Spatio-temporal epidemiology of highly pathogenic avian influenza (H5N1) outbreaks in Nigeria, 2006–2008

Ekong, Pius S.; Ducheyne, Els; Carpenter, Tim E.; Owolodun, Olajide Adewale; Oladokun, Agnes Tinuke; Lombin, L.H.; Berkvens, Dirk

doi:10.1016/j.prevetmed.2011.10.001

Cited by 38 publications

(28 citation statements)

References 22 publications

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“…Although the effect of biosecurity has been discussed in another paper [7], temperature and wind may induce dryness of the environment which may in turn make it easier for the virus to be transmitted between birds. Moreover, the effect of alternating temperature highs and lows may imply seasonality that could alter the transmission and survivability of the virus, which is consistent with the temporal patterns observed by Ekong et al [8]. These authors suggest that the outbreak occurred in different waves.…”

Section: Discussionsupporting

confidence: 86%

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Epidemiological analysis of spatially misaligned data: a case of highly pathogenic avian influenza virus outbreak in Nigeria

Adegboye

Kotzé

2013

Epidemiol. Infect.

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SummaryThis research is focused on the epidemiological analysis of the transmission of the highly pathogenic avian influenza (HPAI) H5N1 virus outbreak in Nigeria. The data included 145 outbreaks together with the locations of the infected farms and the date of confirmation of infection. In order to investigate the environmental conditions that favoured the transmission and spread of the virus, weather stations were realigned with the locations of the infected farms. The spatial KolmogorovSmirnov test for complete spatial randomness rejects the null hypothesis of constant intensity (P < 0·0001). Preliminary exploratory analysis showed an increase in the incidence of H5N1 virus at farms located at high altitude. Results from the Poisson log-linear conditional intensity function identified temperature (−0·9601) and wind speed (0·6239) as the ecological factors that influence the intensity of transmission of the H5N1 virus. The model also includes distance from the first outbreak (−0·9175) with an Akaike's Information Criterion of −103·87. Our analysis using a point process model showed that geographical heterogeneity, seasonal effects, temperature, wind as well as proximity to the first outbreak are very important components of spread and transmission of HPAI H5N1.

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Section: Discussionsupporting

confidence: 86%

“…The location of the weather stations (black stars) and the infected farms (red triangles) are depicted in Figure 1. The occurrence of H5N1 has been described to take place [8], with the suspicion of seasonal effects on the outbreaks (Fig. 2).…”

Section: Estimating Weather Variablesmentioning

confidence: 99%

Epidemiological analysis of spatially misaligned data: a case of highly pathogenic avian influenza virus outbreak in Nigeria

Adegboye

Kotzé

2013

Epidemiol. Infect.

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“…AI desk officers are responsible for all HPAI field investigations, the sample collection and the depopulation of infected premises in their States. In a contemporary paper, Ekong et al (2012) described outbreaks in 28 states. These authors used diagnostic data from the National Veterinary Research Institute for their case definition and listed, in contrast to our findings, the States of Kebbi, Benue and Gombe as outbreak States.…”

Section: Discussionmentioning

confidence: 99%

“…However, no confirmed HPAI outbreaks were reported by AI desk officers in any of these States. We assume that Ekong et al (2012) also used samples collected from healthy birds for their case definition -this can be confirmed for the Gombe State, where at a live bird market swabs from apparently healthy H5-infected ducks were collected (Fusaro et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

Incidence of Highly Pathogenic Avian Influenza H5N1 in Nigeria, 2005-2008

Henning¹,

Bett

Okike

et al. 2012

Transboundary and Emerging Diseases

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Outbreaks of highly pathogenic avian influenza (HPAI) H5N1 occurred in Nigeria between December 2005 and July 2008. We describe temporal and spatial characteristics of these outbreaks at State and Local Government Area (LGA) levels. A total of 25 of 37 States (67.6%; Exact 95% CI: 50.2-82.0%) and 81 of 774 LGAs (10.5%; Exact 95% CI: 8.4-12.8%) were affected by HPAI outbreaks over the period from 2005 to 2008. The incidence risk of HPAI outbreak occurrence at the State level was 5.6% (0.7-18.7%) for 2005, 50.0% (30.7-69.4%) for 2006, 54.5% (29.9-80.3%) for 2007 and 0% for 2008. Only very few LGAs experienced HPAI outbreaks within the affected States. The incidence risk of HPAI outbreak occurrence on a LGA level was 0.3% (0.0-0.9%) for 2005, 6.6% (4.9-8.6%) for 2006, 4.2% (2.9-6.0%) for 2007 and 0% for 2008. The mean period between farmers noticing HPAI outbreaks and reporting them to veterinary authorities, and between reporting HPAI outbreaks and the depopulation of infected premises, was for both 4.5 days; both periods also had medians of 1 day. We have estimated the spatially smoothed incidence risk for the whole outbreak period and identified the existence of a large corridor in the western part of Nigeria and a smaller corridor in south-eastern part, where the risk of HPAI occurrence was lower than in the rest of the country. The effect of HPAI control policies on the outbreaks patterns are discussed, as well as possible reasons why HPAI did not become endemic in Nigeria.

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“…In addition, millions of in-contact domestic poultry and other birds were also culled. However, they were not analysed in this study since it was technically difficult to classify these birds in terms of epidemiological status [susceptible (S), exposed (E), infected (I) and recovered (R)] at the time of intervention, nor was it possible to assess the control measures including (but not limited to) the restriction of bird movement, stamping out of all laboratory confirmed cases and in-contact birds, decontamination of all infected premises and education of farmers [21,22]. Although the overall mean apparent morbidity of HPAI H5N1 outbreaks in poultry in Africa from 2006-2015 was 48.7%, a majority of the affected countries had relatively higher apparent morbidity than this (see Table 1 and Figure 1, details in Appendix).…”

Section: Discussionmentioning

confidence: 99%

Systematic review and meta-analyses of cases and deaths associated with highly pathogenic avian influenza H5N1 in humans and poultry.

Fasanmi¹,

Laleye²,

Fasina³

2016

CABI Reviews

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From 2003 to date (2015), confirmed highly pathogenic avian influenza (HPAI) H5N1 outbreaks in poultry and humans have been reported, however, certain quantitative parameters remain lacking. We obtained 846 reports of HPAI H5N1 outbreaks in poultry in Africa (2006Africa ( -2015, and 844 reports in humans globally (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015) from different databases. Data were filtered and analysed using meta-analyses. The outputs were generated for each country included in the study and for overall morbidities, mortalities and case fatalities (for poultry and humans). Approximately 11.6 million poultry were included in the analyses as susceptible with 1.9 million cases and 1.7 million deaths in poultry. In humans, 449 deaths were linked to influenza A H5N1 infections. For all poultry outbreaks in 2006-2015 in Africa, an overall mean apparent morbidity of 48.7% (n = 1 850 589) was estimated, with overall mean apparent mortality being 40.2% (n = 1 705 388) and overall mean case fatality rate (CFR) for HPAI H5N1 outbreaks in poultry being 86.4% (n = 1 705 388). In humans, the overall mean CFR for A H5N1 globally for 2003-2015 was 62.3% (n = 449). Indonesia, Egypt and Vietnam had higher proportions of all human deaths associated with the A H5N1 and Egypt had a significant age-sex bias. Improved reporting and effective quantitation remain key to understanding the characteristics of the virus.

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Spatio-temporal epidemiology of highly pathogenic avian influenza (H5N1) outbreaks in Nigeria, 2006–2008

Cited by 38 publications

References 22 publications

Epidemiological analysis of spatially misaligned data: a case of highly pathogenic avian influenza virus outbreak in Nigeria

Epidemiological analysis of spatially misaligned data: a case of highly pathogenic avian influenza virus outbreak in Nigeria

Incidence of Highly Pathogenic Avian Influenza H5N1 in Nigeria, 2005-2008

Systematic review and meta-analyses of cases and deaths associated with highly pathogenic avian influenza H5N1 in humans and poultry.

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