adminCatherine Murombedzi H I V Column
MEASURING new HIV infections is not only important to evaluate impact, it is also critical in knowing your epidemic.
Sub-Saharan Africa has a generalised epidemic. People ask what the difference between HIV prevalence and incidence?
When we say the prevalence rate in Zimbabwe has gone down and currently stands at 14,8 percent (WHO 2013) from a high of 25 percent in 2000 what does this entail?
Prevalence is the proportion of people living with HIV at a given time, within a given population. There are several approaches used to estimate HIV prevalence, including probability-based surveys, collection of sentinel surveillance date on people being treated at public health centres.
These can be pregnant women visiting ante-natal clinic, people counselled and tested. There can be special surveys on high risk key populations because the rates differ from the general populace.
What is incidence? Incidence measures on-going transmission (i.e. recent infections). This does not measure the total proportion of the people living with HIV at a given time. Incidence is the rate at which new HIV infections occur in a population (the number of new HIV cases divided by the number of HIV negative individuals at risk over a given time, e.g. one year. (WHO 2015, Consolidated Strategic Information Guidelines for HIV).
So one would ask why prevalence rate has gone down. Could it be mortality rate is high in the population living with HIV? Is it the new lease of life given by anti-retrovirals has meant that people are now living longer?
Incidence provides insight into the current HIV epidemic, intervention targets, prevention programme evaluation, clinical trial design and planning for the future.
Annah Miti, an AVAC fellow pointed out that treatment and success rate were pointers to the lowering of HIV prevalence and incidence.
“Increased treatment and success rate have been effective – so treatment as prevention works. Prevention efforts and behaviour change due to increased awareness play a part,” said Miti.
She said that treatment as prevention had to be scaled up as this was seen that a person with a suppressed viral load had less chances of passing on the HIV virus.
“People with a suppressed viral load have less chances of passing on the HIV virus. Anyway, using protection too is effective and this has seen less people getting infected. Behaviour change will have to be drummed up as this is pivotal in an equation,” said Miti.
She said women should not be left out as this could have a negative impact.
“Everyone has to be captured. Women should not be left out. The gap is there and women have to have controlled
HIV prevention tool since high levels of HIV infections are in women and girls. The daprivine ring has shown partial success.
“In older women chances of infection are reduced by 60 percent. In women aged 21 to 25, it reduced infection rate by 31 percent. For the women under 21, it was not effective and this could be due to lack of adherence in the 18 to 21 age group,” said Miti.
The vaginal ring when inserted lasts a month.
“The ring can be used by discordant couples. This is a plus again for the HIV negative female partner. The study has to go further as ring fencing the virus will be a power tool for women,” said Miti.
A study was conducted on the effectiveness of the vaginal ring in various African countries including Zimbabwe. Malawi, Uganda and South Africa also participated.
Lead researcher, Dr Nyaradzo Mgodi of the University of Zimbabwe, who conducted the research in collaboration with the University of California, San Francisco said that the ring works.
“What we saw, is yes, the ring does work,” said Dr Mgodi.
The survey involved 2 629 women at high risk of contracting HIV virus.
“It is really an exciting time for us women, for us scientists, this ring which is inserted into the vagina, that releases daprivine, does work to prevent HIV,” said Dr Mgodi.
The women were divided into two groups and one was given the daprivine ring and the other a placebo, or a dummy ring which appears real but had no active ingredient or medication.
“If one was at risk, if you use the daprivine ring, your risk is reduced by 27 percent. That was seen across all the 15 sites in Zimbabwe, Malawi, South Africa and Uganda,” said Dr Mgodi.
If we can ring fence the virus and safeguard our women then we should scale it up.
Bringing the idea home to those who grew up in the rural areas, fields that had five strand barbed wires around them kept cattle, goats and donkeys away. It was the stubborn kid goat that penetrated the bottom strand and had a field day in the green.
Feedback: [email protected]
Online Reporter