Acute diarrhoea in young children

E A S Nelson 倪以信

Acute diarrhoea is a very significant cause of morbidity amongst children in Hong Kong. A number of studies undertaken in Hong Kong have assessed the epidemiology of diarrhoeal diseases, and rotavirus has been found to account for approximately 30% of diarrhoea cases among hospitalised children, and about 10% of those seen in the community.¹ In 1997, the Clinical Management System (CMS) was introduced into all Hospital Authority (HA) hospitals to collect uniform discharge data and other information on all patients. Using these data it was found that approximately 12% of all general paediatric medical admissions to HA hospitals for the two-year period from July 1997 to June 1999 were due to acute diarrhoea.²

Based on the ICD codes entered into the CMS, 47% of these diarrhoea admissions were coded as presumed infectious (ICD 009.0-009.3) and 27% as presumed non-infectious (ICD codes 558.9 and 787.91). Specific pathogens coded were rotavirus (ICD 008.61) in 10.3%, other viral (ICD 008.6-008.8) in 1.5%, salmonella (ICD 002-003.9) in 10.9%, Shigella (ICD 004-004.9) in 0.5%, Food Poisoning (ICD 005-005.9) in 0.3% and E Coli and others pathogens (ICD 008-008.5) in 2%. The proportion of diarrhoea admissions coded as rotavirus ranged from 0%-27.9% depending on whether the hospital actively screened for this pathogen, highlighting the likelihood that rotavirus was being under-reported in the CMS data. Similarly other pathogens such as salmonella also appeared to be under-reported based on a previous prospective study that had shown approximately one third of diarrhoea admissions had a bacterial pathogen (majority salmonella) isolated.¹

In community settings, rotavirus is responsible for a smaller proportion of children assessed with diarrhoea but there is generally less data available for ambulatory children. Norovirus and other viral pathogens are currently not routinely screened for in hospital settings, although data from the Department of Health's community-based sentinel surveillance of diarrhoeal diseases have shown the Norwalk agent to be an important pathogen in Hong Kong.

Although an understanding of the epidemiology of diarrhoeal diseases and the nature of the different pathogens is of importance from a public health perspective, it is generally less important for the clinician to be aware of the pathogen, as the majority of children with acute diarrhoea should receive mainly supportive therapy. The Hong Kong College of Paediatricians set up a working group to develop clinical practice guidelines for the management of acute diarrhoea in young children and these have recently been published.³ These guidelines are divided into four parts to facilitate dissemination. The first part is a one page summary of key recommendations, the second part gives all the recommendations for management of acute diarrhoea in young children, the third part details the evidence on which these recommendations are based, and the fourth part consists of tables of evidence and references.

The first two parts of these guidelines* are included as inserts in this issue of the Hong Kong Practitioner. The key messages from these guidelines relate to oral rehydration therapy, nutritional therapy and the use of drugs. Although the recommendations are relatively straightforward, the main hurdle in implementation is likely to relate to a perception amongst caregivers that something is needed to stop the diarrhoea.⁴ Public education will be an important part of the process if these guidelines are to be fully implemented.

Obviously, the ultimate goal in the management of diarrhoeal illness is prevention and there are positive developments in this direction. A vaccine for rotavirus is seen as a priority in view of both the high disease burden in developed and developing countries as well as likelihood that improvements in hygiene and sanitation will not have much significant impact on the disease.⁵ The first licensed rotavirus vaccine, Rotashield (RRV-TV), was recommended for routine immunisation in the US in 1998 but was withdrawn in 1999 as a result of its association with intussusception.⁶ Despite this setback, the withdrawal of RRV-TV has had a number of positive effects, including renewed interest in developing other rotavirus vaccines and testing new vaccines simultaneously in both developed and developing countries. A number of the new vaccines are currently in phase II and III trials with licensure predicted within the next two to three years. A safe and effective rotavirus vaccine will hopefully reduce the need for these management guidelines in the future.