Evolutionary and Ecological Drivers Shape the Emergence and Extinction of Foot-and-Mouth Disease Virus Lineages

Livestock farming across the world is constantly threatened by evolutionary turnover of foot-and-mouth disease virus (FMDV) strains in endemic systems, the underlying dynamics of which remain to be elucidated. Here, we map the eco-evolutionary landscape of co-circulating FMDV lineages within an important endemic virus pool encompassing Western, Central and parts of Southern Asia, reconstructing the evolutionary history and spatial dynamics over the last 20 years that shapes the current epidemiological situation. We demonstrate that new FMDV variants periodically emerge from Southern Asia, precipitating waves of virus incursions that systematically travel in a westerly direction. We evidence how metapopulation dynamics drive the emergence and extinction of spatially structured virus populations, and how transmission in different host species regulates the evolutionary space of virus serotypes. Our work provides the first integrative framework that defines co-evolutionary signatures of FMDV in regional contexts to help understand the complex interplay between virus phenotypes, host characteristics, and key epidemiological determinants of transmission that drive FMDV evolution in endemic settings.

Search for OIE-listed ruminant mycoplasma diseases in Afghanistan

BACKGROUND

Little is known about the occurrence of important diseases of ruminants in Afghanistan because of the conflict affecting the country over the last 40 years. To address this discrepancy, ruminant herds in Afghanistan were screened for OIE-listed mycoplasma diseases, contagious bovine (CBPP) and caprine pleuropneumonias (CCPP).

RESULTS

Of the 825 samples from 24 provinces tested for serological evidence of CBPP caused by Mycoplasma mycoides subsp.mycoides, 20 (3.4%) had ELISA values greater than the positive threshold of 50% though all were less than 55%. Repeat testing of these suspect sera gave values below 50. A smaller number of sera (330) from cattle in nine provinces were also tested by the rapid latex agglutination test (LAT) for CBPP, 10 of which were considered suspect. However, no positive bands were seen when immunoblotting was carried out on all sera that gave suspect results. Serological evidence of Mycoplasma bovis was detected in half of 28 herds in eight provinces. The cause of CCPP, M. capricolum subsp. capripneumoniae was not detected in any of the 107 nasal swabs and lung tissue collected from goats in seven provinces though sample handling and storage were not optimal. However, strong serological evidence was detected in goat herds in several villages near Kabul some of which were over 50% seropositive by LAT and ELISAs for CCPP; immunoblotting confirmed positive results on a selection of these sera.

CONCLUSIONS

The data presented here provide a first assessment of the occurrence of the two OIE listed mycoplasma diseases in Afghanistan. From the results of the testing bovine sera from the majority of provinces there is no evidence of the presence of CBPP in Afghanistan. However the samples tested represented only 0.03% of the cattle population so a larger survey is required to confirm these findings. Serological, but not bacterial, evidence was produced during this investigation to show that CCPP is highly likely to be present in parts of Afghanistan.

Brucellosis and Coxiella burnetii Infection in Householders and Their Animals in Secure Villages in Herat Province, Afghanistan: A Cross-Sectional Study

Background

Brucellosis and coxiellosis are known to be endemic in ruminant populations throughout Afghanistan, but information about their prevalence and factors that affect prevalence in householders and livestock under diverse husbandry systems and pastoral settings is sparse.

Methods/Principal Findings

We conducted a cross-sectional survey to investigate the seroprevalence of brucellosis and Coxiella burnetii in humans and livestock in six secure districts in Herat from 26^th December 2012–17^th January 2013. A total of 204 households with livestock were surveyed in six Kuchi and five sedentary type villages. Blood samples from 1,017 humans, 1,143 sheep, 876 goats and 344 cattle were tested for brucellosis and Q fever. About one in six households (15.7%) had at least one Brucella seropositive person, about one in eight households (12.3%) had at least one Brucella seropositive animal and about one in four (24.5%) had either seropositive animals or humans. Ninety-seven percent of households had at least one C. burnetii seropositive person and 98.5% of households had one or more C. burnetii seropositive animals. Forty- seven householders had serological evidence of exposure to both C. burnetii and Brucella and eight animals were serologically positive for both diseases. Drinking unpasteurised milk (OR 1.6), treating animals for ticks (OR 1.4), milking sheep (OR 1.4), male gender (OR 1.4) and seropositivity to Brucella (OR 4.3) were identified as risk factors for seropositivity to C. burnetii in householders. Household factors associated with households having either Brucella seropositive animals or humans were Kuchi households (OR 2.5), having ≤4 rooms in the house (OR 2.9) and not owning land (OR 2.9).

Conclusions

The results from this study provide baseline information for the planning and monitoring of future interventions against these diseases. The implementation of this study greatly improved collaboration, coordination and capability of veterinary and public health professionals from government, NGOs and donor funded projects.

Our study alerted authorities to a hitherto unrecognised high prevalence of C. burnetii infections, acted as a catalyst for the introduction of a national vaccination programme for protection of sheep and goats from brucellosis using Rev1 vaccine, demonstrated the benefits of a coordinated approach and fostered a better understanding of the nature of infection in different hosts and of the constraints for control faced by government services. A notable feature of the study was the enthusiasm and interest displayed by all of the participants throughout, from heads of government services to field personnel and villagers. Livestock owners regard zoonoses as adversities that affect their livestock and members of their households and do not partition them separately as medical or veterinary problems. Control programs need to take that perception into account and wherever possible avoid vesting ownership separately into veterinary or public health agencies.