Tag: pathogen and their mode of transmission

• A disease vector is an agent who carries and transmits an infectious pathogen into another living organism.
• Vector-borne diseases are human illnesses caused by parasites, viruses, and bacteria that are spread by insects like mosquitoes, sandflies, triatomine bugs, black flies, ticks, tsetse flies, mites, snails and lice. For example, Female Anopheles mosquito is a vector for malaria.
• Hence Vector insects are which spread disease.
  
• So, the correct answer is 'Spread disease'.

• 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.

Biological agents which cause disease are known as pathogens that are the micro-organisms which when successfully infect the human body, multiply and produce toxins in incubation period which interfere with the normal functioning of the body and cause disease. A virus is a small, infectious, biological agent that replicates only inside the living cells of other organisms.

• 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.

Pneumonia is an inflammatory condition of the lung affecting primarily the small air sacs known as alveoli. Symptoms include some combination of a productive or a dry cough, chest pain, fever, and trouble breathing. Pneumonia may spread via airborne droplets from a cough or sneeze. Pneumonia is usually caused by infection with viruses or bacteria and less commonly by other microorganisms, certain medications and conditions such as autoimmune diseases.

Lead arsenate is a stomach poison, not a contact poison. DDT, BHC, and Endrin are contact poisons that kill insects upon physical contact.

• Measles is a highly contagious infectious disease caused by the measles virus. Symptoms include fever, often greater than 40 °C, cough, runny nose, and inflamed eyes. Measles is an airborne disease which spreads easily through the coughs and sneezes of infected people.
  
• Diphtheria is an infection caused by the bacterium Corynebacterium diphtheriae. Symptoms include a sore throat and fever. In severe cases, a grey or white patch develops in the throat. Diphtheria is usually spread between people by direct contact or through the air (droplet).
  
• Pertussis, commonly known as a Whooping cough is a highly contagious bacterial disease. Symptoms include a runny nose, fever, and cough. Pertussis is caused by the bacterium Bordetella pertussis. It is an airborne disease which spreads easily through the coughs and sneezes of an infected person.
• Gonorrhoea is a sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae. Symptoms include burning with urination, discharge from the penis, or testicular pain. Women may have burning with urination, vaginal discharge, vaginal bleeding between periods, or pelvic pain. Hence, it is not transmitted by droplets.

The assertion is true because Taenia (tapeworm) infection is transmitted through undercooked pork containing larvae. The reason is false because the larval stage found in pork is the cysticercus (bladder worm), not the hexacanth (oncosphere), which is the stage found in the egg.