Patient zero, the term scientists used to refer to the person who is the unwitting source of any infection outbreaks, are crucial to predicting the disease transmission course, current trajectory and perhaps a way to stop the outbreak from spreading further. Patient zero must be alive and spreading the disease when the investigation is underway to provide critical information, so it is critical that the tracking is performed early during disease outbreaks.

There were several deadly epidemics in the last decade which had ravaged the lives of many people in cities and rural areas alike. From the MERS infection in South Korea to Ebola outbreak in the African countries to the earlier SARS outbreak in Hong Kong, the work of finding the patient zero had become increasingly vital to help to decipher the nature of these deadly diseases.

Middle East Respiratory Syndrome (MERS)

The MERS-CoV outbreak in South Korea had, till date, claimed 36 lives and infected hundreds of patients (1). The trail of destruction began when a 68-year old man travelled to Bahrain, Saudi Arabia and the United Arab Emirates. Saudi Arabia and the UAE were countries with the most MERS cases and reported the majority of the 440 fatalities which occurred in the region (2). The man failed to notify the authority of his travel history, and only mentioned he had been to Bahrain.

He subsequently developed a cough and fever eight days after his return and had visited four health facilities. He first visited a heath clinic on 11th May in his hometown Asan but the doctors were unable to diagnose his condition correctly due to the lack of travel information. They then refer patient zero to a larger hospital in Pyeongtaek, the St Mary's. The hospital was crowded and it was the perfect condition for the virus to spread. It was at St Mary's where approximately 40% of the total infections occurred.

The patient condition did not improve, unfortunately, and he then went to Seoul to seek better medical treatment. He was visiting a relatively small hospital first, six days after his visit to the health clinic in Asan, where doctors suggested pneumonia from X-rays scans. On the following day, he was transferred to the Samsung Medical Center in Seoul, where he was suspected of contracting MERS and his travel history was clarified. The correct diagnosis was made on 20th May (3).


The 2014 outbreak of Ebola in West Africa presented a different challenge to epidemiologists in tracking the patient zero. The healthcare infrastructure in West African countries was not as complete as that of South Korea, some may even describe them as fragile at best. The disease had killed more than eight thousand people and had caused global panic. However, the origin of the disease could not be confidently identified. It was thought that a toddler from Meliandou, a remote forest village in Southern Guinea was the patient zero. Unfortunately, scientists could not ascertain how he contracted the disease, and the toddler died in December 2013 (4).

Dr Donald Henderson from the Center for Health Security at the University of Pittsburgh, Pennsylvania said there were many uncertainties with regards to Ebola and it was difficult to be pinpoint the Meliandou toddler as patient zero. "Another child or person with vomiting, fever and diarrhoea could have gone misdiagnosed," he said (5).

In March 2014, the Ebola virus had travelled to the major trading centre of Gueckedou in Guinea and continued to spread to neighbouring countries of Sierra Leone and Liberia.

Severe Acute Respiratory Syndrome (SARS)

SARS is another infectious disease brought about by coronavirus which causes symptoms such as fever, cough, severe headache and dizziness. It presents an atypical pneumonia where conventional treatment may not be effective. During the SARS outbreak from November 2002 to July 2003, more than eight thousand people had been infected with close to 800 deaths globally (6).

In the Hong Kong outbreak, the patient zero was a 64-year old professor from Guangdong who had infected 13 tourists when he checked into the Metropole Hotel in Mongkok on 21st February 2003. He was on his way to attend a wedding banquet. By the time of his arrival in Hong Kong, he has been suffering from fever and shortness of breath. In addition, he had self-treated his pneumonia with antibiotics (7).

He sought treatment from the Kwong Wah Hospital Emergency department where x-rays showed “ground-glass appearance”, said Dr Wu Chun-wah, the consultant who treated the patient (7). The professor was admitted to the intensive care unit and unfortunately died on 4th March 2003. MIMS

1. Anon. Archive of MERS-CoV cases in the Republic of Korea [Internet]. WHO. 2015 [cited 2016 Aug 11]. Available from:
2. Park J. Tracing the path of South Korea’s MERS “patient zero” [Internet]. Reuters. 2015 [cited 2016 Aug 11]. Available from:
3. Choe S. MERS Virus’s Path: One Man, Many South Korean Hospitals [Internet]. The New York Times. 2015 [cited 2016 Aug 11]. Available from:
4. Baize S, Pannetier D, Oestereich L, Rieger T, Koivogui L, Magassouba N, et al. Emergence of Zaire Ebola Virus Disease in Guinea - Preliminary Report. N Engl J Med. 2014;(April):1–8.
5. Dara M. Finding patient zero [Internet]. The Pharmaceutical Journal. 2015 [cited 2016 Aug 11]. Available from:
6. Anon. SARS Fast Facts [Internet]. CNN Library. 2016 [cited 2016 Aug 11]. Available from:
7. Benitez. “Patient zero” believed he did not have Sars, inquiry told [Internet]. South China Morning Post. 2003 [cited 2016 Aug 11]. Available from:

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