Vaccination of children in low-resource countries against Shigella is unlikely to present an undue risk of reactive arthritis

Controlled Human Infection Models To Accelerate Vaccine Development

The timelines for developing vaccines against infectious diseases are lengthy, and often vaccines that reach the stage of large phase 3 field trials fail to provide the desired level of protective efficacy. The application of controlled human challenge models of infection and disease at the appropriate stages of development could accelerate development of candidate vaccines and, in fact, has done so successfully in some limited cases. Human challenge models could potentially be used to gather critical information on pathogenesis, inform strain selection for vaccines, explore cross-protective immunity, identify immune correlates of protection and mechanisms of protection induced by infection or evoked by candidate vaccines, guide decisions on appropriate trial endpoints, and evaluate vaccine efficacy. We prepared this report to motivate fellow scientists to exploit the potential capacity of controlled human challenge experiments to advance vaccine development. In this review, we considered available challenge models for 17 infectious diseases in the context of the public health importance of each disease, the diversity and pathogenesis of the causative organisms, the vaccine candidates under development, and each model's capacity to evaluate them and identify correlates of protective immunity. Our broad assessment indicated that human challenge models have not yet reached their full potential to support the development of vaccines against infectious diseases. On the basis of our review, however, we believe that describing an ideal challenge model is possible, as is further developing existing and future challenge models.

The Burden and Etiology of Diarrheal Illness in Developing Countries

Reductions in mortality from diarrheal diseases among young children have occurred in recent decades; however, approximately 500,000 children continue to die each year. Moreover, similar reductions in disease incidence have not been seen, episodes that impact the growth and development of young children. Two recent studies, MAL-ED and GEMS, have more clearly defined the burden and cause of diarrhea among young children, identifying four leading pathogens: rotavirus, CryptosporidiumShigella, and heat stable toxin-producing enterotoxigenic Escherichia coli. Global introduction of rotavirus vaccine is poised to substantially reduce the incidence of rotavirus infection. Interventions are needed to reduce the burden that remains.

Progress and pitfalls in Shigella vaccine research

Renewed awareness of the substantial morbidity and mortality that Shigella infection causes among young children in developing countries, combined with technological innovations in vaccinology, has led to the development of novel vaccine strategies in the past 5 years. Along with advancement of classic vaccines in clinical trials and new sophisticated measurements of immunological responses, much new data has been produced, lending promise to the potential for production of safe and effective Shigella vaccines. Herein, we review the latest progress in Shigella vaccine development within the framework of persistent obstacles.

Shigellosis update: advancing antibiotic resistance, investment empowered vaccine development, and green bananas

PURPOSE OF REVIEW

Shigella is the principal cause of clinical dysentery and an important cause of morbidity and mortality among children in impoverished regions. The purpose of this review is to present key findings in the areas of epidemiology, disease control, and treatment of shigellosis.

RECENT FINDINGS

Recent research activity has advanced the understanding of the epidemiology and host-pathogen interactions. Increased investment and activity in the area of vaccine development have lead to a diversification of candidates and ongoing technical advances yet continue to yield disappointing results in clinical trials in endemic populations and among the most relevant age groups (children under 2 years of age). The description of the rapid spread of quinolone resistance requires monitoring to ensure appropriate case management, particularly in south-east Asia. The evaluation of adjunctive nutritional therapy in endemic areas has supported the use of green bananas in shortening the duration of Shigella dysentery and persistent diarrhea due to Shigella, as well as improving weight gain in early convalescence.

SUMMARY

Despite a great level of activity in basic sciences, there continues to be a large gap in the ability to translate these findings into disease control measures or therapeutic options for individuals living in areas in which shigellosis is endemic.