KABUL, Afghanistan -- U.N. and Afghan health officials flew by helicopter to northeastern Afghanistan, where the United Nations said Sunday that whooping cough was threatening the lives of 40,000 children.

In November, at least 61 children died from the disease in the northeastern district of Khwahan in Badakhshan province, where antibiotics have since been provided to 2,000 children and mothers, the U.N. said.

The latest reports now indicate that whooping cough has affected Darwaz district, north of Khwahan, said David Singh, a spokesman for the U.N. mission in Afghanistan.

An emergency team of health officials from the United Nations and the Afghan Ministry of Health flew Thursday by helicopter to Darwaz and will rush extra supplies of vaccines and vaccination equipment to the affected area in the next few days, Singh said.

Emergency teams also will travel to the remote region from neighboring Tajikistan, which is supporting the effort, the World Health Organization said in a statement.

Whooping cough is a highly contagious disease that can cause weeks of severe coughing, but patients can be treated with antibiotics.

"In populations which are not vaccinated, especially those with underlying malnutrition and other infections, a whooping cough outbreak can lead to a high mortality among infants and young children," the WHO statement said.

It said a two-week regimen of a drug called erythromycin protects non-immunized individuals from the disease.

An emergency mobile clinic had treated 151 patients in Khwahan by Sunday, the WHO statement said.