Sunday, June 9, 2019

Nipah Update: Duration of contact tracing

 Dr KK Aggarwal

This page will be daily updated till the Nipah scare is over. Inputs invited in this white paper.

Duration of contact tracing is 21 days from the time of last contact with a case.

Active fever surveillance

Area: within 5 km radius from the periphery of the affected area (house/village of case/cases).

What has to be done

·         Enlist all houses (and persons): Daily visits to each house and enquire about any person developing any symptoms (like fever, cough, headache (and or other symptoms like altered sensorium, shortness of breath etc.)
·         In case of a person developing symptom: follow steps as below under “What is to be done during contact tracing”
·         Duration: Up to 21 days from the last case in the area
·         Daily reporting: as per the format

Home Quarantine

Who has to be quarantined? All households and close contacts of a suspect case.

·         Till the time test results of symptomatic comes negative or
·         If the test result comes positive then all such persons become contacts and have to be put under contact tracing for next 21 days.


Temporary can be in a room in the house or health facility till the time he/she is shifted by the designated ambulance to the designated health facility.
Following shifting to health facility, place of temporary isolations needs to be disinfected in accordance with prescribed SOPs by Lysol/5% sodium hypochlorite or any disinfectant (if not available)

When the area/district/state can be declared free: 42 days from the date of last positive case reported from the district/state

(Source: National Center for Disease Control, Recommended Community level Public Health Measures for Nipah virus infection)

Contact tracing

·         Who is a contact: any person having history of contact with a case (person who is laboratory confirmed)

·         Each worker or person responsible for contact tracing should:

o   Enlist all the contacts for tracing
o   Distribute Triple layer surgical masks to each household and keep sufficient stock (but avoid misuse/un-necessary use), as it may create fear/panic.
o   IEC on Nipah virus (NiV) infection, symptoms and importance of contact tracing and home quarantine/isolation.
o   Give his telephone number and number of control room/nearest health facility
o   Have location and details of dedicated ambulance and availability of disinfectant

·         Time/duration: when the case can transmit the disease: development of first symptoms (which may be cough and/or fever with headache) till 21 days have passed from the last contact.

·         What is to be done during contact tracing: Visit the person daily or ask him telephonically and

o    Ask him if had developed any fever, cough, headache (and or other symptoms like altered sensorium, shortness of breath etc.)
o    Health education: about keeping a self-watch on developments of symptoms and If anyone develops symptoms, then he or she becomes a suspect case and thus suspect has to:

§  Immediately wear a triple layer mask and put him under self-isolation (means should not go near/maintain a distance of around 3 m) to any other person.
§  Inform concerned health worker (and or nearby doctor) and not to move by himself (unless there is delay and symptoms are getting worse).
§  Dedicated ambulance (with driver and accompanying health staff having full protective gears) to be used for transporting all such suspects
§  Enlist all possible contacts since the time he/she has developed symptoms and inform health worker.
§  Health worker has to put all such persons in contact list for further doing contact tracing for 21 days since the time of last contact with a person having symptoms or till the time the persons test for NiV comes negative.

(Source: National Center for Disease Control, Recommended Community level Public Health Measures for Nipah virus infection)

Time to Act and not React 

There are two approaches to resolve a problem: Action and reaction. This is also applicable to public health problems.

The government often adopts the “reaction” approach first, which is a denial mode.  

No government would acknowledge a public health problem, existing or impending, right away as it could be perceived as tantamount to owning up to the inefficiency or incompetency of health systems in place.

A terrorist attack does not mean failure of the government. The Nipah virus can be likened to a terrorist. 

It’s time for action and not reaction.

When the Zika epidemic threatened Brazil in 2015-16, when the country was preparing to host the 2016 Olympic Games, the army was called into action and asked to join the efforts to control the virus, which was made into a public movement.

·         Public health problems such as Nipah require a multilateral effort. Therefore, any action taken involves education along with participation and involvement of all stakeholders, including the general public. 
·         A district, state, national and international plan of action should be in place.
·         The public health information should include standard relevant messages for everyone and innovations in research. This information should include Dos and Don’ts about eating pork, half-eaten fruits lying on the ground, consuming raw date palm sap or toddy, handling bats, climbing fruit trees, etc.
·         There should be a uniform protocol for all systems of medicine.
·         Doctors from all systems of medicine should refrain from any claims of cure. If they possess any such cure, it should be first submitted to the government for review.
·         The primary source should be traced – pig, bat or human.
·         There should be guidelines and effective system for contact tracing and their management.
·         There should be a standard protocol for case handlers and probable case spreaders.
·         National surveillance in all cases of encephalitis for the cause, Nipah or any other.
·         There should be a protocol for spread of encephalitis to contacts.
·         A government advisory should be issued for handling of dead bodies of people who die due to the infection.
·         The role of police, military and media should be well-defined.


People often use the term index case when they actually mean primary case. Both terms are well-defined for outbreaks, and should not be confused.

The term primary case can only apply to infectious diseases that spread from human to human, and refers to the person who first brings a disease into a group of people—a school class, community, or country.

The index case, however, is the patient in an outbreak who is first noticed by the health authorities, and who makes them aware that an outbreak might be emerging. Even outbreaks of disease that is not spread from human to human, such as Legionnaire's disease, might have an index case.

For many outbreaks, the primary case will never be known—the worldwide HIV epidemic is one example.

In an outbreak that goes unnoticed, no index case is present, but for all outbreaks that are discovered, there will always be one (or more).

In the present Nipah case in Kerala, we now have the index case, which led to notification. But the primary case is yet to be diagnosed. The very fact more than 300 cases are under surveillance means the government has no clue about the primary case.  

The primary case may also be the index case.

The first term is linked to the basic epidemiology of the outbreak, the second rather to the surveillance system and public health action.


·         Siliguri outbreak in 2001: 45 deaths
·         Nadia West Bengal outbreak in 2007: 5 deaths
·         Kerala outbreak in 2018: 17 deaths
·         Kerala 4th June 2019: 1 case

Nipah facts

·         Incubation period: 4-14 days (maximum 45 days)
·         Spreads by droplet infections, so unlikely to spread through air nuclei.  
·         Asymptomatic subclinical infections: Yes
·         Case fatality 40-70%: last year 17 died so there might have been over 34 cases
·         Suspect Nipah in encephalitis cases with following epidemiological parameters:

o    Encephalitis cases from the areas reported NiVD in human population
o    Area with fruit bats showing presence of NiV
o    Fever with altered sensorium reported from health care personnel treating patients with respiratory illness etc.
o    In any person who has recently visited the affected areas

·         Reducing the risk of bat-to-human transmission: 20% of bats in Kerala have tested positive for Nipah

Efforts to prevent transmission should first focus on decreasing bat access to date palm sap and other fresh food products. Keeping bats away from sap collection sites with protective coverings (such as bamboo sap skirts) may be helpful. Freshly collected date palm juice should be boiled, and fruits should be thoroughly washed and peeled before consumption. Fruits with sign of bat bites should be discarded.

·         Nipah virus in domestic animals and reducing the risk of animal-to-human transmission: Horses, goats, sheep, cats and dogs first reported during the initial Malaysian outbreak in 1999. The virus is highly contagious in pigs. Pigs are infectious during the incubation period, which lasts from 4 to 14 days. An infected pig can exhibit no symptoms, but some develop acute feverish illness, labored breathing, and neurological symptoms such as trembling, twitching and muscle spasms. Nipah virus should be suspected if pigs also have an unusual barking cough or if human cases of encephalitis are present.

Gloves and other protective clothing should be worn while handling sick animals or their tissues, and during slaughtering and culling procedures. As much as possible, people should avoid being in contact with infected pigs. In endemic areas, when establishing new pig farms, considerations should be given to presence of fruit bats in the area and in general, pig feed and pig shed should be protected against bats when feasible.

·         Reducing the risk of human-to-human transmission: 75% cases last year were in health care settings exposed to sick patients. Close unprotected physical contact with Nipah virus-infected people should be avoided. Regular hand washing should be carried out after caring for or visiting sick people.

NiV can persist on surfaces, posing risk for fomite-borne NiV transmission.

All NiV case-patients with NiV RNA in their oral secretions died in one study and those without NiV RNA survived suggesting virulence is important. Human-to-human transmission results direct contact with respiratory secretions of severely ill patients.

Only 7% of all Nipah patients are Nipah spreaders. Those with respiratory involvement (difficulty breathing and cough) are more likely to become Nipah spreaders. Bangladesh example: 16 Nipah patients; 12 laboratory-confirmed and 4 probables; of 12 lab confirmed cases 10 showed NiV RNA in oral swab specimens. Surface swab samples for 6 Nipah patients; 5 had evidence of NiV RNA on >1 surface: 4 patients contaminated towels, 3 bed sheets, and 1 the bed rail. Patients with NiV RNA in oral swab samples were significantly more likely than other Nipah patients to die. 

·         Phases in prevention

o  Investigation phase: immediate investigations of exposed people, Notification circular

o  Alert phase

1. Prevention of spread
2. Identification of other possible foci
3. Reporting and dissemination of information
4. Quarantine of infected patient and observation of others
5. Inter-ministerial alert (vety, animal husbandry, health, army, wildlife authorities)
6. Travel alert: whether patient from infected areas can move to other districts or vice versa. It should also talk about local, state, inter -state and International travel alerts if any from time to time.

o   Operational phase: Public awareness and education campaign and set up neighboring states and local disease control centers.

o   Stand-down phase: Last phase after the disease is eradicated. 

There is no National Program for Surveillance of NiV. All these diseases are part of Integrated Disease Surveillance Program (IDSP). 

(Inputs: Dr A C Dhariwal, Dr Shivlal)

Dr KK Aggarwal
Padma Shri Awardee
President Elect Confederation of Medical Associations in Asia and Oceania   (CMAAO)
Group Editor-in-Chief IJCP Publications
President Heart Care Foundation of India
Past National President IMA 

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