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Intestinal Nematodes 151

MICROSCOPIC DIAGNOSTIC FEATURE

General Classification—Ova of nematode (hookworm)
Organism Ancylostoma duodenale and Necator americanus
Specimen Required Fecal specimen
Stage Most diagnostic stage is the ova, as adult larvae are seldom
found in stool samples
Size 50–75 μm for ova
Shape Eggs are slightly oval in shape
Shell Colorless and thin-shelled
Other Features Eggs identical except for slight differences in size for both
Ancylostoma d uodenale and Necator americanus and are
colorless with an embryo in a 4–8 cleaved pattern
Buccal cavities A. duodenale N. americanus
Ovum

Cutting
plates
Teeth

Rhabditiform larvae

Genital primordium Bulb

Filariform larvae
Delmar/Cengage Learning

Notched tail

heartworms, and whipworms. In the late 1800s and early with the sandy and loamy soil, the parasites were bounti-
1900s many southerners, particularly rural residents of ful (Figure 6-12).
Mississippi, were plagued by hookworms. Many homes As a result, hookworms, spread by fecal contami-
in the state at that time did not have indoor plumbing or nation of the environment, had become quite prevalent
proper sanitation facilities for adequate personal hygiene during this period along with other associated diseases
and for disposal of urine and excrement and coupled caused by lack of sanitation. Eggs hatch in the soil and