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It is common in the moist tropics and subtropics. It affects about 1 billion people worldwide. In developing nations

the disease leads to the death of many children by increasing their risk for infections that their bodies would

normally fight off. It is a condition caused by roundworms that affects the small intestine and lungs.

There is very little risk of getting the disease in the United States because of advances in sanitation and waste

control.

Hookworm is a leading cause of maternal and child morbidity in the developing countries of the tropics and

subtropics. In susceptible children hookworms cause intellectual, cognitive and growth retardation, intrauterine

growth retardation, prematurity, and low birth weight among newborns born to infected mothers. In developedcountries, hookworm infection is rarely fatal, but anemia can be significant in a heavily infected individual.

Causes

The disorder is caused by infestation with the roundworms:

Necator americanus

Ancylostoma duodenale

Ancylostoma ceylanicum

Ancylostoma braziliense

The first two roundworms affect humans only. The last two types also occur in animals.Necator can only be transmitted through penetration of the skin whereas

Ancylostoma can be transmitted percutaneously, orally, and probably transplacentally.

Disease Transmission

Transmission of this infection is similar to other soil-transmitted helminths in which the individual walks

barefoot or plays on soil or sand when the eggs or baby worms are present there. Proper disposal of animal feces

will lessen the risk of human infection as pets such as dogs and cats can acquire hookworm infection and deposit

the eggs in soil.

The larvae (immature form of the worm) get into the skin. The larvae move to the lungs via the bloodstream and

enter the airways. The worms are about 1/2 inch long.

After traveling up the windpipe, the larva are swallowed. After the larvae are swallowed, they infect the small

intestine. They develop into adult worms and live there for 1 or more years. Adult worms and larvae are released

in the feces.

Life Cycle Stages

The life cycles of hookworms species are similar. Parasites are dioecious, with male and female organs in separateindividuals. They mate in host's small intestine and the females produce eggs. Following copulation, female lays

her eggs.

EGGusual daily output of eggs for single female hookworm is between 10,000 and 30,000 eggs; eggs are passed

to the environment with feces

RHABDITIFORM LARVA

RHABDITIFORM

LARVA 1(L1)rhabditiform larvae hatch from eggs in a warm soil (~48 hours); it feeds on bacteria and other

microorganisms

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RHABDITIFORM

LARVA 2(L2)rhabditiform larvae first stage molt to rhabditiform larvae second stage by third day

FILARIFORM LARVA (L3)rhabditiform larva second stage molts to filariform larva (L3); this is infectious non

feeding stage of the hookworm; the larvae migrate to the grass blades and "stand up" on their tails ready to stick

to the passing host; the larvae survive for several week without feeding until they exaust their metabolic

reserves; they adhere to the host on contact and penetrate skin causing so-called "ground itch"

IMMATURE ADULTswept by blood stream L3 larvae in about 10 days after entry reach the heart and then, lungs,

where they rupture capillaries and ascend the alveoli, bronchioles, bronchi, and trachea; the host coughs up the

larvae and swallows them; when the larvae reach the small intestine, they settle, start feeding, and undergo two

additional moltings

MATURE ADULT after 2 moltings the parasites mature into adults and mate; intestinal blood loss begins just before

egg production and continues for the life of the worm (up to 5 years); to ensure blood flow, adults release

anticlotting agents (the agents were isolated and applied in therapeutics to block blood coagulation in several

diseases); adult females: 10 to 13 mm (A. duodenale), 9 to 11 mm (N. americanus); adult males: 8 to 11 mm (A

duodenale), 7 to 9 mm (N. americanus)

NOTE:

Adult hookworms reside in the human small intestine, where they attach themselves by gripping intestinal lining

with their mouths. They ingest blood and cause bleeding at the attachment site.

Symptoms

Abdominal discomfort

Blood in the stool

Bloody sputum ( COUGHING OF BLOOD)

Cough

Diarrhea

Fatigue

Fever

Itchy rash

Loss of appetite

Nausea, vomiting

Pale skin

Most people have no symptoms once the worms enter the intestines.

Treatment

Treat complications of anemia (Taking in iron supplement or rich in iron foods)Improve nutrition

If the number of hookworm eggs in your intestines is large enoughmore than 2,000 eggs per gram of stoolyour

healthcare provider will assume that the infection may cause anemia and start treating you.

Parasite-killing medications such as albendazole, mebendazole, or pyrantel pamoate are usually prescribed

Ivermectin, used for other worm infections, does not work for hookworm infections.

Possible Complications

Iron deficiency anemia caused by loss of blood

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Nutritional deficiencies

When to Contact a Medical Professional

Call for an appointment with your health care provider if symptoms of hookworm infection develop.

Prevention and Control

Hookworm vaccine are given

If in an area where hookworm disease is common, or where human feces may be in the soil or sand, you:

Should not walk barefoot on the soil or sand

Should not touch the soil or sand with your bare hands.

Health Education on proper excretion disposal

Animals should also have a proper way of excretion as much as possible.

Vegetables should not be eaten raw.

Improvement in sanitation measure

Note:

In chronic (lasting a long time) hookworm infections, if the number of parasites becomes great enough, you candevelop serious anemia (low red blood cell count). This is due to blood loss from the worms attaching themselves

to the intestines and sucking the blood and tissue juices. When this situation is combined with poor nutrition,

pregnancy, or malaria, the anemia can be severe.

The incubation period is 40 to 100 days or two to eight weeks.

Also it is largely dependent on the number of hookworm parasites with which an individual is infected

References:

Kazura JW. Nematode infections. In: Goldman L, Ausiello D, eds. Cecil Medicine . 23rd ed. Philadelphia, Pa: Saunders

Elsevier; 2007:chap 378.

Maguire JH. Intestinal nematodes (roundworms). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of

Infectious Disease . 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 287.

Genus and species Necator americanus Ancylostoma duodenale

Common name New world hookworm Old world hookworm

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Etiologic agent of Necatoriasis, Ancylostomiasis,

Infective stage Filariform larva

Definitive host Human

Portal of entryUsually via skin penetration rather than

ingestion

Usually via ingestion rather than sk

penetration

Mode of transmission Skin > mouth Mouth > skin

Habitat[59]

Small intestine (jejunum,ileum) Small intestine (duodenum, jejunum

Pathogenic stage L3 Larva

Maturation time in host (days)[59]

4956 53

Mode of attachment Oral attachment to mucosa by sucking

Mode of nutrition Sucking and ingesting of blood

Pathogenesis

Larva ground / dew itch, creeping eruption

Adult IDA Microcytic, HypochromicAnemia

Laboratory diagnosis Concentration methods and direct fecal smear

Treatment Albendazole,Mebendazole, or Pyrantel Pamoate

Length of adult hookworm (mm)[60]

59 for males; 911 for females 811 for males; 1013 for females

Shape[60]

Head curved opposite to curvature of body,

giving a hooked appearance to anterior end

Head continuous in same direction as

body

Egg output per female worm per

day[59]

5,00010,000 10,00025,000

Blood loss per worm per day (ml)[59]

0.03 0.150.23

Temperature at which 90% of eggs

hatch (C)[59]

2035 1535

Diagnostic feature adult Semi-lunar cutting plate; bipartite dorsal ray Male Tripartite dorsal ray

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