Seroepidemiology of Bovine Viral Diarrhoea Virus (BVDV) in the Adamawa Region of Cameroon and Use of the SPOT Test to Identify Herds with PI Calves

Bovine viral diarrhoea, caused by the bovine viral diarrhoea virus (BVDV) in the Pestivirus genus of the Flaviviridae, is one of the most important diseases of cattle world wide causing poor reproductive performance in adult cattle and mucosal disease in calves. In addition it causes immunosuppression and increased susceptibility to other infections, the impact of which is uncertain, particularly in sub-Saharan Africa where animals are exposed to a much wider range and higher intensity of infections compared to Europe. There are no previous estimates of the seroprevalence of BVDV in cattle in Cameroon. This paper describes the serological screening for antibodies to BVDV and antigen of BVDV in a cattle population in the Adamawa Region of Cameroon in 2000. The estimates of herd-level and within herd seroprevalences adjusted for test imperfections were 92% and 30% respectively and 16.5% of herds were classed as having a persistently infected calf (PI) in the herd within the last year based on the “spot” test approach. There was evidence of clustering of herds with PI calves across the north and west of the Region which corresponds with the higher cattle density areas and of self-clearance of infection from herds. A multivariable model was developed for the risk of having a PI calf in the herd; proximity to antelope, owning a goat, mixing with 10 other herds at grazing and the catchment area of the veterinary centre the herd was registered at were all significant risk factors. Very little is known about BVDV in sub-Saharan Africa and these high seroprevalences suggest that there is a large problem which may be having both direct impacts on fertility and neonate mortality and morbidity and also indirect effects through immunosuppression and susceptibility to other infections. Understanding and accounting for BVDV should be an important component of epidemiological studies of other diseases in sub-Saharan Africa

Comparison of a Flow Assay for Brucellosis Antibodies with the Reference cELISA Test in West African Bos indicus

Brucellosis is considered by the Food and Agricultural Organisation and the World Health Organisation as one of the most widespread zoonoses in the world. It is a major veterinary public health challenge as animals are almost exclusively the source of infection for people. It is often undiagnosed in both human patients and the animal sources and it is widely acknowledged that the epidemiology of brucellosis in humans and animals is poorly understood, particularly in sub-Saharan Africa. It is therefore important to develop better diagnostic tools in order to improve our understanding of the epidemiology and also for use in the field for disease control and eradication. As with any new diagnostic test, it is essential that it is validated in as many populations as possible in order to characterise its performance and improve the interpretation of its results. This paper describes a comparison between a new lateral flow assasy (LFA) for bovine brucellosis and the widely used cELISA in a no gold standard analysis to estimate test performance in this West African cattle population. A Bayesian formulation of the Hui-Walter latent class model incorporated previous studies' data on sensitivity and specificity of the cELISA. The results indicate that the new LFA is very sensitive (∼87%) and highly specific (∼97%). The analysis also suggests that the current cut-off of the cELSIA may not be optimal for this cattle population but alternative cut-offs did not significantly change the estimates of the LFA. This study demonstrates the potential usefulness of this simple to use test in field based surveillance and control which could be easily adopted for use in developing countries with only basic laboratory facilities

Communicate to Win : Real-time communication services for location-based learning activities

In recent years, mobile devices have become an integral part of our everyday life in various fields. The technology that powers them is used in various devices, such as smartphones, tablets, and PDAs. These devices hold extensive computation capabilities, along with advanced communication abilities, which are supported by an internet connection and diverse types of motion and location sensors. Mobile devices have changed the way people communicate with each other, for example by providing options to send instant text messages, perform live video calls with others in addition to voice conversations. These capabilities have encouraged educators to exploit mobile technology and promote new types of learning options. There are several new learning possibilities based on tools such as mobile dedicated applications, location-based learning activities, and interactive social related tasks. These new uses require adjustments to educational programs to allow support for this type of learning. The uniqueness of mobile learning, in contrast with the classic learning paradigm, is the ability to connect the learner through enhanced learning materials to the outside environment. This breaks the physical borders that exist in the traditional classroom and creates new learning possibilities, but it has its drawbacks. One of the difficulties that arise from this type of learning is the loss of contact in real time between teacher and student, especially when performing outdoor activities. The Treasure-HIT platform was conceived to create outdoor Treasure Hunt-based games, mainly for educational purposes, by introducing an authoring web platform and a supporting mobile application. The platform includes communication capabilities based on social interactions and cooperative learning with the integration of social networks, and yet real-time educator and student communication is still lacking. Adding real-time communication features provides a way to better support ongoing learning activities, and can take pressure off the learning process for the students, by providing them with a more personal experience and immediate support when needed. This thesis follows the process of addressing this concern in TreasureHIT, including the rationale, the background, the possible options and gradual development of a prototype solution to the problem under the existing Treasure-HIT infrastructure. In the thesis, the advantages of two features are explored: (1) the Realtime Group Tracking Map, which provides a way to monitor the movement and action of groups of players during game time, and (2) Instant Text Messaging service, which allows the game instructor to send custom text messages to the different game groups. The research findings indicate that the new monitoring options provide a solid tool for real-time analysis of the progress of the game and the ability to inform about various issues and solve them in real time. ii Furthermore, the instant message service feature received positive responses from the game-manager and players alike, on the grounds of major improvements to the general game flow and problem solving in real-time

Maps of the Adamawa Region of Cameroon showing location of sampled herds and (a) within herd pestivirus seroprevalence based on juveniles only, (b) within herd pestivirus seroprevalence based on adults only, (c) overall within herd pestivirus seroprevalence and (d) the estimated years since last PI calf was in each herd.

<p>Maps of the Adamawa Region of Cameroon showing location of sampled herds and (a) within herd pestivirus seroprevalence based on juveniles only, (b) within herd pestivirus seroprevalence based on adults only, (c) overall within herd pestivirus seroprevalence and (d) the estimated years since last PI calf was in each herd.</p

Caterpillar plots showing the estimated adjusted and unadjusted within-herd seroprevalence for each of the 142 herds based only on juvenile data, the 95% highest density intervals (HDI) for the adjusted seroprevalences and the probability that each herd is seropositive.

<p>Herds are ordered along the x axis based on the estimated within-herd seroprevalence.</p

Test based classification of individual animals ordered by apparent within-herd seroprevalance and model based estimate of the date of last infection in the herd.

<p>Individual animal results are shown as tiles, blue for negative and red for positive. Multiple animals in a herd for a given age group are overlaid showing as a darker tile in blue or red. Purple tiles represent combinations of positive and negative animals in the same herd and age class. The circles show the model based estimates of time since a PI was last present in each herd. The filled circles would be classified as having a PI present using the rule of 3 or more test positive animals (SPOT test positive).</p