Hookworm Diseases. Necator Americanus

HOOKWORM DISEASES 1. Necator americanus Along withAncylostoma duodenale, wormnNecator americanus grouped as hookworm. Although they have some differences in geographic distribution, they both have similar life cycles. To track the presence of hookworms in the human intestine, direct fecal examination can be carried out (such as in routine fecal examinations), using concentration or fecal culture methods according to Harada Mori. On direct and concentrated examination of feces, eggs can be found or sometimes rhabditiform larvae can be found, although rarely, for example in the feces of constipated sufferers. In fecal culture, both rhabditiform and filariform larvae are looked for, so their morphology needs to be recognized well. Larvae, especially rhabditiform, are difficult to differentiate between N. americanus with A. duodenale, but can be distinguished from larvae S. stercoralis. Egg: - Egg Necator americanus indistinguish able from eggsAncylostoma duodenale - Oval or ellipsoidal in shape - Length 55 – 75 µ, width 35 – 42 µ - Hyaline walled, transparent, thin, one layer - Eggs taken from fresh feces contain 4-8 cells, but if taken from old feces you can get eggs containing rhabditiform larvae. Adult Worms: Macroscopic: - Gray/reddish white color - The posterior end of male worms curves ventrally and has a copulatory bursa - cylindrical, smaller and slimmer than Ancylostoma duodenale, the anterior end faces dorso anteriorly due to its presence cervival curvatera, so it is shaped like the letter S. - Female worms are bigger than males - Male: Length 7 – 9 mm, diameter 0.4 mm - Bursa long and wide - Female: Length 9 – 11 mm - Diameter 0.4 mm Microscopic: - Small buccal capsule, contains: - 1 pair of ventral cutting plates - 1 pair of dorsal cutting plates - 1 pair of subventral/lateral teeth - 1 pair of dorsal teeth½ circle shape - Copulatory exchange: - At the posterior end of the adult male worm, there is a copulatory organreinforced with 7 pairs 'rays': -Dorsalray, deep slits, respectively - Externalodorsal - Posterolateral - Mediolateral - Externalolateral - Lateroventral - Ventroventro - There are a pair of spicules whip-like copulatory ; the end unite and expand, forming a hook. 2. Ancylostoma duodenale Like N. americanusTo track the presence of these worms in the human intestine, direct fecal examination can be carried out using concentration or fecal culture methods according to Harada Mori. On direct and concentrated examination of feces, eggs can be found or sometimes rhabditiform larvae can be found, although rarely, for example in the feces of constipated sufferers. In stool culture, both rhabditi form and filari form larvae are looked for. Rhaditiform Larvae: - length ± 0.25 – 0.5 mm, diameter 17 µm; - mouth open, buccal capsule long, narrow; - the esophagus is shaped like a bottle, the length is ± ⅓ the length of the body; - genital primordium small, unclear/hard to see Filariform Larvae: - slim body, 0.5 – 0.6 mm long; - mouth closed, esophagus short, ± ¼ body length. Adult worms: - Macroscopic:  White grey/reddish color  Fat, the anterior part is slightly tapered, curves dorsally, forming the shape of the letter C  The posterior end of the male worm is curved to have a copulatory bursa ventral And  Female worms are larger than male worms. Male: Long 8 – 11 mm; diameter 0.4 – 0.5 mm Female: Long 10 – 13 mm; diameter 0.6mm - Microscopic:  The buccal capsule is wide, oval in shape, larger transverse diameter.  On the ventral side ('top' in your microscope), there are cutting teeth consisting of 2 pairs of fused teeth, the outer teeth are larger than the inner teeth, the inner teeth have an indistinct median process. Dorsally ('bottom' in your microscope) there is a tooth plate with a median gap  Copulatory bursa: 'dorsal ray' has a shallow slit, respectively23-branched ends (= trifida = tripartite). There are a pair of whip-like copulatory spicules whose ends remain separate or parallel 3. Ancylostoma caninum Although there are reports of this worm infecting humans, it is generally a parasite in dogs, especially in the northern hemisphere. The larval stage can causecreeping eruption' in humans. In this practicum, the buccal cavity is shown as a comparison with the buccal cavity of other hookworms. Adult Worms: - Wide buccal cavity - There are 3 pairs of ventral teeth - The esophagus is a continuation of the buccal cavity