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

The Public Health Importance and Management of Infectious Poultry Diseases in Smallholder Systems in Africa

Poultry diseases pose major constraints on smallholder production in Africa, causing high flock mortality and economic hardship. Infectious diseases, especially viral diseases like Newcastle disease and highly pathogenic avian influenza (HPAI) and bacterial diseases, especially colibacillosis and salmonellosis, are responsible for most chicken losses, with downstream effects on human nutrition and health. Beyond production impacts, poultry diseases directly harm public health if zoonotic, can give rise to epidemics and pandemics, and facilitate antimicrobial resistance through treatment attempts. HPAI, campylobacteriosis, and salmonellosis are the priority zoonoses. Sustainable solutions for poultry health remain elusive despite recognition of the problem. This review summarises current knowledge on major poultry diseases in smallholder systems, their impacts, and options for prevention and control. We find biosecurity, vaccination, good husbandry, and disease-resistant breeds can reduce disease burden, but practical limitations exist in implementing these measures across smallholder systems. Treatment is often inefficient for viral diseases, and treatment for bacterial diseases risks antimicrobial resistance. Ethnoveterinary practices offer accessible alternatives but require more rigorous evaluation. Multisectoral collaboration and policies that reach smallholder poultry keepers are essential to alleviate disease constraints. Successful control will improve livelihoods, nutrition, and gender equity for millions of rural families. This review concludes that sustainable, scalable solutions for smallholder poultry disease control remain a critical unmet need in Africa.

Newcastle disease burden in Nepal and efficacy of Tablet I2 vaccine in commercial and backyard poultry production

Poultry (Gallus domesticus) farming plays an important role as an income generating enterprise in a developing country like Nepal, contributing more than 4% to the national Gross Domestic Product (GDP). Newcastle Disease (ND) is a major poultry disease affecting both commercial and backyard poultry production worldwide. There were more than 90 reported ND outbreaks in Nepal in 2018 with over 74,986 birds being affected. ND is responsible for over 7% of total poultry mortality in the country. Recent outbreaks of ND in 2021 affected many farms throughout Nepal and caused massive loss in poultry production. ND is caused by a single-stranded ribonucleic acid (RNA) virus that presents very similar clinical symptoms as Influenza A (commonly known as bird flu) adding much complexity to clinical disease identification and intervention. We conducted a nationwide ND and Influenza A (IA) prevalence study, collecting samples from representative commercial and backyard poultry farms from across the major poultry production hubs of Nepal. We used both serological and molecular assessments to determine disease exposure history and identification of strains of ND Virus (NDV). Of the 40 commercial farms tested, both NDV (n = 28, 70%) and IAV (n = 11, 27.5%) antibodies were detected in majority of the samples. In the backyard farms (n = 36), sero-prevalence of NDV and IAV were 17.5% (n = 7) and 7.5% (n = 3) respectively. Genotype II NDV was present in most of the commercial farms, which was likely due to live vaccine usage. We detected never reported Genotype I NDV in two backyard farm samples. Our investigation into 2021 ND outbreak implicated Genotype VII.2 NDV strain as the causative pathogen. Additionally, we developed a Tablet formulation of the thermostable I2-NDV vaccine (Ranigoldunga™) and assessed its efficacy on various (mixed) breeds of chicken (Gallus domesticus). Ranigoldunga™ demonstrated an overall efficacy >85% with a stability of 30 days at room temperature (25°C). The intraocularly administered vaccine was highly effective in preventing ND, including Genotype VII.2 NDV strain.

Polymeric-based drug delivery systems for veterinary use: State of the art

One of the challenges to the success of veterinary pharmacotherapy is the limited number of drugs and dosage forms available exclusively to this market, due to the interspecies variability of animals, such as anatomy, physiology, pharmacokinetics, and pharmacodynamics. For this reason, studies in this area have become a highlight, since they are still scarce in comparison with those on human drug use. To overcome many limitations related to the bioavailability, efficacy, and safety of pharmacotherapy in animals, especially livestock and domestic animals, polymers-based drug delivery systems are promising tools if they guarantee greater selectivity and less toxicity in dosage forms. In addition, these tools may be developed according to the great interspecies variability. To contribute to these discussions, this paper provides an updated review of the major polymer-based drug delivery systems projected for veterinary use. Traditional and innovative drug delivery systems based on polymers are presented, with an emphasis on films, microparticles, micelles, nanogels, nanoparticles, tablets, implants and hydrogel-based drug delivery systems. We discuss important concepts for the veterinarian about the mechanisms of drug release and, for the pharmacist, the advantages in the development of pharmaceutical forms for the animal population. Finally, challenges and opportunities are presented in the field of pharmaceutical dosage forms for veterinary use in response to the interests of the pharmaceutical industry.

Isolation and Characterization of Newcastle Disease Virus from Live Bird Markets in Tanzania

Chickens in live bird markets (LBMs) from six different regions of Tanzania were surveyed for Newcastle disease (ND) virus (NDV) and avian influenza virus in 2012. ELISA-based serology, virus isolation, and characterization, including pathotyping was conducted. Virulent NDV was isolated from almost 10% of the tested samples, with two distinct genotypes being detected. One genotype was similar to recent viruses circulating in Kenya and Uganda, which share a northern border with Tanzania. Several viruses of this genotype were also isolated from Tanzania in 1995, the last time surveillance for NDV was conducted in the country. The second genotype of virus from Tanzania was closely related to viruses from Mozambique, a southern neighbor, and more distantly to viruses from South Africa, Botswana, and several European countries. Partial fusion gene sequence from the isolated viruses showed identical fusion cleavage sites that were compatible with virulent viruses. Selected viruses were tested by the intracerebral pathogenicity index, and all viruses tested had scores of >1.78, indicating highly virulent viruses. Serology showed only a third of the chickens had detectable antibody to NDV, suggesting that vaccination is not being commonly used in the country, despite the availability of vaccines in agricultural-related markets. All samples were taken from clinically healthy birds, and it is believed that the birds were sold or slaughtered before showing ND clinical signs. LBMs remain a biosecurity risk for farmers through the return of live infected birds to the farm or village or the movement of virus on fomites, such as uncleaned wooden cages.

Heat-stable sublingual oxytocin tablets as a potential needle-free approach for preventing postpartum hemorrhage in low-resource settings

Postpartum hemorrhage is a major cause of mortality and morbidity related to childbirth in developing countries. The recommended treatment includes administration of oxytocin; however, oxytocin is a heat-labile protein, and it must be given as an intramuscular injection by skilled health care providers. To address these challenges, we developed a freeze-dried oxytocin fast-dissolving tablet (FDT) for sublingual (SL) needle-free administration. Using methods developed previously, we produced a robust FDT that maintained oxytocin stability at 40 °C, 75% relative humidity for 12 months. This formulation contains 9% sucrose, 1.5% (hydroxypropyl)methyl cellulose, 9% mannitol, 4% dextran, 1% carbomer, 1% sodium taurocholate, and 100 IU oxytocin. An in vitro study showed a > 30% reduction in tissue transepithelial electrical resistance after treatment with the oxytocin FDT, implying an increase in the permeability of the mucosal tissue to oxytocin. Anesthetized Yucatan miniature swine were administered a SL FDT, and blood was periodically collected for a pharmacokinetic study. Higher plasma concentrations were seen when larger SL doses were given. The maximum concentrations for SL and intramuscular doses in anesthetized pigs were 207 and 612 pg/mL, respectively. Whether the levels attained will be sufficient to elicit beneficial results in humans is yet to be determined. This study demonstrates the feasibility of our approach for developing a heat-stable oxytocin tablet that can be administered successfully via the SL route.

Eliciting preferences for attributes of Newcastle disease vaccination programmes for village poultry in Ethiopia

Newcastle disease (NCD) is an important disease of poultry, directly affecting the livelihoods of poor farmers across developing countries. Research has identified promising innovations in NCD vaccine development and field trials among village poultry have been promising. However, NCD vaccination is not currently part of village poultry extension programmes in many developing countries. Understanding the preferences for, and relative importance of, different attributes of potential vaccination programmes to prevent NCD will be crucial in designing acceptable and sustainable prevention programmes. This research employed the discrete choice experiment approach to elicit farmers' preference for attributes of NCD vaccination programmes for village poultry in rural Ethiopia. The choice experiment survey was conducted on 450 smallholder farmers. The relative importance of attributes of NCD vaccines to farmers was estimated using a random parameter logit regression model. The preferred NCD vaccine programme had greater bird-level protection (i.e. greater capacity to reduce mortality should NCD occur in a flock), was delivered by animal health development agents, and could be administered via drinking water. Results from simulations on changes in attribute levels revealed that bird-level protection capacity and delivery of vaccine by animal heath extension affect farmers' preferences more than other attributes. These findings suggest that it is important to ensure NCD vaccine programmes offer reasonable capacity to protect against mortality. It also suggests the need to understand farmers' preferred vaccine delivery mechanisms and route of vaccine administration for a wider acceptance of vaccine.

Development of a Vaginal Fast-Dissolving Insert Combining Griffithsin and Carrageenan for Potential Use Against Sexually Transmitted Infections

Precoital, on-demand topical microbicides to reduce a woman's risk of sexually transmitted infections have been in development for nearly 3 decades, but no product has been approved due to acceptability issues and poor adherence in clinical trials. We set out to develop a self-administered vaginal fast-dissolving insert (FDI) produced by freeze-drying that would deliver safe and effective amounts of the antiviral agents griffithsin (GRFT) and carrageenan (CG) and would have properties women and their partners find acceptable. We evaluated FDI physical criteria, attributes of the gel produced upon dissolving, and GRFT stability. The lead formulation, FDI-024, was selected from 13 candidates and contains 4 mg of GRFT, 15 mg of CG, and excipients (the cryoprotectant sucrose and bulking agents dextran 40 and mannitol). The FDI exhibits good friability and hardness and is stable for at least 6 months at up to 40°C/75% relative humidity. It disintegrates in less than 60 s in a physiologically relevant volume (∼1 mL) of simulated vaginal fluid, forming a viscous semi-solid gel with favorable mucoadhesive and spreading properties. The formulation retains the antiviral activity of GRFT and CG against HIV type 1 and human papillomavirus, respectively, in cell-based assays.

Assessing the impact of a novel strategy for delivering animal health interventions to smallholder farmers

In many countries of the developing world village poultry play a vital role in the rural economy, providing a source of protein and valuable income with relatively small investments. In almost all areas in which village poultry are raised Newcastle disease (ND) is identified as one of the biggest causes of poultry loss, this is often coupled with a lack of knowledge of poultry management practices. Inexpensive and effective vaccines are available that are suitable for use in rural village environments, but in many areas service providers and reliable structures for delivery remain an obstacle to uptake of vaccines. To overcome this, GALVmed has implemented a network for vaccine distribution in which individuals in the villages are trained as vaccinators. The vaccinators purchase ND vaccines from local agro-veterinary stores and sell single doses at market determined prices. Implementation of these networks was preceded by a programme of smallholder sensitisation to increase awareness of diseases and flock management practices. Here we present analysis of the impacts of this scheme on village poultry production. We compare the results of a baseline survey carried out before implementation of the networks, with the results of a survey 16-24 months following implementation. We present results in terms of the uptake of ND vaccine, flock size, consumption of poultry meat, and poultry sales from Gairo district in Tanzania, Mayurbhanj district in India and Banke district in Nepal. In all areas, there was a significant increase in the numbers of flocks that were using ND vaccines, with over 75% uptake in all areas, reaching 98% in India. In all areas flock sizes doubled, the numbers of eggs that were set for hatching and that hatched increased by 25-50% and there was an increase in the frequency with which chicken meat was consumed and chickens were sold. Additionally, farmers reported fewer ND outbreaks, but this is prone to reporting bias and so improvements in production cannot be categorically ascribed to ND vaccination. These results have shown that establishing a market driven approach for the distribution of ND vaccines and community sensitisation on poultry husbandry practices results in a high rate of uptake of the vaccines. The results also suggest a reduction in the number of ND outbreaks and improvements to the livelihoods of rural smallholders.

Developing a Flexible Pediatric Dosage Form for Antiretroviral Therapy: A Fast-Dissolving Tablet

Current presentations of the anti-HIV drugs lopinavir and ritonavir make appropriate dosing for children difficult. We conducted a feasibility study to develop a formulation for these drugs with child-safe excipients in a flexible dosage form for children across the pediatric age spectrum. The freeze-drying in blister approach was used to produce fast-dissolving tablets (FDTs), as these can be dispersed in fluids for easy administration, even to infants, and appropriate portions of the dispersion can be given for different ages/weights. We combined various ratios of polymers, surfactants, and bulking agents to incorporate the 2 highly hydrophobic drugs while maintaining drug stability, rapid disintegration, and good handling properties. The final FDT was robust and disintegrated in 0.5 mL of fluid in 10 s with up to 4 tablets dissolving in 2 mL to achieve varying doses accommodated in a common teaspoon. Drug recovery after dissolution in small volumes of liquid or fluid foods was 90%-105%. The final candidate FDT was stable at 40°C, 75% relative humidity for up to 3 months. FDTs are a promising flexible dosage form for antiretroviral treatment for pediatric patients, especially in low-resource settings.

Newcastle disease vaccines-A solved problem or a continuous challenge?

Newcastle disease (ND) has been defined by the World Organisation for Animal Health as infection of poultry with virulent strains of Newcastle disease virus (NDV). Lesions affecting the neurological, gastrointestinal, respiratory, and reproductive systems are most often observed. The control of ND must include strict biosecurity that prevents virulent NDV from contacting poultry, and also proper administration of efficacious vaccines. When administered correctly to healthy birds, ND vaccines formulated with NDV of low virulence or viral-vectored vaccines that express the NDV fusion protein are able to prevent clinical disease and mortality in chickens upon infection with virulent NDV. Live and inactivated vaccines have been widely used since the 1950's. Recombinant and antigenically matched vaccines have been adopted recently in some countries, and many other vaccine approaches have been only evaluated experimentally. Despite decades of research and development towards formulation of an optimal ND vaccine, improvements are still needed. Impediments to prevent outbreaks include uneven vaccine application when using mass administration techniques in larger commercial settings, the difficulties associated with vaccinating free-roaming, multi-age birds of village flocks, and difficulties maintaining the cold chain to preserve the thermo-labile antigens in the vaccines. Incomplete or improper immunization often results in the disease and death of poultry after infection with virulent NDV. Another cause of decreased vaccine efficacy is the existence of antibodies (including maternal) in birds, which can neutralize the vaccine and thereby reduce the effectiveness of ND vaccines. In this review, a historical perspective, summary of the current situation for ND and NDV strains, and a review of traditional and experimental ND vaccines are presented.