Commonwealth Health
 
 


Prevention and treatment of HIV/AIDS
Roger Shrimpton and Andrew Tomkins

Roger Shrimpton and Andrew Tomkins, respectively of the Centre for International Child Health and Institute of Child Health, at the University College London, examine breastfeeding and dietary management for infants and mothers suffering from the devastating disease.

The number of infants born with HIV infections is growing every day, such that they assume an increasingly large area of concern for programmes aimed at preventing HIV/AIDS and mitigating its effects. In Africa this is reversing the improvements in child mortality achieved in the last two decades. The first global policy statement on HIV and infant feeding (UNAIDS, UNICEF, WHO 1997) has been complemented by policy recommendations from a technical consultation on the prevention of mother-to-child transmission of HIV in the light of new findings (WHO 2000). As the epidemic unfolds, nutrition is increasingly understood to be a critical element in both the prevention and treatment of HIV/AIDS. The aim of this article is to review the evidence available showing the importance of nutrition in both prevention and treatment of HIV/AIDS. In particular the role of nutrition in relation to mother to child transmission (MTCT) will be reviewed together with the latest policy recommendations.

HIV/AIDS and breastfeeding
Children represent an increasingly larger proportion of those getting infected and dying from HIV/AIDS than of those living with the disease. At the end of 2001, three million children were living with HIV/AIDS, 0.8 million got infected and 0.6 million died of the disease. The vast majority of these children were in Sub-Saharan Africa, and were infected through mother-to-child-transmission (MTCT).

MTCT can occur during pregnancy, at the time of delivery, and after birth through breastfeeding. Based on a compilation of studies, it is estimated that MTCT rates, in the absence of any preventive intervention, range from 15-30 per cent in the absence of breastfeeding, to 25-35 per cent if there is breastfeeding through 6 months and to 30-45 per cent if there is breastfeeding through 18 to 24 months (De Cock, Fowler, Mercier et al 2000).

With the use of short-course antiretroviral therapy such as nevirapine, transmission rates can be cut by 51 per cent in non-breastfeeding populations and by almost 40 per cent in breastfeeding populations (Semba & Gray, 2001).
The risk factors for MTCT through breastfeeding are various and relate to the timing of infection, the viral load, the pattern of infant feeding and co-existing pathologies in both mother and infant. Severe HIV infections during pregnancy or after delivery have been associated with an increased rate of MTCT through breastfeeding (John, Nduati, MboriNgacha, et al 2001; Semba, Kumwenda, Hoover, et al 1999.)

The risk of HIV transmission through breastfeeding is greatest in early infancy (before 6 months of age), and persists as long as breastfeeding continues, with some studies showing that longer duration of breastfeeding is associated with increased risk of MTCT (Leroy V, Newell ML, Dabis F, et al 1998)
There is increasing evidence that the danger for MTCT through breast milk may not be breast milk per se, but be more the non-exclusive nature of breastfeeding that is so commonly practised in Africa (Coutsoudis 2001).

Various studies have found that inflammatory conditions such as mastitis, fissures and breast abscesses all increase the risk of MTCT through breastfeeding. Poor breastfeeding technique (poor attachment) is a frequent cause of such conditions. It seems that if the breast is not completely emptied, as is often the case in mixed feeding, there is increased risk of inflammation and/or of sub-clinical infection (mastitis) of the breast tissues. This inflammation/infection leads to an increased permeability of the linings of the milk ducts in the mammary glands, with increased leakage of serum contents into breastmilk (Willumsen, Filteau, Coutsoudis, et al 2000).

Whether this is inflammation or sub-clinical infection is still debated (Featherstone 2001). However, independent of this, in HIV infected mothers viral loads in breastmilk are higher when there is mastitis and increased leakage as shown by higher sodium content of breastmilk (Semba, Kumwenda, Hoover et al. 1999). At the level of the child's intestine, during the first six months of life, the gut membrane is more open to the absorption of whole proteins than later in life and the gastric lymph system less well equipped to stop whole proteins reaching the enteric blood system. The introduction of foreign proteins during this period leads to increased likelihood of an allergic response, with inflammation and reduced integrity of the mucosal membrane of the intestine, all of which will increase the facility of penetration across the gut wall by the virus.

The benefits of exclusive breastfeeding in the first six months of life still outweigh the risks for MTCT in most resource-constrained environments. Policy guidelines emphasise the importance of 'informed choice' by parents who have to decide how best to feed their child if the mother tests positive for HIV.
The potential risks of not breastfeeding obviously vary by country and individual conditions. In most industrialised societies the recommendation is not to breastfeed the infant but to use breastmilk substitutes. In most countries where HIV/AIDS is rampant however, the use of breastmilk substitutes will likely result in an even greater number of child deaths than that likely to occur through HIV/AIDS (Fowler and Newell 2000).

A recent study has shown that in Latin America, if exclusive breastfeeding for the first four months of life were practiced, it would save 52,000 lives a year, which is 15 per cent of all infant deaths in that region (Betran, de Onis, Lauer and Villar 2001). The potential benefits of exclusive breastfeeding for six months in Africa are likely to be greater than in Latin America, since the potential risks of not exclusive breastfeeding are greatest in the first six months of life and exclusive breastfeeding rates are poor in most African countries (WHO 2000).

The biggest barrier to the implementation of programmes to prevent MTCT is the lack of voluntary counselling and testing. The prevention of MTCT is predicated on the availability of voluntary and confidential HIV testing and counselling. The enormous problem is that in Africa where the majority of the cases are, few people know their HIV status.

In Sub-Saharan Africa, less than one percent of women in antenatal care in urban areas have access to HIV testing, and in rural areas the number is even smaller (Piot 2001). Even where services are available the stigma attached to being positive is still a great deterrent. The challenge is not only to provide such services but also to increase their usage.

Nutrition and HIV/AIDS
The need and the potential for including nutrition services in the treatment and care of HIV/AIDS patients are great. Where voluntary counselling and testing services are made freely available and HIV/AIDS patients are increasingly discovered, the provision of nutritional services should become a considerable part of the treatment and care regimes that need to be implemented.
The well known synergistic relationship between nutrition and infection is of even more relevance in the case of infection with HIV. Malnutrition increases both the progression of HIV infection and the risk of transmission of the disease from mother to baby. In turn, HIV infection exacerbates malnutrition through its damaging effects on the immune system and with the consequent increase in infections and debilitation capacity to work and/or to produce food is reduced.

HIV/AIDS both causes and/or exacerbates malnutrition. The weight loss and wasting commonly associated with HIV/AIDS is associated with three overlapping processes: reductions in food intake; nutrient malabsorption; and metabolic alterations. Mouth sores, anorexia, depression and loss of appetite cause reductions in food intake. Nutrient malabsorption is caused by frequent diarrhoea and changes in the structure of the intestine, which lead to decreased fat absorption.

HIV/AIDS also has an in-direct effect on malnutrition through the suppression of immunity. Infections lead to metabolic alterations causing increased requirements for nutrients and increased losses of micronutrients. Special diets are part of the treatment of HIV/AIDS patients (Kotler 2000). HIV/AIDS in turn has a profound effect on food security. In Zimbabwe for example, there has been a 61 per cent reduction in maize production, a 49 per cent reduction in vegetable production and a 37 per cent reduction in groundnuts, due to HIV/AIDS deaths amongst the productive adult population. The total number of orphaned children left in the wake of the AIDS epidemic is estimated at 14 million (UNAIDS 2002).

Poor nutrition has long been thought to have an influence on the outcome of HIV/AIDS. Micronutrient deficiencies are more common in people with human immunodeficiency virus infection (Friis & Michaelsen 1998).
People with HIV/AIDS are more likely to have insufficient dietary intake, malabsorption, diarrhoea, and impaired storage and altered metabolism of micronutrients, all of which contribute to the development of micronutrient deficiencies. Low plasma or serum levels of vitamins A, E, B6, B12 and C, carotenoids, Se, and Zn are common in HIV-infected populations.

Micronutrient deficiencies may contribute to the pathogenesis of HIV infection through increased oxidative stress and compromised immunity. Low levels or intakes of micronutrients such as vitamins A, E, B6 and B12, Zn and Se have been associated with adverse clinical outcomes during HIV infection, and new studies are emerging which suggest that micronutrient supplementation may help reduce morbidity and mortality during HIV infection. There is evidence that the oxidative stress caused by the HIV/AIDS, in the face of an inadequate diet, infection may indirectly hasten HIV replication (Semba & Tang 1999). Whilst evidence that the provision of micronutrient supplements reduces the progression of the disease is still lacking, there is evidence that micronutrient supplements can help prevent low birth weight babies amongst mothers that are infected with HIV (Fawzi, Msamanga, Spiegleman, et al 1998).

There is also evidence that the compromised anti-oxidant status, common in HIV infected mothers, increases the likelihood of breast inflammation and hence of vertical transmission. In Tanzania when mothers were given either sunflower oil or refined palm oil as energy supplements during lactation, there was increased transmission amongst mothers receiving the refined palm oil.
This is hypothesised to be due to the higher levels of vitamin E in sunflower oil (Filteau, Lietz, Mulokozi, et al 1999). There is also evidence that vitamin A supplementation of HIV-infected pregnant women may prevent the deterioration in gut integrity in the subgroup of their infants who themselves become infected. Improving vitamin A status of HIV-infected infants may decrease their gastrointestinal morbidity. (Filteau, Rollins, Coutsoudis et al 2001)

HIV/AIDS and dietary management
The dietary management of HIV/AIDS includes both the nutritional care of the mother found to have HIV/AIDS and of the infant, in order to reduce the risks of MTCT. The relative risks of MTCT are different depending on the resource constraints that the infected mother and her family find themselves.
The voluntary and confidential counselling and testing for HIV package of health care provided to pregnant mothers should include a strong nutrition component. The demands of both pregnancy and lactation on maternal body reserves will compound the negative impact HIV infection has on maternal nutritional status.
Large numbers of babies are being born to mothers without becoming infected. However, they have low birth weight. Unless efforts are made to improve maternal nutritional status in HIV-positive pregnant mothers, the progression of the disease is likely to accelerate and the risks that the baby is born both infected and low birth weight will be increased.

The nutrition component of the counselling package should include dietary advice for the mother in order to help her improve her diet, and a micronutrient supplement containing not only iron and folate, but also other anti-oxidant micronutrients.

Every effort should be made to protect and promote exclusive breastfeeding for six months amongst the majority of mothers who either does not know their HIV status, or who are found negative. The strategies for protecting and promoting exclusive breastfeeding are well known and include the full implementation of the code of marketing of breastmilk substitutes, and the implementation of the Baby Friendly Hospital Initiative in all health facilities. (WHO 1981, WHO 1998).

Strengthening the capacity of health facilities to provide lactation counselling services can have dramatically positive effects on exclusive breastfeeding rates over the short term that are beneficial for both infected and non-infected mothers (Haider et al 2000).
Infant feeding mothers should be helped to make choices, including the following options: replacement feeding from birth, exclusive breastfeeding for six months followed by rapid cessation at around six months and introduction of replacement feeding.

For all of these options the task is then to ensure adequate complementary feeding from six months onwards. When replacement feeding is acceptable, feasible, affordable sustainable and safe avoidance of all breastfeeding by HIV-infected mothers is recommended. Otherwise, exclusive breastfeeding is recommended during the first months of life. To minimise HIV transmission risk, breastfeeding should be discontinued as soon as feasible, taking into account local circumstances, the individual woman's situation and the risks of replacement feeding.

In most countries in Latin America HIV-positive women are encouraged to avoid breastfeeding and in some cases even provided with breastmilk substitutes. In the resource-constrained situations encountered in most Sub-Saharan African countries replacement feeding from birth is not an option. The rapid cessation of exclusive breastfeeding at around six months and a rapid transition to exclusive replacement feeding requires considerable advice and counselling support for the mother and her family in order to be successful (Piwoz, Huffman, Lusk et al 2001).

The capacity to carry out such counselling is remarkably weak in most country settings where HIV/AID prevalence rates are rising rapidly.
The problem of ensuring adequate complementary feeding is compounded in the infants of HIV/AIDS infected mothers since the nutritional benefits of continued breastfeeding are missing after six months of age. The provision of 'transitional foods' more commonly known as weaning foods, are recommended for the period between 6 and 12 months of age (WHO 1998). In the absence of breastmilk some form of replacement milk should be used, such as goat's milk or cow's milk if they are available. Ensuring the nutritional adequacy of transitional foods with regard to both nutrient and energy density and food safety is a demanding task that requires considerable supportive counselling and advice. In the second year of life the problem is less acute since the child has acquired teeth and can be fed from the family pot using chopped or minced preparations.

During the period of complementary feeding the provision of a micronutrient supplements is recommended since ensuring their provision through transitional foods is often not easy and the infant is likely to already have been born with inadequate stores of iron and vitamin A for example, that need to be replenished.

Conclusions and recommendations
Dealing with the risks of MTCT is assuming increasing importance in HIV/AIDS programmes. Whilst in industrialised countries mothers are advised not to breastfeed their babies, such advice is not appropriate in most non-industrialised countries. The benefits of exclusive breastfeeding in the first six months of life are likely to outweigh the risks of MTCT in most resource-constrained environments where HIV/AIDS prevalence rates are increasing. In such situations the rapid cessation of breastfeeding and the switch from exclusive breastfeeding to exclusive replacement feeding at about six months of life seems the most pragmatic approach, but implementation may meet many cultural barriers.
The adoption of MTCT reduction strategies based on changes in infant feeding practices requires a heavy investment in the capacity to carry out voluntary counselling and testing for HIV/AIDS. The nutrition component of such counselling is considerable, and should include improved capacity for lactation counselling and management, nutrition education, and micronutrient supplementation for both the mother and child.

References
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