Ancylostoma braziliense mouthparts<unk> s in humans include ancylostomiasis and necatoriasis. Ancylostomiasis is caused by Ancylostoma duodenale, which is the more common type found in the Middle East, North Africa, India, and (formerly) in southern Europe. Necatoriasis is caused by Necator americanus, the more common type in the Americas, sub-Saharan Africa, Southeast Asia, China, and Indonesia. Other animals such as birds, dogs, and cats may also be affected. A. tubaeforme infects cats, A. caninum infects dogs, and A. braziliense and Uncinaria stenocephala infect both cats and dogs. Some of these<unk> s can be transmitted to humans. Morphology A. duodenale worms are grayish white or pinkish with the head slightly bent in relation to the rest of the body. This bend forms a definitive hook shape at the anterior end for which<unk> s are named. They possess well-developed mouths with two pairs of teeth. While males measure approximately one centimeter by 0.5 millimeter, the females are often longer and stouter. Additionally, males can be distinguished from females based on the presence of a prominent posterior copulatory bursa. N. americanus is very similar in morphology to A. duodenale. N. americanus is generally smaller than A. duodenale with males usually 5 to 9 mm long and females about 1 cm long. Whereas A. duodenale possesses two pairs of teeth, N. americanus possesses a pair of cutting plates in the buccal capsule. Additionally, the hook shape is much more defined in Necator than in Ancylostoma. Life cycle life cycle The<unk>  thrives in warm soil where temperatures are over 18 °C. They exist primarily in sandy or loamy soil and cannot live in clay or muck. Rainfall averages must be more than 1000 mm (40 inches) a year for them to survive. Only if these conditions exist can the eggs hatch. Infective larvae of N. americanus can survive at higher temperatures, whereas those of A. duodenale are better adapted to cooler climates. Generally, they live for only a few weeks at most under natural conditions, and die almost immediately on exposure to direct sunlight or desiccation.<unk>  of the host is by the larvae, not the eggs. While A. duodenale can be ingested, the usual method of<unk>  is through the skin; this is commonly caused by walking barefoot through areas contaminated with fecal matter. The larvae are able to penetrate the skin of the foot, and once inside the body, they migrate through the vascular system to the lungs, and from there up the trachea, and are swallowed. They then pass down the esophagus and enter the digestive system, finishing their journey in the intestine, where the larvae mature into adult worms. Once in the host gut, Necator tends to cause a prolonged<unk> , generally 1 to 5 years (many worms die within a year or two of<unk> g), though some adult worms have been recorded to live for 15 years or more. Ancylostoma adults are short-lived, surviving on average for only about 6 months. However, the<unk>  can be prolonged because dormant larvae can be "recruited" sequentially from tissue "stores" (see Pathology, above) over many years, to replace expired adult worms. This can give rise to seasonal fluctuations in<unk>  prevalence and intensity (apart from normal seasonal variations in transmission). Civilian Public Service workers built and installed 2065 outhouses for<unk>  eradication in Mississippi and Florida from 1943 to 1947. They mate inside the host, females laying up to 30,000 eggs per day and some 18 to 54 million eggs during their lifetimes, which pass out in feces. Because 5 to 7 weeks are needed for adult worms to mature, mate, and produce eggs, in the early stages of very heavy<unk> , acute symptoms might occur without any eggs being detected in the patient's feces. This can make diagnosis very difficult. N. americanus and A. duodenale eggs can be found in warm, moist soil where they eventually hatch into first-stage larvae, or L1. L1, the feeding noninfective rhabditoform stage, will feed on soil microbes and eventually molt into second-stage larvae, L2, which is also in the rhabditoform stage. It will feed for about 7 days and then molt into the third-stage larvae, or L3. This is the filariform stage of the parasite, that is, the nonfeeding infective form of the larvae. The L3 larvae are extremely motile and seek higher ground to increase their chances of penetrating the skin of a human host. The L3 larvae can survive up to 2 weeks without finding a host. While N. americanus larvae only infect through penetration of skin, A. duodenale can infect both through penetration and orally. After the L3 larvae have successfully entered the host, they then travel through the subcutaneous venules and lymphatic vessels of the human host. Eventually, the L3 larvae enter the lungs through the pulmonary capillaries and break out into the alveoli. They then travel up the trachea to be coughed and swallowed by the host. After being swallowed, the L3 larvae are then found in the small intestine, where they molt into the L4, or adult worm stage. The entire process from skin penetration to adult development takes about 5–9 weeks. The female adult worms release eggs (N. americanus about 9,000–10,000 eggs/day and A. duodenale 25,000–30,000 eggs/day), which are passed in the feces of the human host. These eggs hatch in the environment within several days and the cycle starts anew.
Hookworm infection
Pinworm infection
Soil-transmitted helminthiasis
Intestinal parasite infection
Strongyloidiasis
Tick infestation
Acariasis
Myiasis