Nipah has returned to Kerala exactly a year after the successful containment of an outbreak in Kozhikode, which claimed 21 human lives.

This time it appeared in a Thrissur resident whose exact contact history is not known. Unlike last year, there is only a single case so far and it appears there is no indication of human-to-human transmission. But it reiterates the fact that the virus is circulating in its natural reservoir/source, the Pteropus spp bats (fruit bats/flying foxes), in Kerala. Fruit bats are present across India and the risk of transmission from bat to human exists but chances are rare. However, the chances of human-to-human transmission in hospital settings appears to be very high. While we cannot do anything to eliminate the Nipah virus from its natural source, we can reduce the risk of human-to-human transmission in healthcare facilities.

So, the action plan should be to educate people not to get close to fruit bats or consume bat-eaten fruits, besides strengthening surveillance and infection control practices in hospitals at all levels across India. The impending monsoon increases humidity and may enhance hospital-based human-to-human transmission of Nipah, hence it is important to contain the current outbreak at the earliest. In fact, basic public health protocols in diagnosis, treatment and hygiene can tackle Nipah and other illnesses that the monsoon brings with it.

Controlling influenza

Influenza virus activity is already on a rise and is expected to peak during monsoon. It may account for 20-40 per cent of fever-related hospitalisations. An anti-viral therapy is available but it is most effective when administered early during the illness and will reduce mortality and hospitalisation.

The public health response against Influenza in India is focused only on the recent pandemic strain Influenza A H1N1 pdm09, though other strains of Influenza A H3N2 and Influenza B viruses are equally important. Each time, Influenza A H1N1 pdm09 activity rises, the public health system is caught off guard.

Influenza is transmitted by respiratory droplets and contact. Covering the mouth while coughing and the practice of frequent hand-washing may prevent infection. Vaccines are available against Influenza. However, due to frequent changes in the virus and short-lived immunity, it requires yearly vaccination. In fact, India should consider vaccinating persons with co-morbid conditions, and pregnant women.

Dengue is another disease to be expected in the monsoon and post-monsoon season. While most cases are mild, it can develop into severe Dengue haemorragic fever (DHF), Dengue Shock Syndrome (DSS) and involvement of multiple organs, leading to increased mortality. The intermittent rain and fresh water collection during the monsoon leads to an increase in Aedes aegypti mosquito density. It is an indoor mosquito and bites during the early morning and late evening. Mosquito breeding source reduction and avoidance of mosquito bites are the best strategies for preventing dengue.

Leptospirosis (rat fever) is another monsoon worry. It is caused by a bacteria called Leptospira. A natural source of leptospira are animals such as rats, cattle and dogs.

Exposure to stagnant water containing leptospira leads to infection and it has a high mortality rate. If diagnosed early it can be effectively treated with Penicillin or Doxycycline. Floods increase the risk of leptospirosis. Doxycycline prophylaxis helped Kerala prevent leptospirosis following the great floods in 2018.

The writer is Director, Manipal Institute of Virology, Manipal Academy of Higher Education, which played a key role in detecting and controlling last year’s Nipah outbreak in Kerala