[This will be located on the right side-bar, under "Coronavirus MERS-Cov" for future reference]
1. Introduction
Coronaviruses are a large family of viruses that can cause a range of illnesses in humans, from the common cold to severe acute respiratory syndrome (SARS). These viruses also cause disease in a wide variety of animal species.
In late 2012, a novel coronavirus that had not previously been seen in humans was identified for the first time in a resident of the Middle East. The virus, now known as the Middle East Respiratory Syndrome Coronavirus (MERS-‐CoV),1 has caused more than 50 laboratory-‐confirmed cases of human infection. Thus far, all patients infected with MERS-‐CoV have had a direct or indirect link to the Middle East, however, local non-‐sustained human-‐to-‐human transmission has occurred in other countries, in people who had recently travelled to the Middle East.
All MERS-‐CoV patients have primarily had respiratory disease, although a number of secondary complications have also been reported, including acute renal failure, multi-‐organ failure, acute respiratory distress syndrome (ARDS), and consumptive coagulopathy. In addition, many patients have also reported gastrointestinal symptoms, including diarrhoea. More than half of infected patients have died. The majority has had at least one comorbid condition, but many have also been in previous good health. A small number of cases had had co-‐infection with other viruses including influenza A, parainfluenza, herpes simplex, and pneumococcus. As of 6 June, the median age of reported laboratory-‐ confirmed cases is 56 years (Range 2–94 years) and majority (72%) are males.2 A current update of the cases can be found at WHO’s Coronavirus website.
The MERS-‐CoV virus is thought to be an animal virus that has sporadically resulted in human infections, with subsequent limited transmission between humans. The evidence for the animal origin of the virus is circumstantial. Nevertheless, the alternative explanation to explain the sporadic appearance of severe human cases with long periods of time between them, and the wide geographical area over which the virus was apparently distributed, is unrecognized ongoing transmission in people. Surveillance efforts since the discovery of the virus and retrospective testing of stored respiratory specimens suggest this is not the case.
The virus has been demonstrated to grow well in cell lines that in the past have commonly been used for diagnostic viral cultures. Finally, early comparisons with other known coronaviruses suggest a genetic similarity to viruses previously described in bats. However, even if an animal reservoir is identified, it is critical to identify the types of exposures that result in infection and the mode of transmission. It is unlikely that transmission occurs directly from animals to humans and the route of transmission may be complex requiring intermediary hosts, or through contaminated food or drink.
A considerable proportion of MERS-‐CoV cases have been part of clusters in which limited non-‐sustained human-‐to-‐human transmission has occurred. Human-‐to-‐human transmission has occurred in health care settings, among close family contacts, and in the work place. Sustained transmission in the community beyond these clusters has not been observed and would represent a major change in the epidemiology of MERS-‐CoV.
A number of unanswered questions remain on the virus reservoir, how seemingly sporadic infections are being acquired, the mode of transmission from animals to humans and between humans, the clinical spectrum of infection, and the incubation period.
2. Purpose and scope of the document
This document provides a standardized approach for public health authorities and investigators at all levels to plan for and conduct investigations around confirmed and probable cases of MERS-‐CoV infection. It should be read in conjunction with other detailed guidance referenced throughout the text, such as current laboratory testing guidelines and study protocols. It will be updated as necessary to reflect increased understanding of MERS-‐CoV transmission and control.
Most of the advice given in this document will apply primarily to countries in which infection is presumed to have originated from an animal or environmental source, and the exposures that result in infection remain the critical questions. In countries that have secondary transmission related to imported cases, however, the recommendations for finding secondary cases and observing subsequent community transmission are still valid, though on a more limited scale. Similarly, the case-‐control study recommended as a high priority in the second part of the document is not applicable to countries with imported cases, since the purpose of the study is to uncover the non-‐human exposures leading to infection. However, other studies on health care facility transmission and clinical management are still recommended.
As with nearly all recent emerging novel pathogens, most early cases of MERS-‐CoV infection will likely be detected by astute clinicians rather than through established indicator or sentinel surveillance systems. Therefore, the most effective tool in detection will be awareness among the health care providers. An effective detection system will also need to include a readily available channel by which clinicians can report suspect cases, and an effective response mechanism. The Western Pacific Regional Office of WHO (WPRO) has published a guide for event surveillance.3
This document addresses two general categories of activities that need to be undertaken to deal with newly identified cases. The first involves further case finding, case description, and surveillance enhancements in the area where the case is discovered. The primary purpose of these activities is to fully describe the epidemiology of the cases, identify and monitor close contacts of the cases and determine the extent of spread of the virus in the area (sections 3 and 4). The second group of activities is a number of discrete studies aimed at answering critical questions related to MERS-‐CoV (section 5).
[Continued, see Document link below]
1
http://www.who.int/csr/disease/coronavirus_infections/NamingCoV_28May13.pdf
2 WHO Coronavirus website:
http://www.who.int/csr/disease/coronavirus_infections/en/.
3
http://www.wpro.who.int/emerging_diseases/documents/eventbasedsurv/en/
Document Link:
http://www.who.int/csr/disease/coronavirus_infections/MERS_CoV_investigation_guideline_Jul13.pdf
