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Commentary
Mild and
Asymptomatic MERS-CoV
Cases Confirmed
Recombinomics
Commentary 22:15
June 19, 2013
Of the eight newly confirmed cases, six people — all health-care workers — were known to have been sick at the time of the outbreak.
A seventh health-care worker, who had not been identified as part of the cluster at the time, tested positive. He or she reported having been sick, though not sick enough to require hospitalization,
The eighth case was a household contact of a confirmed case. When asked, the person did not recall having been sick
Testing continues on seven more individuals who are currently designated "indeterminate
The above comments provide more detail on the MERS-CoV ICU outbreak in Jordan in the spring of 2012. In addition to the 2 confirmed cases, WHO designated 11 additional cases as “probable” based on linkage to the confirmed cases and each other. Disease onset dates strongly supported transmission among the health care worker s (HCWs) as well as transmission to their contacts. 9 of the 11 probable cases were HCWs, and they represented a wide range of presentations ranging from two cases who recovered without hospitalization or treatment to severe cases who were hospitalized for approximately 1 week.
These probable cases, as well as other HCWs and contacts, were tested using new antibody tests. Two confirmed cases had not been identified previously because they had not been hospitalized and had mild or no symptoms. Six additional positives were health care workers, while seven more cases were positive on one of two antibody tests. They will be tested further and will likely be confirmed after further adjustments of the test. In addition, two of the probable cases were not tested.
It is likely that three of the seven cases who were positive on one of the antibody tests were among the probable case and the four additional patients who were positive represent more mild cases who were not hospitalized because symptoms were minimal or absent.
Thus, of the 19 cases who were confirmed (10), probable but not tested for antibodies (2), or positive on one antibody test (7), 8 recovered without hospitalization, and 2 were hospitalized for 2 or 3 days. For the 9 more serious cases, 2 died.
The results for the Jordan ICU cluster are similar to results for onward transmission cases outside of the Middle East. There have been 7 such cases reported in four countries (England, France, Tunisia, Italy). Five cases were apparently healthy when infected and all quickly recovered. Three recovered without treatment or hospitalization, while two were briefly hospitalized. They were discharged a few days after hospitalization because they were PCR negative. Thus, these milder cases were only PCR positive for a few days and if tested a few days after disease onset they would have been negative. Two of the onward transmission cases not well when infected. The fatal was had been diagnosed with a brain tumor, while the case that remains hospitalized was infected while hospitalized because of a heart attack.
The disease severity and outcomes for the Jordan ICU cluster and onward transmission cases were similar to each other, but markedly different than the confirmed cases in the Kingdom of Saudi Arabia )KSA). 32 of the 49 confirmed cases have died, and 10 more remain hospitalized. Only 7 of the 49 cases have been discharged. Thus, the case fatality rate (CFR) for KSA confirmed cases with outcomes is 82%.
These differences are related to testing. In KSA most confirmed cases were seriously ill and hospitalized when tested. Details on testing of contacts is limited, but if samples are collected after index cases are confirmed, it is likely that symptomatic contacts will have recovered and most samples will be collected at sub-optimal times (may days after disease onset) or from sub-optimal sites (upper respiratory tract), leading to false negatives for milder cases.
The confirmation of milder cases in Jordan by antibody tests as well as onward transmission cases outside of the Middle East by PCR highlights the wide range of clinical presentation of MERS-CoV infected cases and the CFR for these cases is markedly different than those reported in the KSA.
Thus, the Jordan outbreak is much like outbreaks reported for SARS coronavirus in 2003, and the CFR is similar to the 10% CFR reported for SARS-CoV.
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