Monitoring the outcomes of interventions against Taenia solium: options and suggestions.

There is an increasing interest in reducing the incidence of human neurocysticercosis, caused by infection with the larval stage of Taenia solium. Several intervention trials are currently assessing various options for control of T. solium transmission. A critical aspect of these trials will be the evaluation of whether the interventions have been successful. However, there is no consensus about the most appropriate or valuable methods that should be used. Here, we undertake a critical assessment of the diagnostic tests which are currently available for human T. solium taeniasis and human and porcine cysticercosis, as well as their suitability for evaluation of intervention trial outcomes. Suggestions are made about which of the measures that are available for evaluation of T. solium interventions would be most suitable, and which methodologies are the most appropriate given currently available technologies. Suggestions are also made in relation to the most urgent research needs in order to address deficiencies in current diagnostic methods.

Sensitivity of partial carcass dissection for assessment of porcine cysticercosis at necropsy.

Many interventions against Taenia solium are evaluated by assessing changes in the prevalence of porcine cysticercosis ascertained by carcass dissection. Financial and logistical difficulties often prohibit dissection of entire pig carcasses. We assessed 209 pigs from rural areas of Cameroon and Peru for the presence of T. solium cysticerci and determined the distribution of parasites within the musculature of infected animals. Considering the presence of cysts in the tongue, masticatory muscles and heart, 31 of the 38 (81%) naturally infected animals were identified as having cysts. Dissection of only the tongue, masticatory muscles and heart provides a relatively sensitive and highly specific method for diagnosis of porcine cysticercosis.

Development of a low-dose fast-dissolving tablet formulation of Newcastle disease vaccine for low-cost backyard poultry immunisation.

The immunisation of backyard poultry is critical for maintaining healthy flocks to provide nutrition and income for low-resource farmers worldwide. A vaccine presentation for flocks of less than 50 birds could make it more affordable and accessible, increasing uptake and impact. Fast-dissolving tablets (FDT) of Newcastle disease virus (NDV) vaccine were produced by freeze drying the LaSota NDV strain combined with excipients into tablets containing a small number of doses and packaged in polymer blister sheets. The NDV-FDT vaccine maintained virus stability for more than six months at 4°C, based on plaque assay and egg infectivity dose data. Stability was further confirmed in a challenge study, where the tablet vaccine elicited a strong immune response and provided 100 per cent protection to vaccinated chickens infected with a virulent strain of NDV. The vaccine tablet can be diluted in water (no needle or syringe required) and administered either in drinking water or with a dropper via an intraocular and/or intransal route. Results indicate that FDTs containing a small number of doses are a feasible presentation for backyard poultry farmers. The compact packaging of the FDTs will also provide cost savings in storing and distributing the vaccine in the cold chain.

Vaccination for the control of Rift Valley fever in enzootic and epizootic situations.

Vaccination continues to be the most effective way to control Rift Valley fever (RVF), a zoonotic insect-borne viral disease of livestock. The irregular, cyclical and persistent nature of RVF in its occurrence in enzootic situations suggests that the vaccination strategy to be considered for these regions should be different from what is envisaged for free from risk regions. Currently available RVF vaccines have been extensively used for the control of the disease. However, these vaccines have shortcomings that have encouraged many research groups to develop new vaccine candidates that would address a large number of the current challenges, and be suitable for use both in disease-free regions and in different contingency and emergency preparedness strategies. The characteristics of different RVF vaccines and vaccination strategies are discussed in this report.

A high oxfendazole dose to control porcine cysticercosis: pharmacokinetics and tissue residue profiles.

Oxfendazole (OFZ) is efficacious for porcine cysticercosis at 30 mg/kg. OFZ is not registered to be used at this dose. The assessment of the OFZ and metabolites [(fenbendazole sulphone (FBZSO2), fenbendazole (FBZ)] plasma pharmacokinetic and tissue residue profiles after its oral administration to pigs and the withdrawal period for human consumption were reported. Forty-eight pigs allocated into two groups received OFZ (30 mg/kg) orally as a commercial (CF) or as experimental formulation (SMF). Samples (blood, muscle, liver, kidney and fat) were collected over 30 days post-treatment and analyzed by HPLC. OFZ was the main compound recovered in plasma, followed by FBZSO2 and low FBZ concentrations. OFZ AUC0-LOQ (209.9±33.9 µg·h/ml) and Cmax (5.40±0.65 µg/ml) parameters for the CF tended to be higher than those for the SMF (AUC0-LOQ: 159.4±18.3 µg h/ml, Cmax: 3.80±0.35 µg/ml). The highest total residue (OFZ+FBZSO2+FBZ) concentrations were quantified in liver, followed by kidney, muscle and fat tissue. FBZSO2 residue levels were the highest found in muscle (0.68±0.39 µg/g) and fat (0.69±0.39 µg/g). In liver and kidney the highest residues corresponded to FBZ (5.29±4.36 µg/g) and OFZ (2.86±0.75 µg/g), respectively. A withdrawal time of 17 days post-treatment was established before tissues are delivered for human consumption.