Было проведено длительное лечение,

Было проведено длительное лечение, а так же диагностика заболевания. И уже к концу 1991 года в результате данных мероприятий болезнь была побеждена. Число заболевших было равно нулю.

Результаты (английский) 1:

A long-term treatment, and diagnosis of the disease. And by the end of 1991, as a result of these activities, the disease had been conquered. The number of cases was zero.

Результаты (английский) 2:

Prolonged treatment was carried out, as well as disease diagnostics. And by the end of 1991 as a result of these activities, the disease has been defeated. The number of cases was zero.

Результаты (английский) 3:

It was followed by a long-term treatment, as well as disease diagnosis. And by the end of 1991, as a result of these activities disease has been defeated. The number of cases was equal to zero.