Missouri - Credit Wikipedia
#18,309
A week ago, in CDC Update On Missouri H5 Case - Details On Two Symptomatic Contacts, we belatedly learned of two symptomatic contacts of the Missouri H5 case, which the CDC described as:
- One household contact of the patient became ill with similar symptoms on the same day as the case, was not tested, and has since recovered.
- Also shared by Missouri, subsequently, a second close contact of the case – a health care worker – developed mild symptoms and tested negative for flu.
Late yesterday, the CDC announced that Missouri has informed them of a 3rd symptomatic contact - again in a Health Care Worker - who, like the household contact, was not tested.
Although this lack of testing is disappointing, the index patient - who was hospitalized on Aug 22nd - was only identified as having HPAI H5 retrospectively, during the first week of September. Since the `window' for PCR testing for influenza is relatively brief, delayed follow-up epidemiological investigations can be difficult.
Hopefully serological testing will provide additional information, assuming these contacts consent.
Given the circumstances, it is entirely possible we'll never get a satisfactory answer as to how this person in Missouri was infected. The fact that no further cases have turned up, a full month after the index case, is encouraging.
Some excerpts from last night's update follow:
Situation Update
September 20, 2024 – CDC continues to respond to the public health challenge posed by a multistate outbreak of avian influenza A(H5N1) virus, or "H5N1 bird flu," in dairy cows, poultry and other animals in the United States. CDC is working in collaboration with the U.S. Department of Agriculture (USDA), the Food and Drug Administration (FDA), Administration for Strategic Preparedness and Response (ASPR), state public health and animal health officials, and other partners using a One Health approach.
Since April 2024, 14 human cases of avian influenza A(H5) virus infection have been reported in the United States. Four of these cases were associated with exposure to sick dairy cows and nine were associated with exposure to avian influenza A(H5N1) virus-infected poultry. 12 The source of the exposure in the most recent case, which was reported by Missouri on September 6, has not been determined. The immediate risk to the general public from H5 bird flu remains low.
On the animal health side, USDA is reporting that 213 dairy herds in 14 U.S. states have confirmed cases of avian influenza A(H5N1) virus infections in dairy cows as the number of infected herds continues to grow. USDA reports that since April 2024, there have been A(H5) detections in 36 commercial flocks and 22 backyard flocks, for a total of 18.68 million birds affected.
Among other activities previously reported in past spotlights and ongoing, recent highlights of CDC's response to this include:
Missouri Case Update
Missouri continues to lead the investigation into the H5 case with technical assistance from CDC in Atlanta. CDC's original report about the case in Missouri is available: CDC Confirms Human H5 Bird Flu Case in Missouri | CDC Newsroom. Earlier this week, the Missouri Department of Health and Senior Services collected blood samples from the person who tested positive for H5N1 in Missouri and a household contact who became ill on the same day and was not tested. Both persons have since recovered. The samples are being sent to CDC for serologic testing to look for antibodies to avian influenza A(H5) virus, which would indicate a previous infection. The simultaneous development of symptoms in two people does not support person-to-person spread but suggests a common exposure.
As part of the ongoing contact investigation, Missouri identified one additional health care worker contact who had developed mild respiratory symptoms and was not tested for influenza as the illness had resolved before the investigation began. Serologic testing will be offered to this second health care worker. As CDC previously reported, one health care worker with exposure to the infected individual was tested for influenza and was negative. CDC continues to closely monitor available data from influenza surveillance systems, particularly in affected states, and there has been no sign of unusual influenza activity in people, including in Missouri.
Last week, CDC reported on sequencing of the clinical specimen from the Missouri case.
