Yoshiro Nagao

Publications (3)6.59 Total impact

• Source

  Available from: Brian de Souza

  Article: Suppression of Plasmodium falciparum by serum collected from a case of Plasmodium vivax infection.

  Yoshiro Nagao, Masako Kimura-Sato, Porntip Chavalitshewinkoon-Petmitr, Supatra Thongrungkiat, Polrat Wilairatana, Takafumi Ishida, Peerapan Tan-Ariya, J Brian de Souza, Srivicha Krudsood, Sornchai Looareesuwan
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  ABSTRACT: It has frequently been reported that Plasmodium vivax suppressed Plasmodium falciparum and ameliorated disease severity in patients infected with these two species simultaneously. The authors investigate the hypothesis that immunological responses stimulated by P. vivax may play a role in suppressing co-infecting P. falciparum. Sera, taken sequentially from one of the authors (YN) during experimental infection with P. vivax, were added to in vitro cultures of P. falciparum. Cross-reactive antibodies against P. falciparum antigens, and cytokines were measured in the sera. Significant growth inhibitory effects upon P. falciparum cultures (maximally 68% inhibition as compared to pre-illness average) were observed in the sera collected during an acute episode. Such inhibitory effects showed a strong positive temporal correlation with cross-reactive antibodies, especially IgM against P. falciparum schizont extract and, to a lesser degree, IgM against Merozoite Surface Protein (MSP)-119. Interleukin (IL)-12 showed the highest temporal correlation with P. vivax parasitaemia and with body temperatures in the volunteer. These results suggest the involvement by cross-reactive antibodies, especially IgM, in the interplay between plasmodial species. IL-12 may be one of direct mediators of fever induction by rupturing P. vivax schizonts, at least in some subjects. Future studies, preferably of epidemiological design, to reveal the association between cross-reactive IgM and cross-plasmodial interaction, are warranted.
  Malaria Journal 02/2008; 7:113. · 3.19 Impact Factor
• Article: Distribution of two species of malaria, Plasmodium falciparum and Plasmodium vivax, on Lombok Island, Indonesia.

  Yoshiro Nagao, Yoes Prijatna Dachlan, Soedarto, Sri Hidajati, Subagyo Yotopranoto, Kusmartisnawati, Sri Subekti, Bariah Ideham, Yoshio Tsuda, Masato Kawabata, Masahiro Takagi, Somchai Looareesuwan
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  ABSTRACT: Medical and entomological surveys were conducted to determine the risk factors of Plasmodium falciparum and P. vivax infections on Lombok Island, Indonesia, to find the risk factors and the main mosquito vectors for each malaria. Multivariate longitudinal analysis demonstrated two significant risk factors for infection with P. falciparum: disappearance of P. vivax parasitemia (p<0.001) and a specific study site (p<0.001). In contrast, younger age (p=0.024) and the interpolated virtual density of An. subpictus (p=0.041) were significantly associated with increased risk of infection with P. vivax. Thus, it seems that the distribution of P. vivax was determined largely by the presence of An. subpictus, whilst that of P. falciparum was influenced by antagonism with P. vivax. This result shows the importance of following-up treated P. vivax patients to identify recrudescence of P. falciparum in this area.
  The Southeast Asian journal of tropical medicine and public health 10/2003; 34(3):495-500. · 0.60 Impact Factor
• Source

  Available from: Apiwat Tawatsin

  Article: Climatic and social risk factors for Aedes infestation in rural Thailand.

  Yoshiro Nagao, Usavadee Thavara, Pensri Chitnumsup, Apiwat Tawatsin, Chitti Chansang, Diarmid Campbell-Lendrum
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  ABSTRACT: An intense epidemic of dengue haemorrhagic fever in 1998 prompted the Thai government to investigate the feasibility of focalized vector (Aedes aegypti) control programmes. We tested for correlations of three indices of Aedes larval abundance (housing index, container index and Breteau index) against 38 socio-economic and four climatic variables. Availability of public water wells, existence of transport services and proportion of tin houses were positively associated with larval indices. Private water wells, health education, health insurance coverage, thatched houses and use of firewood for cooking were negatively associated. These probably represent both direct effects on breeding sites (private vs. public wells decrease necessity to store water, and health education may encourage breeding site removal), and more general effects of health-related attitudes, housing quality and remoteness from urban areas. Indices were positively associated with daily minimum temperature, an increase in precipitation from the previous month (reflecting the onset of the rainy season) and daily maximum temperatures of approximately 33-34 degrees C. The associations were used to derive statistical models to predict the rank order of larval indices within the study area (Spearman's correlation coefficients = 0.525-0.554). The study provides a rational basis for identifying possible social interventions, and for prioritizing previously unsurveyed villages for further monitoring and focalized vector control.
  Tropical Medicine & International Health 08/2003; 8(7):650-9. · 2.80 Impact Factor