.png){kind=small}
EL VIRUS DE NIPAH, LA NUEVA
PANDEMIA ?
THE NIPAH VIRUS, THE NEW
PANDEMIC ?
NIPAH VIRUS TRANSMISSION
Previously published here are reviews of the following viruses with
the potential for human mortality,
prior to the
Sars-Cov-2 pandemic:
1.) HANTAVIRUS I, THE ESPECIES AND THE INVASION OF RATS.
2.) HANTAVIRUS II, DISEASES AND VIRUS INVOLVED.
3.) CONGO-CRIMEA HEMORRHAGIC FEVER VIRUS.
4.) THE HEARTLAND VIRUS, ANOTHER TICK TO DIE.
5.) THE POWASSAN VIRUS, REVIEW.
1.) HISTORY:
The NIPAH virus (NiV) was first identified in 1998, during a massive outbreak that occurred between March and May in Malaysia and Singapore. The virus was isolated from samples of pigs and humans in the village of Kampung Sungai Nipah, hence the name.
The Malaysian virologist Kaw Bing Chua (b. 1953), then a doctoral student at the University of Malaya (Kuala Lumpur), played a key role in the discovery of NiV. In January 1999 he observed under the microscope brain tissue from a pig with ENCEPHALITIS from Ipoh (Perak state) and identified a new paramyxovirus, which was later confirmed at the CDC in Atlanta.
At the CDC in Atlanta the French Epidemiologist, Dr. Pierre Rollin and collaborators finished identifying the Nipah Virus (NiV), which had already been discovered by the Malaysian Virologist Kaw Bing Chua, being classified wthin the Family: PARAMYXOVIRIDAE, Genus: HENIPAVIRUS.
It was the first zoonosis by a henipavirus described after the Hendra virus outbreak in Australia in 1994.
2.) START AND EVOLUTION OF THE OUTBREAK:
The 1998‑1999 outbreak began in pig farms in Ipoh, in Perak state, on the west coast of Peninsular Malaysia, where pigs showed intense coughing, tremors and signs of encephalitis.
It is believed that, during the drought associated with El Niño in 1998, fruit bats of the genus Pteropus (Pteropus vampyrus) left the mangroves and fed on fruits in the farms, contaminating pig feeders and drinkers with saliva and urine.
The pigs acted as amplifying hosts, with a high intra-species R0, and the trade of infected animals allowed spread from Perak to the states of Negeri Sembilan and Selangor and, through imported pigs, to Singapore.
"The Factor Ro is the basic reproductive number of a pathogen, which measures its initial transmission capacity in a susceptible population without interventions. It represents the average number of people directly infected by one infected person before they recover or die."
"For the Nipah virus, the R0 is estimated between 0.3 and 1.5-3 in human outbreaks, indicating limited but explosive spread in closed settings like families or hospitals through close contact with body fluids.
Initially the outbreak was mistakenly attributed to Japanese encephalitis, leading to mosquito fumigation campaigns and vaccination, measures ineffective against NiV.
Only after identification of the new henipavirus was the decisive measure taken to cull over one million pigs between March and May 1999, which succeeded in interrupting transmission; the last human death was recorded on May 27, 1999.
In total approximately 265 human cases and about 105 deaths were recorded (40% mortality), and over one million pigs were culled to control the outbreak, correcting the initial interpretation of Japanese encephalitis..
The NIPAH virus (NiV) is a single-stranded RNA virus belonging to the family PARAMYXOVIRIDAE, genus HENIPAVIRUS. Its natural reservoir are FRUGIVOROUS BATS of the genus PTEROPUS, which remain infected asymptomatically and EXCRETE the virus in SALIVA, URINE, FECES and other fluids.
Transmission to humans occurs mainly in a ZOONOTIC way:
- Bat-pig-human.
- Bat-human.
- Bat-date palm sap-fruit-pig or human.
- Under certain circumstances, person-to-person transmission through respiratory secretions.
The main route of transmission was the one described at the beginning, the Bat contaminates with its fluids either saliva, urine or feces, fluids, the fruits of its habitat and the VIRUS passes to the pig or human when eating them.
It is NOT contaminated pork meat as happened with swine fever AH1N1, it is droplets of saliva and fluids from contaminated pigs that pass to humans when handling pigs or contaminated fruits.
HUMAN to HUMAN contamination only occurs in closed spaces from an infected human to a healthy person, such as hospitals or exclusion zones, and is considered 10% of cases.
The vector or reservoir and transmitter bats INVOLVED are:
1.) PTEROPUS VAMPYRUS: (Malaysian fruit bat) which was responsible or the initial outbreak in 1998-1999 in Malaysia, contaminating fruits and water for pigs.2.) PTEROPUS GIGANTEUS: (Indian flying fox): Main contaminating agent of the recurrent outbreaks in Bangladesh and India, through saliva and urine in raw date juice.
3.) PTEROPUS LYLEI: In Thailand and Cambodia
4.) PTEROPUS HYPOMELANUS: In the Philippines and Indonesia.
As an IMPORTANT fact: THERE ARE NO natural populations of PTEROPUS in Europe or the Americas.
5.) SYMPTOMS IN HUMANS:
- The incubation period of the NIPAH VIRUS (NiV) is usually 4‑14 days, although intervals of up to 45 days have been described.
- The initial phase: usually lasts between 1 and 5 days with a range of 3 to 14 days, and is characterized by fever, headache, muscle pains, vomiting, sore throat and, in some cases, dyspnea.
- Evolution: Many patients evolve rapidly, in 24‑48 hours, toward an ACUTE ENCEPHALITIS with confusion, seizures, cerebral edema thrombosis and coma, and even death . In other cases encephalitis presents between 5 and 14 days.
- Respiratory disorders: 30% of cases also present significant respiratory involvement, with cough and pneumonia.
- The basic reproductive number (R0) between humans estimated is low, around 0.3‑0.7, although in closed environments it increases exponentially.
NOTE: Among survivors, 50% of patients present long-term neurological sequelae, including parkinsonian syndromes and myelitis.
In some cases the possibility of latent infections with clinical reactivation months or years after the initial episode has been described.
6.) SYMPTOMS IN CONTAMINATED PIGS:
INCUBATION PERIOD: 2 to 14 days.The main symptoms are respiratory and neurological:
- Respiratory Symptoms: Acute fever, intense characteristic cough described as "barking" or "sneezing", nasal discharge, difficulty breathing, open mouth, in severe cases hemoptysis (blood in sputum).
- Neurological Symptoms:
Tremors, nystagmus, muscle contractions, spasms, seizures, teeth grinding and sudden death, abortion.
There may be asymptomatic infections with low mortality (1-5%), in some cases up to 20%.
7.) LETHALITY AND STATISTICS:
A.) LETHALITY OF THE VIRUS:
The lethality rate of the NIPAH VIRUS (NiV) varies between outbreaks, but is approximately between 40% and 75%, of cases with an average close to 68%, but in some cases outbreaks have caused 80% or more deaths, in some small outbreaks 100%.
B.) STATISTICS:
- Initial Outbreak 1998-1999: Malaysia/Singapore: 265 cases, 105 deaths, mortality: 40%
- Bangladesh: 2001: 9 cases, 8 deaths, mortality: 89%.
- Bangladesh: 2004-2005: 12 cases, 11 deaths, mortality: 92%.
- Bangladesh: 2009: 9 cases, 2 deaths, mortality: 25%.
- Kerala/India: 19 cases, 17 deaths, mortality: 89%.
- Bangladesh: 2024: 2 cases, 2 deaths, mortality: 100%.
- Bangladesh: 2025: 4-5 cases, 4-5 deaths: Mortality: 100%.
- Kerala/India: 2025: 2 cases, 2 deaths. Mortality: 100%.
- West Bengal/India: 2026: 2 cases, 1 death; Mortality: 50%.
NOTE: Between 2001 and 2025, Bangladesh reported 347 cases and 249 deaths: mortality: 71.7%.
In India, approximately 100 cases have been reported with a mortality rate ranging from 65-90%.
In other countries such as Indonesia and the Philippines, fewer than 20 cases have been reported with an overall case fatality rate exceeding 50%.
8.) DIAGNOSIS:
The diagnosis of Nipah virus (NiV) infection in humans is made through:
A. Clinical suspicion: Onset of fever, respiratory symptoms, general malaise, acute encephalitis, and a history of contact with pigs or ingestion of contaminated fruit, or residence in the region of potentially infected humans.
B. RT-PCR test: This is a molecular test (Reverse Transcriptase Polymerase Chain Reaction), which, when investigating Nipah virus (NiV), is originally only performed in BSL-4 laboratories (maximum biosafety level, CDC, Pasteur).
Subsequently, a kit (TRUENAT), developed by the Molbio Diagnostics laboratory in India, was invented for rapid field diagnosis of the Nipah virus. It was validated by the ICMR-NIV (National Institute of Virology of the Indian Council of Medical Research) during outbreaks in Kerala.
With this method, the sample taken—oropharyngeal swab, urine, or blood—is processed in the field, and the result is available in less than one hour.
C.) ELISA Serology: This is used to determine antibodies in convalescent states, with results in 4–48 hours.
In the case of the Nipah virus (NiV), it is not necessary to wait "days" for a positive result. With the RT-PCR test, the sensitivity behaves as follows:
- Onset of symptoms (days 0–3): Positive in approximately 50–70% of cases.
- Days 4–7: Peak viral load: over 95% positivity.
- Days 8-14: Declines rapidly: negative in approximately 50% of cases, especially after day 10.
- Post-convalescence: Negative: IgM/IgG serology (ELISA) is used to determine if infection occurred.
9.) TREATMENTS:
There is currently no specific antiviral treatment approved for NIPAH virus (NiV) in humans; experimental treatments have been used.
Management is primarily aimed at improving survival through intensive care, which is effective in 60-80% of cases, especially in early stages.
- INTENSIVE CARE:
- Intravenous hydration and nutrition to prevent shock.
- Mechanical ventilation in the ICU for severe encephalitis/pneumonia.
- Control of seizures (diazepam, phenytoin) and cerebral edema (mannitol).
10.) EXPERIMENTAL TREATMENTS:
1.) RIBAVIRIN: Used in Malaysia in 1998-99, reducing mortality from 71% to 40%.
2.) mAb m102.4: A human monoclonal antibody that neutralizes the HENIPA VIRUSES NIPAH and HENDRA by blocking glycoprotein G (cell receptor binding).
It was used successfully in Australia between 2010 and 2020 in 18 human cases with high exposure to the HENDRA virus, and 100% survived. Only one infected human from that cohort survived with this monoclonal antibody.
Regarding Nipah virus (NiV), it has been used in animals (infected ferrets) 10 hours post-infection with 100% survival.
3.) REMDESIVIR: Has proven effective in animals (primates).
NOTE: There are no documented public human cases of NIPAH VIRUS (NiV) successfully treated with m102.4, but its efficacy against HENDRA virus validates its potential against Nipah virus in emergencies.
11.) WHY THERE IS NO NIPAH VIRUS IN EUROPE AND THE AMERICAS:
No autochthonous outbreaks of NIPAH VIRUS (NiV) have been documented in Europe or the Americas, and the risk is considered very low.
The main reason is the ABSENCE of bats of the genus Pteropus (which is the reservoir and transmitter) on these continents.
This is explained by the fact that their NATURAL DISTRIBUTION is limited to tropical and subtropical regions of ASIA, OCEANIA, and parts of AFRICA.
The temperate climate of many European and American areas is also not optimal for the classic habitats of PTEROPUS.
In EUROPE, insectivorous bats from other groups predominate, while in AMERICA, frugivorous bats belong to different families.
12.) WHY A NIPAH VIRUS PANDEMIC IS UNLIKELY:
The NIPAH VIRUS does not behave like a pandemic pathogen compared to the SARS-CoV-2 virus.
Its potential for transmission Human-to-human transmission is relatively inefficient, with an R0 of 0.2-0.7, requiring close and prolonged contact with the respiratory secretions or fluids of an infected human for transmission to occur.
Its natural reservoir, the PTEROPUS bat, is restricted to Southeast Asia and parts of the Old World.
Furthermore, the NIPAH VIRUS has not demonstrated sustained long-range aerosol transmission, as occurred with the COVID-19 virus.
However, in light of the two cases that appeared in January 2026, the WHO issued a global alert, as it did in 2023 with the MARGBURG, and nothing came of it.
Undoubtedly, we must remain vigilant because these viruses can mutate and change their behavior patterns.
Best regards to all.
Dr. José Lapenta
Dr. José M. Lapenta
==============================================================
3.-Molecular Pathogenesis of Nipah Virus (2025).
4.) Nipah virus: epidemiology, pathogenesis, treatment, and prevention (2024).
5.) Nipah virus outbreak in Malaysia (2003).
6.) Nipah virus infection of pigs in peninsular Malaysia (2000).
7.) Nipah virus encephalitis (2008).
8.) Transmission of henipaviruses (2018).
10.) The pathogenesis of Nipah virus: A review (2022).
11.) La OMS considera “bajo” el riesgo de expansión del brote de virus Nipah en India (2026).
13.) Nipah virus: Kerala reports second death in four months (2018).
14.) [Progress in prevention and control of Nipah virus disease] (2022).
15.) Nipah virus, an emerging zoonotic disease causing fatal encephalitis (2022).
16.) Nipah viral encephalitis or Japanese encephalitis? MR findings in a new zoonotic disease 2000).
18.) Nipah virus: pathogenesis, genome, diagnosis, and treatment (2025).
20.) Treatment of acute Nipah encephalitis with ribavirin (2001).
==============================================================
.png)