Responding to the COVID-19 Pandemic in Developing Countries: Lessons from Selected Countries of the Global South.

Reviewing selected policy responses in Asia and South America, this paper draws pragmatic lessons for developing countries to better address the COVID-19 pandemic. It argues that not acting quickly and adequately incurs much higher costs. So-called 'best practices', while useful, may be inappropriate, especially if not complemented by effective and suitable socio-economic measures. Public understanding, support and cooperation, not harsh and selective enforcement of draconian measures, are critical for successful implementation of containment strategies. This requires inclusive and transparent policy-making, and well-coordinated and accountable government actions that build and maintain trust between citizens and government. In short, addressing the pandemic crisis needs 'all of government' and 'whole of society' approaches under credible leadership.

Comparative study on the pathogenesis of the generated 9a5b Newcastle disease virus mutant isolate between chickens and waterfowl.

Lentogenic Newcastle disease viruses (NDVs), circulating among waterfowl, have the potential to become highly pathogenic by replication in chickens. The pathological studies that compare NDV infections in chickens and waterfowl are rare. The virulent 9a5b mutant NDV isolate was generated by passaging the lentogenic Goose/Alaska/415/91 NDV isolate in chickens. The pathogenesis of the virulent 9a5b mutant isolate is unknown in both chickens and waterfowl. In this study, the virulent 9a5b mutant NDV isolate was inoculated intranasally in 32-day-old specific pathogen-free white Leghorn chickens and Japanese commercial ducks. Unlike ducks, which remained clinically normal throughout the study, chickens had depression, gasping, oral discharges, and greenish-white soft feces. Gross and histologic lesion patterns as well as viral replication supported the differing clinical outcome. Ducks had slight inflammation mainly in respiratory and digestive tracts, whereas slight nonpurulent encephalitis, necrotizing pancreatitis, tubulointerstitial nephritis, and mild inflammation in respiratory and digestive tracts were detected in chickens. In agreement, interferon-beta (IFN-ß)-immunopositive signals were more intense in lung tissue of ducks than that of chickens, and NDV replications were detected intensively in chicken tissues. These results suggest that the 9a5b mutant NDV isolate is more virulent in chickens, and slight histological lesions were induced in ducks even with virulent NDVs.

Selection in mixtures of food particles during oral processing in man.

OBJECTIVES: Two processes underlie food comminution during chewing: (1) selection, i.e. every particle has a chance of being placed between the teeth and being subjected to (2) breakage. Selection decreases with particle number by saturation of breakage sites, and it depends on competition between smaller and larger particles for breakage sites. Theoretical models were tested which describe competition between various sizes X. In the one-way model, small particles cannot compete with larger ones because of their smaller height. In the two-way model, small particles may compete when piled between antagonistic teeth. DESIGN: Five subjects participated in one-chew experiments on cubes made of Optosil®. The critical particle number (nc(X)) at which saturation starts, and the number of breakage sites (nb(X)) were determined by varying particle numbers (nX) for single-sized cubes of 1.7-6.8mm. Using nc(X) and nb(X), the models predicted relationships between number of selected particles (ns(X)) and nX in one-chew experiments using simple mixtures with only two sizes. A fixed number (mean 6 or 26) of larger cubes (X=6.8 or 3.4mm) was mixed with various numbers (16-1024) of smaller cubes (X=4.8, 2.4 or 1.7mm), thus varying the factors X, nX, and possible particle piling (for X<4mm). RESULTS: The one-way model was largely followed with small numbers of smaller particles and the two-way model with large numbers. CONCLUSIONS: The two-way model applies to chewing a food which yields a loose aggregation of different-sized particles following an initial phase, whereas other circumstances may be favourable for the one-way model. As conditions of a food bolus can be approached by embedding hard Optosil particles in a soft medium, the models will, apart from dentistry, be of interest for controlling flavour release in food engineering.

Histopathological alterations in immune organs of chickens and ducks after experimental infection with virulent 9a5b newcastle disease virus.

The chicken and duck are important hosts of Newcastle disease virus (NDV) with distinctive responses to infection. NDV infection in ducks is often subclinical and chronic, while in chickens the infection is clinically apparent and transient. These differences may be due to in part to the host response to NDV infection. This study compares the histopathological changes in the spleen, thymus and bursa of Fabricius following infection with NDV in chickens and ducks. The 9a5b isolate of NDV was inoculated intranasally into specific pathogen-free chickens and Japanese commercial ducks. NDV nucleoprotein (NDV-NP) and interferon (IFN)-ß were detected in tissues by immunohistochemistry (IHC), apoptosis was detected by haematoxylin and eosin staining, caspase-3 IHC and the TUNEL assay. Labelling of NDV-NP and lymphoid depletion were most marked in chicken tissues. The pattern of apoptosis in the spleen differed between chickens and ducks. In chickens there were numerous apoptotic cells in the peri-ellipsoidal white pulp and the peri-ellipsoidal, peri-arteriolar and peri-venous lymphoid sheaths, while apoptosis in duck spleens was mainly within the germinal centres. Lymphoid depletion was the main feature in the bursal and thymic tissues of chickens, but apoptosis was marked in these organs in ducks. Expression of IFN-ß appeared earlier and was more intense in the tissues from ducks compared with those from chickens. The differences in IFN-ß and NDV-NP expression may reflect the relative clinical severity of the infection in the two avian species.