August Issue 2014

It sounds like something out of a sci-fi horror film — a parasite that feeds on the human brain, with a merciless fatality rate over 95 per cent, and only three known survivors worldwide. The water parasite, known as Naegleria fowleri, has claimed six lives in less than two months this year, four in 2013 and 10 in 2012. But the actual figures in Pakistan could be much higher, given the several cases that go unreported.

What makes this ‘brain-eating’ amoeba such a stealthy killer isn’t just the exceedingly quick progression of the resultant symptoms, but the fact that they are difficult to recognise to begin with, being unusually similar to those of meningitis, or even the common cold. Patients with Primary Amebic Meningoencephalitis (PAM) start out with a fever, nausea and headache, developing the more serious symptoms of seizures and coma only later. Diagnosis is therefore almost always incorrect, fatally delaying treatment. “Patients usually come in after two to three days, by which time the symptoms are so advanced that there’s little we can do,” says Dr Afia Zafar, a consultant microbiologist at the Aga Khan University (AKU). But even if patients were diagnosed earlier, the absence of a cure for the infection means this might not be too helpful. Dr Syed Faisal Mahmood, assistant professor of adult infectious diseases at AKU, reiterates, “It’s difficult to say whether early therapy would help because there is no established cure for PAM, although a drug called Miltefosine has recently shown some promise.”

Among the parasite’s victims in Pakistan, a pattern has been noted since 2012: They all hail from Karachi (except 28-year-old Shakeel Ahmed, who was from Hyderabad), they’re all male (except for the nine-month-old infant from Gulshan-e-Iqbal) and none of them has a history of swimming. Internationally, most cases of PAM contract the infection after swimming in a freshwater lake or pond that contains the parasite in its active form, in water that is roughly between 30 and 46 degrees Celsius. In Pakistan, however, the casualties do not have this history, suggesting that they contracted the infection after inhaling tap water, which, unlike freshwater, is supposed to be thoroughly chlorinated. While drinking the contaminated water is harmless, taking it up the nose allows the parasite to travel up to the brain.

Azam Khan, the deputy chief engineer (electrical and mechanical) at Karachi’s Water and Sewerage Board (KWSB), which is responsible for pumping water to the entire city, except for the Defence Housing Authority, finds this pattern curious. “Let’s accept for an instant that these deaths were due to Naegleria in tap water. Then why hasn’t a single woman died, even though they comprise roughly 50 per cent of the city’s population? Do none of them pray and do wuzu using tap water? Why is this parasite only killing young males?” he questions. According to studies conducted by the AKU’s Naveed Ahmed Khan, chair department of biological and biomedical sciences, young men are more likely to perform ablution — including pushing water up the nose — more vigorously than women, and more likely to do so at mosques, where the purity of water is suspect, giving them greater exposure to the parasite.

Azam Khan insists that chlorination is only a secondary solution, and that keeping a clean water tank is more important in preventing pathogens from flourishing. “The low concentration of chlorine in the water is not the reason for these deaths. The real issue is stagnant water, which allows Naegleria to flourish. Cleaning the tank solves 80 per cent of the problem, while water chlorination, only 20 per cent,” he says. He is right, of course. Keeping a clean tank is important, but it’s not the most practical solution. “How can you ask 20 million people to clean and chlorinate their water tanks? Clean water is the KWSB’s responsibility,” says Dr Khan.

Despite his misgivings, Azam Khan mentions the sodium hypochlorite cylinders (contaning chlorine in a liquid form) recently set up at 10 different points in the city, where chlorine concentrations were found to be low; 0.1 and 0.25 parts per million (ppm) as opposed to the 0.5-1 ppm level that should be maintained. This appears to be a straightforward solution, however, considering that the parasite has been taking lives in Karachi since at least 2008, the authorities have decided to avail of it rather late. Part of the Karachi Metropolitan Corporation (KMC)’s health team, Irfan Khan is the focal person on Naegleria fowleri, and he says water purification was never an issue. “Back in 1998/1999, we used powdered chlorine and it was potent enough to disinfect the volume of water we were distributing. But since then, Karachi’s population has increased immensely.” More than doubling in the last 15 years, such a large population demands more water. More water means a greater concentration of chlorine is required, but using a greater concentration of chlorine at the chlorination plant is not an option: “We treat water with a 2 ppm concentration at the plant. Increasing this would mean that the water supplied to those living nearest to the plant will have very high concentrations of chlorine, which is harmful,” says Azam Khan. Furthermore, now that settlements have expanded in all directions and the water travels a greater distance, more chlorine dissipates in transit.

An increasing population is exacerbating the crisis in more ways than one. Azam Khan says that “people who live near the KWSB’s main water lines have punctured it in several places. They collect water from here and then sell it, and these holes mean that a lot of chlorine leaks out.” Karachi’s water shortage also encourages many people to dig underground reservoirs in their homes, where they store water delivered in tankers — the source of which is often a mystery. “The water accumulates here for days, and this is a problem,” says Irfan Khan.

Using chlorine to disinfect water is not the most sustainable solution, in any case. As a highly unstable compound, chlorine evaporates quickly. This means that the further water travels from the pumping station, the lower the concentration of chlorine — and the more contaminated the water — will be. “No matter what form of chlorine you add to the water, gas or liquid, it will simply evaporate. It’s a very reactive molecule, so it’s not going to last too long. A few hours maybe, but chlorine is not a long-term solution,” says Dr Khan. Filtration is, by far, the more practical and cost-efficient method for Karachi, he believes.

Treating water at home is always an option, and simply adding 125 ml of domestically available chlorine to every 1,000 gallons of water should do the job, according to Dr Zafar. Even though Dr Mahmood says, “It’s tricky, because you don’t know how much chlorine there is in the water to begin with and how much more you need to add. Too much chlorine makes the water unusable (causing asthma and skin rashes to some).”

But, the public remains apathetic. “People say there’s nothing wrong with our water, that it doesn’t need to be tested,” says Azam Khan, sharing the conversations he has had with residents during his water-testing rounds. “We are all so conscious about the clothes we wear; whether they match and if they meet the latest fashion criteria, but we never think twice about the water we use,” says Irfan Khan. Moreover, the infection’s seasonal nature — “It’s just for a few weeks, when the temperature rises and the water becomes hot,” Dr Zafar explains — and the fact that it’s not contagious, means self-help strategies don’t look too promising. The least the public can do is to employ preventative measures like using a nose plug when going swimming and using only boiled (which also kills the parasite) or bottled water for nasal irrigation during wuzu, and otherwise.

While the few people who know about the parasite might be apathetic, many others are completely ignorant about it. Compared to official awareness efforts for dengue and malaria, which are also summer diseases, those for Naegleria fowleri are almost non-existent. In fact, if more people are finding out about the parasite in Pakistan, it’s simply because more people are dying. Six deaths later, the KMC is only talking about initiating public awareness campaigns: “In August, we’re going to start handing out posters and conducting awareness sessions in schools, as they are closed for the summer holidays right now,” says Dr Salma Kausar, the KMC’s senior medical and health director.

The deaths reported mainly in Karachi, however, may also reflect a reporting bias. Many others could be dying from PAM in interior Sindh and the Punjab, where young boys play in open canals to escape the blistering summer heat — only, these deaths are not being reported. “We are not looking for Naegleria in other places. The man who died in Park Lane Hospital was from Hyderabad, which means that there is a need to check for the parasite in other cities too. If there are more cases in Karachi, I would say it just means that the doctors here have managed to pick up on it,” says Dr Zafar.

Naegleria fowleri is just one of at least two other ‘brain-eating’ parasites that have been found in Karachi’s water supply, Dr Khan reveals. And without an effective decontamination process, a serious health crisis looms on the horizon.

This article was originally published in Newsline’s August 2014 issue.