AN EVALUATION AND UPDATE OF GUINEA WORM (DRACUNCULUS MEDINENSIS) AS AN ENDEMIC PARASITIC ORGANISM IN NIGERIA
Guinea worm is an endemic parasitic organism that belongs to the phylum Nematoda. The worm has its scientific name as (Dracunculus Medineansis). Guinea worm cause a disease called, “Dracunculiasis” or “Dracunculosis”. The disease of Dracunculus Medinensis can be described in latin as “disturbance with little dragon”. (Barry, 2007). The worm is found to be about 2 – 3 feet in length. (Hunter, 2007). Guinea worm is also found to be a nematode that causes an incapacitating disease, which affect people in poor, remote areas of Africa, Yemen and India (Watts, 2001). This disease caused by Dracunculus Medinensis (Guinea worm) is a long established human infection which was clearly referred to by various authors from India, Greece and the Middle East in antiquity. In historic times, the infection caused by Guinea worm occurred in Algeria, Egypt, Gambia, Guinea Conakry, the Middle East, South America and the West Indies. (CDC 1999).
In Nigeria, the infection of guinea worm occurred in late 1980s. Its connection of the infection with water sources was recognized early and it was also known that if the pre-patent period were not so long, the mode of infection would have been plain and clear many centuries earlier (Abolarin, 1999). It was found that the larvae expelled from emerging female worms in the limbs of sufferers, developed in fresh water, Cyclops living in ponds, which got ingested through drinking water. Female worms which are pre-emergent can easily move through the connective tissues, but when they are about to emerge to the surface, a few larvae are being released into the sub-dermis through a rapture at the anterior end. The reaction of the host results in the formation of a burning, painful blister, which bursts in a few days to give a shallow ulcer, and there is a marked inflammatory response against the cuticle of the entire worm, preventing its removal.
The expulsion of the worms is done with a bacteriological sterile blister fluid which contains larva surrounded by polymorph nuclear neutrophils with macrophage, lymphocytes and eosinophils. After the expulsion of thousand of the larvae, the end of the worm dies up and this mode of expulsion is repeated a few times, with complete worm being extruded in a few weeks. The lesson then gets resolved quickly, but the track of the worm becomes secondarily infected in about half of all the cases, and patients become severely incapacitated. (Ahearn, et al 1996). A study in Nigeria shows that about 60% patients, mostly in the age bracket of 15-49 years old of both school and working age, were disabled for an average of 12 – 13 weeks during the yam and rice harvesting period. The female worms sometimes burst in the tissues, resulting in a very large pus-filled abscess and cellulites (Caincross, et al 2002 and Ahearn, et al 1996).
1.1 AN EVALUATION OF GUINEA WORM (DRACUNCULUS MEDINENSIS) AS AN ENDEMIC PARASITIC ORGANISM IN NIGERIA
Guinea worm is one of the most studied human parasites in Nigeria, with history of its behaviour reaching as far back as the second century. This worm brings about painful and burning sensation which is experienced by infected patient and has resulted to the disease called guinea worm disease (Dracunculiasis). (Bulcher, et al 2005). In Nigeria, endemic areas; people who are infected by the worm are incapacitated due to the disease it causes. It keeps people out of the work and their activities especially farmers, manual workers and students, thus leading to the poor state of several sectors in the country. (Wikipedia, 2009, Bulcher et al 2005). Dracunculus Medinensis (Guinea worm) is known to be endemic mostly in areas where there is no safe water supply for drinking purposes. In 2008, 5,000 cases were discovered as compared to 201,453 cases in 1991. In Nigeria, the main endemic areas are:
In Nigeria (2009) (between January and March) Guinea worm disease was declared free (Lawal, 2009).
1.2 SEASONAL NATURE OF GUINEA WORM (DRACUNCULUS MEDINENSIS)
There are two patterns of seasonality that occur in Nigeria (areas of endemicity) but this depends on the climatic factors (Guiguemde, 2007). Transmission of guinea worm disease during the rainy season from May to August with a peak in June and July. This pattern usually occurs in the Northern part of the country (Guiguemde, 2007) Transmission of the disease caused by guinea worm during the dry season which may occur as from September to January, as found in some parts of Oyo state, particularly in areas with shallow ponds which dry up by January. Dracunculiasis continues towards the dry season in Anambra state and Kwara state. This pattern is related to the consumption of water from ponds formed in the beds of seasonal rivers (Guiguemde, 2007).
1.3 EPIDEMICITY AND ENDEMIC AREAS OF GUINEA WORM IN NIGERIA
Transmission of Dracunculiasis depends on the provisions of water sources, which has important consequences for the designation of eradication programs. Its occurrence takes place in a limited number of areas of endemicity on which these eradication programs are meant to focus. (Nwosu et al 2010). In Nigeria, in 1991, over 201,453 cases were reported in about 4,576 villages, (Cairncross, et al 2002). In Ohaozara, Ebonyi state, 5,058 individuals were examined, but a total of 2,422 individuals had either blisters or its ulcers. In 2002, between January and August, the number of cases reduced to about 1,438 cases in Ebonyi state. Among the 16 states of Nigeria’s 36 states affected which includes Plateau, Kwara, Oyo, Anambra, Borno and Niger states, Ebonyi state has the highest incidence of the disease caused by guinea worm (Udonsi, 2002, Adeyeba, et al 1999).
Sex-specific prevalence rate were 50% for males and about 44.4% for females, while age related cases ranges between 30% to 31% among individuals below 20 years, and between 64.5 – 71% among individuals above the age 20 within 1991 endemic year in the country. (United Nation’s Office, 2002). In Oyo state, as of 1988, about 17,000 people were infected, but were reduced to 300 in 1991. As of 1987, a total of 650,000 cases were discovered across the nation. (Lawal, 2009). In 2008, the number of cases discovered was about 5,000 cases of guinea worm infection nationwide. (Wikipedia, 2009). In Ribi and Kanje village in Awe local government area of Plateau state, Nigeria, 982 people were found infected, (Nwobi et al, 1999) which most the infections occurred on the lower limbs of the victims. Emergency of worms from the palm, wrist and upper arm were also encountered. Out of 982 case discovered, 206 persons were totally incapacitated, 193 disabled (amputee) and 431 suffered mere incapacity, while 152 were unaffected, but between January and March 2009, no case of guinea warm was discovered in Nigeria (Lawal Iyabo, 2009).