. Fomites are associated particularly with hospital-acquired infections, as they are possible routes to pass pathogens between patients. Researchers have discovered that smooth (non-porous) surfaces like doorknobs transmit bacteria and viruses better than porous materials like paper money.