Essential Role of Vitamin C and Zinc in Child Immunity and Health

Child survival efforts can be effective only if they are based on accurate information about causes of deaths. Here, we report on a 4-year effort by WHO to improve the accuracy of this information. WHO established the external Child Health Epidemiology Reference Group (CHERG) in 2001 to develop estimates of the proportion of deaths in children younger than age 5 years attributable to pneumonia, diarrhoea, malaria, measles, and the major causes of death in the first 28 days of life. Various methods, including single-cause and multi-cause proportionate mortality models, were used. The role of undernutrition as an underlying cause of death was estimated in collaboration with CHERG. In 2000-03, six causes accounted for 73% of the 10.6 million yearly deaths in children younger than age 5 years: pneumonia (19%), diarrhoea (18%), malaria (8%), neonatal pneumonia or sepsis (10%), preterm delivery (10%), and asphyxia at birth (8%). The four communicable disease categories account for more than half (54%) of all child deaths. The greatest communicable disease killers are similar in all WHO regions with the exception of malaria; 94% of global deaths attributable to this disease occur in the Africa region. Undernutrition is an underlying cause of 53% of all deaths in children younger than age 5 years. Achievement of the millennium development goal of reducing child mortality by two-thirds from the 1990 rate will depend on renewed efforts to prevent and control pneumonia, diarrhoea, and undernutrition in all WHO regions, and malaria in the Africa region. In all regions, deaths in the neonatal period, primarily due to preterm delivery, sepsis or pneumonia, and birth asphyxia should also be addressed. These estimates of the causes of child deaths should be used to guide public-health policies and programmes.

We are continually exposed to organisms that are inhaled, swallowed, or inhabit our skin and mucous membranes. Whether these organisms penetrate and cause disease is a result of both the pathogenicity of the organism (the virulence factors at its disposal) and the integrity of host defence mechanisms. The immune system is an interactive network of lymphoid organs, cells, humoral factors, and cytokines. The essential function of the immune system in host defence is best illustrated when it goes wrong; underactivity resulting in the severe infections and tumours of immunodeficiency, overactivity in allergic and autoimmune disease. In this review we have covered the normal function of the immune system in recognising, repelling, and eradicating pathogens and other foreign molecules.

Viral respiratory tract infection (VRTI) is the most common illness in humans. Despite the high incidence, the economic impact of non-influenza-related VRTI has not been rigorously explored. Our objectives were to obtain an updated incidence of non-influenza-related VRTI in the United States and to quantify the health care resource use (direct costs) and productivity losses (indirect costs) associated with these infections. A nationwide telephone survey of US households (N = 4051) was conducted between November 3, 2000, and February 12, 2001 to obtain a representative estimate of the self-reported incidence of non-influenza-related VRTI and related treatment patterns. Direct treatment costs measured included outpatient clinician encounters, use of over-the-counter and prescription drugs, and associated infectious complications of non-influenza-related VRTI. Absenteeism estimates for infected individuals and parents of infected children were extrapolated from National Health Interview Survey data. Of survey respondents, 72% reported a non-influenza-related VRTI within the past year. Respondents who experienced a self-reported non-influenza-related VRTI averaged 2.5 episodes annually. When these rates are extrapolated to the entire US population, approximately 500 million non-influenza-related VRTI episodes occur per year. Similarly, if the treatment patterns reported by the respondents are extended to the population, the total economic impact of non-influenza-related VRTI approaches $40 billion annually (direct costs, $17 billion per year; and indirect costs, $22.5 billion per year). Largely because of the high attack rate, non-influenza-related VRTI imposes a greater economic burden than many other clinical conditions. The pending availability of effective antiviral therapies warrants increased attention be paid to this common and expensive illness.