1.0 DEFINITION OF ENTERIC WORM
Enteric worm are define as organisms that live in the intestine of humans or animals and invest their food from the intestine to grow. The most common of the parasitic-worms that infect the human intestine are viz.:
Reound Worms (-Asearis spp)
Hook Worms (Ancycostoma duodenate and Necator spp).
Whip worms (Irichuris trichiura)
Pin Worms (Enterobius Vermicularis)
The presence of these various types of worms in large numbers coupled with the poor living habits of large segments of the world population has made the control of these worms difficulty and their eradication nearly impossible. That human life and the worms have been in separately interrelated is quite a challenge to mouth transmission dynamics and also that man cannot control the entry into his mouth of materials that pass through his anus is a puzzle. Here, helminthiasis (literally means infections and parasites caused by worms) is the worst culprite.
1.1 SOURCES OF INFECTION
The primary source of worm infestation is the food or water contaminated with infected faeces. When these parasites are passed out through the anus, some of them find their way to food used by man and get it contaminated. Examples are Ascaris eggs on vegetables such as Solanium, lettuce, Cabbage and other vegetables eaten raw or poorly washed. So when men feed on such contaminated foods they get infected. Another source is the soil, that is the soil borne infections stage. Here the eggs of these wormshatch in the soil and the third stage larva (Lz) find its way into the host by actively boring into the skin. Examples are the hookworms (Necator, strongy bodies, Ancylostoma etc.). Some soil-borne infective larval stage exploits human behavioural pattern for its entry. The soil transmitted intestinal nematodes – round worms AscarisLumbricoides, ancylostomsduodenele and Nectatoramericanus rank highest among all the helminthes and their prevalence in different communities serves as an index of socio-economic status. Ascaris and Trichuris affect the health of children especially, the former being a frequent cause of complications and death in many parts of the world, the later causing severe and stubborn – dysentery. The hookworms are recognized as important causes of anaemia particularly in older children and young adults. The obvious high rank of hookworm infection as a cause of debilating disease placed it first among helminthiasis to be attacked on a wide scale.
1.2 LIFE CYCLE OF WORMS HELMINTHES
These enteric parasitic worms all pass through a series of development stage before the adult stage is reached where the – organism becomes sexually mature and a new life cycle develop. These are several live cycles depending on the organisms involved. Within the life cycle, one on several phases of parasitic multiplication may occur depending one species it may be sexual or asexual.
DIRECT AND INDIRECT LIFE CYCLES
There are two types of life cycle viz.:
i. Direct life cycle
ii. Indirect life cycle
DIRECT LIFE CYCLE
Here a single host species is required for the parasite to complete it development example Trichuris trichiura and ancylostoma duodenale.
INDIRECT LIFE CYCLE
Here two or more species of host are required for the parasite to complete its life cycle example – TaenisSaginata – requires two hoots for it to complete its life cycle. In the life cycle of ascaris, Trichuris, ancylostoma, Necator and other helminthes that commonly infect human being, the soil received the faecal contamination stages which are not infective i.e. free living then the soil provides conditions under which development to the infective stage can take place. It provides protection for the infective stage for a period during which it fortuitously may be brought into contact with a susceptible individual whom it may enter by mouth (Ascaris, Trichuria and Ancylostoma) or by skin (Necator). This the soil serves the parasite essentially the same manner as an intermediate host. In the life cycle of Ascaris or in Ascariasis infection – ingesting worm eggs contamining infective larvae inside infects A patient. The eggs hatch in the small intestine, then the larvae are liberated and then penetrated the intestinal wall, gain entrance into muscular system.
From here they enter the liver, heart and finally the lungs. It is in the latter organ that they reside for a week or more and induce preumonitis reactions. Following this they ascend the respiratory tract to the pharynx where the larvae are swallowed and then mature into adult worms in small intestine after several – weeks. The eggs are released in the faeces in a non-embryonated condition and they are incubated in the soil for a few weeks in order that the infective larva may develop. In children ascariosis seems to be more of a hand-to-mouth kind of transmission, whereas in adult the contamination of food with infective eggs is probably the chief source of infection Muller (1989). In the case of Hookworms i.e. Ancylostoma and especially Necator, a patient becomes infected by the contact of his/her skin to infective larvae.
Penetration of the skin by infective hookworm larva produces a dermatitis known as dewitch or ground itch. After skin penetration, the larvae are eventually carried to the heart, then enter the arterial circulation, and within a day or two, filter out in the lung capillaries. After growth and development in the lungs for about a week, the larvae break into the alveolar sacs, ascend the respiratory tract and are swallowed and then develop into mature hookworms in the small intestine in a mouth or two. Here the worms mate and the female lays eggs, which pass out in the faeces. Necator lays about 10,000 eggs daily while Ancylostoma lays 10,000 eggs daily. (Havard Dictionary 35th Edition).
Under suitable conditions of the soil, the eggs develop and hatch into rhabdit form larva, which then grows and develop and then hatch into filariform larva of the worm.
1.3 PATHOGENICITY OF HOOK WORM
Pathogenicity describes the origin of damage caused by parasites and how these damage originated through the activities of parasites. The pathogenicity of different enteric worms. Cestodes and intestinal parasitic nematodes are briefly described here:
The first sign of hookworm infection is frequently a skin reaction at the site of larval penetration. This is known as “ground itch” and is usually more severe in those individuals previously infected. On the entering the host the larvae migrate through the heart and lungs and mild respiratory symptoms may devel9op. After migrating up to the traches the larvae are swallowed. They reach the small intestine and develop into mature worms. The adult hookworm causes chronic blood loss. It has been estimated that a single Ancylostoma – duodenals worm ingests about 150 ML (0.15ml) of blood per day and a Necatoramericanus worm about 30 ML (0.03ml). the Chronic loss of blood cause anaemia and Oedema, resulting in severe cases in retardation of growth and mental.
The fertile egg is avoid, non-embyonated and the egg shell has an outside rugose – layer of material while the infertile egg is ellipsoid, being longer and narrower than fertile eggs. Eggs will obviously not be present if the infection is only with male worm and in such cases radiographic detection is order.
AIMS AND OBJECTIVE OF THE STUDY
(i) To examines the prevalence level of parasitic worm infection in Enugu State, using Asata Zone as a case study.
(ii) To know the most frequently occurring worms in our pupils in primary schools.
STATEMENT OF PROBLEM
The human environment and human – behaviour are highly synchronized with the life cycle of worms and other parasites such that there are very high chance of infection. The primary school pupils are more exposed because of their careless habit and ignorance.
Ho - Very wormy environment signifies high infections rate
detectable from school samples.
Hi - Although habit is synchronized with transmission, worm
infestation if any, can n0t be detected from stool samples.
SIGNIFICATION OF STUDY
A parasitological stool analysis can be used to diagnose intestinal infections with endoparasites such as helminthes worms, by identification of their segments, ova, or whole worm in the stool.
LIMITATION OF STUDY
This study will be focused on parasitic helminthes (worms) that are enteric. Such parasitic worm infections, which are among major disease of mankind. Include giant round worm caused by Ascarislumbricodides, Hook worm etc.
1.4 DISEASES CAUSED BY PARASTIC WORMS (ENTERIC) AND THEIR TRANSMISSION MODES
LOCATION IN HOST
Adults in small intestine larvae in muscle, brain
Ingestion of uncookal pork
Taeniasis (adult) Cysticercosis (larvae)
Anal-oval transfer of eggs or Ingestion of infected insects
Plerocercoid in fish
Adults in small intestine migratory larvae in river, lungs, trachea Ectopic infection
Eating viable eggs from faeces contaminated soil or food.
Ingestion of eggs from – feaces contaminated soil.
Small intestine, larvae through lungs.
Through skin, infected soil from drinking contaminated water.
1.5 PARASITE AND WORM FOUND IN STOOL
WORM IN STOOL
1.6 CONTROL AND PREVENTION OF ENTERIC PARASITIC WORMS
The control of infectious diseases generally is not concerned basically with a person who is sick, but with preventing the spread of the disease in a community. The methods adopted for each disease are based on knowledge of the natural history of the parasite involved and attempts to break its life cycle at as many points or stages as possible. The cure of a disease is the province of the medical doctor, but prevention can follow on understanding of the basic scientific principles underlying the cause and spread of diseases in man and animals. The methods of control of these worms include the prevention of environmental contamination, prevention of exposure to infection, prevention of successful maturation and disease, destruction of intermediate hosts and vectors and integratal control.
Schad (1985), cite appropriate prevention of exposure to infection is achieved by proper food sanitation, the provision of safe drinking and bathing water, meat inspection and processing. Meat inspection and processing is a public health measure taken to avoid eating meat with bladder worm (cysticerci) of T. Solium, T. Saginata. Prevention of environmental contamination involves proper environmental sanitation, the prevention of successful maturation and disease involves the use of chemotherapentic agents. The control of taeniasis and cysticercosis is accompanied by through cooking of beef, pork and pork-by products or other potentially infected food products. Control can also be achieved by maintaining high standard of sanitation and treatment of cases. In the case of hookworm infections, control depends on the prevention fo soil form becoming infected by:
- Providing and using adequate latrines
- Avoiding the use of untreated human faeces as fertilizer
- Treating individuals as part of control and health education programme
- Preventing infective larvae penetrating the skin of the feet by wearing
adequate protecting foot wear. Open sandals are not effective barriers to infection in farm boots are better.
Organised efforts to combat worm infestation have been extensive and have in divers ways benefited millions of people in many parts of the world. Control of intestinal helminthiasis may be viewed as a step wise operation, which begins with population whose major health problems are related to such basic needs as foods, housing and sanitation and ends when these needs are so nearly satisfied that transmission of infection meets natural barriers. Efforts have also been made for the establishment of public health departments and general health services installation of toilets, administration, which has served to influence individuals and community attitudes favourably on matters of sanitation, nutrition and other aspects of disease prevention. But in general, however, their diorect effects on the prevalence of infection have been disappointingly slight. Campaigns on worms, more or less continuously made relatively small though important direct contributions to the reduction of worm prevalence but without marked progress in the treatment of infected individuals.
The climate, water resources and types of agricultural practices in many parts of the world especially Nigeria are well suited to the propagation of the various intestinal worms. Again the unhygienic habits and poor sanitation in the urban and rural areas contribute immensely to the frequent wide spread of infection.
In general, ascaviasis, trichuriasis and Anaylostomasis, individually or in combination are important public health problems through out the tropical regions and are among the major casues of illness in all the under developed areas. The prevalence and intensity of the disease vary directly with the degree of insanitation, and the extent to which indocility extends into cooler/area depends upon the amount and frequency of faecal contamination of soil, food and water in the immediate vicinity of permanent inhabitations.
Based on the above statements, the WHO (1982) have mapped a number of control option. They are sub-divided into two categories:
(a) Environmental control, which includes improved sanitation, uninfected
water and food supply, ensuring that diet is free of parasite eggs and larvae and also nutritionally balanced. The mass should be education of in these matters as well as in good personal hygiene and the reasons for practicing it.
(b) Mass Treatment Control:
This involves treating the whose family with suitable worms – expeller
periodically. The suitable worm expeller should be effective, broad spectrum, in expensive and relatively safe for all the families.
1.7 DIAGNOSIS OF WORM INFECTION
For hookworm infection, the pneumonitis phase cannot be diagnosed with certainty, but if there is a history of dermatries in a patient’s body areas likely to have been in contact with the soil, hookworm infection would be suspected. Parasitologically, a stool examination is all that is required for mature hookworm infection and the microscopic identification of the characteristic eggs in the faeces – determines definite diagnosis. Clinically, chronic anaemia and debility in patients living in an endemic areas is suggestive, but may be caused by malnutrition, malaria, amoebiasis and other helminthiasis. In Ascariasis infection, the pneumonitis casued by the migrating larvae is often not diagnosed but the accompanying eosinophilia is suggestive. The adult worms are some times seen as clear spaces on X-rays after a barium meal (the gut of the worm may show as a thin central line of contract medium). Parasitologically, eggs are usually plentiful in the faeces although a distinction must be made between fertile and infertile eggs. Direct faecal smears using about 2mg of faeces are satisfying and the brine floatation method works as well.
Six million and 6.5% were examined in Japan in 1964 and 6.5% were passing eggs of Ascaris, with about 70 notified deaths, Muller (1989). Infection rates reported recently from various countries are 58% in Brazil. 15 – 20% in Columbia. 25 – 40% Surinam, 4% in children in Eastern Kentucky (USA) and 6% in Ethopia. The larvas of both parasitic and free living forms are unable to survive temperatures below 8oc or above 40oc for more than a few days. They have little resistance to drying, excessive moisture or marked changes in temperature. Strongyloides infections are rarer almost everywhere than hookworm infection.
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