Infection of Ancylostoma | Parasite infection

Infection of ancylostoma is the common parasite infection case met at human being.

Synonyms :
Hookworm infection, hookworm, hookworm disease

Etiology :

Hookworm is the common name for blood-sucking nematodes of the Ancylostomatidae family; the two species that most commonly infect humans and cause this parasite infection are Ancylostoma duodenale and Necator americanus.
Classic hookworm disease is a gastrointestinal (GI) infection with chronic blood loss leading to iron deficiency anemia and protein malnutrition. The disease is caused by A duodenale, the major anthropophilic hookworm, and, less commonly, by the zoonotic species Ancylostoma ceylanicum.
Cutaneous larva migrans is a parasite infection caused most commonly by larvae of Ancylostoma braziliense, whose definitive hosts include dogs and cats. The manifestations of cutaneous larva migrans are limited to the skin.
Eosinophilic enteritis is a gastro intestinal infection caused by the dog hookworm Ancylostoma caninum. This parasite infection disease is characterized by abdominal pain but no blood loss.
N americanus causes only "classic hookworm disease," as defined above.
In 1880, an epidemic called miners' anemia occurred among Italian laborers building the Saint Gotthard railway tunnel in the Swiss Alps. A duodenale was responsible for the epidemic.

Pathophysiology:
Some of this parasite infection pathophysiology are : Eggs deposited on warm, moist soil develop into infective larvae over 5-7 days. Infective larvae are developmentally arrested and nonfeeding. If unable to infect a new host, the larvae die when their metabolic reserves are exhausted, usually in about 6 weeks. Humans are the major reservoir, and infection is maintained by continual contamination of soil by human feces.

Internationally:
Hookworm infection with human-host species has an estimated global prevalence of 1 billion people (These parasites drain the equivalent of all the blood from approximately 1.5 million people every day.) This parasite infection Infection is most prevalent in tropical and subtropical zones, roughly between the latitudes of 45°N and 30°S. Hookworm infection occurs only in isolated temperate areas.
Infection is endemic in most developing countries. However, even in endemic regions parasite infection is usually confined to rural areas, especially where human feces are used for fertilizer or where sanitation is inadequate. In developed countries, infection is most commonly encountered in travelers, emigrants, and adoptees from developing countries.
A duodenale is the predominant species in the Mediterranean region, northern regions of India and China, and North Africa which cause this parasite infection. A ceylanicum is found in focally parasite infection endemic areas in southern Asia. N americanus is the predominant species in southern China, Southeast Asia, the Americas, most of Africa, and parts of Australia. This differential distribution is not absolute, and mixed infections with both species are common in individual patients.
In endemic areas, highest prevalence is among school-aged children and adolescents, which may be because of age-related changes in exposure and the acquisition of immunity. Once infected, children are more vulnerable to developing morbidity because dietary intake often fails to compensate for intestinal losses of iron and protein, especially in developing countries. A fulminant form of acute GI hemorrhage associated with acute ancylostoma infection has been described in newborns.

Other problem
Other problem of this parasite infection are : Once iron deficiency anemia from blood loss is diagnosed, keep in mind that rare causes of intestinal blood loss (eg, polyps, Meckel diverticulum) are far less common in developing countries.Respiratory symptoms with peripheral eosinophilia should suggest a parasitic etiology.Differentiation between scabies and cutaneous larva migrans is not always easy, especially if the latter occurs with atypical rash. Important distinguishing criteria for scabies are history of exposure, crusty lesions on the hands or feet, and generalized pruritus.

Form of infection
Classic hookworm infection
Humans acquire infection either by exposing skin to soil contaminated with A duodenale or N americanus larvae or by ingesting soil contaminated with A duodenale larvae. In this case parsite infection larval skin penetration requires contact with contaminated soil for 5-10 minutes.
The larvae elaborate a protease that helps the organisms bore through the skin. Larvae entering via the skin migrate through the venous and lymphatic circulation. After traversing pulmonary capillaries, larvae enter lung alveoli and ascend the airways, where they are coughed up and swallowed. Orally ingested larvae may undergo extraintestinal migration or remain in the GI tract.
During the migratory phase, larvae evoke an eosinophilic inflammatory response.
After passively reaching the proximal small intestine, larvae develop into adult, sexually mature male and female worms. Within the small intestine, the adult worm attaches with its mouth to the mucosa and begins to feed. Using its teeth or cutting plates, powerful esophageal muscles, and hydrolytic enzymes, the hookworm digests the plug of tissue within its buccal capsule. At the same time, the worm releases a potent anticoagulant, causing profound bleeding from eroded capillaries in the lamina propria. Worms change location every 4-8 hours, producing minute, bleeding, mucosal ulcerations.
Larvae require about 6-8 weeks from the time of skin penetration to develop into adults. Worms mate in the small intestine, and the females deposit fertilized eggs into the lumen. Eggs begin to appear in feces about 8-12 weeks after infection.
Some A duodenale larvae, however, may undergo a period of extraintestinal dormancy after penetrating the skin before resuming their migration to the gut for maturation. This dormancy period can last weeks or months. As a result of this dormant period, intestinal ancylostomiasis can occur up to a year after initial exposure to infective larvae. The repositories of these dormant larvae may be muscle tissue, or the dormant larvae may enter the mammary glands and breast milk, which may account for cases of infantile ancylostomiasis in Africa, China, and India.

Cutaneous larva migrans
The infective larvae of zoonotic species such as A braziliense do not elaborate sufficient concentrations of hydrolytic enzymes to penetrate the junction of the dermis and epidermis. These larvae remain trapped superficial to this layer, where they migrate laterally at a rate of 1-2 cm/d and create the pathognomonic serpiginous tunnels of cutaneous larva migrans. Larvae can survive in the skin for about 10 days before dying (even in untreated persons).

Eosinophilic enteritis
Larvae of A caninum typically enter a human host by skin penetration, although infection by oral ingestion is possible. In this parasite infection case larvae probably remain dormant in skeletal muscles and create no symptom.
In some individuals, larvae may reach the gut and mature into adult worms. Why some individuals sustain A caninum development and then respond with a severe localized allergic reaction is unknown.
Adult worms secrete various potential allergens into the intestinal mucosa. Some patients have been reported to have increasingly severe recurrent abdominal pain, which may be analogous to a response to repeated insect stings.