Fever persists for many despite negative dengue and chikungunya tests, but IEDCR says there is no evidence of a new virus

Many people in the country are going to doctors with fever, headache, body aches and weakness. But tests for dengue or chikungunya are coming back negative, and even after multiple tests the specific cause of some patients' fever remains unknown.

This has raised the question of whether a new virus is spreading. However, the Institute of Epidemiology, Disease Control and Research (IEDCR) says no evidence of infection by any new virus has been found in recent times.

Professor Dr Ahmed Nawsher Alam, chief scientific officer of the IEDCR's virology department, told BBC Bangla that infections from several known diseases, including dengue and measles, are currently being seen. Influenza and other respiratory viruses may also be circulating.

In his view, even if dengue or chikungunya tests are negative, another virus may still be present. Influenza, respiratory syncytial virus (RSV) and adenovirus infections also cause fever and other symptoms.

However, he said it is not possible to test every patient's sample, so the specific virus often cannot be identified.

Professor Dr Nelson Tapas Mondal of the medicine department at Enam Medical College and Hospital told BBC Bangla that patients with various types of viral fever have been seen over the past few months, but it cannot be confirmed in every case which virus is responsible.

He said many patients have dengue-like symptoms without dengue being detected in tests, and some are taking comparatively longer to recover. More testing is needed to be sure whether a new virus is responsible, but not all patients can afford those tests and facilities to detect every virus are not available everywhere.

Former Bangladesh Medical University medicine professor Dr A B M Abdullah said that before thinking of a new virus as the cause of fever, the possibility of known diseases should be considered. Influenza, typhoid and pneumonia, among other causes, can also produce fever.

He said the symptoms of dengue, chikungunya, influenza and Covid-19 overlap, so a disease cannot be diagnosed from symptoms alone.

Doctors say that when fever occurs, it is important to seek medical advice keeping dengue in mind. A negative dengue test does not by itself settle that the patient does not have dengue; the reliability of the result depends on what type of test is done and how many days after the fever began it is performed.

Dr A B M Abdullah said severe abdominal pain, repeated vomiting, bleeding, unusual restlessness or lethargy can be danger signs of dengue. Complications can appear even after the fever subsides, so a falling fever should not be taken to mean a full recovery.

Doctors advise adequate rest and fluids for fever patients. Professor Nelson Tapas Mondal said paracetamol may be used as needed to reduce fever and body aches, but no other painkiller should be taken without a doctor's advice.