CALCUTTA. The cholera epidemic came to eastern India with a column of 100,000 refugees who had trekked 60 grueling miles westward from East Pakistan in the third week of May. Exhausted, hungry and without adequate shelter, the refugees there easy prey for the particularly virulent strain of the disease they had brought with them.

By last week, the epidemic had spread all along the border of the Indian state of West Bengal. The Indian Government had an estimated 68,000 cholera cases on it's hands, almost all of them refugees And the cholera scare did in the West what, eight weeks of Indian pleading for help to cope with the refugee flood had failed too do. The Westerns community was shaken out of its lethargy, and relief supplies poured into Calcutta in such amounts that the local aid agencies weren't able to handle the volume.

With the aid cargo piling up at Calcutta's international airport and cramming the city's dilapidated warehouses, India has begun to turn back some new offers of help and British experts on the scene are urging efforts to reduce the head of steam created in Britain on the cholera issue.

Paradoxically, the international aid that flowed so generously last week came after the worst of the epidemic may have passed as a result of India's own efforts. By employing locally manufactured vaccine, saline solution and antibiotics and diverting medical personnel from all over India, the local authorities appear to have stemmed the cholera tide. Although perhaps crude by Western standards, these methods have been largely effective. The death rate has fallen from 50 percent to 10 percent of those infected, and the rate of spread seems stabilized.

What the Indians fear now is that the world community could quickly revert to its previous indifference, satisfied that in the drama of the moment it stepped in and did the job. Yet two or three months hence India will still be facing a herculean task caring for the refugees. Pneumonia, dysentery and malnutrition will remain in the refugee camps even if the cholera threat is brought under control. The financial burden will still be far beyond India's capacity.

There are now 5 million refugees from East Pakistan in India. Half of them at most enjoy the relative shelter and security of the 500 or so temporary camps. Some of the others have found accommodation with Bengali relations and friends along the frontier, but this has placed an intolerable strain on family budgets. The rest are left to wander the flat lowlands of West Bengal with hardly a trace of food or shelter.

And still the refugees flow across the border-at a rate of 100,000 a day, according to a report to Parliament last week by the Deputy Minister for Rehabilitation, Balgovind Verma. The Minister predicted that the number of refugees would grow to 7 to 8 million before the flood was spent.

Last week, the monsoon rains began sweeping in from the Bay of Bengal, and within minutes of the first lashing onslaughts the camps were reduced to mud-choked wilderness. Pathetic rush matting under which families huddled from the deluge disintegrated in the wind.

Bedraggled refugees are drifting toward the streets of Calcutta, where upward of 30,000 homeless peasants nightly jostle with cattle, dogs, cats and goats for the choicest sleeping positions on the pavements.

The initial refugee influx was a mixed bunch of Moslems and Hindus fleeing the Pakistani Army crackdown against the autonomy movement of East Pakistan. The overwhelming majority since then have been Hindus. Whether or not it reflects the policies of Pakistani President Yahya Khan, the signs are that the army is moving against minority groups-Hindus, Christians and Buddhists-with the intention of driving these problems next door.

President Yahya has broadcast appeals for the refugees to return to their homeland. He has promised amnesty for political leaders and security for their followers. But none of his promises has prompted the slightest movement back across the frontier.