The Union health ministry on Tuesday released guidelines for treating coronavirus disease patients simultaneously infected with dengue, malaria or other infections, flagging the risk of seasonal epidemics and underscoring the medical challenges of treating double infections.

The health ministry has pointed out that several seasonal epidemic-prone diseases can mimic some symptoms of Covid-19 and diagnostic tests for “co-infections” with dengue, malaria, H1N1 influenza, scrub typhus or bacterial infections must be undertaken whenever suspected.

Bacterial co-infections must be suspected in moderate or severe cases of Covid-19 that do not respond to treatment, the ministry said in the guidelines that also recommend different sets of diagnostic tests for malaria, viral or bacterial infections.

The guidelines recommend the use of the anti-viral oseltamivir under the prescribed dosage for patients co-infected with influenza. In case of an outbreak of seasonal influenza, oseltamivir “blanket therapy” should be considered for all patients with Covid-19, the ministry said.

Infectious disease specialists say the guidelines that emphasise the need for appropriate diagnosis will become increasingly relevant as long-prevalent infections hit patients already infected by Covid-19 with or without symptoms.

“This was bound to happen — we’ve been expecting this. Some patients will test positive for Covid-19 along with other infections,” said Anup Warrier, an infectious disease expert in Kochi who has seen Covid-19 patients with dengue, malaria, and leptospirosis, a bacterial infection.

Leptospirosis is contracted through exposure to infected rodent urine, often during the monsoon or post-monsoon months. Scrub typhyus is also a bacterial infection contracted through the bites of certain mites. Both leptospirosis and scrub typhus are easily treated with antibiotics.

Warrier said co-infections could be particularly challenging because up to 80 per cent of Covid-19 infected persons might have no symptoms. When such patients turn up with a co-infection and high fever, they might be mistakenly classified only as Covid-19 positive patients.

“Our approach to fevers should be just as what it was before Covid-19. We have to look for the patterns of illness and symptoms of other possible infections and rule them out,” Warrier said.

The ministry’s guidelines call on doctors to maintain a high degree of suspicion for infections that are common in their geographical locations. For instance, leptospirosis and dengue outbreaks have in the past occurred in post-monsoon months.

“Sometimes, managing co-infections can be tricky because treatment goals are aimed at opposite directions,” Nitin Gupta, assistant professor of infectious diseases at the Kasturba Medical College, Manipal, told The Telegraph.

Patients with severe Covid-19 are at risk of clotting for which treatment guidelines recommend low-molecular weight heparin (LMHW), a blood thinning medication. However, dengue increases the risk of platelet depletion and bleeding that makes the use of LMWH a challenge.

While symptoms such as fever or headache are shared across these infections, Gupta said, there are, however, signs and symptoms that doctors could use to differentiate between them.

He recalls a patient with fever who also had red eyes and jaundice which are not typical symptoms of Covid-19. The patient was found positive for both Covid-19 and leptospirosis. Another patient with high fever and a low platelet count was found Covid-19 negative but positive for dengue.