HOOKWORMS (ANCLYOSTOMIASIS)

 HOOKWORMS (ANCLYOSTOMIASIS)

Hookworm disease is a common helminth infection that is predominantly caused by Necator Americanus(predominant US species) and Ancylostoma duodenaleThe worms have a flexed necks forming a hook-like appearance hence the name.Infestation with these worms cause a condition known as ancylostomiasis and a type of anaemia previously referred to as miner’s anaemia

The hookworm is a parasitic nematode worm that lives in the small intestine of its host, human.Hook worm disease is also called uncinariasis Hookworm is a leading cause of maternal and child morbidity in the developing countries of the tropics and subtropics.

*CAUSES*

Two species of hookworms commonly infect humans, Ancylostoma duodenale and Necator americanus. Necator americanus predominates in the America, Sub-Saharan Africa, Southeast Asia, China, and Indonesia. Ancylostoma duodenale predominates in the Middle East, North Africa, India and (formerly) in southern Europe.

Ankylostomiasis, alternatively spelled anchylostomiasis and also called helminthiasis, is the disease caused by hookworms. It is caused when hookworms, present in large numbers, produce an iron deficiency anemia by voraciously sucking blood from the host's intestinal walls.

TRANSMISSION

Infection is normally acquired via the skin (percutaneous route) from filariform (infective) larvae in the soil contaminated by human faeces; or orally via the ingestion of contaminated food. Through eating undercooked meat containing the larvae of Americana duodenale which have migrated into the muscles of the animal, where they can survive for 26-34 days.

LIFE CYCLE

The infected person passes eggs in stool which hatches to produce rhabditiform larvae within 1-2 days.Rhabditiform larvae (L1) undergo 2 successive molts and after 5-10days they become filariforms (L3)In the warm, moist, shady soil the larvae develops and reach the filariform (infectious) stage

Filariforms live in the top 2.5cm of soil (loam soil) and move vertically towards oxygen and moistureUpon contact with the skin, the filariform penetrate it usually on the feet and are carried to the lungs.The larvae may also enter the human body through the mucous membrane of the mouth

After entering the alveoli, they ascend the bronchi and are swallowed.In the small intestines, they develop to reach maturity within 4 -7 weeks after infection.Adult worms attach to the intestinal wall by use of bucal capsule and lay large numbers of eggsThe eggs hatch in the soil and develop into rhabiditiform and then filarifoms that are able to penetrate the skin.

Man is the only hostThe process then becomes cyclicThe worm usually lives about 1 year but it may survive for 5 years or moreEach day a female A. duodenale lays 10,000-30, 000 eggs while the N. Americanus lays 5,000-10,000

SIGNS AND SYMPTOMS

It is asymptomatic in a well nourished person esp. with light infectionGround itchy dermatitis esp. on the feetItchy erythema which develops through papules and vesicles and pustule stages.May develop paroxysmal cough with blood stains in sputumEpigastric pain like that of duodenal ulcer when the worms attach and feed in the duodenum

Vomiting may developPatient may develop some sort of diarrhoea and the condition resembles GiardiasisAnaemia in the under nourished clients may developHypothermiaPuffy face and peripheral oedema or ascitesTarchycardia, tachypnoeaRetarded mental and physical development in children

DIAGNOSIS

*History:* overcrowded residence, poor sanitary conditions, signs and symptomsStool microscopy: the characteristic egg may be recognized in stool.Pallor in heavy infectionsStool occult blood will be positiveOedema due to anaemia must be differentiated from that of heart failure

TREATMENT

AIM:

To reduce the worm loadThe most common treatment for Hookworm are Benzimidazoles (BZAs), specifically albendazole and mebendazole. BZAs kill adult worms by binding to the nematode’s β-tubulin and subsequently inhibiting microtubule polymerization within the parasite.

Albendazle 400mg startMebendazole 500mg stat or 100mg BD x 3/7

LevimasolePyrantel Pamoate (Combatrin) 100mg/kg statIf moderate anaemia associated with hookworm, oral Iron tablets may be used.If bleeding is severe enough, slow transfusion of blood with Frusemide 20mg in each unit may be given.

PREVENTION

The infective larvae develop and survive in an environment of damp dirt, particularly sandy and loamy soil. Do not defecate in places other than latrines, toilets etc.Do not use human excrement or raw sewage or untreated 'night soil' as manure/fertilizer in agricultureDeworm Hand washing

All reactions:

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