Glossary:
Antibody
Specific antibodies destroy the pathogen. If a person is infected again by the same pathogen, the lymphocytes make antibodies much faster.
Antitoxin
A type of antibody produced to counteract the toxins produced by bacteria.
Communicable (infectious) Disease
Disease caused by pathogens that can be passed from one organism to another.
Clinical Trials
Test potential new drugs on healthy and patient volunteers.
Microorganisms
Organisms that are usually single-celled and can only be seen using a microscope . They include bacteria, fungi, viruses. and protists.
Non-Communicable Diseases
are not infectious and cannot be passed from one organism to another.
Pathogens
microorganisms that cause disease.
Phagocytosis
Phagocytes engulfs the pathogens and digest them.
Placebo
A medicine that does not contain the active drug being tested, used in clinical trials of new medicines.
Preclinical Testing
Is carried out on a potential new medicine in a laboratory using cells, tissues, and live animals.
Vaccine
Dead or inactive pathogenic material used in vaccination to develop immunity to a disease in a healthy person.
Vaccination involves introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies.
If the same pathogen re-enters the body the white blood cells respond quickly to produce the correct antibodies, preventing infection.
Pathogens are microorganisms that cause infectious disease.
They may be viruses, bacteria, protists or fungi. They may infect plants or animals and can be spread by direct contact, by water or by air.
Bacteria and viruses may reproduce rapidly inside the body. Bacteria may produce poisons (toxins) that damage tissues and make us feel ill.
Viruses live and reproduce inside cells, causing cell damage.
White blood cells help to defend against pathogens by:
• phagocytosis
• antibody production
• antitoxin production.
B3: Infection and Response
B3: Infection and Response
Pathogen | Disease | Symptoms | Method of transmission | Control of spread |
Virus | Measles | Fever, red skin rash. | Droplet infection from sneezes and coughs. | Vaccination as a child. |
Virus | HIV | Initially flu like systems, serious damage to immune system. | Sexual contact and exchange of body fluids. | Anti-retroviral drugs and use of condoms. |
Virus | Tobacco mosaic virus | Mosaic pattern on leaves. | Enters via wounds in epidermis caused by pests. | Remove infected leaves and control pests that damage the leaves. |
Bacteria | Salmonella | Fever, cramp, vomiting, diarrhoea. | Food prepared in unhygienic conditions or not cooked properly. | Improve food hygiene, wash hands, vaccinate poultry, cook food thoroughly. |
Bacteria | Gonorrhoea | Green discharge from penis or vagina. | Direct sexual contact or exchange of body fluids. | Use condoms. Treatment using antibiotics. |
Protists | Malaria | Recurrent fever. | By an animal vector (mosquitoes). | Prevent breeding of mosquitoes. Use of nets to prevent bites. |
Fungus | Rose black spot | Purple black spots on leaves. | Spores carried via wind or water. | Remove infected leaves. Spray with fungicide. |
Antibiotics, such as penicillin, are medicines that help to cure bacterial disease by killing infective bacteria inside the body. It is important that specific bacteria should be treated by specific antibiotics.
Antibiotics cannot kill viral pathogens.
New drugs are extensively tested for: | Efficacy | Make sure the drug works. |
Toxicity | Check that the drug is not poisonous. | |
Dose | The most suitable amount to take. |