tetanus - biology
...ute injury or medical condition. (3, 4, 5) Host Response – Once the bug is established in the body, it starts churning out toxin. This travels slowly — 75mm to 250mm a day — along the nerves to the spinal cord and central nervous system, affecting the release of neurotransmitters and muscle control. Tetanospasmin spreads through tissue into the lymphatic system and the vascular system. Tetanospasmin enters the nervous system, and then migrates through to the (1)National travel health network and centre, http://www.nathnac.org/pro/factsheets/documents/Tetanus.pdf (2) Dr Roger Henderson, ‘tetanus what it is and how to avoid it’, Sunday Times, 11/02/2001 (3) US food and drug administration, FDA Consumer magazine (July-August 1996), http://www.fda.gov/fdac/features/696_tet.html (4)medical net.com, Melissa Stoppler M.D. http://www.medicinenet.com/script/main/art.asp?articlekey=47225 (5)University of Utah health sciences centre, 2003, http://uuhsc.utah.edu/healthinfo/pediatric/Infectious/tetanus.htm central nervous system (CNS) by retrograde axonal transport. Affected neurons are stopped from releasing the inhibitory neurotransmitters GABA (gamma-amino butyric acid) and glycine (blocking inhibitor pulses). This leads to the failure of motor reflex responses to be inhibited from sensory stimulation (unopposed muscle contraction, spasm and seizure). Toxins are produced and disseminated via the blood and lymphatics. Toxins act at several sites within the CNS including peripheral motor end plates, spinal cord and brain. (1, 7, 6) Symptoms – Incubation periods vary from 3 – 21 days, in general, the further the injury from the central nervous system, the longer the incubation period. The shorter the incubation period, the higher the chance of death. On the basis of clinical findings, 3 different forms of tetanus have been described: 1- Local tetanus: persistent contraction of the muscles in the same anatomical area as the injury 2- Cephalic tetanus: occasionally occurring with ear infections or injuries to the head. There is involvement of the cranial nerves. 3- Generalised Tetanus: this accounts for 80% of tetanus. Neonatal tetanus is a form of generalised tetanus. Generalised tetanus is what most people refer to as tetanus (also known as lockjaw). The first signs of tetanus are spasms around the area of infection. However once the toxins enter the blood stream other symptoms start, usually in the face with spasms of the chewing muscles (trismus), which makes it hard to open ones jaw (hence the name lockjaw) and causes difficulty in swallowing. The spasms may spread through to other muscles, to the neck making the head tilt to the chest making breathing difficult, to the back muscles making the spine rigid (opisthotonos). Other symptoms include: fever, fast pulse, sweating, spasms of the diaphragm and elevated blood pressure. Complications: spasms of the vocal cord can interfere with breathing. Fractures of the spine or long bones may result from convulsions or sustained contractions. Hyperactivity of the nervous system may lead to hypertension or abnormal heart beat. (1, 5, 7, 8,11) Treatment – Large doses of antibiotic drugs, antimicrobial drugs and a muscle relaxant are usually given to a suspected tetanus patient. Penicillin and metronidazole will help decrease the amount of bacteria but it has no effect on the toxoid produced by the bacteria. All wounds should be thoroughly cleaned. Necrotic tissue and foreign material should me removed. If the wound is large standard practice is to remove as much of the damaged muscle as possible (by surgery). This will limit the amount of toxin that can be produced. This procedure is called debridement. It is recommended that people with tetanus receive TIG (tetanus immune globule) as it can remove unbound tetanus toxin. (1)National travel health network and centre, http://www.nathnac.org/pro/factsheets/documents/Tetanus.pdf (5)University of Utah health sciences centre, 2003, http://uuhsc.utah.edu/healthinfo/pediatric/Infectious/tetanus.htm (6) Melissa Sweet, ‘anyone for tetanus’, Bulletin with Newsweek, 04/02/2003, Vol. 121 Issue 6358, p59 (7) Biology Daily, 06/01/2005, http://www.biologydaily.com/biology/Tetanospasmin (8) Britain health encyclopaedia, http://www.britain.tv/health_illness_encyclopaedia_t_tetanus.shtml (11) World book medical encyclopaedia, 1995, pg 858 Giving the drug diazepam directly into a vein can control the muscle spasms themselves. In extreme cases it may be necessary to use a curare to paralyse the patient and using a machine to keep them breathing. (1,8,10) Prevention – In Australia and other industrialised countries tetanus is very rare (around 30 new cases each year in Australia), however in Africa and Asia tetanus remains a common killer, especially amongst babies where animal dung has been used to seel the umbilical cord after birth. Unsanitary conditions such as t...