Kerala's monsoon season has once again brought with it heightened concerns over infectious diseases. In recent weeks, the state has reported a surge in Shigella infections, including outbreaks linked to schools in Wayanad, while health authorities continue surveillance for Nipah virus amid new cases in Kozhikode, and West Nile fever cases in Ernakulam, two infections that have caused periodic concern in the state over the past decade. The clustering of these diseases has raised anxiety among families, especially because they spread in different ways and can range from mild illness to severe, life-threatening complications.
While Shigella is a bacterial infection transmitted through contaminated food and water, Nipah is a zoonotic virus that can spread from animals to humans and, in some situations, between people. West Nile fever, meanwhile, is a mosquito-borne viral illness that is often asymptomatic but can occasionally affect the brain and nervous system.
Experts stress that awareness, not panic, is the best response. "Shigella, Nipah and West Nile are infections that have recently caught lots of people's attention. It is normal for people to get worried when they hear about such diseases, especially if they do not know much about them. Understanding these illnesses and knowing when to seek medical help is extremely important," says Dr Aishwarya R, Consultant, Infectious Diseases, Aster Whitefield Hospital, Bengaluru.
Why Monsoon Increases Disease Risk
The monsoon creates ideal conditions for several infectious diseases. Water contamination, flooding, increased humidity, mosquito breeding and disruptions in sanitation systems can all increase the risk of disease transmission. According to the Ministry of Health and Family Welfare and the World Health Organization (WHO), monsoon months are often associated with a rise in waterborne, foodborne and vector-borne illnesses across India.
The current situation in Kerala highlights how multiple disease threats can emerge simultaneously, requiring vigilance from both health authorities and the public.
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Shigella: The Highly Contagious Gut Infection
Among the three diseases, Shigella has been responsible for the largest number of recent reported cases in Kerala. "Shigella is an infection of the intestine caused by bacteria that can be contracted through contaminated food, contaminated water and unclean hands," explains Dr Aishwarya.
According to WHO, Shigella is one of the leading bacterial causes of diarrheal disease worldwide and is particularly dangerous among children. What makes the bacteria especially concerning is its high infectivity. "This bacteria can cause severe disease with an extremely low infectious dose. Even houseflies can deposit the bacteria on food," says Dr Aishwarya.
Common symptoms include:
- Loose stools or diarrhea
- Stomach pain and cramps
- Fever
- Nausea
- Blood in stools
The expert warns against self-medication.
"A common mistake people make is taking anti-motility drugs to stop bowel movements. This can lead to catastrophic outcomes in patients with shigellosis," she says. Any episode of bloody diarrhea should be treated as a medical emergency requiring prompt evaluation and treatment.
Nipah Virus: Rare But Potentially Deadly
Kerala has experienced multiple Nipah outbreaks since 2018, making it one of the few regions in the world with recurring human cases. Currently, a man is in critical condition and 76 others are affected due to the most recent cluster in Kozhikode. The state health authorities are keeping a close watch on any developments around this Nipah cluster.
According to WHO, Nipah virus is carried by fruit bats and can spread to humans through contaminated fruits, infected animals or close contact with infected individuals. "Nipah is a completely different illness and is far more serious. It is triggered by a virus that can jump from animals to humans and, in certain instances, from person to person through close contact," says Dr Aishwarya.
Early symptoms often resemble common viral illnesses and may include:
- Fever
- Headache
- Body aches
- Fatigue
- Weakness
The challenge is that some patients can rapidly deteriorate. "The real concern is that some patients can progress to breathing difficulties or brain-related complications. If someone develops symptoms in an affected area, they should seek medical attention immediately," she adds. WHO estimates that Nipah outbreaks have had case fatality rates ranging from 40% to 75%, making early detection critical.
West Nile Fever: The Mosquito-Borne Threat
West Nile fever has also come under the spotlight after recent alerts in Kerala. Unlike Shigella and Nipah, West Nile virus is transmitted through mosquito bites. "Nearly 70 to 80% of infected individuals may have no symptoms at all," says Dr Aishwarya. Among those who develop symptoms, illness often resembles dengue or other viral fevers.
Symptoms may include:
- Fever
- Headache
- Body aches
- Fatigue
- Skin rash
According to WHO, fewer than one per cent of infected individuals develop severe neurological disease. "Those most at risk are older adults and people with weakened immunity, who may develop complications affecting the brain and nervous system," she explains.
How Families Can Protect Themselves
Despite the diversity of these infections, many preventive measures overlap.
Dr Aishwarya recommends:
- Washing hands thoroughly with soap and water.
- Drinking safe and treated water.
- Consuming freshly prepared food.
- Keeping food covered.
- Preventing mosquito bites using repellents and protective clothing.
- Seeking medical advice promptly when symptoms develop.
"It would be safe to say that fever does not always indicate a seasonal illness and stomach problems do not always come from food eaten outside. At the same time, there is no need to panic. Good hygiene practices, safe food and water habits, mosquito prevention and timely medical consultation can prevent serious complications," she says.
The Season Of Outbreaks Is Coming: What This Means
Kerala's experience reflects a broader challenge facing India. Climate change, urbanisation, population density and changing environmental conditions are increasing the risk of emerging and re-emerging infectious diseases.
For families, recognising warning signs and following preventive measures remains the most effective defence. Public health experts say that community awareness, surveillance and timely medical care are essential to limiting outbreaks and preventing severe outcomes.
The rise in Shigella infections alongside ongoing vigilance for Nipah virus and West Nile fever underscores the complex infectious disease landscape that Kerala faces during the monsoon. While each disease spreads differently and carries distinct risks, experts emphasise that awareness, hygiene, mosquito control and early medical attention can significantly reduce complications.
Rather than panic, doctors urge families to stay informed, monitor symptoms carefully and follow public health guidance to stay safe during the rainy season.
Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.