Tetanus infection taken from rusty sharp objects such as nails is not due to the rust (as what some people believe). It is due to the organisms that reside on it. The gram-positive bacteria Clostridium tetani is the one responsible for the series of symptoms experienced by the patient. The most prevalent sign that can be seen is lockjaw and risus sardonicus (facial spasm).
As the infection spreads on the upper body muscles, the individual will suffer difficulty in swallowing, stiffed neck and later on, difficulty in breathing.
The mode of entry of the organism into the host's body is through wounds. Deep puncture wounds, burns, lacerations, etc. is a good mode of entry and the infection can spread fast if the individual is not immunized. The bacteria, when inside the body, produces a powerful toxin called tetanospasmin. This toxin causes muscle spasm when it binds to the motor nerves that control muscle movement. Continuous spasm happens when tetanospasmin inhibits the release of gamma-aminobutyric acid and glycine which are inhibitory neurotransmitters.
There are four known forms of tetanus. These are: generalized tetanus, neonatal tetanus, cephalic tetanus and local tetanus.
The four forms differ according to areas affected and cause of infection.
If generalized tetanus (descending muscle spasm from head to toe) occurs, the patient exhibits opisthotonos body position wherein there is whole-body rigidity and the patient arches his or her back with arms bent and hands locked into fists and shaking uncontrollably. Opisthotonos can last up to several minutes and will occur in several episodes until the patient fully recovers from the infection. This form is fatal because it affects all skeletal muscle. It can start from local tetanus that is not given any attention.
Neonatal tetanus is very common to babies born in an unsterile environment. It is said that this form is very common among third world countries. This affects neonates or babies that are less than a month old. It usually happens several days after the baby is born from mothers who are not immunized. Instruments not properly sterilized and used during delivery of the neonate causes the infection that will start from the unhealed umbilical stump as this is an open wound. The umbilicus that connects the infant to his or her mother is cut during delivery and if unsterile instrument is used, it will cause infection to the newborn.
In cephalic tetanus, the patient gets the infection from head injuries and otitis media. The clostridium tetani bacterium spreads infection affecting the facial nerves. This form of tetanus is very rare and its symptoms include lockjaw, facial rigidity, difficulty in swallowing, etc. It can progress to generalized tetanus if left untreated.
The last form is the local tetanus and it occurs when the infection has not yet spread throughout the body. The patient experiences muscle spasms on the injured area or near it and this can last for many weeks. If the patient is immunized or has taken medications, the symptoms will eventually subside. This form is less fatal but it is likely to become one if not given attention because it will develop into generalized tetanus.