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close this bookMalnutrition and Infection - A review - Nutrition policy discussion paper No. 5 (UNSSCN, 1989, 144 p.)
close this folderMALNUTRITION AND INFECTION - by Andrew Tomkins and Fiona Watson1
View the document(introduction...)
View the document1. THE NUTRITION CYCLE
View the document2. THE INFECTION CYCLE
Open this folder and view contents3. INFECTION AND RISK OF MALNUTRITION
Open this folder and view contents4. MALNUTRITION AND RISK OF INFECTION
View the document5. LOW BIRTH WEIGHT AND RISK OF INFECTION
Open this folder and view contents6. CONCLUSIONS
Open this folder and view contents7. BIBLIOGRAPHY
View the document8. ALPHABETICAL LISTING OF REFERENCES IN BIBLIOGRAPHY
View the document9. NUTRITION AND INFECTION RE-EXAMINED: A RETROSPECTIVE COMMENT BY NEVIN S SCRIMSHAW

2. THE INFECTION CYCLE

Just as the word ‘malnutrition’ has suffered from a lack of clear understanding, there is also confusion with the terms ‘disease’ and ‘infection’. Disease and infection are often used synonymously, but there are important distinctions. In a pure sense disease is only present when the host displays clinical manifestations of infection and where infection leads to abnormalities of organ function. In addition a certain number of organisms must be present before an infection can be termed disease.


FIGURE 2

Figure 2 a simplified model of the way in which infection occurs is shown. Most pathogens which affect nutrition are temporary residents in the human host. Indeed, the sophisticated immune defence systems which protect against colonisation and tissue invasion are remarkably effective in the well nourished host. Chandra (1980) has reviewed the ways in which the immune process is affected by malnutrition. Once the pathogen is established within the body there are variations in the severity, duration and extent of the infection which may be affected by the factors listed in Table 2.

TABLE 2

FACTORS AFFECTING THE INFECTION CYCLE

Health care

- Preventive

- Immunisations


Promotive

- Vitamin A/iron supplementation


Curative

- Chemotherapy
(antimalarials/antibiotics)

Environment

- Water supply,



sanitation,



personal hygiene,



crowding

- respiratory infections


insects

- malaria


climate

- measles


sexual patterns

- AIDS

Care during illness

- Breast feeding, oral rehydration, appropriate refeeding diet, time available to feed child.

It is important to stress that ‘association’ does not equal ‘cause’. An example of this is the uncertainty about the relative importance of malnutrition, crowding and other factors in the development of severe measles. Those with greatest growth impairment may also have the most marked deficiency of micronutrients. They might come from homes where the mother is forced to work away from the child during the day and where lack of time or money prevents visits to a health centre for antibiotics. If the child lives in an area with poor sanitation there is a greater risk of post-measles diarrhoea and if the housing is poor there is a greater risk of post-measles pneumonia. Thus there is a great variety of possible outcomes from an attack of measles. Malnutrition may be regarded as a marker of a high risk child/family unit rather than merely a biological risk factor for increased severity of infection in an individual. It must be recognised that in a complex situation where many variables affect the outcome of infection it may not be easy to show the statistical strength of a single variable such as nutritional status.