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Forgotten disease: HIV/AIDS | part 5/13

There is one disease that is more stigmatised than the others, one that is not forgotten in its defining sense, but which is forgotten in the sense that treatment is limited, expensive, and unrealistic for those infected.

HIV/AIDS:

human immunodeficiency virus/acquired immunodeficiency syndrome

This picture shows the budding of new HIVs from the infected human cell.

 Most people know the name of the disease, but little more. In fact, HIV is the virus itself while AIDS is the condition that occurrs when the virus has killed the patient’s immune defence cells. The virus and the illness are in most people’s eyes an African problem and it is true that about 70% of all infected live in Sub-Saharan Africa. However, a whole 1,2 million people are supposed to be infected in North America and about 4 million in Asia. It is currently supposed to affect 33-35 (depending on source) million people world-wide – it is a major world problem.

Illness

Two parts to this illness: the virus and the condition.

The virus

The virus essentially attacks and infiltrates the body’s immune defence cells causing these to die. The virus is actually not one, but several different viruses in the class of Retroviridae and the genus Lentivirus. The species differs and there is a larger list of subtypes. There are two major types: HIV 1 and HIV 2 – HIV 1 is thought to originate from chimpanzees and gorillas in western Africa; HIV 2 originates from sooty mangabeys (another ape) found in Senegal and Ghana. HIV 1 is the more deadly and is the cause of the AIDS pandemic and can be divided into the M, N, O, and P subgroups, but HIV 2 is also known to cause AIDS.

The condition

The virus infects the body’s macrophages, dendritic cells, and T-cells, viz. most often the CD4+ lymphocytes, by attaching itself to them via its gp120 protein to the e.g. T-cell’s CD4+ protein. The CCR-5 protein then induces the fusion of the membranes. An inherent property of lentiviruses is that they have a single-strand RNA strand, not DNA, and this strand is injected when the cytoplasms merge as the HIV’s membrane fuses with that of the T-cell. The RNA is converted into DNA by reverse transcriptase and is inserted into the T-cell’s genome strand using DNA integrase. Hence, the virus is literally replacing part of the human body. The infected T-cell now produces HIV RNA and amino acids that form new HIV viruses and their protein coats. These viruses then spread throughout the body the infection rate increases. The T-cells then die, causing AIDS as the immunodeficiency occurs when the majority of T-cells are denatured. At the replication of the viral RNA, which happens 10 billion times per day, there is a chance of mutation of one nucleotide per 9 200 nucleotides, meaning resistance could develop.

The virus is then spread via blood transfusions, sexual intercourse, or during birth (i.e. mother-to-child transmission, MTCT). Everyday activities such as sharing food and water, kissing, shaking hand, or using the same toilet are not factors that spread the condition. AIDS occurs when the body catches a secondary, an opportunistic, disease due to the decreased immune defence strength.

Prevention

Since HIV is spread mainly through intercourse, sex education with its implications would indeed help to decrease the number of new infections (regular latex condoms give an 85% protection). In addition, testing for the disease can prevent its spread and lessen the effect on the patient and taking an anti-HIV cure when infection occurs actually helps prevent the virus’ transmission (tested between discordant couples); this is known as PrEP (pre-exposure prophylaxis). There is also a post-exposure prophylaxis (PEP) given to e.g. health-care workers following needle sticks. Male circumcision could possibly help to decrease the risk for the infection from woman to man by about 60%. Prevention of mother-to-child transmission (PMTCT) is without intervention between 15 and 45%, but with intervention that could be decreased to virtually 0%. Consistency in the anti-retroviral therapy (ART) may cause the risk of transmission to a partner to decrease by 96% by keeping the number of viruses as low as possible.

ARVs from South Africa, 2005. Photographer: Mariella Furrer.

Treatment

Anti-retrovirals (ARVs) help bring the number of viruses in the body down so the CD4 count (i.e. the remaining number of T-cells) stays high. To treat the opportunistic disease that follows AIDS is one thing, and often it is in theory possible to treat those (they could be malaria, cholera, tuberculosis, measles, etc.), but to get to the viral infection itself is impossible. This is because antibiotics per se only target cells – and the virus is not a cell. And today, research has not been able to target viruses – HIV is thus today not 100% curable. But, it is treatable! ARVs combats the HIV infection by suppressing the viruses, hence preventing opportunistic infections and death. However, these so vital ARVs are expensive. Thanks to generics and access to drug campaigns (such as MSF’s Access Campaign, which was started after the organisation received the Nobel Prize) the price has gone down from an initial 100 000 dollars per year to 1 000 dollars per year. However, in low-income countries this fee is too high. And with big pharmaceutical companies constantly fighting to patent drugs, ART is threatened – not because we do not have the ARVs, but because the greedy and the privileged want to hold on to them. Local infrastructures can hinder the spread and use of ART, due to long distances between homes of the patients and the health-care centres, as well as the lack of regular check-ups or scanning for the disease.

Why dangerous?

  • It is a killer throughout the world, at the moment infecting about 34 million people, two-thirds of them in Africa.
  • Spreads through blood, bodily fluids in sex, and birth.
  • If left untreated, the HIV kills off a person’s immune defence in 10-20 years time – this condition is AIDS
  • AIDS leaves the body defenceless to opportunistic infections and it is such an infection that kills, not the HIV/AIDS itself.
  • It is not curable and current research is not doing enough to find a cure or better treatment, and although millions receive ART today too many people go untreated and even undiagnosed, risking further spread of the virus and pandemic.

http://www.who.int/mediacentre/factsheets/fs360/en/index.html

http://en.wikipedia.org/wiki/Subtypes_of_HIV

http://en.wikipedia.org/wiki/AIDS#Epidemiology

http://www.biology.arizona.edu/immunology/tutorials/aids/treatment.html

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