Hookworms are roundworms or nematodes that live in the intestine of man and animals. There are two species of hookworm that affect humans namely:
ANCYTOSTOMA DUODENALE AND NECATUS AMERICANUS
A. duodenale in a small cylindrical white, grey or reddish brown (due to ingested blood) thread-like worm. The body is curved with the dorsal aspect concave and the ventral aspect dorsally. The cervical curvature gave it the name hookworm.
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Both male and female worms have a buccal capsule containing two pairs of teeth for attaching to small intestinal Mucosa. The male worm is about 8-11mm in length and 0.4mm thick. It has a copulatory bursa at the rear end consisting of an umbrella-like an expansion of the cuticle.
The female is about 11.3mm in length and 6mm thick, slightly larger than the male and has the body cavity occupied by the ovary and coiled uterine tubules packed with eggs. The maximum egg output occurs between 15-18months after injection.
The interval between infection and final disappearance of the egg from the stool averages six (6) years. The female produces 25-35000 eggs each day and some 18 to 54 million during its lifetime.
The eggs are oval or elliptical, measuring 60µm to 40µm colourless and bile stained with a thin transparent hyaline cell membrane and when laid contain two to four segments. where Hookworm is endemic everyone who walks barefooted is liable to contact the disease. N. americanus closely resemble A. duodenale, it is shorter and slender and can be distinguished from A. duodenale by the position of the vulva in the female which is the anterior third of the body and bullal capsule which is smaller, than that of A. duodenale having a cutting plate instead of teeth morphologically the ova of A. duodenale and N. americanus cannot be differentiated. However while A. duodenale has 4, 8 or 16 blastospheres, N. americanus has not less than 8 blastospheres. The female organism lays about 6000-20,000 eggs daily and has a life duration and average of five years.
GEOGRAPHY DISTRIBUTION OF HOOKWORM
Hookworm is prevalent throughout the tropics and subtropics it is estimated to infect as many as 1 million people worldwide. it is numerous in areas where the soil is often contaminated with human faces. Children may have a higher risk of infection if they play or walk barefooted in contaminated soil.
is found distributed predominantly to the north and east of the endemic zones. It is predominantly found along the Mediterranean Coast of Europe and Africa, Northern India, China and Japan. Also, the infection is predominant in hot and humid areas between latitudes 35N and 30S. Infection may occur in mine and other places where the temperature and humidity areas such as to favour the development cycle of the worm. An important consequence of this knowledge of the human hookworm interaction is that in any community some individuals will tend to continue on re-infection.
The people or group of people mostly at risk with the worm infection are those with impaired iron status or iron deficiency anaemia. Adolescent girls, women of childbearing age and those that are pregnant are vulnerable.
HOOKWORM: AETIOLOGY OF HOOKWORM INFECTION,