A journal of the plague weeks

India was devastated last summer by an outbreak of bubonic plague, followed by the even worse pneumonic plague - or was it? New research casts doubt on the diagnoses

MADRAS is a jumbled tropical city with a population of five and a half million, flanked by a magnificent but polluted beach that stretches for 60 unbroken miles along the Bay of Bengal. It was my point of arrival in the Indian subcontinent, and I quickly learnt the first rule for survival in the city. If you glimpse a stretch of open water, hold your breath and head away from it as quickly as possible.

I had arrived in India in early January 1995 to do research for a book on diseases. How, I wondered, have human activities affected our illnesses? India seemed a logical place to find out, for here the effects of human alteration of the environment are at their most extreme. As I travelled around the country during the next few months, I talked to dozens of scientists and bureaucrats about dozens of diseases. Yet everywhere I went, the first topic was inevitably the apparent outbreak of pneumonic plague that had petrified the world in September 1994.

I finished the trip in a state of sceptical confusion. Had the outbreak in question really been plague? If it had not, as many Indian scientists claimed, what had prevented the disease from breaking out when conditions seemed so ideal for it?

Plague is a serious infectious disease caused by the bacterium Yersinia pestis. It mainly affects rodents, but is transmissible to humans by the bites of rodent fleas. A bite from an infected flea leads to bubonic plague, characterised by swollen lymph glands (called "buboes"). Pneumonic plague, which affects the lungs, can occur as a complication of bubonic plague and is spread from person to person by coughing.

The first probable outbreaks of plague in India are recorded in the ancient chronicle of the Bhagvata Purana, dating from as long ago as 1500 BC. In the year AD 1031, a new wave of plague swept in from central Asia with the army of Sultan Mohammed, and in succeeding centuries Tamerlane and other conquerors from the north brought plague along with the other disasters of war. Plague's dreadful toll continued to the present century. Wave after wave of the disease swept over the subcontinent between 1898 and 1918, killing an astonishing total of 12.5 million people - a quarter as many as died in the whole of Europe during the Black Death of 1348.

The last really serious outbreaks before 1994 took place during the massive dislocation of populations triggered by the partition of India and Pakistan in 1948. By the 1970s, with only a few possible but unconfirmed cases being reported, it seemed the disease had effectively disappeared. Then, in August 1994, a local doctor reported the finding of numerous dead rats, known as a "ratfall", and of flea bites affecting villagers in the district around the small town of Beed, some distance inland from Bombay.

Starting on 26 August, villagers began to turn up in the local clinics with high fever. Some had severely swollen lymph nodes in the armpits and groin. On 2 September, KK Datta, the director of the National Institute of Communicable Diseases in Delhi, got a worried phone call from a health officer in the city of Poona, near Beed. Blood sera from the patients were shipped to Delhi, and tested over the next few days for antibodies against the plague bacillus Yersinia pestis. When seven of the 10 samples appeared to be positive, Datta arranged for a team of entomologists and microbiologists to fly to the area.

The number of cases in the villages near Beed continued to increase, eventually totalling 460, but surprisingly there were no deaths. Children continued to play in the streets even though they suffered from severely swollen lymph nodes. If this had really been plague, they would have been delirious and unable to move. Further, there were no instances of the massive lung, brain and gut infections that inevitably begin to appear as a plague outbreak advances.

The focus of attention suddenly shifted to Surat, a grim industrial city on the coast some 250 kilometres north of Bombay and 400 kilometres from Beed. The city had been hit hard by monsoon rains in August, which had left piles of garbage and dead animals everywhere. On 19 September, people began to appear in the city's hospitals with a frightening set of symptoms. They had high fever, were racked with coughs, had great difficulty breathing and they showed blood in their sputum. Could this be plague as well?

Yes, it could. The classical form of bubonic plague can only be spread by fleas, which pick up the infected blood and transfer it to a new victim. But in pneumonic plague, the most infectious state, the bacteria multiply in the lungs and spread through the air to people nearby. When plague reaches the pneumonic stage, it can spread rapidly, particularly when people are crowded together. It appeared that the cases in Surat were pneumonic, unlike those in Beed.

When news of the plague spread through Surat, panic ensued. Over the next three or four days, the city essentially shut down. Bus and train stations were besieged by frantic people trying to leave. Among those who fled, unfortunately, were many of Surat's doctors. At the height of the panic, all but two international airlines stopped flights to India. The Gulf states, among India's most important trading partners, banned imports of Indian foodstuffs. At airports around the world, passengers arriving from India were scrutinised for signs of fever. In Toronto, airport workers donned gloves and masks.

A World Health Organisation team arrived in India in October, but none of its efforts at culturing the bacteria was successful because all the cultures were contaminated - and the Indian government did not allow samples to be taken out of the country for testing by WHO laboratories.

Despite the difficulties and bureaucratic hurdles, the WHO's report concluded that there did appear to have been a plague outbreak, though its true extent was unclear. Yet members of the team were very puzzled by the lack of mortality in the Beed area. Indian scientists were perplexed as well. In November 1994, two letters appeared in The Lancet, one from a group at the All India Institute of Medical Sciences in New Delhi, the other from T Jacob John, head of microbiology at the Christian Medi-cal College in Vellore, southern India. Both questioned whether the outbreaks could have been plague.

Jacob John was the first scientist I talked to about the plague. Vellore, 120 kilometres from Madras, is a cheerful and relatively clean market town. The CMC Hospital, founded on the first day of this century, is its pride and joy. People from all over India come there for treatment. Over lunch in the hospital's spartan cafe-teria, John was definite. There were better explanations than plague for the outbreak of disease, both in Beed and Surat. In Beed, the outbreak might have been tularemia, which can mimic the swollen lymph nodes of plague without its mortality. The outbreak in Surat might have been due to another bacterium altogether, Pseudomonas pseudomallei, which can produce symptoms like those of pneumonic plague, but again without the plague's severity.

Later, while I was giving a talk at the hospital, my wife was startled to see a sweeper casually kill a wild bandicoot rat that had strayed in from some nearby rice field. These rats can play host to an astonishing variety of human diseases, including plague. They are everywhere in southern India, often living in close association with humans. When I mentioned this incident to John, he agreed that conditions in this part of the country were certainly ripe for the plague. There was no obvious reason why it should not have happened in Beed and Surat. But the question was, did it happen?

My next encounter with a piece of the plague puzzle was in Calcutta. The impact of this most poverty-stricken of India's cities can be overwhelming. A visitor flying in at night descends over huge areas on Calcutta's outskirts where the only light is from flickering fires. They mark where hundreds of thousands of refugees from Bangladesh eke out a miserable existence in decades-old camps. On the narrow streets of the city itself, lined with rotting buildings that look like decaying fangs, 70,000 rickshaw pullers ply this most demeaning and killing of trades amid stunning juxtapositions of wealth and poverty. Of course, residents can wander the superb botanical gardens or ride on the new underground system, and the intellectual life of Calcutta is the most exciting in India. But the city's economy is still reeling from the deluge of refugees that descended on it after Partition, and from the collapse of the jute industry.

I was surprised, when I visited Cal-cutta School of Tropical Medicine, to enter through colonnades webbed with immense cracks, precariously supported by wooden scaffolding. The deputy director, AK Hati, awaited me in an office that had been virtually stripped of furnishings. He explained that the newest branch of Calcutta's underground system lay directly below, and because of inadequate shoring of the soft subsoil, the building was collapsing. They were in the process of evacuating the entire school, and as a result science had almost ground to a halt.

Hati told me his school had tested the blood of 100 evacuees arriving in West Bengal from Surat, and none had shown any sign of plague. The disease certainly hadn't reached Calcutta. In spite of its swarming rats, the city has seen no more than a handful of possible plague cases since the 1960s. Dr Hati put Calcutta's obvious misery into perspective. No matter how bad it may seem, he said, there are worse places. He told me a delegation had recently arrived from poverty-stricken north-eastern Brazil to find out how Calcutta had managed to lower its infant mortality rate so dramatically in recent years.

Later, in Delhi, I got a very different story about the plague. Geeta Mehta, head of the Lady Hardinge Department of Microbiology, was as fascinated by this emerging detective story as I was. She drove me to the north of the city to visit the Infectious Disease Hospital. In late September, this small 100-bed hospital had been overwhelmed by more than a thousand patients. Whenever plague had been suspected, sick people were sent there by every other hospital in the area. Its director, Dr RC Panda, a tall and imposing man, told me he had worked frantically for 20 days, and had not gone home for a week during the height of the epidemic.

Sometimes recovery could be astonishingly swift when the anti-biotic tetracycline was given. On 24 September, a patient from Surat who had turned up ill at another Delhi hospital had been hastily transferred to Panda's. He suffered from severe chest pain and could only murmur, "I am sinking." Two hours after the man had been given streptomycin and tetracycline, Panda returned to his bedside to find he had been able to get up and go to the bathroom. When he saw Panda, he greeted him with the joyful cry: "You have saved me!"

Later, I talked with KK Datta, director of the National Institute of Communicable Diseases, at his office in Delhi. Joining us was Dr S Patanayak, who had been in Surat as acting director of regional control of diseases at the time of the oubreak. Both were passionate in their insistence that it had been the plague. Datta bombarded me with rhetorical questions. How could such a severe and swift outbreak be due to Pseudomonas, as Jacob John had suggested? There was no evidence that this disease acted in such a way. And if the disease was viral pneumonia, or caused by a hantavirus, why had so many patients responded so quickly to antibiotics, which kill only bacteria? Datta did admit that more of an attempt should have been made to culture the bacilli, but excused this by pointing out that nobody at the agency had the expertise any more. Dealing with the plague in India had become a lost art.

Travelling through other parts of India, I tried to make sense of this swirl of claims and counterclaims. Several scientists had suggested that the Indian government's insistence that it was plague was a defensive reaction. They were afraid they would lose face with the electorate if they admitted they'd made a mistake and thrown everyone into a needless panic. But was the panic needless? People in Surat were dying of something, and in large numbers, and the preliminary WHO report had indeed supported the government's contention. But the government's refusal to countenance alternative explanations was unnerving.

In Bombay, the situation became more confusing still after another interspecies encounter. It took place outside our excellent hotel. Across the street, late on the night of our arrival, we saw numerous rats swarming insouciantly among the people sleeping there. As I left India, I was still scratching my head over this bewildering set of clues. More pieces of the puzzle may eventually fall into place, though whether this mystery will ever be resolved is moot.

Two commissions have been set up, one by the Indian Academy of Sciences, the other by the government. Both are headed by V Rama-lingaswami, former director-general of the Indian Council of Medical Research. They recently reported that plague bacilli had indeed been cultured from the Surat patients, but only after a lapse of weeks or months. But the evidence is still tenuous; an equally determined effort might easily have succeeded in culturing the bacillus from any random sample of people in India's teeming slums. The plague bacillus continues to play peekaboo with scientists searching for it across India's confusing epidemiological and political landscape.

Had there been plague in India? My guess was that there might have been plague in Surat, but I agreed with Jacob John that the Beed outbreak was probably something else. As I stared out the aircraft window on my homeward journey, at India's shrouded landscape, one thing seemed certain. Twentieth- century science is the only thing preventing an explosion of disease in the overcrowded subcontinent.

Surat and the Beed district were flooded within days by 10 million antibiotic pills, and the Beed area was sprayed with tons of DDT. I knew that, down there beneath the haze, the burgeoning population of India has never been better off or better fed. The widespread starvation of past generations has been replaced by relative abundance. But is this surface prosperity no more than the hectic flush on the cheeks of a moribund patient? How long can these stop-gap measures be continued? Can they buy enough time for education and the empowerment of women to have an effect on India's population explosion and the destruction of its environment? Only time will tell, and there is not much time left.

9 Christopher Wills is a professor of biology at the University of California, San Diego. His latest book, published by HarperCollins, is 'The Runaway Brain'. His new book, 'Plagues', from which this article is adapted, will appear early next year.