Form and Function

A Blind Man Infected From Onchocerciasis      The Onchocerca volvulus parasite can only survive when it is inside of a host. Once it is attached to its host, the female disburses her larvae into the skin and tissue of the host, where the parasites begin to grow and mature into adults. After mating, the pregnant females then release thousands of larvae into the bloodstream of the host. These larvae are responsible for the diseases in which the host accumulates including dermatitis, lymphadenopathy, and most commonly, blindness (Truant 1998). Onchocerca volvulus is the second leading cause of blindness in the world (Globisch 2013).
     The life cycle of a Onchocerca volvulus starts out when an infected larvae bites on a human host, which is similar to the insect Aedes aegypti because they also host upon humans. The transfer of Onchocerca volvulus is similar to the parasite Babesia caris as it is also transferred through the bite of an insect. Babesia caris, isAdult Onchocerca volvulus Worms transferred by a tick into a host of a dog or fox rather than a human where it then leads the host to feeling very unwell and can sometimes even lead to death. The larvae then develops into an adult worm in the dermis or connective tissue of the host. These female worms live in coiled-up subcutaneous tissues and can be anywhere from 30 to 80 centimeters in length. The females also produce 700- 1500 microfilarias, the embryonic larva of the nematode in a single day. Dracunculus medinensis is similar to Onchocerca volvulus because after they reproduce, the female worms both migrate to subcutaneous tissues of the human body. The male larvae tend to move freely in the skin tissues of the host where it is typically 3-5 centimeters long. The microfilariae produced by the female then migrate throughout the body of the host into the upper dermis and eyes (Institutional Links 2013).
      Another fly can get infected if it feasts on a host which is already infected by the parasite. When a blackfly ingests a microfilariae with its blood meal it can very easily pick up the parasite. The microfilariae then enters the first larval stage where it remains until it matures and then takes over the saliva of the fly. As the fly the finds its next host, human or animal, the larvae then passes into the host’s bloodstream and the cycle starts all over again.
     If a person is affected by Onchocerca volvulus in the area of the eye, it can lead to severe damage of the eye and even lead to blindness. However, if it is noticed in the early stages, it can be cured by the use of drugs that kill the larvae in the body which is the source of inflammation in the eye. This treatment however, can take a very long time and can last anywhere from 10 to 15 years because that is the lifespan of the matured worm present in the humans body (Onchocerciasis 2006). Woman's Infected Eye
     Blindness has been a huge fear of many Africans because of the terrible effect that it can have on not only a persons life, but it can also be a burden for the people around them as well. Many people in Africa have therefore chosen to move away from the rivers and savannahs for fear that they may catch the parasite. This has lead to decreasing amounts of productivity and agriculture in these fertile soil areas which inturn increases poverty in these areas as well (World Health Organization 2014).
      Onchocerca volvulus is a very mobile parasite that can travel fast because of it’s ability to transfer through humans, animals, and black flies. This can be very harmful to humans, just as Sarcaphaga carnaria and Naegleria fowleri which also use humans as hosts of the parasites, because you can potentially get it anywhere, at any time. Even though there is new research being conducted on drugs that can help the early effects of the parasite, there are still these organisms living in a persons' body, which can live in a body for sometimes over 15 years. With more technology and studies being done on this organism, we can find a better way to keep humans safe and keep this detrimental organism contained.

                                   Let's learn about the life history and reproduction of this parasite!