Kerala is currently facing concerns over two very different infectious diseases: West Nile virus and Shigella infection. While both illnesses can cause fever and serious health complications, they differ significantly in how they spread, who is most vulnerable, and the symptoms they cause. West Nile virus is spread primarily through the bite of infected mosquitoes. Although West Nile fever is less familiar to the public than dengue or chikungunya, health experts caution that it can sometimes result in severe neurological complications. Recognising the symptoms, understanding the risks, and adopting preventive measures are crucial as Kerala faces multiple infectious disease threats during the monsoon season. Health experts say understanding these differences is crucial for early diagnosis and prevention.

West Nile Virus: A Mosquito-Borne Threat

The World Health Organisation, estimates that nearly 80% of infected individuals remain asymptomatic, meaning they may not even know they have been infected. About 20% develop West Nile fever, a flu-like illness that can cause:

  • High fever
  • Severe headache
  • Body aches
  • Joint pain
  • Vomiting
  • Diarrhoea
  • Skin rash

Although most patients recover within days or weeks, fatigue and weakness may persist for months in some cases. In rare instances, particularly among older adults and people with weakened immune systems, the virus can affect the brain and nervous system, leading to potentially life-threatening conditions such as encephalitis (brain inflammation) or meningitis.

Also read: West Nile Fever Detected In Kerala Amid Shigella Alert: Symptoms, Prevention Tips

Shigella Infection: A Highly Contagious Bacterial Disease

Unlike West Nile virus, Shigella is a bacterial infection that spreads through contaminated food, water, poor sanitation, or direct contact with infected individuals. The infection primarily affects the intestines and is known for causing severe gastrointestinal symptoms.

According to Dr. Neha Rastogi, Senior Consultant, Infectious Diseases, Fortis Memorial Research Institute, young children and older adults are among the most vulnerable groups. "Young children under five years of age are particularly susceptible because their immune systems are still developing. Elderly individuals are also at higher risk as age-related health conditions can weaken the body's ability to fight infections," she explains.

Symptoms: How They Differ

While both illnesses can cause fever, the symptoms are otherwise quite different. West Nile fever usually presents with:

  • Fever
  • Headache
  • Muscle and joint pain
  • Rash
  • Fatigue
  • Vomiting or diarrhoea

Shigella Symptoms

Shigella infection commonly causes:

  • Frequent diarrhoea
  • Bloody stools
  • Abdominal cramps
  • Fever
  • Nausea and vomiting
  • Severe dehydration

Doctors warn that dehydration can become dangerous, especially in young children. Dr. Rastogi advises parents and caregivers to watch for warning signs such as frequent diarrhoea, blood in stools, vomiting, dry mouth, and reduced urination. "Anyone experiencing these symptoms should seek medical attention promptly, as early diagnosis and treatment can help prevent serious complications," she says.

Also read: Shigella Infection Alert In Kerala: Doctors Explain Who Is Most At Risk

Who Is Most At Risk?

West Nile Virus

Those at greatest risk of severe illness include:

  • Adults over 60 years
  • Cancer patients
  • Organ transplant recipients
  • People with weakened immune systems
  • Individuals with chronic health conditions

Shigella Infection

According to Dr. Rastogi, the most vulnerable groups include:

  • Children under five years
  • Elderly individuals
  • People undergoing cancer treatment
  • Individuals living with HIV
  • Those taking immunosuppressive medications
  • Communities with poor sanitation and limited access to clean drinking water

Prevention Strategies

Since the diseases spread differently, prevention measures also differ.

  • Preventing West Nile Virus
  • Use mosquito repellents
  • Wear full-sleeved clothing
  • Eliminate stagnant water around homes
  • Use mosquito nets and screens

Preventing Shigella Infection

  • Wash hands thoroughly with soap and water
  • Drink safe, clean water
  • Properly cook food
  • Wash fruits and vegetables before consumption
  • Maintain good sanitation practices

"Good hygiene remains one of the most effective ways to prevent Shigella infections," says Dr. Rastogi. Although both West Nile virus and Shigella infection are causing concern in Kerala, they are fundamentally different diseases. West Nile virus is a mosquito-borne viral illness that is often symptom-free but can occasionally cause serious neurological complications. Shigella, on the other hand, is a highly contagious bacterial infection that primarily affects the digestive system and can lead to severe dehydration. Health experts stress that awareness, hygiene, mosquito control measures, and early medical attention remain the best tools for preventing complications and protecting vulnerable populations.



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