Shigellosis : challenges & management issues.

Infectious diseases kill about 11 million children each year while acute diarrhoeal diseases account for 3.1 million deaths in children under 5 yr of age, of which 6,00,000 deaths annually are contributed by shigellosis alone. Shigellosis, also known as acute bacillary dysentery, is characterized by the passage of loose stools mixed with blood and mucus and accompanied by fever, abdominal cramps and tenesmus. It may be associated with a number of complications of which haemolytic uraemic syndrome is the most serious. Shigellosis is caused by Shigella spp. which can be subdivided into four serogroups namely S.sonnei, S.boydii, S.flexneri and S.dysenteriae. Organisms as low as 10-100 in number can cause the disease. Shigellosis can occur in sporadic, epidemic and pandemic forms. Epidemics have been reported from Central American countries, Bangladesh, Sri Lanka, Maldives, Nepal, Bhutan, Myanmar and from the Indian subcontinent, Vellore, eastern India and Andaman and Nicobar islands. Plasmid profile of shigellae in Kolkata has shown a correlation between presence of smaller plasmids and shigellae serotypes- indicating epidemiological changes of the species. Diagnosis of shigellosis is essentially clinical. Laboratory diagnosis includes stool culture and polymerase chain reaction (PCR). Treatment includes use of an effective antibiotic, rehydration therapy (if there is dehydration) and appropriate feeding during and after an episode of shigellosis. Hand-washing is the single most important strategy for prevention of transmission of shigellosis from person to person. A safe and effective vaccine should be developed against the more important circulating strains i.e., S. dysenteriae type 1 and S. flexneri 2a.

Cultural and social context of dysentery: implications for the introduction of a new vaccine.

Dysentery, a severe form of diarrhoeal disease, is a major cause of morbidity and mortality. Paradoxically, virtually no studies have been conducted to examine beliefs and behaviours associated with dysentery. The explanatory model of dysentery was explored in a community in Dhaka, Bangladesh, to understand the acceptability of a vaccine against dysentery. A local term for bloody dysentery is widely known, and residents describe a progression of symptoms, which closely mirrors the biomedical model of the disease. Due to the symbolic significance of blood loss and the fact that there is much uncertainty regarding treatment, bloody dysentery is perceived to be extremely serious. Causal interpretations most commonly relate to humoral theories, and remedies involve the consumption of 'cooling' foods that will reduce the heat associated with dysentery. Despite many misconceptions about vaccines and the fact that this approach contradicts aetiological explanations, the perceived severity of the illness makes vaccines attractive compared to other preventative measures. The results illuminate relevant information for the implementation of a new vaccine.

The health belief model and factors relating to potential use of a vaccine for shigellosis in Kaeng Koi district, Saraburi province, Thailand.

Shigellosis is an important cause of morbidity and mortality throughout the world. Approximately, 1.1 million deaths occur a year due to this disease, making it the fourth leading cause of mortality worldwide. This paper explores local interest in and potential use of a vaccine for shigellosis in Thailand where Shigella poses an important public-health concern. Data for this study were collected during June-November 2002 from 522 subjects surveyed using a sociobehavioural questionnaire in Kaeng Koi district in central Thailand. The community demand and likely use of a vaccine were examined in relation to the Health Belief Model, which provides analytical constructs for investigating the multiple issues of local readiness to accept and access a new vaccine. As the key outcome variable, most respondents showed interest in receiving a vaccine against dysentery which they thought would provide useful protection against the disease. However, there was only a moderate number who perceived dysentery as serious and themselves as susceptible to it, although it was perceived to cause some burden to and additional expense for families. Most people identified a number of groups who were thought to be especially vulnerable to dysentery, such as the elderly, pre-school, and school-age children, and poor labourers. Other outcomes of the study included the identification of acceptable and convenient sites for its delivery, such as government health clinics and private clinics, and respected sources for information about the vaccine, such as health clinic personnel and community health volunteers. This information suggests that components of the Health Belief Model may be useful in identifying community acceptance of a vaccine and the means of introducing it. This health information is important for planning and implementing vaccine programmes.

Acceptability and accessibility of a Shigellosis vaccine in Nha Trang city of Viet Nam.

The acceptability and accessibility of a hypothetical Shigella vaccination campaign was explored. A household survey was conducted with 539 randomly-selected residents of six communes in Nha Trang city of Viet Nam. Four categories of acceptability, such as refusers, low acceptors, acceptors, and high acceptors, were established, Refusers were significantly more likely to be elderly women and were less likely to know the purpose of vaccinations. Low acceptors tended to be male, elderly, and live in urban areas. Low acceptors perceived the disease as less serious and themselves as less vulnerable than acceptors and high acceptors. In terms of accessing vaccination, the commune health centre workers and commune leaders were the preferred sources of information and commune health centres the preferred location for vaccination. Direct verbal information from healthcare providers and audio-visual media were preferred to written information. The respondents expressed a desire for knowledge about the side-effects and efficacy of the vaccine. These findings are significant for targeting specific messages about shigellosis and vaccination to different populations and maximizing informed participation in public-health campaigns.

Perceptions of Shigella and of Shigella vaccine among rural Chinese: compatibility with Western models of behavioral change.

Shigella remain a major source of morbidity and mortality in developing countries, including China. In response, national and international researchers are actively working to develop vaccines that will be effective against dysentery and diarrhea caused by shigella dysentariae. With the growing recognition of the problems associated with sustained vaccine acceptance and usage, researchers and policy makers recognize the importance of conducting theory-based qualitative research to inform vaccine development program efforts. Accordingly we undertook this qualitative study involving 81 residents of one of China's rural communities with high rates of dysentery. The semi-structured interviews suggest that a Western model of behavioral change offered a useful research construct. Consistent with the model is the community's strong perception of 'response efficacy' of vaccines, particularly in comparison with water and sanitation and disease treatment. Residents were eager to vaccinate their children despite variable perception of disease severity, while they were less consistent in their interest in vaccinating adults; this enthusiasm for vaccinating children was attributed to China's 'one child per couple' policy. Intervention implications are discussed.