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Chapter: Introduction to Human Nutrition: Food and Nutrition-Related Diseases: The Global Challenge

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HIV/AIDS - Food and Nutrition Related Diseases

Infection with HIV and the consequent development of AIDS is a global pandemic already responsible for more than half of total deaths in some developing countries.

HIV/AIDS

 

Introduction

 

Infection with HIV and the consequent development of AIDS is a global pandemic already responsible for more than half of total deaths in some developing countries. It is estimated that since the early 1980s when the syndrome was described and the virus iden-tified, this infectious disease has already killed more than 25 million people, including at least half a million children. A third of these deaths occurred in sub-Saharan Africa, where more than half of the 33.4–46 million people currently infected with HIV live. The pandemic has a devastating and tragic social, eco-nomic and demographic impact on previous devel-opment and health gains in developing countries. It affects mostly young, sexually active adults in their reproductive years as well as babies born from infected mothers. To understand the nutritional challenges of HIV/AIDS it is necessary to understand how the virus is transmitted and to follow the clinical course of the infection. The virus characteristics, its binding to cell surface receptors, its entry into cells of the immune system, its replication and transcription, as well as its genetic variability, and different classes of the virus have been intensively researched and described, forming the basis for the development of antiretrovi-ral drugs to treat HIV/AIDS. More about this can be found in the clinical nutrition textbook of this series or at http://en.wikipedia.org/wiki/HIV.



Transmission of HIV

 

Because there is still no vaccine against HIV and no cure available, the emphasis is on prevention of trans-mission of the virus. It is transmitted from person to person via certain body fluids: blood (and blood products), semen, pre-seminal fluid, vaginal secre-tions, and breast milk.

 

The majority of HIV infections are acquired through unprotected sexual contact when sexual secretions of one partner come into contact with genital, oral, or rectal mucous membranes of another. The estimated infection risk per 10 000 exposures (without a condom) to an infected source varies from 0.5 to 50, depending on the type of exposure.

 

The blood transmission route is responsible for infections in intravenous drug users when they share needles with contaminated persons. Although blood and blood products are these days mostly checked for HIV, unhygienic practices in some developing coun-tries, needle prick injuries of nurses and doctors, as well as procedures such as tattoos, piercings, and scarification rituals pose some risk for infection.

 

Transmission of the virus from an infected mother to her child can occur in utero during pregnancy, during childbirth (intrapartum), or during breast-feeding. The transmission rate between untreated infected mothers and children is approximately 25%. This risk can be reduced to 1% with combination antiretroviral treatment of the mother and cesarean section. The overall risk of a breastfeeding mother to child is between 20% and 45%. Recent studies have shown that this risk can be reduced three- to fourfold by exclusive breastfeeding for up to 6 months. Exclu-sive breastfeeding for 6 months is therefore the present recommendation from the WHO for infected mothers in developing countries “unless replacement feeding is acceptable, feasible, affordable, sustainable and safe for them and their infants before that time.”

 
The clinical course of HIV infection: progression to AIDS

 

The different stages of HIV infection dictate different types of nutritional intervention. Even before infec-tion, the vicious cycle of undernutrition and poverty in developing countries may increase vulnerability to infection: the hopelessness and despair of poverty could lead to alcohol abuse, violence, rape, and irre-sponsible sexual behaviors, increasing exposure to the virus. In addition, malnutrition could compromise the integrity of the immune system, increasing vul-nerability to infection. Breaking this cycle by appro-priate public health nutrition interventions in poverty alleviation programs may indirectly also impact on HIV transmission.

 

Stage 1: Incubation period

 

There are no symptoms during this stage and its duration is usually 2–4 weeks.

 

Stage 2: Acute infection (seroconversion)

 

There is rapid viral replication during this stage. It may last from a week to several months with a mean duration of 28 days. The symptoms in this stage include fever, lymphadenopathy, pharyngitis, rash, myalgia, malaise, headache, and mouth and esoph-ageal sores.

 

Stage 3: Asymptomatic or latency stage

 

This stage may last from a few weeks up to 10 or 20 years, depending on the nutritional status and drug treatment of the individual. It is characterized by

 

none or only a few symptoms, which may include subclinical weight loss, vitamin B12 deficiency, changes in blood lipids and liver enzymes, and an increased susceptibility to pathogens in food and water.

 

Stage 4: Symptomatic HIV infection

CD4+ cell counts (the immune cells containing the CD4 receptor, which binds the virus and which is destroyed during viral replication) have decreased from normal values of 1200, to between 200 and 500 cells/µl. Wasting is a characteristic symptom and is defined as an involuntary loss of more than 10% of baseline body weight. Other symptoms include loss of appetite, white plaques in the mouth, skin lesions, fever, night sweats, TB, shingles, and other infections. Nutrition interven-tions may help to preserve lean body mass, “strengthen” the immune system and slow progres-sion to stage 5.

 

Stage 5: AIDS

The CD4+ counts are now below 200 cells/µL. The immunosuppression is severe and leads to many possible opportunistic or secondary infections with fungi, protozoa, bacteria and/or other viruses.

Malignant diseases and dementia may develop. This is the final stage, and if not treated by antiretroviral drugs and specific drugs for the secondary infec-tions it invariably leads to death.

 

Nutrition and HIV/AIDS

 

The role of nutrition in HIV/AIDS is complex. As mentioned above, malnutrition could contribute to increased vulnerability to infection in developing countries. The virus probably increases nutritional needs, while its effects on the nervous and digestive system lead to decreased appetite and intakes, impaired digestion, and malabsorption. The conse-quent loss of lean body mass gave the infection its original African name of “thin disease.” There are indications that improved nutrition may slow the progression of HIV infection to AIDS. There is evi-dence that nutritional support can help in the toler-ance of antiretroviral drugs and their side-effects and assist in the management of some of the secondary infections of AIDS.

 

The optimal diet for people living with HIV/AIDS is not known. At least one study (the THUSA study in South Africa) indicated that asymptomatic infected subjects who regularly included animal-derived foods in their diets had better health outcomes than those on plant-based diets and with high omega-6 polyun-saturated fat intakes. The nutritional recommenda-tions for people living with HIV/AIDS are therefore evidence informed and not totally evidence based at this stage. Global recommendations have recently been evaluated by the Academy of Science of South Africa.

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