Parasites, in fact ‘monsters’, may enter your body without your knowledge. In reality one becomes aware of their presence only when the condition becomes worse and much harm has been caused. Following are two of the rarest but world’s most dangerous parasites which invade different parts of your body.
Naeglria fowleri (Brain infecting amoeba)
Naeglria fowleri lives in fresh water lakes, rivers, hot water springs, thermal discharges of power plants, aquariums and sewage. It prefers living in warm waters rather than salty lakes. When people wade through shallow water bodies, they stir up the bottom where most of the water is contaminated by amoeba. Consequently, these monsters enter through the nose and are attracted to the nerve cells and specifically to the olfactory nerve N. fowleri. It is from this nerve that this amoeba gets its name. It hijacks the host nerve cell in search of food and shelter using special mouth shaped structure and punches a hole in the cell membrane. Gradually, it eats up proteins and other contents required in order to survive. N. fowleri also secretes an enzymes which dissolves the brain cells and it becomes easier to invade.
There are three stages in its life cycle- cysts, trophozoites, and flagellated forms. It defends itself by forming a protective coating called cyst around its surface. This also proves to be helpful during unfavourable conditions, while in favourable conditions it reproduces. Moreover, cysts render it impervious to the host immune system. When attacked by macrophages, it sheds off its coat and escapes. In its second stage, the trophozoites (infective forms) replicate by promitosis (a process in which nuclear membrane remains intact). It is this form of amoeba which infects human body by entering through the nasal mucosa and migrating to the brain causing primary amoebic meningoencephalitis (PAM). These trophozoites are found in cerebrospinal fluid (CSF). They interconvert into non feeding flagellated forms which are also sometimes found in CSF.
Acanthamoeba (eye infecting ameoba)
Acanthamoeba has been found in fresh water, soil, contact lens equipment, dental treatment units, dialysis machines, air conditioning systems, and mammalian cell cultures. It also feeds on other microbes, mainly bacteria. Bacteria occur naturally in human eyes. Acanthamoeba penetrates through the skin and goes deeper into the cornea of eye. It can also find its way into the cornea through a minor cut caused by the contact lens and can live in the space between the eye and contact lens. It feeds on the proteins from the corneal cells and can cause severe tissue damage if left untreated.
Its lifecycle consists of two stages cysts and trophozoites. Their entry can occur through eye, the nasal passages to the lower respiratory tract or through damaged skin. Replication of trophozoites take place through mitosis. After entering the body through the respiratory system or skin it invades the Central Nervous system and causes a disease called granulomatous mebic encephalitis (GAE) while its entry in the eye causes severe keratitis particularly in those who use contact lenses.