Nipah Virus

Nipah Virus (NiV) is an emerging zoonotic virus that poses a serious health risk due to its high mortality rate and ability to spread through both animal-to-human and human-to-human transmission. It is considered a priority disease by the World Health Organization (WHO) due to its potential to cause outbreaks or even pandemics.

Transmission

• Animal-to-Human: The primary natural hosts of the virus are fruit bats of the Pteropodidae family, which can transmit the virus to both wild and domestic animals (such as pigs, dogs, etc.).

  Human-to-Human: Direct human-to-human transmission can also occur through respiratory droplets, especially when an infected individual coughs or sneezes, or through contaminated food (such as fruits eaten by bats).

Symptoms of NiV Infection

NiV infection can range from mild symptoms to severe neurological complications. Here are the common symptoms:

1. Early Symptoms:

   • Fever

   • Headache

   • Muscle pain (myalgia)

   • Nausea and vomiting

   • Sore throat

   • Cough

   • Respiratory discomfort

2. Progression to Severe Symptoms:

   • Acute encephalitis (inflammation of the brain) with symptoms like:

     • Dizziness

     • Drowsiness

     • Altered state of consciousness

   • Severe Encephalitis: In critical cases, it can lead to seizures, coma, and death within 24-48 hours.

   • The case fatality rate ranges between 40–75% (or higher), with the prognosis worsening if encephalitis develops.

Treatment and Prevention

Currently, there are no specific treatments or vaccines for NiV. Management primarily involves supportive care to alleviate symptoms. However, research into vaccines and therapeutic treatments continues, and the virus remains a major focus of global health organizations like WHO.Geographical Distribution of NiV Outbreaks

NiV has mostly been seen in Asia, particularly in countries like Malaysia, Bangladesh, India, the Philippines, and Singapore. The first outbreak occurred in 1998-1999 in Malaysia, where it was linked to pig farming. Since then, the virus has caused sporadic outbreaks in South and Southeast Asia, with notable outbreaks in India and Bangladesh.

• India: Kerala has reported multiple outbreaks, and as of recent reports, 425 individuals have been placed on the contact list in the state, as officials monitor potential cases.

• Bangladesh: Multiple outbreaks have been reported in rural areas, often linked to the consumption of contaminated fruits.

Ebola Virus Disease (EVD)

Ebola Virus Disease (EVD), formerly known as Ebola Hemorrhagic Fever, is a severe and often fatal disease that primarily affects people and nonhuman primates. It is one of the deadliest viral diseases, with occasional outbreaks mostly occurring in sub-Saharan Africa.

History and Discovery

• First Discovered: The Ebola virus was identified in 1976 near the Ebola River in what is now the Democratic Republic of Congo (formerly Zaire).

• Common Hosts: The virus primarily affects humans and nonhuman primates, such as monkeys, gorillas, and chimpanzees.

Species of Ebola Virus

Ebola virus belongs to a group of viruses within the genus Ebolavirus, with several distinct species:

1. Zaire ebolavirus (Ebola virus) – Most deadly and responsible for the majority of outbreaks.

2. Sudan ebolavirus – Second-most common.

3. Taï Forest ebolavirus (formerly Côte d’Ivoire ebolavirus).

4. Bundibugyo ebolavirus – Detected during a 2007 outbreak in Uganda.

5. Reston ebolavirus – Found in monkeys but does not cause disease in humans.

6. Bombali ebolavirus – A newly identified species found in bats.

Transmission

Ebola is primarily transmitted through close contact with infected individuals or animals.

1. Animal-to-Human Transmission

• Primary hosts: Fruit bats of the Pteropodidae family are the natural hosts of the Ebola virus.

• Humans can become infected by coming into contact with blood, secretions, or organs of infected animals like fruit bats, monkeys, gorillas, chimpanzees, and forest antelopes.

• Infected animals found dead or ill in the wild, particularly in forests, pose a significant risk.

2. Human-to-Human Transmission

• Direct Contact: Transmission occurs when a person comes into contact with blood, body fluids, or tissues of someone infected with Ebola, particularly if the person is sick or has died from the disease.

• The virus can spread through broken skin or mucous membranes (like the eyes, nose, or mouth).

• Healthcare workers and family members who care for infected individuals are at higher risk of transmission.

Signs and Symptoms

The incubation period for Ebola is typically 2 to 21 days, with symptoms appearing most commonly between 8 to 10 days after exposure.

Early Symptoms:

• Fever

• Fatigue

• Muscle pain

• Headache

• Sore throat

• Vomiting

• Diarrhea

Severe Symptoms:

• Impaired kidney and liver function.

• In some cases, internal and external bleeding can occur, leading to hemorrhagic manifestations (bleeding from the gums, eyes, and nose).

• Severe symptoms include shock, organ failure, and death if untreated.

Diagnosis

Due to the similar symptoms of Ebola and other infectious diseases (e.g., malaria, typhoid fever, meningitis), confirming an Ebola infection requires laboratory testing. Some diagnostic methods include:

1. ELISA (Enzyme-Linked Immunosorbent Assay) – This test detects antibodies to the virus in the blood.

2. RT-PCR (Reverse Transcription Polymerase Chain Reaction) – Detects Ebola virus RNA in patient samples.

3. Viral Culture – Grows the virus from patient samples, but this method is time-consuming.

4. Immunohistochemistry – Detects viral proteins in tissues.

Vaccines and Treatment

Currently, there is no specific cure for Ebola. Treatment is supportive, focusing on hydration, maintaining blood pressure, oxygenation, and treating any secondary infections. However, experimental treatments are under investigation.

Vaccines:

• The Ervebo (rVSV-ZEBOV) vaccine is highly effective in protecting individuals from the Zaire strain of Ebola virus, which has caused the most significant outbreaks.

• Ervebo was used in the 2014-2016 West African Ebola outbreak and subsequent outbreaks in DR Congo.

• However, it only protects against the Zaire strain and does not offer protection against other species like Sudan or Bundibugyo.

Other Experimental Therapies:

• Treatments like monoclonal antibodies (e.g., ZMapp) and antiviral agents are also being tested, although they are not yet widely available.

Global Impact and Outbreaks

Ebola outbreaks have primarily occurred in sub-Saharan Africa, but the virus has caused global concern due to its high mortality rate and the potential for international spread. Some notable outbreaks include:

• West Africa (2014–2016): The largest Ebola outbreak in history, with over 28,000 cases and more than 11,000 deaths.

• Democratic Republic of Congo: Regular outbreaks, including a significant one in 2018–2020.