The sleeping sickness

 The sleeping sickness:
                                                                                                                   This cycle starts with a bite from a taxi fly. if the fly bites someone who's already sick it ingests parasites as well as blood these parasites called trypanosomes accumulate in the fly's gut .20 days later they migrate to the taxi flies salivary glands and are ready to infect another victim when the fly next bites the parasite enters the lymphatic system and then passes into the bloodstream and circulates through the body at first the hosts immune defenses attack the parasite to shield themselves the parasites mutate change form and escape from the hosts immune system until they're recognized and attacked by another wave of antibodies. This cycle of attack and defense is repeated several times .it's accompanied by symptoms such as intermittent fever headaches and joint pain symptoms that mirror the inner struggle between the immune cells and the parasites these first phase symptoms are sometimes too mild to be detected but this is when it is actually easiest to treat the disease if it isn't treated in time the parasites advanced the brain.

The blood-brain barrier is there a filter to protect the brain against pathogens toxins and hormones circulating in the blood but the trypanosomes breach it at this stage the disease is much more difficult to treat as the blood-brain barrier also blocks some drug molecules. if the trypanosomes managed enter into the brain, the sleep pattern becomes erratic. Infected people develop poor coordination and become confused alternating between episodes of severe fatigue and agitation sleeping during the day ,they can't sleep at night .The deterioration of the nervous system leads to coma.If left untreated sleeping sickness is fatal .