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THE PATTERNS OF TRANSMISSION, PREVALENCE AND INTENSITY OF SOIL TRANSMITTED HELMINTHIASIS IN NSUKKA ZONE, ENUGU STATE


Project topic for Biology department

CHAPTER ONE

INTRODUCTION

1.1 Background of the study

Soil transmitted helminthiasis are diseases caused by group of helminthes with direct life cycle through the soil environment to man and domestic animals. Life cycle usually involves soil contamination with eggs or larvae of parasitic worms defecated by man and domestic animals, development of the eggs or larvae to infective stages and infection of man or other animal either by the oral-route or active penetration of the skin (Cheesebrough, 2006). Oral-route transmission is facilitated by the use of contaminated household items, eating contaminated food or with dirty fingers. It has also been suggested that houseflies (Musca domestica) may facilitate the contamination of household items and foods stuff. Playing in a dirty environment especially where there are unhygienic practices and sanitation is below standard facilitate transmission.

Eating unwashed fruits and putting contaminated fingers in the mouth especially by children who play in the soil or with domestic animals lead to oral-route infection, playing in the soil also leads to larval penetration of the skin. The major soil transmitted helminthes in Nigeria include Ascaris lumbricoides, Trichuris trichiura, Ancylostoma duodenale, Necator americanus, Strongyloides stercolaris, Entorobius vermicularis ,and Toxocara species, A.duodenale and N. americanus which together cause hookworm infection, and Strongyloides stercolaris are transmitted by direct skin penetration while the rest gain entry by oral-route.

Knowledge, attitude and management of ascaris vary greatly among different people. Most children especially the school aged are either not aware or do not care of the consequences of playing in contaminated environments. Poor hygiene habit s such as not cleaning with soap and water after using the latrines also expose both children and adults to infections. Some individuals also do not seek treatment against helminthes infection, while others claim that intestinal worms are useful compounds of food digestion. Ignorance, illiteracy and poverty have been shown to create favorable conditions upon which soil transmitted helminthes thrive. These and lack of awareness on the mode of transmission of these diseases sustain poor management strategies in most endemic communities.

According to W.H.O. (1987), people’s attitude to disease control depends on what they know about such disease, its mode of transmission, pathological consequences, prognosis (forecast of the course of a disease) and economic importance. Where this knowledge is misconstrued, transmission goes unhindered. Soil transmitted diseases have been endemic in Nsukka and surrounding communities for a long time, However, while the literature is loaded with information in their distribution in time and space, little has been done on the knowledge, attitude and management of this disease in the area. Such information is indispensable for the formation and implementation of effective and sustainable control programme against the diseases in the area.

1.2 Statement of the problem

According to Brown and Neva (1983) parasitic helminthes may have either simple or complicated lifecycle. The degree of damage done to the hosts is however varied. Soil transmitted helminthes thrive and persist in human communities in which poverty, inadequate sanitation, lack of access to health care and overcrowding are entrenched. Additionally, the habits of bare feet on sand and eating unwashed fruits and vegetables also encourage the transmission of helminthic infection, these habits occur mostly in rural areas.

The world health organization (WHO, 1989) estimates that over two billion people are infected with one or more soil transmitted helminthes, mainly Ascaris lumbricoides, hookworm and Enterobius vermicularis. The prevalence of soil transmitted helminthiasis differ from region-region. Although several studies have been conducted in the prevalence of intestinal helminthiasis in Nigeria, there are still localities including the study area in Nsukka for which epidemiological information is not available. (WHO, 1989) recommends that a baseline survey in rural communities be done to determine prevalence of worm infestation before instituting any worm control measures and treatment should be given accordingly to the survey.

Presently, there is no national school-based helminth control programme in Nigeria. This study sought to determine the prevalence and patterns of soil transmitted helminthiasis. This study will serve as a baseline for any further evaluation of proposed regular deworming programmes at school, rural areas and state in general.

1.3 Aims and Objectives of the Study
The aims of this study is to determine the patterns of transmission, prevalence and intensity of soil transmitted helminthiasis in Nsukka zone, Enugu state.

1.4 Specific Objectives

1 To determine the profile of and seasonal distribution of soil transmitted diseases in selected communities of varying levels of urbanization in Nsukka zone by means of eggs transmitted helminthes present in the environment.

2 To determine the socio-environmental factors including water supply and sanitation that affect the transmission of the diseases in the communities.

3 To ascertain the knowledge, attitude and management of the disease in different communities.

4 To determine the patterns of distribution of prevalence and intensity infection by age, gender, occupation and other demographic variables in the various communities.

5 To identify factors that significantly contribute to the transmission of soil transmitted helminth diseases observed in the communities.

1.5 Research Questions

1. What are the distribution of soil transmitted diseases in the selected communities in Nsukka?

2. What are the socio-environmental factors that affect the transmission of the diseases in the communities?

3. Ascertain the knowledge, attitude and management of the disease in different communities.

4. What are the ways to determine the patterns of distribution of prevalence and intensity infection by age, gender and occupation?

5. What factors significantly contribute to the transmission of soil transmitted helminth diseases observed in the areas?

1.6 Research Hypothesis
1. They are distributed by means of eggs of transmitted helminthes and their larvae being present in the environment and in a viable condition and the environment is contaminated when the eggs or larvae reaches the soil in human faeces and man becomes exposed to these infective agents.

2. Poor personal hygiene and bad habit at defecation are the strongest factors that affect transmission of helminthes.

3. Knowledge, attitude and management of ascariasis vary greatly among different people. Most children are not aware or do not care of the consequences of playing in contaminated environments. Poor hygiene habits such as not washing with soap and water after using the latrines also expose both children and adults to infections, some individuals also do not seek treatment against helminthes infections while others claim that intestinal worms are useful components of digestion.

4. In terms of age dependent, distribution prevalence is said to be very high between the age of 4 and 14. It has been reported that intensity of infection measured by worm burden after expulsion chemography or by egg excretion per gram of host faeces is especially higher in children than adults in many given community. Occupation is a factor in terms of exposure to helminthes infection. For instance, farmers who farm in lands where there is indiscriminate defaecation of human faeces are known to be exposed to infection egg or larvae of soil transmitted helminthes.

5. The use of unclean soil contaminated feeding bottles, plates, cups and other utensils, indiscriminate defaecation in bushes and other surroundings, improper cleaning after using the latrine, infrequent wearing of foot-wears and eating unwashed vegetables and fruits.

1.7 Significance of the Study
In rural communities where inadequate sanitation and lack of access to good health care are commonly found, soil transmitted helminthes prevail greatly. The world health organization (WHO, 1989) recommends that a baseline survey in rural areas be done to determine prevalence of worm infestation before instituting any worm control and treatment should be given adequately. This study was conducted to assess the prevalence, intensity and environmental risk factors affecting the transmission of soil transmitted helminthiasis in randomly selected communities in Nsukka to determine the effect of people’s knowledge on the mode of transmission of the diseases and to facilities for water supply and sanitation in each of the communities. Soil transmitted helminthes are very disturbing to the health and most be controlled in order to better the lives of people living both in urban and rural areas.

1.8 Operational Definition of Terms
Ascaris lumbricoides: The large human round worm, the incidence rates for this parasites are very high with >1500 million cases of infection annually of which about 210 million cases are symptomatic.

Enterobius vermicular is: A pin worm or thread worm infection, an extremely nematode infection, particularly in temperate areas and seen particularly in children.

Ancylostoma duodenale and Necator Americanos: These are hookworms seen in the tropics and sub-tropics and have a worldwide distribution. There are >1200 million cases of hookworm infection annually of which about 100 million cases are symptomatic.

Pathology: Is the study of disease.

Pathogenesis: The development of a disease and chain of events leading to that disease.

Epidemiology: The branch of medicine which deals with the incidence, distribution and possible control of diseases and other factors relating to health.

Helminthiasis: Also known as worm infection, is any macro parasitic worm disease of humans other animals in which a part of the body is infected with parasitic worms known as helminthes.

Helminthes : Commonly known as parasitic worms that feed on living hosts for nourishment and protection.

Endemicity : A disease or condition regularly found among particular people or in a certain area.

Rhabditiform : Early development larval stages of soil-borne nematodes which precede the infection’s third-stage filariform larva.

Detoxification : The action of removing harmful substances from the body or blood.

Sexual dimorphism: Is the condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs.

Unembryonated eggs: Stage of an egg which does not contain an embryo.

Moulting: The process of shedding feathers, hairs or skin before new growth occurs.

Lymphatic: Small thin channels similar to blood vessels that do not carry blood but collect and carry tissue fluid called lymph from the body to ultimately drain back into the blood stream.

Pulmonary migration: The penetration of infective larvae in the intestinal wall where larvae migrate into lungs through the blood stream.

Prevalence: The fact or condition of being prevalent or commonness.


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