Tuesday, 6 May 2014

MERS-CoV by sex, week and age...

Two quick charts on the Middle East respiratory syndrome coronavirus (MERS-CoV; which I verbalize as "murrs coronavirus" just fyi )data.

The first chart shows a rise in the proportion of females (pinked dashed line; right-hand axis) during the Jeddah outbreak over recent weeks. But this does not change the fact that males still make up the majority of humans positive for MERS-CoV. For camels - I don't know sex, but juveniles seem to more often have RNA detected and less often have MERS-CoV antibodies present.

It's interesting that a similar rise in the proportion of positive females occurred in April-2013 when there was another healthcare-related outbreak around Al-Ahsa.

It would be nice to know what the sex breakdown is when comparing index cases to non-index cases. Does human-to-human spread involve more females as it goes along than does acquisition from camels - these presumably being a more common source for the sporadic cases that trigger each smaller cluster? Could a rise in the proportion of females be useful as a marker for an impending extended outbreak? Do men have most of the contact with camels? A few question marks there.

The sex distribution, by week, of MERS-CoV positive people and the proportion of those,
each week, who are female (shown using a 6-day moving average).
Click on image to enlarge.

The second chart plots the average age each week (an orange dot) and plots a 10-day moving average. The moving average continues to show the cyclical pattern I alluded to in my last post of this chart - whatever it means or doesn't mean. 

During the Jeddah outbreak, the average age appears to have dropped compared to prior to just the outbreak. But there is a lot of movement in the average age over time. Although, there does seem to be a downward trend after the Apr-2013 outbreak as well and another after something happened in October. Do we know of an outbreak in Oct-2013? Could this mark one that occurred but that we didn't hear about? Am I wearing my tinfoil hat again? So many questions.

Age drops among the tested population may be another marker of the wider or differently composed population that is being infected during human-to-human spread compared to when cases are sporadic and perhaps more closely camel-contact related. 

The average age, each week, of MERS-CoV positive people and a trend shown 
using a 6-day moving average.
Click on image to enlarge.

Or it may be nothing but noise from the incomplete data we have to play with here.