[show abstract][hide abstract] ABSTRACT: Climate variability is an important component in determining the
incidence of a number of diseases with significant health and
socioeconomic impacts. In particular, vector born diseases are the most
likely to be affected by climate; directly via the development rates and
survival of both the pathogen and the vector, and indirectly through
changes in the surrounding environmental conditions. Disease risk models
of various complexities using different streams of climate forecasts as
inputs have been developed within the QWeCI EU and ENHanCE ERA-NET
project frameworks. This work will present two application examples, one
for Africa and one for Europe. First, we focus on Rift Valley fever over
sub-Saharan Africa, a zoonosis that affects domestic animals and humans
by causing an acute fever. We show that the Rift Valley fever outbreak
that occurred in late 2010 in the northern Sahelian region of Mauritania
might have been anticipated ten days in advance using the GFS numerical
weather prediction system. Then, an ensemble of regional climate
projections is employed to model the climatic suitability of the Asian
tiger mosquito for the future over Europe. The Asian tiger mosquito is
an invasive species originally from Asia which is able to transmit West
Nile and Chikungunya Fever among others. This species has spread
worldwide during the last decades, mainly through the shipments of goods
from Asia. Different disease models are employed and inter-compared to
achieve such a task. Results show that the climatic conditions over
southern England, central Western Europe and the Balkans might become
more suitable for the mosquito (including the proviso that the mosquito
has already been introduced) to establish itself in the future.
[show abstract][hide abstract] ABSTRACT: Coccidiosis, caused by species of the apicomplexan parasite Eimeria, is a major disease of chickens. Eimeria species are present world-wide, and are ubiquitous under intensive farming methods. However, prevalence of Eimeria species is not uniform across production systems. In developing countries such as Ethiopia, a high proportion of chicken production occurs on rural smallholdings (i.e. 'village chicken production') where infectious diseases constrain productivity and surveillance is low. Coccidiosis is reported to be prevalent in these areas. However, a reliance on oocyst morphology to determine the infecting species may impede accurate diagnosis. Here, we used cross-sectional and longitudinal studies to investigate the prevalence of Eimeria oocyst shedding at two rural sites in the Ethiopian highlands.
Faecal samples were collected from 767 randomly selected chickens in May or October 2011. In addition, 110 chickens were sampled in both May and October. Eimeria oocysts were detected microscopically in 427 (56%, 95% confidence interval (95% CI) 52-59%) of the 767 faecal samples tested. Moderate clustering of positive birds was detected within households, perhaps suggesting common risk factors or exposure pathways. Seven species of Eimeria were detected by real time PCR in a subset of samples further analysed, with the prevalence of some species varying by region. Co-infections were common; 64% (23/36, 95% CI 46-79%) of positive samples contained more than one Eimeria spp. Despite frequent infection and co-infection overt clinical disease was not reported. Eimeria oocysts were detected significantly more frequently in October (248/384, 65%, 95% CI 60-69%), following the main rainy season, compared to May (179/383, 47%, 95% CI 42-52%, p < 0.001). Eimeria oocyst positivity in May did not significantly affect the likelihood of detecting Eimeria oocyst five months later perhaps suggesting infection with different species or immunologically distinct strains.
Eimeria spp oocysts may be frequently detected in faecal samples from village chickens in Ethiopia. Co-infection with multiple Eimeria spp was common and almost half of Eimeria positive birds had at least one highly pathogenic species detected. Despite this, all sampled birds were free of overt disease. Although there was no evidence of a difference in the prevalence of oocysts in faecal samples between study regions, there was evidence of variation in the prevalence of some species, perhaps suggesting regional differences in exposure to risk factors associated with the birds, their management and/or location-specific environmental and ecological factors.
[show abstract][hide abstract] ABSTRACT: Understanding the nature of human contact patterns is crucial for predicting the impact of future pandemics and devising effective control measures. However, few studies provide a quantitative description of the aspects of social interactions that are most relevant to disease transmission. Here, we present the results from a detailed diary-based survey of casual (conversational) and close contact (physical) encounters made by a small peer group of 49 adults who recorded 8,661 encounters with 3,528 different individuals over 14 non-consecutive days. We find that the stability of interactions depends on the intimacy of contact and social context. Casual contact encounters mostly occur in the workplace and are predominantly irregular, while close contact encounters mostly occur at home or in social situations and tend to be more stable. Simulated epidemics of casual contact transmission involve a large number of non-repeated encounters, and the social network is well captured by a random mixing model. However, the stability of the social network should be taken into account for close contact infections. Our findings have implications for the modelling of human epidemics and planning pandemic control policies based on social distancing methods.
Journal of The Royal Society Interface 10/2008; 5(26):1001-7.