Malaria vaccine

Several vaccines for malaria have been developed over the past few decades, but none offer complete protection. Now, for the first time, US researchers have developed a vaccine that protects 100% of those given five doses of the vaccine.

New malaria vaccine the first to offer complete protection, The Conversation, 8 August 2013. Also on Ars Technica and The Hindu.

Chest X-rays are not effective at detecting TB infections

Enlarged microscopic image of TB-causing bacteria, Mycobacterium tuberculosis

When I immigrated to the UK as a student, I had to do something that I wasn’t expecting. I had to carry with me a recent chest X-ray. I thought this was completely unnecessary. Why should I be exposed to X-rays for no good reason?

Turned out that there was a reason. It was to stop the spread of tuberculosis (TB) in the UK. Immigrants from sub-Saharan African and the Indian subcontinent are more likely than other immigrants to be infected by TB.  The UK has seen TB cases increase continuously over the past 30 years. Between 1998 and 2009 the numbers rose by 50% to 9040 cases. Most of those affected are foreign-born people. TB infection rates in the UK today are as high as they were in the 1930s, and they are among the highest in any developed country.

The rise in number of cases is despite chest X-ray screening that immigrants have to undergo. That’s because of TB’s quirky ability to show up many years after the TB-causing bacteria infected a person. Researchers find that early detection makes it easier to treat TB, because more severe infections are becoming resistant to current treatments.

With an aim to improve detection rates, Onn Min Kon, a physician at Imperial College London, and colleagues report, in a paper just published in Thorax, that chest X-rays are actually not as effective at detecting TB. Instead, they suggest, the UK government should use an advanced test called interferon-gamma release assays (IGRA).

IGRA works on the principle that when the TB-causing bacteria are exposed to a set of chemicals, which are harmless to humans, it causes them to release a protein called interferon-gamma. If a patient who has been given these chemicals breathes out interferon-gamma, then he is infected by TB (the latent variety or not).

Although a previous consultation with the National Institute for Health and Clinical Excellence had recommended the use of IGRA, it had made that recommendation in combination with chest X-rays. What Dr Kon’s work finds that a more cost-effective, and still efficient, method would be to just use IGRA. It would also spare the patient from being exposed to X-rays!

This research is one among many other papers published in Thorax’s special issue dedicated to TB which coincides with the upcoming World TB day.  

Reference: Pareek, Bond, Shorey, Seneviratne, Guy, White, Lalvani & Min Kon, Community-based evaluation of immigrant tuberculosis screening using interferon γ release assays and tuberculin skin testing: observational study and economic analysis, Thorax 2013

Image from here.

India and endosulfan: A bitter harvest

India’s response to the ill-effects of a toxic pesticide has been slow and inadequate

Endosulfan, a pesticide, has been poisoning villagers in India over the past two decades. Its use has caused physical and mental ailments among thousands of children and adults and deaths of many hundreds. In 2011 India agreed to ban endosulfan, and, more recently, it offered compensation to its victims. But now it is falling short to keep both those promises.

The pesticide, once commonly used, damages the central nervous system and causes hormonal changes in mothers and babies. It leads to many birth defects including cerebral palsy, a condition that causes physical disability. Worse still, it lingers in the environment without degradation, leading to its accumulation in the food chain and causing lasting ill-effects.

Commitment to ban?

In 2011 at the Stockholm Convention 128 countries, including India, added endosulfan to the list of pollutants that they agree to phase out of use. Following India’s commitment at Stockholm and after years of effort by the Democratic Youth Federation of India, a non-governmental organization, in May 2011 the Supreme Court banned the use of endosulfan in the country but allowed its exports to exhaust remaining stocks. At present India has 2000 tonnes of the pesticide and raw materials enough to make a further 4000 tonnes of it. As international demand for the pesticide has plummeted, the government has been forced to dispose this stash.

In July, because the Indian government was not ready to foot a $40 million bill for the disposal of endosulfan’s raw materials, it asked the Supreme Court to lift the ban on making the pesticide. In November the Supreme Court’s expert committee requested giving in to this demand. Citing that the treaty that Indian signed allows it up to six years to phase out endosulfan, so it could allow endosulfan’s manufacture and use without breaking its commitment. This recommendation was made even though the committee accepts that endosulfan is harmful to human health.

Sadly, endosulfan remains popular among farmers too. Manufacturing of the pesticide, if allowed, will be greeted with strong demand. Before the ban, India was the largest producer and consumer of endosulfan. It is cheap, easily available and curtails a variety of pests. For those unaware of its environmental consequences, there is little reason to not use it.

Studies show ill-effects of endosulfan use across the country. Kerala is the worst affected state. A 2012 state report linked the pesticide to 4000 afflicted and 700 deaths, many of whom suffered the fate because of aerial spraying over nearby cashew plantations. In some villages 50% homes have a child or an adult with severe disabilities.

In May the Kerela government, based on the recommendations of the National Human Rights Commission, agreed to pay compensation to the victims of endosulfan in Kerela. The amount varied from Rupees 300,000 ($5,500) to 500,000 ($9,500) depending on the victim’s suffering. But despite protests in September and December, the government has only paid 101 out of the 2453 victim families.

The request to allow manufacturing of endosulfan exposes the government’s inability to dispose the raw materials. If undisposed, the chemicals lie in poorly maintained warehouses. A task force setup to inspect one such warehouse in Periya, Kerala, after locals complained of foul smell, found endosulfan leaking from rusted steel drums. The warehouse also lacked storekeepers, fire safety equipment and first-aid kits, posing a serious threat to nearby villages and water bodies.

Endosulfan rehabilitation project, setup by Kerala last year to help the afflicted, started an operation to deal with such cases. Their first task was to contain the leaking drums. They are now hoping to get help from the government for disposal and detoxification, said Mohammed Asheel, the project officer.

Far too little, far too late

Pratibha Patil, former President of India, promised to double public spending on health care to 2.5% of the GDP by 2017. Among its first steps is a $5 billion free drugs plan, the implementation of which began in October. Surely then the Indian government can, apart from preserving the ban, also afford to stop poisoning its own people for a mere $40 million and also compensate those already poisoned.

Image from here.