ABSTRACT
In the present study, samples of Oesophagostomum spp. collected from pigs from different geographical localities in mainland China were characterized genetically by polymerase chain reaction-linked single-strand conformation polymorphism (PCR-SSCP) and restriction fragment length polymorphism (PCR-RFLP) techniques using genetic markers in the internal transcribed spacers (ITS) of nuclear ribosomal DNA (rDNA). The second internal transcribed spacer (ITS-2) was amplified from 51 individual nodule worms by PCR, and the amplicons were analyzed by SSCP. With the exception of slight microheterogeneity, SSCP analyses displayed two distinct banding profiles that allowed the identification of all Oesophagostomum spp. samples examined into two groups, the first one represented O. dentatum, and the second one may represent O. quadrispinulatum. Then, the entire ITS was amplified from individual samples, and the amplicons were digested with restriction endonuclease Pst I. The results of RFLP analyses were consistent with that of SSCP. Sequence analysis of ITS rDNA supported the identification and differentiation of Chinese Oesophagostomum spp. samples into two species, namely, O. dentatum and O. quadrispinulatum. These PCR-based approaches provide useful complementary tools to traditional methods for the accurate identification of Oesophagostomum spp. (irrespective of developmental stage) and have implications for studying the ecology and population genetic structures of these parasites and for the prevention and control of the diseases they cause.
Subject(s)
Oesophagostomiasis/veterinary , Oesophagostomum/classification , Oesophagostomum/genetics , Swine/parasitology , Animals , China , Cluster Analysis , DNA, Helminth/chemistry , DNA, Helminth/genetics , DNA, Ribosomal Spacer/chemistry , DNA, Ribosomal Spacer/genetics , Molecular Sequence Data , Oesophagostomum/isolation & purification , Phylogeny , Polymerase Chain Reaction , Polymorphism, Restriction Fragment Length , Polymorphism, Single-Stranded Conformational , Sequence Analysis, DNAABSTRACT
<p><b>OBJECTIVE</b>To evaluate the effects of prevention and control strategies on hepatitis A.</p><p><b>METHODS</b>Surveillance data on hepatitis A from 1990 to 2006 in Tianjin was analyzed, and the coverage rate of hepatitis A vaccine among targeted population was estimated, to compare the anti-HAV IgG level of children younger than 15 years old in 1999 and in 2005.</p><p><b>RESULTS</b>Results showed that a) the morbidity of hepatitis A decreased from 25.26/10(5) in 1990 to 0.82/10(5) in 2006; b) the ratio of hepatitis A in viral hepatitis decreased from 30.43% in 1990 to 1.05% in 2006; c) the estimated coverage rate was 72.7%; d) the positive rate of anti-HAV among children younger than 15 years old in 2005 was distinctly higher than that in 1999.</p><p><b>CONCLUSION</b>Positive results showed that it was successful to use hepatitis A vaccine as the strategy to prevent and control hepatitis A in the past five years in Tianjin.</p>
