Infection of Ancylostoma-DRUGS HEALTH

Synonyms :
Hookworm infection, hookworm, hookworm disease

Etiology :

Hookworm is the common name for blood-sucking nematodes of the Ancylostomatidae family; the 2 species that most commonly infect humans 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 an 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 GI infection caused by the dog hookworm Ancylostoma caninum. The 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:
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.) 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 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. A ceylanicum is found in focally 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 Problems to be Considered:
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.