The World Health Organization (WHO) set a target to eradicate polio, using vaccines, by the year 2000. However, cases are still being reported in some parts of the world after this date. What explains these new cases of polio? 1 Some parts of countries are difficult to reach because of poor transport or wars. 2 There is not enough research to develop more effective vaccines. 3 Records of vaccinated and unvaccinated people are incomplete.

What defines infectious diseases?

A hurricane destroys a large town on an island. People move away from the town and set up tents, where sanitation is …

Which statement correctly explains why viruses are unaffected by penicillin?

A molecule of oxygen diffuses from the air in an alveolus to haemoglobin in a red blood cell. Assuming that the molec…

Specific monoclonal antibodies can be used to treat some forms of cancer. One example is trastuzumab, which can be us…

The HIV virus causes illness by infecting and destroying T-helper cells. This leads to AIDS and an inability to produ…