Nipah virus infection is newly emerging zoonosis, which has spread panic in parts of India. Vinay Pathak, General Manager – Technical, 3M India, gives an insight about the preventive measures that should be taken into account to stop the disease from spreading
What is Nipah virus (NiV)?
Nipah virus (NiV) is a member of the family Paramyxoviridae, genus Henipavirus. NiV was initially isolated and identified in 1999 during an outbreak of encephalitis and respiratory illness among pig farmers and people with close contact with pigs in Malaysia and Singapore. Its name originated from Sungai Nipah, a village in the Malaysian Peninsula where pig farmers became ill with encephalitis. Given the relatedness of NiV to Hendra virus, bat species were quickly singled out for investigation and flying foxes of the genus Pteropus were subsequently identified as the reservoir for NiV (Distribution Map).
In the 1999 outbreak, Nipah virus caused a relatively mild disease in pigs, but nearly 300 human cases with over 100 deaths were reported. In order to stop the outbreak, more than a million pigs were euthanized, causing tremendous trade loss for Malaysia. Since this outbreak, no subsequent cases (in neither swine nor human) have been reported in either Malaysia or Singapore.
In 2001, NiV was again identified as the causative agent in an outbreak of human disease occurring in Bangladesh. Genetic sequencing confirmed this virus as Nipah virus, but a strain different from the one identified in 1999. In the same year, another outbreak was identified retrospectively in Siliguri, India with reports of person-to-person transmission in hospital settings (nosocomial transmission). Unlike the Malaysian NiV outbreak, outbreaks occur almost annually in Bangladesh and have been reported several times in India.
How is it transmitted?
Transmission of Nipah virus to humans may occur after direct contact with infected bats, infected pigs, or from other NiV infected people. In Malaysia and Singapore, humans were apparently infected with Nipah virus only through close contact with infected pigs. The NiV strain identified in this outbreak appeared to have been transmitted initially from bats to pigs, with subsequent spread within pig populations. Incidental human infections resulted after exposure to infected pigs. No occurrence of person-to-person transmission was reported in this outbreak. Conversely, person-to-person transmission of Nipah virus in Bangladesh and India is regularly reported. This is most commonly seen in the family and caregivers of Nipah virus-infected.
What are the signs and symptoms?
Infection with Nipah virus is associated with encephalitis (inflammation of the brain). After exposure and an incubation period of five to 14 days, illness presents with three to 14 days of fever and headache, followed by drowsiness, disorientation and mental confusion. These signs and symptoms can progress to coma within 24-48 hours. Some patients have a respiratory illness during the early part of their infections, and half of the patients showing severe neurological signs showed also pulmonary signs. During the Nipah virus disease outbreak in 1998-99, 265 patients were infected with the virus. About 40 per cent of those patients who entered hospitals with serious nervous disease died from the illness. Long-term sequelae following Nipah virus infection have been noted, including persistent convulsions and personality changes. Latent infections with subsequent reactivation of Nipah virus and death have also been reported months and even years after exposure.
What is risk of exposure?
In the Malaysia and Singapore outbreak, Nipah virus infection was associated with close contact with Nipah virus-infected pigs. In Bangladesh and India, where Nipah virus infection is more frequent, exposure has been linked to consumption of raw date palm sap and contact with bats. Importantly, human-to-human transmission has been documented and exposure to other Nipah virus infected individuals is also a risk factor.
How to prevent?
To reduce exposures to NiV it is recommended that bats, and contact with or consumption of bat droppings be avoided, including consumption of raw date palm sap. Additionally, contact with sick pigs should be avoided. Individuals in affected areas should follow the advice of their local public health authorities.
Hand hygiene is strongly emphasised. It is of the highest importance that hand hygiene be performed thoroughly and often, including before and after donning and before and after doffing personal protective equipment (PPE).
Prior to potential occupational exposures to NiV, a risk assessment must be done by competent experts appointed by the employer. PPE should be selected based primarily on the potential exposures and need for protection against infective fluids and agents. However, work conditions, environmental conditions, tasks and accessibility to decontamination facilities should also be considered.
Workers should be trained on the risks, mitigating effects of the PPE, and their use. Training should be mandatory and thorough and followed by mentoring before workers engage in any activities.
PPE can help reduce exposures to infectious material. However, it is very important that all local infection control protocols and manufacturer’s user instructions be followed when putting on (donning) and removing (doffing) the equipment to avoid contamination. Additionally, local infection control practices and manufacturer’s user instructions should be followed when cleaning any reusable PPE.
Emphasis should be put on the importance of consistent use and implementation of standard precautions by all healthcare workers when providing care to all patients, regardless of their diagnoses. These precautions include a wide range measures, including the use of PPE.
It is recommended that investigating teams take a laminated photocopy of these pages into the field for reference.
It is recommended that the following clothing and PPE be used by those performing necropsies. Those collecting blood samples of suspected cases to help confirm diagnosis should consider the following clothing and PPE:
- Long sleeve overalls
- Rubber boots
- Gloves, taping these to the sleeves of the overalls, preferably two sets of gloves
- A plastic apron that can be disinfected or discarded
- A face shield or similar eye and mucous membrane protection
In addition to the PPEs, specific work procedures must be followed to help reduce exposure to virus. These include minimising the creation of aerosols. Health workers should be trained on the risks, mitigating effects of the PPE, and their use. Training should be mandatory and thorough and followed by mentoring before workers engage in any activities.
Surgical/ medical masks or respirators are another type of PPE recommended for those in contact with potential NiV cases. These products may need to be fluid resistant depending upon the eye and face protection being worn.
Particulate respirators are designed to help reduce the wearer’s exposure to certain airborne particles. Currently, health authorities have not documented NiV as being transmitted from infected individuals via airborne route. However, droplets containing the NiV that have become aerosolised (e.g. from coughing, sneezing, vomiting, medical procedures, and surfaces etc.) may have the potential to come into contact with a person’s mucous membranes in their nose or mouth or non-intact skin. Therefore, respiratory protection reduce exposure to infectious aerosols. They may also help limit inadvertent touching of the nose, mouth and/ or eyes (if a full-facepiece or powered-air respirator is used). Respiratory protection is recommended for workers performing certain tasks such as aerosol-generating procedures, laboratory procedures, and autopsies.