Monday, January 07, 2019

Saudi MOH: Third Case In Riyadh MERS Cluster


On Friday, in Saudi MOH: Another Household Cluster Of MERS,
we looked at what appeared to be the second household cluster of MERS in Saudi Arabia in the past three weeks, this time involving two males (age 54 Primary & 86 secondary) residing in the same Riyadh household. 
Both cases were hospitalized, and neither reported any recent camel contact.
Today the Saudi MOH is reporting a 3rd case out of Riyadh - a 33 y.o. male - again listed as a secondary household contact, who is reportedly in home isolation.

Given the status of `home-isolated', this patient is likely either only very mildly ill, or is (hopefully) completely asymptomatic, and was only detected through routine lab testing of close contacts of the first two patients.

Up until late 2015 the Saudis treated `asymptomatic' RT-PCR positive MERS-CoV test results (usually discovered while contact testing during a hospital outbreak) as something `less' than a MERS case.
They were rarely reported, and were not included in their official MERS statistics.
In 2015 World Health Organization issued a particularly strong rebuke (without singling out the Saudis) on the handling of asymptomatic cases in their 2015 WHO Statement On The 10th Meeting Of the IHR Emergency Committee On MERS. 
Since then, we've seen a substantial jump in the number of `asymptomatic' (or perhaps, mildly symptomatic) cases reported out of Saudi Arabia. 
Although primarily considered a respiratory disease, MERS-CoV - like nearly all viral infections - can present with a wide range of symptoms, which leaves serious questions over how one defines `symptomatic.

Earlier this year, the WHO listed some of the `milder' symptoms that may be associated with MERS-CoV infection, including:
Low-grade fever, cough, malaise, rhinorrhoea, sore throat without any warning signs, such as shortness of breath or difficulty in breathing, increased respiratory (i.e. sputum or haemoptysis), gastro-intestinal symptoms such as nausea, vomiting, and/or diarrhoea and without changes in mental status (i.e. confusion, lethargy).
Since the initial signs of MERS infection are often similar to a cold or the flu, differentiating who is - and who isn't - infected can be a extremely difficult, even for doctors used to seeing cases (see Evaluation of a Visual Triage for the Screening of MERS-CoV Patients). 

And while the jury is still out on how much of an infection risk an asymptomatic MERS patient poses, in recent years we've seen increasing evidence suggesting transmission to others is possible. Last month, we looked at:

Asymptomatic Middle East Respiratory Syndrome Coronavirus (MERS-CoV) infection: Extent and implications for infection control: A systematic review
Jaffar A.Al-Tawfiq abc Philippe Gautretd

The proportion of asymptomatic MERS cases were detected with increasing frequency as the disease progressed overtime. Those patients were less likely to have comorbid disease and may contribute to the transmission of the virus.
Despite these unknowns, home isolation is often used in lieu of hospitalization for asymptomatic or mildly ill cases in the Middle East. While hospital isolation of MERS positive cases is the most conservative route, the WHO accepts that in-hospital care may not always be an option.

In mid 2018 the WHO issued an interim guidance update called:

Home care for patients with Middle East respiratory syndrome coronavirus (‎MERS-CoV)‎ infection presenting with mild symptoms and management of contacts: interim guidance

WHO-MERS-IPC-18.1-eng.pdf (‎363.5Kb)‎
World Health Organization. (‎2018)‎. Home care for patients with Middle East respiratory syndrome coronavirus (‎MERS-CoV)‎ infection presenting with mild symptoms and management of contacts: interim guidance. World Health Organization.

License: CC BY-NC-SA 3.0 IGO

The reality is, there are almost certainly undetected asymptomatic or mildly symptomatic MERS cases in the community, and - assuming the WHO guidelines are followed - the home isolation of asymptomatic or mildly symptomatic cases likely adds little to the risks of further transmission.

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