Intestinal Parasites Among Unity Primary School Pupils, In Oraifite, Ekwusigo L.g.a., Anambra State, Southeastern Nigeria

parenchyma may be replaced by masses of eggs. Rarely, eggs will be carried to the lungs or other organs by the blood stream. Hepatomegaly can become severe, and eggs become encased in granulomatous tissue, with heavy infiltration of eosinophils and other leukocytes (Choe et al, 1993).

The first obvious clinical sign of S. haematobium infection is blood in the urine; for intestinal schistosomiasis, it is blood in stool. A consequence of the deposition of schistosome eggs in mucosa and tissues. The clinical and life-threatening complications of schistosomiasis include bladder cancer or serious kidney malfunction, in S. haematobium infection, and severe complications of the liver and spleen, in intestinal schistosomiasis. In addition to these clinical complications it is becoming increasingly appreciated that the effects of infection are worse than previously thought and that schistosomiasis, as well as soil-transmitted helminthes, exert subtle, yet significant, insults on the growth, education and productivity of individuals. For example, intense schistosome infection in children may result in poorer short-term memory and slower reaction times. Heavy burdens of schistosome infection can be associated with reduced growth.

Many cases of diphyllobothriasis are apparently asymptomatic or have poorly defined symptoms associated with other tapeworms, such as vague abdominal discomfort, diarrhea, nausea, and weakness.

Almost a fourth of the population of Finland may be infected with Diphyllobothrium latum, and about 1000 of these people have pernicious anaemia (Bondorff, 1956).

Cyclospora cayetanensis is capable of causing prolonged gastro­intestinal disorder. Globally, this is characterised by persistent and intermittent watery diarrhea accompanied by weight loss and other symptoms, in both immunocompetent and immunocompromised individuals irrespective of sex and age (Fryauff et al, 1999). The disease process which emanates may be the consequences of the reactions of human host to the parasites invading the host’s tissue, causing destruction and damage to the tissue, or the result of the parasites depriving the human host of some essential nutrients (Woodrouff, 1965).

Many parasitic infections, especially those of helminthic origin are asymptomatic, could produce mild or, in a typical case, confusing symptoms. These are often neglected until bizarre, serious or chronic clinical pictures are present. Infection with Balantidium coli can be without symptoms unless the ciliates invade the intestinal wall. Invasion can cause inflammation and ulceration, leading to dysentery with blood and mucus being passed in the faeces (Chessbrough, 2000). About one in five infections are symptomatic as usually reported. Usually the course is chronic with recurrent episodes of diarrhea of varying severity (Ikeh, 1999). The course can be culminative and fatal in debilitated patients. Bowel movements can number from 5 to 24 and are moisty or watery, contains mucus and sometimes blood, and have a pigeon odour (Ikeh, 1999).

Very occasionally, severe intestinal amoebiasis causes overwhelming amoebic colitis which can be fatal. Other rare complications of invasive amoebiasis cause appendicitis and inflammatory masses in the bowel referred to as amoebomas (Chessbrough, 1999). Amoeba may enter the blood stream and be carried to the liver and other parts of the body where they can form an abscess. This is ten times more common in adults than in children, with a higher frequency in men (Chessbrough, 1999).

Attachment of trophozoites of Giardia lamblia to the brush border could produce a mechanical irritation and obstruct absorption. Giardia infection leads to a derangement of the normal villus architecture in some patients. This derangement includes shortening of the villi, crypt cell hypertrophy, and increased inflammatory cell infiltration in the lamina propia (Wiser, 2000). Giardia also interfere with the ability of the intestine to absorb nutrients and secret digestive enzymes when they entirely cover the epithelial surface and some even migrate up to the bile duct to the gall bladder and cause crampy pain or jaundice (Nester et al, 1998).

STRATEGIES FOR CONTROL

In the past, the objective of intestinal parasite control was to eradicate the infection. However, helminthes are extremely difficult to eradicate in communities where poverty and inadequate water and sanitation prevail, due to the high transmission potential of these parasites (Anderson and May, 1991). As a consequence, the current control strategies for intestinal parasites have shifted from eradication to controlling morbidity, using chemotherapy, supported by health education and improved water, feeding and sanitation. The design and implementation of chemotherapy programmes have greatly benefited from an improved understanting of the dynamics of helminthes. Mathematical models have been used to explore the consequences of control (Anderson and May, 1991).

Sanitation and Hygiene

Undoubtedly improved sanitation and hygiene are essential for the long-term control of parasitic diseases. The availability of latrine facilities is associated with lower helminth and protozoan intensities. However, the impact of introducing sanitation on infection levels may only be evident after decades (Esrey et al, 1991) and may not be completely effective. For example, in one study, hookworm prevalence declined by only 4% after the introduction of latrines (Huttly, 1990). Despite associations between hookworm infection and use of footwear to protect from exposure to infective larvae, there is debate as to whether promotion of footwear is an effective control strategy (Albonico et al., 1999). Furthermore, the impact of footwear on interrupting hookworm transmission has probably been overestimated, given that N. amerianus infective larvae penetrate all aspects of the skin and A. duodenale larvae are orally infective. The long time required for improved sanitation and behavior change to occur necessitates a need for a quick acting, medium-term measure to control helminth infections, namely chemotherapy (Albonico et al., 1999).

Chemotherapy

Their broad spectrum of activity, low cost, high efficacy and ease of administration mean benzimidazole anthelminthics are the current cornerstone of helminth control (Savioli et al., 2002). This is particularly true for resource-poor nations that cannot afford expensive sanitation measures. Four anthelminthics are available for the treatment of hookworm: albendazole, levamisole, mebendazole and pyrantel pamoate. Previously, the use of benzimidazole drugs was contraindicated in pregnancy because of uncertainty over possible teratogenicity. However, a recent WHO consulation have reviewed the evidence and concluded that pregnant and lactating women should be considered a high-risk group and included in treatment campaigns (Allen et al., 2002).

Anthelminthic drugs used for mass chemotherapy in the Republic of Korea have evolved continuosly. Santonin-kainic acid was administered in 1969 and early 1970s, piperazine was used from 1971 to 1981, pyrantel pamoate from 1973 to 1988, mebendazole from 1983 to 1993, and albendazole since 1988 (Hong et al., 2006). Mebendazole and albendazole have been produced as Korean products in the Republic of Korea at cheap prices and supplied at no cost to school children by the government (Hong et al., 2006).

Several treatment trials have clearly shown that regular chemotherapy can reduce the morbidity associated with intestinal parasitic infection. This impact is most clearly demonstrated for anaemia. In Kenya, anthelminthic treatment reduced intensities of hookworm and other helminth infections and improved haemoglobin among school children (Stephenson et al., 1989).

Because albendazole and mebendazole are provided as a single dose tablets and patients do not need to be weighed, most control programmes are based on the use of these drugs. The recent comprehensive reviews have assessed the efficacy of albendazole and mebendazole against soil transmitted helminths (Benneth and Guyatt, 2000; Horton, 2000). In their review, Benneth and Guyatt (2000), assessed the relative efficacy of 400mg single-dose albendazole, 500mg single-dose mebendazole and multiple-dose mebendazole. Whereas all drug regimens were highly effective against A. lumbricoides, the patterns for T. trichiura and hookworm were more variable. New studies conducted in Zanzibar, Tanzania indicate that the efficacy of mebendazole decreases with frequent and repeated use (Albonico et al, 2003). Reviewing albendazole alone, Horton (2000) found a wide variation in cure rates (33.3 - 100%), he remarked that substantial reduction in egg count was observed. He noted that very heavy infection with N. americanus may require more than one dose to achieve complete cure. The current and planned widespread use of benzimidazoles for treating helminth infection in human populations has raised concerns of the potential of drug resistance (Albonico, 2003). There have been recent reports of mebendazole drug failures in N. americanus in Mali (De Clerq et al., 1997), and pyrantel pamoate failure against A. duodenale in Western Australia (Reynoldson et al., 1997). Geerts and Gryseels (2001) stated that the conclusive evidence of drug resistance in humans has yet to be provided. By contrast, benzimidazole drug resistance as a consequence of mutations in nematode tubulin alleles is now a well-described phenomenon among parasitic nematodes of sheep and cattle (Conder and Campbell, 1995). Although findings of drug resistance in veterinary helminthes cannot to extrapolate directly to human studies, they can provide important lessons on measures to offset the development of drug resistance, including treatment frequency, population targeting of treatment, underdosing and switching the drug used (Geerts and Gryseels, 2001). As mentioned above, how best to use available anthelminthics to control disease within human communities has benefited from an improved understanding of helminth transmission dynamics (Anderson and May, 1982; Anderson and Medley, 1985; Anderson and May, 1991). Theoretical studies have shown that the precise impact of drug treatment will depend on the proportion of the population treated and the efficacy of the anthelminthic. Because distributions of helminthes are highly aggregated within human communities, targeted treatment of the heavily infected groups will have the greatest impact. Experience over the last two decades across a range of epidemiological settings has shown that the simplest and most practical form of targeting involving school-based treatment (Partnership for Child Development, 1997). Recent analysis has demonstrated that the cost of school-based treatment, including delivery costs, where both geohelminth and schistosomiasis are treated is less than $1 per child treated per year and that geohelminth alone can cost as little as $0.10 per child treated per year (Partnership for Child Development, 1999).