Ancylostoma Species Research Articles

Outbreak of Cutaneous Larva Migrans among British Military Personnel in Belize

Cutaneous larva migrans (CLM) is a common skin condition, seen most frequently in tropical or semitropical countries. It is caused by dermal invasion by filariform larvae of a variety of nonhuman nematodes. The commonest etiological agents are the hookworms of domestic cats and dogs (Ancylostoma species), man being infected by environmental skin contact with free-living larvae released from ova passed in animal feces. 1 In the natural host the larvae enter the bloodstream and migrate to the gastrointestinal tract, where they mature into the adult form. If man is infected as an incidental host, the larvae enter the dermis but are unable to reach the blood. The result is a “wandering” larva in the dermis, which in turn causes an intense inflammatory response. The incubation period until the symptoms appear varies typically from a few hours to several days, but may rarely be months or years.The characteristically serpiginous pruritic lesions are usually found on parts of the body that have been in contact with the ground. This is usually the soles of the feet, but will vary according to the individual’s behavior. For instance, lesions can be seen anywhere on the body in a tourist who has been sunbathing on infective ground. 2 The condition is self-limiting but extremely uncomfortable, and treatment with antihelminthic agents is usually rapidly effective.

Investigating hookworm genomes by comparative analysis of two Ancylostoma species

BackgroundHookworms, infecting over one billion people, are the mostly closely related major human parasites to the model nematode Caenorhabditis elegans. Applying genomics techniques to these species, we analyzed 3,840 and 3,149 genes from Ancylostoma caninum and A. ceylanicum.ResultsTranscripts originated from libraries representing infective L3 larva, stimulated L3, arrested L3, and adults. Most genes are represented in single stages including abundant transcripts like hsp-20 in infective L3 and vit-3 in adults. Over 80% of the genes have homologs in C. elegans, and nearly 30% of these were with observable RNA interference phenotypes. Homologies were identified to nematode-specific and clade V specific gene families. To study the evolution of hookworm genes, 574 A. caninum / A. ceylanicum orthologs were identified, all of which were found to be under purifying selection with distribution ratios of nonsynonymous to synonymous amino acid substitutions similar to that reported for C. elegans / C. briggsae orthologs. The phylogenetic distance between A. caninum and A. ceylanicum is almost identical to that for C. elegans / C. briggsae.ConclusionThe genes discovered should substantially accelerate research toward better understanding of the parasites' basic biology as well as new therapies including vaccines and novel anthelmintics.

Persistent Cutaneous Larva Migrans Due to Ancylostoma Species

Cutaneous larva migrans is considered to be a self-limited parasitic infection of about 2 to 8 weeks' duration, though it has been reported to persist for as long as 55 weeks. In this case, a healthy 47-year-old white man had multiple serpiginous lesions typical of cutaneous larva migrans for 18 months. A biopsy taken 2 months before presentation showed a parasite consistent with Ancylostoma species deep in a hair follicle. The patient initially responded to topical thiabendazole, but relapse occurred when therapy was discontinued. Oral thiabendazole cured the problem after 22 months of infestation. Cutaneous larva migrans may sometimes be long-standing, here almost 2 years, even in a healthy patient. Organisms may reside deep in the hair follicles. Topical thiabendazole may not penetrate to this depth, necessitating oral thiabendazole therapy.

Metalloproteases of infective Ancylostoma hookworm larvae and their possible functions in tissue invasion and ecdysis

To infect their hosts, hookworm larvae must exsheath and migrate through connective tissue. A modified in vitro skin chamber was used to show that the human hookworm Ancylostoma duodenale and the zoonotic canine hookworm Ancylostoma caninum penetrate epidermis, basement membrane, and dermis in similar ways. These similarities in tissue invasion properties reflect the observed biochemical similarities in parasite protease composition. The larvae of both species contain protease activity that is inhibited by o-phenanthroline; this identifies the proteases as metalloproteases. The enzyme activities exhibit an alkaline pH optimum between pH 9 and 10. During modified sodium dodecyl sulfate-polyacrylamide gel electrophoresis in which a protein substrate (either casein or gelatin) was used, the protease activities resolved into a major band at an Mr of 68,000 and a minor band at an Mr of 38,000. Proteases were released by living A. caninum larvae in vitro and degraded purified and radiolabeled casein to smaller peptides. Motile hookworm larvae were also incubated with purified and radiolabeled connective tissue macromolecules in vitro. Both Ancylostoma species degraded human fibronectin to a 60,000-Mr polypeptide intermediate, but could not degrade solubilized bovine elastin or human laminin. In contrast, the obligate skin-penetrating nematode Strongyloides stercoralis degraded all three substrates. This biochemical difference may explain some observed differences in invasiveness.

Hookworm antigens: the potential for vaccination

Hookworms rank with Ascaris as the most prevalent soil-transmitted helminths of man. Up to 1000 million people may be infected. Not all suffer the life-threatening anaemia that reflects heavy burdens of hookworms, but even mild iron-deficiency anaemia due to hookworms can lead to intellectual and growth retardation - especially among infected children. Health education, mass chemotherapy and the sanitary disposal of faeces have been the traditional mainstays of hookworm control, but more recently chemotherapy targeted only to heavily infected individuals who appear predisposed to hookworm anaemia has emerged as a realistic alternative. Ultimately, however, knowledge of the molecular immunology of hookworm infection may provide the basis for rational vaccine development. Although the evidence for acquired immunity to hookworms in man is not strong, work is now underway to identify and to characterize antigens from third and fourth larval stages and adults of Necator americanus and species of Ancylostoma (Table 1). As this article shows, the work provides real promise for improved immunodiagnosis and possible vaccination.

Incidence and importance of common intestinal parasites among the population of the Punjab in North-West-India.

From November 1968 to December 1973 stool investigations were carried out in 7,314 patients. Intestinal parasites were found to be present in 4,294 patients; the results were negative in 3,080 patients. A detailed case history was available in 4,700 cases. In 40% of the patients with positive results one or several types of parasites were present. No difference was observed with regard to sex, cast or religion. The prevalence of Sikhs among the patients with hookworm infections is no doubt due to the heavier infection rate among the rural population which mainly consists of Sikhs. In the second decade of life parasite infestation increases sharply. Hymenolepis nana was found in all age groups. Ameba, ancylostoma and ascaris were prevalent among the rural population. Hydroxychinolins and phenanthrolin derivatives have proved effective in the treatment of amebiasis. The subacute myelo-optico-neuropathy reported in recent years is attributed by some to the medicament itself and by others to the presence of a virus. Dehydroemetine appears to be the drug of choice against amebic infestation of the liver. Other authors report good results with metronidazol. The authors of this study found that treatment is only successful if a sufficiently high dosage is administered for an adequate length of time. Piperazin derivates have proved effective in the treatment of ascaridiases, with a cure rate of 80–85%. No side-effects were seen. Hook-worm infections were treated with bephenium hydrochloride and also tetrachloraethylen which is more effective but more toxic. The cure-rate was 80%. Bisothiocyanate, which acts specifically against hook-worms, was administered and proved effective against both species of ancylostoma. Satisfactory results were obtained with a single dose of 150 mg of bitoscanate. The consequences of intestinal parasite infections among the population are discussed and prophylactic measures are outlined.

A Common Source Outbreak of Cutaneous Larva Migrans

CUTANEOUS larva migrans, often called creeping eruption, is caused by larval nematodes entering the skin of the poorly adapted human host. The linear cutaneous eruptions that result have been noted isince 'the late 1800's; however, Kirby-Smith and co-workers in 1926 proved the causative agent to be the feline or canine strain of the cat hookworm, Ancylostoma braziliense (1). Uncinaria, necator, bunostomum, and other species of Ancylostoma have been incriminated occasionally; however, natural exposure to A. braziliense is by far the most frequently reported cause of cuitaneous larva migrans. During the construction of a new hospital at Patrick Air Fiorce Base in Florida, a group of workmen developed an unusual dermatitis. When I was informed of this on September 2, 1964, I visited the construction area. The general foreman said that seven of the nine men (a painter and pipefitters) who worked in the 3-foot-high crawl space (an area of 41,000 square feet) under the new hospital had an extremely irritating skin malady. The workers believed that they had contracted it in the crawl space and declared that unless the situation wals remedied, ;they would walk off the job. The foreman called eight of the men from the crawl space (the ninth man was visiting his physician for treatment), so that I could see their lesi,ons. Five men had lesions typical of those caused by A. braziliense. One man's lesions were those of an atypical infection. Two men apparently were not yet infected.

On the Occurrence of a Species of Ancylostoma Closely Related to A. duodenale in an African Lemur

On the Occurrence of a Species of Ancylostoma Closely Related to A. duodenale in an African Lemur