Contact tracing the first Middle East respiratory syndrome case in the Philippines, February 2015

Abstract

Background:
Middle East respiratory syndrome (MERS) is an illness caused by a coronavirus in which infected persons develop severe acute respiratory illness. A person can be infected through close contacts. This is an outbreak investigation report of the first confirmed MERS case in the Philippines and the subsequent contact tracing activities.

Methods:
Review of patient records and interviews with health-care personnel were done. Patient and close contacts were tested for MERS-coronavirus (CoV) by real time-polymerase chain reaction. Close contacts were identified and categorized. All traced contacts were monitored daily for appearance of illness for 14 days starting from the date of last known exposure to the confirmed case. A standard log sheet was used for symptom monitoring.

Results:
The case was a 31-year-old female who was a health-care worker in Saudi Arabia. She had mild acute respiratory illness five days before travelling to the Philippines. On 1 February, she travelled with her husband to the Philippines while she had a fever. On 2 February, she attended a health facility in the Philippines. On 8 February, respiratory samples were tested for MERS-CoV and yielded positive results. A total of 449 close contacts were identified, and 297 (66%) were traced. Of those traced, 15 developed respiratory symptoms. All of them tested negative for MERS.

Discussion:
In this outbreak investigation, the participation of health-care personnel in conducting vigorous contact tracing may have reduced the risk of transmission. However, being overly cautious to include more contacts for the outbreak response should be further reconsidered.

Full text

Outbreak Investigation Report
WPSAR Vol 6, No 3, 2015 | doi: 10.5365/wpsar.2015.6.2.012
www.wpro.who.int/wpsar 1
a Department of Health, Sta Cruz, Manila, Philippines.
b Field Epidemiology Training Program, Epidemiology Bureau, Department of Health, Sta Cruz, Manila, Philippines.
Submitted: 18 June 2015; Published: 27 July 2015
doi: 10.5365/wpsar.2015.6.2.012
Background: Middle East respiratory syndrome (MERS) is an illness caused by a coronavirus in which infected persons
develop severe acute respiratory illness. A person can be infected through close contacts. This is an outbreak investigation
report of the first confirmed MERS case in the Philippines and the subsequent contact tracing activities.
Methods: Review of patient records and interviews with health-care personnel were done. Patient and close contacts were
tested for MERS-coronavirus (CoV) by real time-polymerase chain reaction. Close contacts were identified and categorized.
All traced contacts were monitored daily for appearance of illness for 14 days starting from the date of last known exposure
to the confirmed case. A standard log sheet was used for symptom monitoring.
Results: The case was a 31-year-old female who was a health-care worker in Saudi Arabia. She had mild acute respiratory
illness five days before travelling to the Philippines. On 1 February, she travelled with her husband to the Philippines while
she had a fever. On 2 February, she attended a health facility in the Philippines. On 8 February, respiratory samples were
tested for MERS-CoV and yielded positive results. A total of 449 close contacts were identified, and 297 (66%) were
traced. Of those traced, 15 developed respiratory symptoms. All of them tested negative for MERS.
Discussion: In this outbreak investigation, the participation of health-care personnel in conducting vigorous contact tracing
may have reduced the risk of transmission. However, being overly cautious to include more contacts for the outbreak
response should be further reconsidered.
Middle East respiratory syndrome (MERS) is an
illness caused by a coronavirus whereby infected
persons develop severe acute respiratory illness
with symptoms of fever, cough and shortness of breath.
The virus spreads from an infected person to others
through close contact (droplet infection) such as caring
for or living with an infected person; the incubation
period is 14 days.1
As of 7 July 2015, the World Health Organization
(WHO) has reported 1368 laboratory-confirmed MERS
cases, including at least 487 related deaths.2 The first
case of MERS occurred in Saudi Arabia in 2012; cases
have since been reported from countries in the Arabian
Peninsula, Europe, North Africa, South-East Asia and
the United States of America. The recent MERS cases in
the Republic of Korea and China resulted from a single
Contact tracing the fi rst Middle East
respiratory syndrome case in the
Philippines, February 2015
Sheryl Racelis,a Vikki Carr de los Reyes,a Ma Nemia Sucaldito,a Imelda Deveraturda,ab John Bobbie Rocaab and
Enrique Tayaga
Correspondence to Sheryl Racelis (email: sherylqracelis@gmail.com).
exported case with a travel history in the Middle East
and subsequent human-to-human transmission.2
In February 2015, the first confirmed case of MERS
in the Philippines was detected. This report describes
the MERS case and the subsequent contact tracing
activities.
METHODOLOGY
Case investigation
An in-depth investigation form developed by Public
Health England1 was completed using the case’s
medical records and interviews with the health care
workers (HCW) that cared for the case. Nasopharyngeal
swab (NPS) and oropharyngeal swab (OPS) were tested

WPSAR Vol 6, No 3, 2015 | doi: 10.5365/wpsar.2015.6.2.012 www.wpro.who.int/wpsar
2
Racelis et alFirst Middle East respiratory syndrome case, Philippines, 2015
for MERS-coronavirus (CoV) using real time-polymerase
chain reaction at the Research Institute for Tropical
Medicine.
Contact tracing
Close contacts categories were identified as per the
Philippines’ interim guidelines for MERS surveillance
and contact tracing.3 Category A are passengers on the
same flight as a confirmed MERS case seated in the
surrounding three rows; Category B are passengers on
the same flight as a confirmed MERS case seated in
the surrounding three rows that travelled onto another
country (i.e. transited in the Philippines only); Category
C are those that lived with, worked with or cared for
a confirmed case; Category D are close contacts of a
suspect or probable case who died with MERS symptoms;
Category E, developed during this investigation, included
patients in the adjacent room of the health facilities of
the confirmed case, all HCW from the facility where the
case attended and all other passengers on the flight.
The total number of contacts for each relevant category
was gathered from quarantine officers, HCW and family
members of the cases.
All contacts who were found were initially interviewed
face to face using a standard close contact questionnaire
headed by the Philippine Field Epidemiology Training
Program investigation team and subnational surveillance
officers trained in filling out the form; the patients from
the adjacent rooms were interviewed over the phone.
Contacts were then monitored daily for appearance of
illness for 14 days starting from the date of last known
exposure to the confirmed case. A standard symptom
log sheet was used to record these details. Contacts
in Category A, C and D were prioritized for MERS-CoV
laboratory testing except for those HCW in Category
C who had full personal protective equipment (PPE).
All Category E airplane passengers traced by the
Philippines Integrated Disease Surveillance and Response
Surveillance Officers Nationwide were also tested.
The collected NPS/OPS specimens were all tested at the
Philippines Research Institute for Tropical Medicine.
RESULTS
Case investigation
The index case was a 31-year-old female who worked
as a HCW in Saudi Arabia. She was four weeks
pregnant.
On 26 January 2015, she had rash, fever and
cough and was diagnosed with hypersensitivity reaction
in Saudi Arabia. On 1 February, she travelled with
her husband to the Philippines while she had a fever.
On 2 February, she attended Health Facility A (a health
facility in the Philippines) as she had difficulty breathing,
a productive cough and high-grade fever. She was initially
seen at the outpatient department, transferred to the
emergency department for admission and subsequently
admitted in a private room. She was managed as a
case of asthmatic bronchitis and was attended by the
on-duty obstetrician-gynaecologist, pulmonologist and
otolaryngologist. On 8 February, she still had persistent
fever and cough. Her specimens were collected and
tested for MERS-CoV. On 10 February, the test yielded
positive results (Figure 1).
Figure 1. Timeline of events, MERS case, the Philippines, 2015
KSA, Kingdom of Saudi Arabia; MERS-CoV, Middle East respiratory syndrome coronavirus; PHL, Philippines; RT-PCR, real time-polymerase
chain reaction.
26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11
January February
Fever,
rashes
Arrived from
KSA to PHL with
cough in-fl ight
Consulted and
admiƩ ed at
Health Facility A
Tested for
MERS-CoV
Confi rmed MERS
by RT-PCR and
transferred to
Health Facility B
Kingdom of Saudi Arabia The Philippines

WPSAR Vol 6, No 3, 2015 | doi: 10.5365/wpsar.2015.6.2.012
www.wpro.who.int/wpsar 3
First Middle East respiratory syndrome case, Philippines, 2015Racelis et al
of MERS from the physician at Health Facility A led to
an early diagnosis and perhaps averted additional cases.
Upon laboratory confirmation, the confirmed case was
immediately isolated upon at the designated MERS
Health Facility B. This action may have reduced the risk
of transmission to close contacts and the community.
Urgent initiation of contact tracing activities by health-
care personnel, quarantine officers and the investigation
team may have also contributed.
Although there are still some gaps in understanding
the risk of transmission of MERS-CoV, comprehensive
contact tracing to prevent the occurrence of subsequent
infections is recommended.4 According to the Philippines
guidelines for MERS,3 close contacts of probable and
confirmed MERS cases should be followed up and
monitored for symptoms until 14 days after the last
exposure; the usual definition for close contacts is those
who lived with, worked with and cared for a confirmed
case. At least one country’s department of health does
not consider HCW using full PPE during exposure as
close contacts and does not recommend laboratory
screening for asymptomatic close contacts;5 however, in
this investigation, Category E contacts were added. This
may have been an overly cautious response and added
burden especially as all contacts were then monitored
for 14 days and tested even if they were asymptomatic.
If these Category E contacts were excluded, then 94%
of close contacts would have been traced. Whether to
include Category E contacts in future investigations
The patient was then transferred to Health
Facility B, a designated MERS hospital, and was
placed in an isolation room with negative pressure.
She was attended by infectious disease specialists and
obstetrician-gynaecologists; the rest of her hospital
stay was uneventful with mild respiratory symptoms.
On 19 February, the patient was discharged as she had
remained afebrile for more than 48 hours and had two
negative sputum and NPS/OPS tests for MERS-CoV.
She recovered completely at home after her discharge
with no known reappearance of fever.
Contact tracing
There were 449 close contacts identified: Category E
(n = 359), Category C (n = 82) and Category A (n = 8).
There were no Category B or D contacts. From these,
297 (66%) were found and 154 (34%) were tested or
screened. The 15 contacts who developed symptoms all
belonged to Category C (household members and HCW
with direct exposure); all yielded negative results for
MERS-CoV (Table 1).
DISCUSSION
We report on the investigation of the first confirmed case
of MERS-CoV in the Philippines. A history of travel to
MERS-affected countries and the appearance of fever
and respiratory symptoms are critical clues to guide
health providers to suspect MERS. The strong suspicion
Table 1. Contacts by category and status, MERS, the Philippines, 2015
Close contacts category* Total Traced (%) Symptomatic Laboratory results
Category A 8 3 (38) 0 3 negative
Category B 0 – – –
Category C (total)
• HCW at Health Facility A (without PPE)
• HCW with full PPE
• Household close contacts
82
55
22
5
82 (100)
55 (100)
22 (100)
5 (100)
0
11
1
3
55 negative
1 negative
5 negative
Category D 0 – – –
Category E (total)
• Patients from adjacent room
• Other HCW from Health Facility A
• Other fl ight passengers
359
8
122
229
212 (59)
8 (100)
122 (100)
82 (36)
–
0
0
–
–
–
–
82 negative
Total 449 297 (66) 15 146
HCW, health-care workers; MERS, Middle East respiratory syndrome; PPE, personal protective equipment.
* Category A, Flight contacts within 3 rows of case; Category B, Flight contacts within 3 rows of case who travelled onto another country;
Category C, contacts who lived with, worked with, or cared for case; Category D, close contacts of a suspect or probable case who died
with MERS symptoms; Category E, patients in the adjacent room of the health facilities of case, all HCW from the facility where case
attended and all other flight contacts of case.

WPSAR Vol 6, No 3, 2015 | doi: 10.5365/wpsar.2015.6.2.012 www.wpro.who.int/wpsar
4
Racelis et alFirst Middle East respiratory syndrome case, Philippines, 2015
Confl icts of interest
None declared.
Funding
None.
Acknowledgements
We are grateful for the cooperation and support of
the Regional and Epidemiological Surveillance Unit of
Calabarzon, the local government and Municipal Health
Office of Laguna and Evangelista Medical Specialty
Hospital. We would also like to thank the surveillance
unit and laboratory staff of Research Institute for Tropical
Medicine for testing the samples and assisting us in the
investigation.
References
1. The first few hundred (FF100): enhanced case and contact
protocol v6.2 – Epidemiological protocols for comprehensive
assessment of early Middle East respiratory syndrome
Coronavirus cases and their close contacts in United Kingdom.
London, Public Health England, April 2014 (https://www.gov.
uk/government/publications/mers-cov-epidemiological-protocols-
to-assess-cases-and-their-close-contacts-in-the-uk, accessed
20 July 2015).
2. Middle East respiratory syndrome coronavirus (MERS-
CoV): Summary of current situation, literature update
and risk assessment – as of 7 July 2015. Geneva, World
Health Organization, 2015 (http://www.who.int/csr/disease/
coronavirus_infections/risk-assessment-7july2015/en/, accessed
20 July 2015).
3. Memorandum No. 2013–0205 (MERS-CoV): Technical
guidelines, standards and other instructions for reference in the
surveillance on Middle East respirator y syndrome Coronavirus.
Manila, Department of Health, 20 July 2013.
4. Updated rapid risk assessment: Severe respiratory disease
associated with Middle East respiratory syndrome coronavirus
(MERS-CoV), Fifteenth update. Stockholm, European Centre for
Disease Prevention and Control (ECDC), 8 March 2015 (http://
ecdc.europa.eu/en/publications/Publications/MERS_update_08-
Mar2014.pdf, accessed 20 July 2015).
5. Middle East respiratory syndrome Coronavirus (MERS-CoV):
CDNA national guidelines for public health units. Canberra,
The Department of Health, 2014 (http://www.health.gov.au/
internet/main/publishing.nsf/Content/cdna-song-mers-cov.htm,
accessed 20 July 2015).
6. Van Doremalen N, Bushmaker T, Munster VJ. Stability of Middle
East respiratory syndrome coronavirus (MERS-CoV) under
different environmental conditions. Euro Surveillance: European
Communicable Diseases Bulletin, 2013, 18(38):pii=20590.
pmid:24084338
should be assessed, especially considering the additional
burden that including an extra 359 contacts had on the
response efforts.
Furthermore, in this investigation, all contacts
who developed symptoms were Category C. As more
than half of reported secondary cases of MERS were
HCW,2,6,7 this group is strongly recommended for close
monitoring and immediate testing. In this investigation,
these contacts were tested for MERS immediately and
had negative results.
None of the identified passengers from the case’s
flight developed symptoms; to date, there had been no
documented cases infected with MERS on board aircraft.8
However, the contact tracing of flight passengers is
recommended. The European Centre for Disease Control
recommends tracing the entire plane or at least seven
rows on either side of the case;9 tracing those within two
rows of a case was recommended by WHO for MERS
case investigations.8,10
This investigation has some limitations as 34% of
close contacts were unable to be traced, most of whom
were passengers from the same flight as the confirmed
case. Obtaining details of these contacts was difficult as
not all passengers provided an address or phone number
on their passenger arrival cards. Therefore their health
status was not established, although there has been no
reports of other MERS cases associated with this flight.
A strength of the study was that all Category C contacts
were traced.
There were no secondary cases reported from this
MERS case, which may suggest that the response from
the Philippines was effective. Factors that contributed
to the large number of cases in the previous MERS
outbreaks, including gaps in infection control in health
facilities, crowded emergency departments, insufficient
awareness of MERS by HCW and patients seeking
multiple consultations11 were insignificant in this
investigation. Exported cases of MERS are still likely,
and therefore preparedness is required. The Philippines
has established guidelines to direct the control and
prevention of MERS cases.3

WPSAR Vol 6, No 3, 2015 | doi: 10.5365/wpsar.2015.6.2.012
www.wpro.who.int/wpsar 5
First Middle East respiratory syndrome case, Philippines, 2015Racelis et al
eu/en/publications/publications/0906_ter_risk_assessment_
guidelines_for_infectious_diseases_transmitted_on_aircraft.pdf,
accessed 20 July 2015).
10. WHO guidelines for investigation of cases of human infection
with Middle East respiratory syndrome coronavirus (MERS-CoV).
Geneva, World Health Organization, 2013 (http://www.who.int/
csr/disease/coronavirus_infections/MERS_CoV_investigation_
guideline_Jul13.pdf, accessed 20 July 2015).
11. High-level messages. Manila, World Health Organization Regional
Office for the Western Pacific, 2015 (http://www.wpro.who.int/
mediacentre/mers-hlmsg/en/, accessed 20 July 2015).
7. Assiri A et al.; KSA MERS-CoV Investigation Team. Hospital
outbreak of Middle East respiratory syndrome coronavirus.
The New England Journal of Medicine, 2013, 369:407–416.
doi:10.1056/NEJMoa1306742 pmid:23782161
8. Parry-Ford F et al. Public health response to two incidents
of confirmed MERS-CoV cases travelling on flights through
London Heathrow Airport in 2014 – lessons learnt. Euro
Surveillance: European Communicable Diseases Bulletin, 2015,
20(18):pii=21114. pmid:25990234
9. Technical report: Risk assessment guidelines for infectious
diseases transmitted on aircraft. Stockholm, European Centre for
Disease Prevention and Control, 2009 (http://www.ecdc.europa.