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152 CHAPTER 6

TABLE 6-1 Differentiation Between N. americanus and A. duodenale

GENUS AND SPECIES NECATOR AMERICANUS ANCYLOSTOMA DUODENALE

Common Name New World hookworm, American Old World hookworm
murderer
Etiologic Agent of Necatoriasis, Uncinariasis Ancylostomiasis, Wakana disease
Infective Stage Filariform larva Filariform larva
Definitive Host Humans Humans
Portal of Entry Usually via skin penetration rather Usually via ingestion rather than skin
than ingestion penetration
Mode of Transmission Skin . Mouth Mouth . Skin
Habitat Small intestine (jejunum, ileum) Small intestine (duodenum, jejunum)
Maturation in Host (days) 49–56 53
Mode of Attachment Oral attachment to mucosa by Oral attachment to mucosa by sucking
sucking
Mode of Nutrition Sucking and ingesting of blood Sucking and ingesting of blood
Pathogenesis Larva—ground/dew itch, creeping Larva—ground/dew itch, creeping eruption;
eruption; adult—IDA Microcytic, adult—IDA Microcytic, Hypochromic Anemia
Hypochromic Anemia
Laboratory Diagnosis Concentration methods and Direct Concentration methods and Direct
Fecal Smear Fecal Smear
Treatment Albendazole, mebendazole, or Albendazole, mebendazole, or pyrantel
pyrantel pamoate pamoate
Length of Adult 5–9 for males; 9–11 for females 8–11 for males; 10–13 for females
Shape Head curved opposite to curvature Head continuous in same direction
of body, giving a hooked appearance as the body
to anterior end
Temperature at which 90% 20–35 15–35
of eggs hatch (C)
Diagnostic Feature—Adult Semilunar cutting plate; bipartite Male–Tripartite dorsal ray
dorsal ray
Diagnostic Feature—Egg Morula Same

the larval stages can penetrate the skin of those not prac- practice preventive measures outlined by health depart-
ticing proper sanitation and care in avoiding exposure ments and other authorities. Continued adherence to
(Figure 6-13). Diagnostic characteristics of a hookworm preventive measures is necessary to prevent reinfection.
egg are its thin shell with an oval or ellipsoidal shape Common rules to practice to ensure protection from
ranges from 57 to 76 μm x 35 to 47 μm in size. parasitic infections include the following instructions:
Hookworms cannot survive, except in ideal soil ■ Do not defecate outside latrines or toilets that are pro-
conditions and temperatures which place a geographic vided for convenience and safety. Even burying the
restriction on where they are found. To control and feces in soil may allow propagation of the parasites in
prevent infections by hookworms, it is necessary to the soil and cause infections to other hosts weeks later.