Six patients admitted to two hospitals in Nepalgunj, the main town in Banke district, showed symptoms of the disease, media reports in Nepal said Wednesday.
After examining the patients at Nepalgunj Medical College and Kohalpur Teaching Hospital, the doctors there advised them to go to India for medical tests, Kantipur, Nepal's largest daily, reported.
"Three patients were admitted in our hospital and on the basis of clinical examinations, we suspect them to be suffering from dengue," M. Kidwai, director of Nepalgunj Medical College, told the daily.
"However, as we do not have the facilities for conducting the advance test that could confirm the preliminary diagnosis, we have asked them to go to India."
The three patients have been sent to King George Medical College in India's Lucknow city.
One of the three, Kaluram Chaudhuri, is a migrant Nepali worker from Bardiya district in far western Nepal who had returned home from Rajasthan in India about a week ago.
The 25-year-old had come to the hospital for treatment after a bout of fever. Of the three others who went to the Kohalpur Teaching Hospital, 55-year-old Vidya Mahajan, who was suffering from high fever and haemorrhage, has been sent to New Delhi for treatment.
However, the district government health authorities professed ignorance about the suspected dengue patients.
After an outbreak of the disease in several India cities, resulting in the death of at least 51 people, according to unofficial figures four towns across the border in Nepal remain tense.
Besides Nepalgunj, they are Biratnagar, home of Prime Minister Girija Prasad Koirala, Chitwan, a popular tourist destination famed for its one-horned rhino and alligator population, and Birgunj, Nepal's industrial hub.
According to G.D. Thakur, chief of disease control at the Department of Health Services, the ades agepti, the mosquito that carries the virus, can easily come to Nepal via the open 1880-km border and even the daily Indo-Nepal flights.
The lack of diagnostic facilities in rural areas as well as small towns makes Nepal a vulnerable target for dengue. Hospitals on the Indo-Nepal border often prefer to ask patients to go to India for treatment.
Though some of the laboratories in the capital have the capability to conduct tests for dengue, it is often easier for Nepalis living along the border to cross over to Indian cities for treatment than travel all the way to Kathmandu.
After the disease assumed epidemic proportions in India, a private laboratory in the capital, Everest International Clinic, is offering free tests for dengue patients. There was no immediate official reaction to the reports Wednesday.