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Isao Arita

Publications and source records attributed to Isao Arita.

14 recordsLinked to original sources
PubMed2005

Distribution of HBV genotypes among HBV carriers in Benin:phylogenetic analysis and virological characteristics of HBV genotype E.

AIM: To determine the distribution of Hepatitis B virus (HBV) genotypes in Benin, and to clarify the virological characteristics of the dominant genotype. METHODS: Among 500 blood donors in Benin, 21 HBsAg-positive donors were enrolled in the study. HBV genotypes were determined by enzyme immunoassay and restriction fragment length polymorphism. Complete genome sequences were determined by PCR and direct sequencing. RESULTS: HBV genotype E (HBV/E) was detected in 20/21 (95.2%), and HBV/A in 1/21 (4.8%). From the age-specific prevalence of HBeAg to anti-HBe seroconversion (SC) in 19 HBV/E subjects, SC was estimated to occur frequently in late teens in HBV/E. The comparison of four complete HBV/E genomes from HBeAg-positive subjects in this study and five HBV/E sequences recruited from the database revealed that HBV/E was distributed throughout West Africa with very low genetic diversity (nucleotide homology 96.7-99.2%). Based on the sequences in the basic core promoter (BCP) to precore region of the nine HBV/E isolates compared to those of the other genotypes, a nucleotide substitution in the BCP, G1757A, was observed in HBV/E. CONCLUSION: HBV/E is predominant in the Republic of Benin,and SC is estimated to occur in late teens in HBV/E. The specific nucleotide substitution G1757A in BCP,which might influence the virological characteristics, is observed in HBV/E.

Adolescent↗
PubMed2005

Smallpox vaccine and its stockpile in 2005.

Smallpox vaccine was the most important tool in the successful eradication of smallpox. In 1980, this achievement made it possible for all nations to cease smallpox vaccination. However, the threat of smallpox bioterrorism has made it necessary to reconsider the need for vaccination. Over the past 3 years, many nations have set up action plans for use in the event of such an attack. The setting up of these plans was not simple. Several factors needed to be considered, including the judgement of risk, vaccine complications, conventional vaccines versus new vaccines, optimal stockpile of smallpox vaccine, and its use for different target populations in different emergency situations. Here, I review measures taken by the USA, Japan, and other nations, and discuss likely national and global efforts in 2005 and subsequently, in view of the fact that half of the world's population is now apparently unvaccinated and that this proportion will increase with time.

Europe↗
PubMed2004

Role of a sentinel surveillance system in the context of global surveillance of infectious diseases.

In some nation states, sustained integrated global epidemiological surveillance has been weakened as a result of political unrest, disinterest, and a poorly developed infrastructure due to rapidly increasing global inequality. The emergence of severe acute respiratory syndrome has shown vividly the importance of sensitive worldwide surveillance. The Agency for Cooperation in International Health, a Japanese non-governmental organisation, has developed on a voluntary basis a sentinel surveillance system for selected target infectious diseases, covering South America, Africa, and Asia. The system has uncovered unreported infectious diseases of international importance including cholera, plague, and influenza; current trends of acute flaccid paralysis surveillance in polio eradication; and prevalence of HIV, syphilis, hepatitis B, and hepatitis C in individual areas covered by the sentinels. Despite a limited geographical coverage, the system seems to supplement disease information being obtained by global surveillance. Further development of this sentinel surveillance system would be desirable to contribute to current global surveillance efforts, for which, needless to say, national surveillance and alert system takes principal responsibility.

Communicable Disease Control↗
PubMed2004

Eradication of infectious diseases: its concept, then and now.

The concept of disease eradication emerged as recently as the mid-20th century. The successful eradication of smallpox resulted in the concept of the extinction of the causative agent in man as well as in the environment, leading to the cessation of all control measures including vaccination. Subsequently, world resources have been invested in global polio eradication and measles eradication in the Western Hemisphere. The former is apparently now at the "end game", the latter, after successful campaign in the Americas, aims at program development worldwide. However, both endeavors are being challenged by delays in schedules, unexpected technical problems, lack of global coordination, and ever-increasing political unrest. It is proposed that disease eradication be redefined as the extinction of the pathogen in man, not in nature, making for a more flexible approach in the post-eradication period. Smallpox eradication was a rare event. That concept is unrealistic in today's world.

Communicable Disease Control↗
PubMed2003

Distribution of hepatitis B virus (HBV) genotypes among HBV carriers in the Cote d'Ivoire: complete genome sequence and phylogenetic relatedness of HBV genotype E.

The characteristics of hepatitis B virus (HBV) genotype E are not well known because only a few studies have been carried out by complete genome analysis. The aim of this study was to elucidate the distribution of HBV genotypes in Cote d'Ivoire, and to clarify the genotype-related characteristics of genotype E. The distribution of HBV genotypes among 48 HBV carriers in Cote d'Ivoire was determined using serological and genetic methods. The characteristics of genotype E were evaluated by complete genome sequences, and further investigations of small S gene, basic core promoter (BCP) mutation, and precore mutation were undertaken. HBV genotype distribution among the 48 carriers was 6.3% for genotype A, 6.3% for genotype D, and 87.4% for genotype E. Complete genomes of two genotype E strains were sequenced, and found to have 98.2% to 99.2% homology at the nucleotide level when compared with genotype E strains reported previously. In 24 genotype E carriers, the precore mutation was detected in 75% of the patients without HBeAg, in contrast to only 25% of the patients with HBeAg (P < 0.05). All 24 strains have T at nucleotide 1858 in the precore region. In contrast, BCP double mutation was detected in 17% of the patients with HBeAg, and 33% of the patients without HBeAg. These results indicated as the following: (1) genotypes A, D, and E of HBV exist in Cote d'Ivoire and genotype E is the most prevalent; (2) genotype E spread with low genetic diversity over the complete genome in West Africa; (3) HBV precore and/or BCP double variants were common among the patients with genotype E infections.

Amino Acid Sequence↗
PubMed2003

Polio eradication.

Explore the source record for details and available documents.

Health Promotion↗
PubMed2002

Cost-effectiveness of measles elimination in Latin America and the Caribbean: a prospective analysis.

BACKGROUND: In 1994, the Americas set a goal of interrupting indigenous measles transmission from the Western Hemisphere by 2000. To accomplish this goal, the Pan American Health Organization (PAHO) developed an enhanced measles vaccination strategy. METHODS: Cost data was collected at PAHO for Latin American and Caribbean (LAC) countries covering 96% of the region's population on components of the routine programs, and the 'follow-up' activities from member countries. In order to interpret our findings we have compared the present scenario regarding measles with one that would have ensued if past trends continued. RESULTS: For the entire LAC population, estimated cost of elimination program will be US$ 571 million in present value terms. INTERPRETATION: The vaccination strategy toward achieving elimination of measles costs USD 244 million, incremental from the cost of vaccination before the elimination program. Within 2000-2020, the current program will have prevented the occurrence of 3.2 million cases of measles and 16,000 deaths. Thus, vaccination strategy prevents a single case of measles at the cost of USD 71.75 and prevents a death due to measles at the cost of USD 15,000. The case fatality rate depends on a well functioning treatment program for measles cases. The vaccination strategy saves a total of USD 208 million in treatments costs due to reduced incidence of measles.

Adolescent↗
PubMed2002

Duration of immunity after smallpox vaccination: a study on vaccination policy against smallpox bioterrorism in Japan.

The success of global smallpox eradication in 1980 led all the nations of the world to discontinue smallpox vaccination. To date, however, the threat of deliberate release of smallpox virus has led health authorities to reconsider smallpox vaccination and at the same time, to urge to evaluate duration of the immunity of the population vaccinated before 1980. Although available data is scarce and incomplete, the study suggests that protective immunity lasts longer in a good percentage of vaccinees, although the real percentage and duration are not known. Accordingly, how to establish a national vaccination policy for preparedness in Japan and elsewhere was discussed. The study is intended to cause interest and debate among the medical and public health community.

Bioterrorism↗