Tag Archives: Syphilis

HIV treatment: Antiretroviral therapy increases risk of syphilis

HIV treatment could increase people’s susceptibility to developing another sexually transmitted infection, syphilis. Highly active antiretroviral therapy (HAART) could indeed deregulate the body’s immune response to the bacteria that causes syphilis.

Introducing HAART has been a turning point in the fight against HIV and Aids. The drugs, which are now taken by millions globally, successfully reduce the risk of the virus developing resistance, decrease mortality rates, and improve HIV patients’ quality of life.

Since the turn of the century, it is estimated that the number of new infections fell by 35% and Aids-related death by 28% – alongside prevention, the distribution of antiretroviral therapy was key to this success.

However, the fact that HAART is so effective has led to unexpected problems. Many people have started to believe that transmission is now much less likely and that getting infected with HIV is not a death sentence anymore. As a result sexual risk-taking is believed to be on the rise.

This is particularly the case among men who have sex with men, with many engaging in unprotected sex. This leaves them vulnerable to other sexually transmitted diseases and data shows that there has been a rapidly escalating outbreak of chlamydia, gonorrhoea and infectious syphilis in this group in recent years.

However, among men already infected with HIV, the rate of syphilis infection has grown more rapidly than that of other sexually transmitted infections, leading scientists to investigate whether HIV treatments could increase people’s susceptibility to the disease.

Bacteria Treponema pallidum

The team, led by Dr Michael Rekart from the University of British Columbia, reviewed scientific literature to analyse the impact of HAART on behavioural and immune system changes. The data they collected enabled them to create risk models to assess the likelihood of syphilis infection – in which people taking HAART were predicted to have more sexual partners and to have greater susceptibility to Treponema pallidum, the bacteria responsible for syphilis.

The models suggest that both factors combined – having a greater number of partners and a greater susceptibility to the bacteria – produced a peak in the number of infections that was greater than that associated with either factor alone.

Syphilis Bacterium. Treponema Pallidum Subsp. Pallidum On Cultures Of Cotton Tail Rabbit Epithelium Cells Sf1Ep. Treponema Pallidum Is The Causative Agent Of Syphilis. In The United States Over 35 600 Cases Of Syphilis Were Reported By Health Officials In 1999. (Photo By BSIP/UIG Via Getty Images)

Syphilis Bacterium. Treponema Pallidum Subsp. Pallidum On Cultures Of Cotton Tail Rabbit Epithelium Cells Sf1Ep. Treponema Pallidum Is The Causative Agent Of Syphilis. In The United States Over 35 600 Cases Of Syphilis Were Reported By Health Officials In 1999. (Photo By BSIP/UIG Via Getty Images)

The scientists also came up with an explanation as to why HAART increases susceptibility to Treponema pallidum. Reviewing biological evidence available in past research, they say that active antiretroviral therapy may alter the innate and acquired immune responses in ways that enhance susceptibility to Treponema pallidum. This heightened susceptibility could be a major factor in the rising incidence of syphilis in HIV-positive men who have sex with men.

The complete findings are now published in the BMJ.

A number of limitations

The study provides new ways to consider the rising number of syphilis infections, but it does not in any way suggest that people should stop taking HAART. Instead, the focus should be on prevention and on explaining that these drugs do not stop other sexually transmitted diseases.

A number of limitations to the study can be highlighted. In an editorial, three scientists have warned that the reason why syphilis cases appear to be more prevalent than other sexually transmitted infections is that gonorrhoea and chlamydia are often asymptomatic, and most cases are often missed because extragenital testing is not performed.

HAART has saved many lives and improved the quality of life of HIV-positive patients (Bruce Forster)

HAART has saved many lives and improved the quality of life of HIV-positive patients (Bruce Forster)

Additionally, the models greatly simplify reality. Taking HAART does not necessarily increase the number of sexual partners and does not look at couples’ dynamics in sufficient details. “They assume that all partnerships have the same level of syphilis risk, whereas the reality may be more complicated… They model increased behavioural risk through increasing number of partnerships, but do not capture other aspects of transmission risk, such as decreased use of condoms within partnerships”, the scientists note.

Likewise, they do not include in the models how being at a different stages of an HIV infection influences the risk of getting syphilis.

However, the findings are interesting because they remind health professionals that effectively treating and preventing HIV should not limit their efforts to control other sexually transmitted infections.

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Sexual Health Experts Warn Of New Syphilis Threat

Sexual health experts say they are deeply concerned about several outbreaks of syphilis among heterosexual teenagers.

In recent years the infection has been largely confined to older adults, particularly homosexual men.

But clusters of the disease are being seen in Teesside, Hampshire, Rochdale and central Scotland among teenagers.

The British Association for Sexual Health and HIV says there are likely to be other cases going unreported too.

Since the late 1990s there has been a sharp rise in cases of syphilis. Most of these have been in homosexual men, often in their 20s or 30s.

But recently there have been several small outbreaks across Britain of syphilis in heterosexual teenagers – described in detail in the International Journal of STD and Aids.

Any outbreak of syphilis among young people, among teenagers is unexpected. Syphilis shouldn’t be happening in those groups and we really don’t know why it’s there” -Peter Greenhouse Sexual health consultant

It should be stressed that the number of cases described is small – the largest outbreak has been just over 30 in a year – but the reports highlight problems in tracing sexual contacts, raising fears of further undiagnosed cases, and the spread of disease within the wider sexually active population.

Peter Greenhouse, a sexual health consultant based in Bristol who speaks for the British Association for Sexual Health and HIV (Bashh), says these cases must be taken seriously.

“Any outbreak of syphilis among young people, among teenagers is unexpected. Syphilis shouldn’t be happening in those groups and we really don’t know why it’s there. So if we can see a small number of outbreaks in a small number of young people it means there must be others going on as well.”

Martin Murchie, president of the Society of Sexual Health Advisers, agrees that the number of cases diagnosed may just be the “tip of the iceberg”.

He says increasing numbers of people, including teenagers, are arranging to have anonymous sex through social networks. He warns that this is making the task of tracing sexual contacts even harder.

“The way that people meet for sex is very different and changing in society. That in itself can be problematic in trying to trace contacts because some people may change their username that they had originally on the social network site, or the health service itself may not be able to access the social networking site.”

Dr Patrick French, a consultant in Genito Urinary Medicine in London, says there is no room for any complacency. He says syphilis is a serious disease that can lead to heart disease, stroke and dementia, and raises the risk of acquiring HIV.

“The worry is that if syphilis gets into the wider sexually active population of young people it could then become a common and endemic infection. Before syphilis became unusual in the UK in the 1980s it was a major cause of ill health and that’s no longer the case. So it’s a very important infection to try and prevent.”

Many experts fear that sexual health services in England may be hampered by the government’s proposals to move them from the NHS to local council control.

Peter Greenhouse, from Bashh, says: “Some of the services may be privatised or cut down in terms of resources, so we may lose some of our health adviser teams.”

But the Department of Health rejected these concerns.

A spokesman said: “Our reforms won’t fragment sexual health services. Under our plans, the responsibility for most sexual health services will go to local councils. This will allow councils to make crucial links between improving sexual health and their other responsibilities.”

Original Article by Adam Brimelow, Health Correspondent at BBC News

The following video from LiveStrong.com contains more information about Syphilis.

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Miniature Lab Can Diagnose HIV & Syphilis In The Field

In a brilliant cross-pollination of engineering, physics and biology, scientists have developed a credit-card sized device that can diagnose HIV and syphilis in the remotest parts of the world in just minutes!

Children in Rwanda

Children at an orphanage near Butanre in Rwanda. Photograph: Andrew Parsons/PA

People who live in the poorest and remotest parts of the developing world often have their lives cut short by disease — preventable or curable disease. The first essential step to fighting these diseases is correctly identifying them. But in the developing world, disease detection is often prohibitively expensive. In a brilliant cross-pollination of engineering, physics and biology, scientists have developed an affordable credit-card sized device that can accurately diagnose HIV and syphilis in just minutes.

This device, known as the microfluidic chip, or mChip, requires just one microlitre of whole blood to detect specific diseases with comparable efficiency to bench-top assays but at a significantly lower cost. Further, mChip detection takes less than 20 minutes, whereas bench-top assays require several hours or more to complete. Developed by an international team of scientists headed by Samuel Sia, associate professor of Biomedical Engineering at Columbia University in New York City, mChip was successfully field tested in the African nation of Rwanda.

“The microfluidic design is very simple”, said Dr Sia. “It’s essentially a .. linear channel that’s been looped around in various ways.”

Figure 1, abc.

DOI: 10.1038/nm.2408 [enbiggen]

Above is a photograph of the mChip (Figure 1a). This credit card-sized cassette is manufactured from plastic and each mChip cassette can test seven samples (one per channel), and requires no moving parts, electricity or external instrumentation. Instead, it has small holes moulded into the plastic so reagent-loaded tubes can be attached. A scanning electron microscope image shows a cross-section of the microchannels that the blood and reagents flow through (made of injection-molded plastic [Scale bar, 500 μm]; Figure 1b) and a light micrograph shows a close-up of the channel meanders, which can be clearly seen with the naked eye (Scale bar, 1 mm; Figure 1c).

Figure 1, de.

DOI: 10.1038/nm.2408 [embiggen]

The principles for how the mChip work are well known, straightforward and, quite frankly, beautiful.

“In different parts of this microfluidic channel, we have different zones where we pattern in a molecule that captures what we want to detect”, Dr Sia said.

The mChip relies on the passive delivery of multiple reagents. These reagents (Figure 1d) are preloaded in the correct sequence in a narrow tube and separated from each other by an air bubble. These reagents pass over a series of four dense meanders, the mChip’s detection zones, before exiting the chip into a disposable syringe. This manually controlled syringe generates the vacuum that pulls the blood and liquid reagents through the mChip’s meanders.

The basic principle of the mChip’s bioassay is based on the well-known and widely-used Enzyme-linked immunosorbent assay, ELISA, which produces a strong easily-detectable signal through enzyme-mediated signal amplification. Each mChip detection zone — meander — is coated with specific “capture proteins” that bind to antibodies against particular disease organisms (Figure 1e). If these antibodies stick, the series of reagents that passes over these antibody-antigen complexes then stick to them thereby amplifying the signal by creating an “immunosandwich” comprised of reduced silver ions stuck to gold nanoparticle-conjugated antibodies.

“At the end, the silver development reagent develops into solid silver if you have the gold nanoparticles captured on the surface”, explained Dr Sia. “The thickness of the silver film that’s formed reflects the amount of analyte that was originally in sample.”

Depending on whether colour develops, the test can be read as either positive or negative with the naked eye, or it can be quantified using a low-cost optical analysis.

Figure 1, f.

DOI: 10.1038/nm.2408 [embiggen]

The above figure shows the absorbance traces of a complete HIV-syphilis duplex test whilst the reagents pass through the detection zones (Figure 1f). In this graphic, the high optical density (OD) peaks indicate when the air bubble spacers pass through the detection zones. The train of preloaded reagents mimics the precise order in which specific reagents are added and removed from traditional ELISA plates. This particular sample was identified as HIV negative and syphilis positive (it was confirmed as correct against a reference standard).

Even though the mChip uses silver and gold, it is still very affordable — essential for wide-spread use in the developing world.

“The material for making the cassette is just pennies in plastic and even the reagents — because we use such low volumes — only cost a few pennies”, remarked Dr Sia. “We think that after packaging it together, it will cost a few dollars.”

When field-tested on hundreds of people’s samples in Rwanda, the mChip simultaneously diagnosed HIV and syphilis from individual one-microlitre samples of unprocessed whole blood with sensitivities and specificities that rival those of more expensive and time-consuming benchtop assays.

Unlike most current rapid tests, the mChip test does not require special training to interpret the signal. Overall, the mChip is a cost-effective and elegant integration of technologies for miniaturizing complex laboratory assays to diagnose and detect infectious diseases in remote settings.

Here’s a video where several of the developers demonstrate and discuss the mChip:

Original Article by at Guardian Science.

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