Biology

The human body is able to surviveagainst the potential pathogens like bacteria and virus because of its immune system developed. Human body produces antibodies to immobilize pathogens for removal from the body when they able to multiply above a level of equilibrium situation. This immune system can be disturbed by chemical toxins in the system.

Bacteria or Virus which is difficult to control   Mostly the human illness was caused by viruses and bacteria on earth. Bacteria are small single celled organisms and live in every part of earth. The disease causing bacteria are called pathogenic bacteria.

Control of bacteria The infections caused by bacteria can be recovered by using some antibiotics. Antibiotics (metabolic products of one microorganism that kill other microorganisms) stop the metabolic processes of particular bacteria .However bacteria are developing resistant strains. Human body is developing immunity to the many of diseases. Immunisation is useful to prevent many important bacterial diseases like Hemophilus influenza Type b (Hib), tetanus and whooping cough. Bacteria can be controlled by chemotherapy also. The basis for this is selective toxicity. Selective toxicity means chemical which was used will kill the intended pathogen without serious injury to the host.

Whereas virus is still smaller microorganism compared to bacteria able to reproduce in living cells only. When compared to bacteria virus are difficult to control. So in medical science most communicable diseases are viral in origin.

Control of viral infections Antibiotics are not useful to control viral infections, due to their host cell specificity. Antiviral drugs interfere with viral enzymes. Whereas antiviral drugs are available for diseases like influenza, herpes, hepatitis B and C and HIV (research is going on). For curing of hepatitis B a naturally occurring protein called interferon produced in the laboratories.  It is also possible to vaccinate many serious viral infections such as measles, mumps, hepatitis A and hepatitis B and smallpox. The control of viral infection by intracellular antiviral proteins referred to as restriction factors is becoming an important issue of infectious disease research now a day. Viral diseases are spread by coughs, sneezes, vomits, bites from infected animals or insects and exposure to infected bodily fluids through activities such as sexual intercourse or sharing hypodermic needles. So when compared to bacterial diseases viral diseases are difficult to cure.