An analysis of the spatial and temporal patterns of highly pathogenic avian influenza occurrence in Vietnam using national surveillance data

Pfeiffer, Dirk U.; Minh, Phạm Quang; Martin, Vincent; Epprecht, Michael; Otte, Martin J.

doi:10.1016/j.tvjl.2007.05.010

Cited by 183 publications

(226 citation statements)

References 7 publications

Supporting

Mentioning

205

Contrasting

Unclassified

Order By: Relevance

“…The statistical relationship between ducks and HPAI H5N1 virus presence and the role of ducks as reservoir has been discussed elsewhere (10,14,(20)(21)(22). However, we found a strong and consistently positive association with rice cropping intensity across epidemic waves and countries.…”

Section: Discussionsupporting

confidence: 63%

“…1 and 2). The spatial pattern of wave II in Thailand is explored in further detail in Gilbert et al (10) and Tiensin et al (19), and the temporal and spatial patterns of waves I-III in Vietnam are examined in Pfeiffer et al (14). However, the results obtained from the statistical analysis of outbreak distributions in relation to risk factors are more consistent than one would expect on the basis of the contrasted spatial patterns between waves ( Table 1).…”

Section: Resultsmentioning

confidence: 96%

“…In previous work, it was demonstrated that the risk of HPAI H5N1 virus presence was associated with free-ranging duck numbers in Thailand (10) and the local abundance of both duck and geese in Vietnam (14), in addition to other risk factors such as chicken numbers, human population, and topographical features. Both studies also found evidences of a relationship between HPAI H5N1 virus presence and rice production.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Mapping H5N1 highly pathogenic avian influenza risk in Southeast Asia

Gilbert

Xiao

Pfeiffer

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

277

305

View full text Add to dashboard Cite

The highly pathogenic avian influenza (HPAI) H5N1 virus that emerged in southern China in the mid-1990s has in recent years evolved into the first HPAI panzootic. In many countries where the virus was detected, the virus was successfully controlled, whereas other countries face periodic reoccurrence despite significant control efforts. A central question is to understand the factors favoring the continuing reoccurrence of the virus. The abundance of domestic ducks, in particular free-grazing ducks feeding in intensive rice cropping areas, has been identified as one such risk factor based on separate studies carried out in Thailand and Vietnam. In addition, recent extensive progress was made in the spatial prediction of rice cropping intensity obtained through satellite imagery processing. This article analyses the statistical association between the recorded HPAI H5N1 virus presence and a set of five key environmental variables comprising elevation, human population, chicken numbers, duck numbers, and rice cropping intensity for three synchronous epidemic waves in Thailand and Vietnam. A consistent pattern emerges suggesting risk to be associated with duck abundance, human population, and rice cropping intensity in contrast to a relatively low association with chicken numbers. A statistical risk model based on the second epidemic wave data in Thailand is found to maintain its predictive power when extrapolated to Vietnam, which supports its application to other countries with similar agro-ecological conditions such as Laos or Cambodia. The model's potential application to mapping HPAI H5N1 disease risk in Indonesia is discussed.animal husbandry ͉ epidemiology ͉ remote sensing ͉ spatial modeling

show abstract

Section: Discussionsupporting

confidence: 63%

Section: Resultsmentioning

confidence: 96%

mentioning

confidence: 99%

See 1 more Smart Citation

Mapping H5N1 highly pathogenic avian influenza risk in Southeast Asia

Gilbert

Xiao

Pfeiffer

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

277

305

View full text Add to dashboard Cite

show abstract

“…A field trial with H5N2 vaccine in Hong Kong in 2002 showed that vaccinated chickens were protected from disease, and HPAI H5N1 virus transmission was reduced [2]. The same was concluded for vaccination with H5N1 and H5N2 vaccines in Vietnam (2005) [3] and Mexico (1995) [4], although due to the various control strategies and vaccines implemented during these epidemics it was not possible to claim a direct relationship between reduced transmission and the applied vaccination strategy. The latter is a common problem in field studies, because many factors, e.g.…”

Section: Introductionmentioning

confidence: 99%

Effect of H7N1 vaccination on highly pathogenic avian influenza H7N7 virus transmission in turkeys

Bos¹,

Nielen²,

Koch³

et al. 2008

Vaccine

View full text Add to dashboard Cite

a b s t r a c tThis study describes the results of a transmission experiment with highly pathogenic avian influenza (HPAI) H7N7 virus in 12-week-old turkeys. Cloacal and tracheal swabs as well as serum samples were taken to monitor the infection both in inoculated and in susceptible contact turkeys, which were all either unvaccinated, vaccinated once or vaccinated twice with H7N1. Swabs were tested by real-time RT-PCR and serum samples with hemagglutination inhibition test (HI). Unvaccinated contact birds had a mean infectious period of 6.2 days, and an estimated transmission rate parameter of 1.26 per infectious bird per day. However, no virus shedding was found in inoculated vaccinated turkeys and thus we concluded that vaccination with H7N1 protected against challenge with HPAI H7N7 virus.

show abstract

“…Since late (Minh et al, 2009, Pfeiffer et al, 2007. Since then, the epidemic waves of H5N1 among poultry had apparently subsided and the cases have been absent for approximately 14 months until the end of May 2007 when the 4 th epidemic wave was identified in the Red River Delta (Minh et al, 2009).…”

Section: Introductionmentioning

confidence: 99%