CDC

On 29 May, CDC changed its H5N1 reporting schedule from weekly to monthly while Idaho dairy herds remained actively infected. The agency's human-case count had remained at 71 since 6 March, leaving the scale of later human spillover unclear as the dairy outbreak expanded.

CDC's own journal published evidence on 12 May that the B3.13 strain dominant in US dairy cattle replicates efficiently in human nasal tissue. The reporting change therefore matters to CDC's core surveillance role: its public count is a national signal for a zoonotic outbreak whose animal spread was still developing.

On 5 June, CDC published modelling for the Bundibugyo Ebola outbreak that put the reproduction number at 2.51 and identified patient isolation as the decisive control measure. Its model found that raising isolation to 70% reduced the chance of a 20,000-case trajectory to 1%.

That work gave CDC a defined analytical role in a response where its field presence was less clear. By 13 July, reported isolation had fallen to about 39%, further from the threshold in CDC's model. For CDC, the gap turned a published model into a continuing test of whether outbreak evidence can shape operations.

By 24 July, CDC's national measles count reached 2,318 confirmed cases, exceeding the 2,289 recorded during all of 2025. Maintaining The National count places CDC at the centre of how state outbreaks become a single US public-health picture.

The same reporting exposed a practical limitation. Pennsylvania reported 139 cases while CDC's national map showed 134, according to tracking cited on 24 July. For CDC, reconciling such differences is part of the surveillance function, particularly when The National total is setting a new annual high.