- Before technological advances were developed, diagnosis of
Oesophagostomiasis could only be confirmed by exploratory surgery
identification of the worm as Oesophagostomum spp. Unlike other
parasitic diseases, Oesophagostomiasis cannot be diagnosed by eggs in the
stool since they are rarely found and when they are found, they cannot be
distinguished from hookworm eggs. The following is a review of three
recently developed diagnostic techniques that have aided in identifying
the presence of the parasite or the disease itself. Diagnosis plays a
pivotal role in treating and eventually eliminating a parasitic disease.
It is important that advances in diagnostic techniques
Diagnosis of the Parasite
prevalence of Oesophagostomum
bifurcum and Necator americanus infections using specific PCR
amplification of DNA from faecal samples."
Verweij and Pit. Tropical Medicine and International
Health. 2001. 6:726-731.
Although identification of eggs in the stool cannot be used to
distinguish Necator americanus and Oesophagostomum, the eggs
from stool samples can be grown in culture for 7 days and then the
parasites in the L3 stage can distinguish the two species (this technique
is known as coproculture). This study
developed an alternative method of identifying the two parasites from
fecal samples. Specifically, they used PCR to amplify DNA from the feces
in order to determine the prevalence of each parasite. They
compared the specificity of detection by PCR to the prevalence of each
parasite as determined by the coproculture assays. O. bifurcum-PCR
identified 57 out of 61 samples known to contain O. bifurcum by
coproculture. Similarly, N.americanus-PCR identified 136 out 147
samples known to contain N.americanus. In addition, both PCR
assays for the two parasites detected DNA is samples that were not
identified via the coproculture technique. No O. bifurcum DNA was
found in 91 controls from non-endemic areas. Thus, this study concluded
that these specific PCR assays were useful in determining the prevalence
of N.americanus and O. bifurcum infection.
Agarose gel of PCR samples. The upper gel contains O. bifurcum
samples in lanes 2, 3, 4, 6, and 7. No specific product in lanes 1, 5,
8, 9, and 10. The lower gel contains specific N. americanus
samples in all lanes except 7 and 10.
Oesophagostomum bifurcum and Necator americanus by PCR-RFLP
of rDNA." Romstad and Gasser. Journal of
Parasitology. 1997. 83:963-966.
This study developed a molecular diagnostic assay to
distinguish between Oesophagostomum bifurcum and by using the ribosomal DNA as a genetic marker of each
parasite. The rDNA was analyzed by PCR-linked restriction fragment length
polymorphism using a variety of restriction enzymes. These restriction
fragments showed that there was no difference in band pattern within a
species but there was a difference in pattern across species. They were
able to conclude that the fragment lengths of the rDNA were valid genetic
markers because they distinguished between the two parasites.
Diagnosis of the
Detection and Assessment of Preclinical Oesophagostomum
bifurcum-Induced Colonic Pathology." Storey and
Spannbrucker. Clinical Infectious Disease. 2001.
The goal of this study was to determine if
colonic-wall pathology induced by
infection in asymptomatic/pre-clinical patients could be determined my
ultrasound. 464 people that ranged from highly infected to
uninfected as determined by stool samples were examined by ultrasound.
128 asymptomatic people out of 364 people from endemic regions were
positive for colon pathology as determined by ultrasound. No colon
nodules were seen in people from non-endemic towns. Thus, ultrasound is
a potentially useful detection tool to identify pre-clinical
Oesophagostomiasis. This has important implications for
the prevention and treatment of this disease.
Sample Ultrasound and Stick Drawing
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