Infectious Diseases

Infectious diseases Pathogen Organism which causes disease e.g. bacterium, virus, protocista (one celled organism) Transmission Transfer of pathogen from one organism to another – may involve a vector World wide importance Countries and numbers Prevention and control Need to understand pathogen and its transmission Attitude of individuals, local government, pharmaceutical companies and the world health organisation

Malaria Name of pathogen Transmission Worldwide importance Prevention and control

MalariaMalaria – the life cycle of the pathogen Plasmodium

Malaria Name of pathogen - Plasmodium species (one eukaryote cell = Protocista) Transmission – vector needed; female Anopheles mosquito infected blood drunk; then pathogen passed to an uninfected person in saliva Worldwide importance – tropics e.g. China, India, South America, West Indies Prevention and control – prevent completion of mosquito life cycle; vaccination difficult as many antigens; treatment affected by drug resistance; sickle cell allele gives protection

Can you explain these words? How are they involved in recovering from infectious diseases? Antibodies Antibiotics Resistance to antibiotics

Antibiotics (p215-6) Antibiotic - a chemical produced by one microorganism which is able to destroy or inhibit the growth of another microorganism Resistance - due to mutation so new allele of gene produced. The antibiotic no longer affects the micororganism.

Key words which may confuse you antigen antibody antibiotic resistance What does each word mean? How are the words connected?

Infectious diseases Pathogen Organism which causes disease e.g. bacterium, virus, protocista (one celled organism) Transmission Transfer of pathogen from one organism to another – may involve a vector World wide importance Countries and numbers Prevention and control Need to understand pathogen and its transmission

AIDS True or false? How much do you know about AIDS?

Kaposi’s sarcoma in an AIDS patient

AIDS orphans in Lesotho, southern Africa

The pathogen – HIV

AIDS – Acquired Immune Deficiency Syndrome Pathogen – HIV = human immunodeficiency virus Transmission – in body fluids e.g. blood, semen, vaginal fluid, across placenta, breast milk Worldwide importance – pandemic Symptoms – diseases which immune system cannot deal with because the T helper lymphocytes do not function Prevention and control – education, screening, human genome project?

Could the human genome project help to eradicate diseases like malaria and AIDS? Identify people immune to the disease Isolate the relevant gene Then either identify the protein antigen and use it to develop a vaccine Or give gene therapy to people at risk e.g. sickle cell allele gives resistance to malaria e.g. some people seem to be immune to the effects of HIV page 151

Work on Antibiotics 1) Antibiotic - a chemical which is able to kill or inhibit the growth of bacteria or fungi 2) Practical – culture your bacteria E. coli or Micrococcus luteus on an agar plate and compare with a plate with antibiotic discs added. Draw and explain the results of the antibiotic sensitivity test. 3) Distinguish between each pair of terms and include examples bacteriostatic or bacteriocidal antibiotics broad spectrum or narrow spectrum antibiotics susceptible or resistant strains of bacteria 4) Page 216 – answer SAQ about antibiotic sensitivity 5) Why must we be careful about how antibiotics are used?

TB – Tuberculosis – key words Mycobacterium. bovis/tuberculosis coughingpoor housing cows milkbadgers HIV and AIDShuman migration mutations in bacteriamalnutrition

TB - Tuberculosis Pathogen = Mycobacterium tuberculosis or M. bovis(both are bacteria) Transmission – in airbourne droplets or unpasteurised milk TB was thought to be eradicated due to vaccination, better diet and improved housing. So why has there been an epidemic recently in some countries? Answer – see p 213 e.g. bacteria resistant to antibiotics; the AIDS pandemic; poor housing; inadequate vaccination; immigration; TB bacteria in badgers and cows

Questions on HIV and AIDS 1)What do the letters HIV and AIDS mean? 2)Why is AIDS called an epidemic and pandemic? 3)Why was the epidemic in USA and Europe initially among homosexual men? 4)Why are haemophiliacs no longer at risk from HIV infection? 5)Give details of HIV and AIDS symptoms 6)What social and economic effects does AIDS have in developing and developed countries? 7)How can HIV transmission be controlled? Do you think that AIDS be eliminated? 8) Exam question – June