to me. Trophozoites, schizonts, gametocytes, to him. He was talking fast. Yes, easy to mistake P. knowlesi for P. malariae if that’s what you’re looking at, I agreed. No wonder the methods of molecular genetics have opened new vistas of discrimination. No wonder this zoonotic malaria was misdiagnosed for so long. Then we went downstairs to visit his wife in the lab.
Janet Cox-Singh is a small woman with short auburn-black hair and fine features, her speech reflecting almost no trace of her Belfast origins. She sat at a lab bench, not far from the PCR machine, before her own large computer monitor, and beneath shelves on which rested boxes filled with filter-paper samples of blood, dried and packed away, a precious archive of raw material from which she and her husband had extracted much of their data. Think of it as DNA jerky. “We developed this PCR method so we could take blood spots on filter paper and do very nice malaria epidemiology from very remote places,” Cox-Singh told me. Kapit Division, Sarawak, is indeed a remote place if anywhere is.
Nearby on the floor rested several large liquid-nitrogen storage tanks for transport of frozen specimens, a more cumbersome method of bringing blood to the laboratory, not quite obsolete but now circumvented, for their purposes, by the filter-paper technique. After the first trip upriver, during which Singh had pricked eight fingers and blotted up eight samples, yielding the first signal of P. knowlesi, he and Cox-Singh continued their data gathering with visits to the Kapit hospital and nearby longhouses. They also expanded their reach by delegating the filter-paper technique. They sent kits of such papers to other parts of Sarawak, in the hands of trained helpers, and got back blood spots, dried but valuable. Using an old-fashioned paper punch (carefully sterilized to avoid contamination), they punched two small dark dots out of each paper and processed those dots through the PCR machine. Two crusty dots held about twenty microliters of blood, just enough for extracting DNA. Then the DNA had to be selectively amplified so they could work with it. Cox-Singh began describing to me the particular method they used, known as “nested PCR,” diagramming it roughly on the back side of a journal paper as she spoke. Small subunits, fifteen hundred nucleotides, ribosomal RNA. I stared at the squiggles. Once they possessed amplified product, they sent that off to a mainland lab for genetic sequencing. The sequenced results were a longish series of letters, a passage written in genetic code as though to spell a choking expletive (ACCGCAGGAGCGCT . . . !), which could be entered into a vast online database for matching against known referents. That’s how they had identified P. knowlesi in those first samples, she said, and in many more since.
Her husband pulled down a box and opened it. “This is our collection of blood spots,” he said with quiet pride. Borneo is off the beaten path and, I suppose, not many science journalists visit. Inside the box was a neat file of plastic envelopes, each one containing a piece of porous paper no bigger than a business card; on each card was a rusty black spot. Near the center of the dark spot, on the card I inspected closely, was a perfectly round little hole. The punched dot, missing there, had already surrendered its secrets to science. DNA confetti.
During their first two years of work on the Kapit population, using filter-paper dots and PCR, the Singh–Cox-Singh team (like all scientists, they have helpers and colleagues) found 120 cases of P. knowlesi. Under earlier diagnostic assumptions and methods, most or all of those people would have been judged to have P. malariae, the benign form, and therefore received little or no medical care. They would have suffered, or worse. Properly diagnosed, and treated aggressively with drugs such as chloroquine, they had recovered. The paper describing those results appeared in an august British journal, The Lancet, delivering solid proof of what the strange case of BW the Surveyor had suggested: that P. knowlesi malaria is a zoonotic disease.
Expanding their search between 2001 and 2006, the team identified hundreds more cases of P. knowlesi, including 266 from Sarawak, 41 from Sabah (the other Malaysian state on the island of Borneo), and 5 from an area of Peninsular Malaysia just northeast of Kuala Lumpur—not far, probably, from where BW caught his case in 1965. They also found P. knowlesi in most of the long-tailed macaques from which they were able