Poultry farms increase biosecurity measures before fall's wild bird migration
The National Chicken Council (NCC) yesterday released recommendations for preventing the spread of highly pathogenic avian influenza to farms that raise and breed broiler chickens.
The recommendations, which were developed by a working group of veterinarians and avian flu experts, are intended to increase biosecurity on poultry farms before wild birds begin migrating south from Canada in the fall.
Many of the biosecurity measures are intended to reduce foot traffic on poultry farms. They include limiting visitors, avoiding contact with wild and domestic birds, discouraging equipment sharing between farms, providing new footwear or a means of disinfecting shoes before entering broiler chicken houses, implementing pest and wild bird management, and treating farms as biosecure zones with appropriate signage and protocols.
The NCC also cited the importance of providing avian flu prevention training to farmers and farm staff and the need for ongoing collaborations between poultry farms and biosecurity officials.
In related news, Iowa State University (ISU) has cancelled classes at its 11-acre poultry teaching and research farm as a means of preventing avian flu outbreaks, according to an Associated Press story yesterday in the Des Moines Register. ISU has elected instead to provide poultry management classes to approximately 500 students by video.
ISU typically holds six classes per year at the farm, which houses a flock of rare chickens with old inbred genetic lines that differ from chickens currently produced commercially. The university sees the teaching method change as an opportunity to teach students about biosecurity and interactions between fowl, humans, and disease.
Cyclosporiasis outbreak nearing 500 cases in 30 states
From Aug 18 to Aug 21, 19 additional cases of Cyclospora cayetanensis infection occurred and 1 state, North Carolina, saw its first case in the ongoing outbreak, bringing the case count to 495 cases in 30 states, according to an update yesterday from the Centers for Disease Control and Prevention (CDC).
Hospitalization has been necessary in 21 cases; there have been no associated deaths. The majority of case-patients (293 [59%]) had illness onset on or since May 1 and had no history of international travel.
Clusters have been identified in Wisconsin, Texas, and Georgia, with investigations still under way in the latter two states. The Wisconsin and Texas clusters have been preliminarily linked with ingestion of cilantro as a possible vehicle, but findings are not conclusive.
An Aug 25 Food and Drug Administration (FDA) notice says traceback investigation has shown a link between restaurants where cilantro from the Mexican state of Puebla was served and case-patients in the clusters. The FDA notice discusses the fact that US outbreaks of cyclosporiasis in the summers of 2012 through 2014 were also linked with cilantro from Puebla, although the association was not confirmed.
On Jul 27, FDA implemented "a supportive framework of import controls to detain without physical examination shipments of fresh cilantro from the state of Puebla from Apr 1, 2015, through Aug 31, 2015, as well as this time period in ensuing years," the agency's notice says.
States involved in the outbreak include Arkansas (3 cases), California (2), Connecticut (3), Florida (10), Georgia (23), Illinois (8), Iowa (1), Kansas (2), Maryland (1), Massachusetts (10), Michigan (2), Missouri (1), Montana (3), Nebraska (1), New Jersey (6), New Mexico (2), New York (excluding NYC) (9), New York City (21), North Carolina (1), Texas (168), Utah (1), Virginia (3), Washington (2), and Wisconsin (10).
Aug 25 CDC update
Aug 25 FDA notice
Jul 28 FDA import alert
Aug 19 CIDRAP News item on outbreak
Modeling study demonstrates efficacy of single-dose cholera vaccine
A single dose of oral cholera vaccine (OCV) may prevent more cases and deaths than a two-dose campaign during an outbreak when vaccine supplies are limited, according to a study yesterday in PLoS Medicine.
Investigators from Johns Hopkins Bloomberg School of Public Health and Medecins Sans Frontieres (MSF) assembled mathematical models to determine the efficacy of a single dose of OCV and applied their results to recent cholera outbreaks in Zimbabwe, Haiti, and Guinea.
Models were set up to calculate an OCV minimum relative single-dose efficacy (MRSE) that would be as or more effective than administering two doses with the same amount of vaccine. Currently, international licensing recommends two doses of OCV 2 weeks apart, but low supplies of vaccine make it difficult for public health officials to provide vaccination coverage during a large outbreak.
The mathematical model simulated efficacy of a single OCV dose by factoring in a meta-analysis of effectiveness studies and scenarios related to cholera transmission and vaccination campaign coverage. The study predicted that a single dose must be 35% to 56% as efficacious as two doses to prevent the same number of cases. On the basis of the models, investigators calculated the MRSE to be 57%.
Short-term effectiveness was estimated to be 77% for two doses of OCV (95% confidence interval [CI], 57%-88%) and 44% for a single dose (95% CI, –27%-76%). The effectiveness of a single dose of OCV decreased by 1% every 3, highlighting the importance of vaccination during the early days of an epidemic.
Investigators applied efficacy data to three recent cholera outbreaks: the 2008-09 epidemic in Zimbabwe; the 2010-11 wave of outbreaks in Port-au-Prince, Haiti; and the 2012 epidemic in Conakry, Guinea. Models assumed 50% coverage of the population with a single dose of OCV.
In Zimbabwe, a single-dose campaign could have prevented 1.16 times as many cases as a two-dose campaign with the same quantity of vaccine, or 70,584 cases (95% prediction interval [PI], 55,943-86,205 cases).
In Haiti, a single-dose campaign could have averted 1.05 times as many cases as a two-dose campaign with the same quantity of vaccine, or 78,317 cases (95% PI, 57,435-100,150 cases).
In Guinea, a single-dose campaign may have prevented 1.21 times as many cases as a two-dose campaign with the same quantity of vaccine, or 2,826 cases (95% PI, 2,490-3,170 cases).
An important aspect of the modeled effects is the fact that one dose of OCV may increase herd immunity but also will make an individual more vulnerable to infection if s/he is exposed to cholera bacteria. Single-dose efficacy results thus apply more to population than to individual infection risk.
Investigators cautioned that, due to the limited amount of available data, an evaluation of field effectiveness should be a priority in any single-dose OCV campaign. Cholera outbreaks currently result in 2 to 3 million cases and 100,000 deaths globally each year.
Aug 25 PLoS Med study
California hospital reports duodenoscope-related Pseudomonas infections
California health and hospital officials are investigating an outbreak of Pseudomonas bacterial infections related to contaminated duodenoscopes, according to an Aug 19 story in the Los Angeles Times.
Huntington Memorial Hospital in Pasadena reported Pseudomonas infections in three patients who received duodenoscopy procedures. The infections were discovered in June after a review of laboratory samples and are believed to be related to contaminated reusable duodenoscopes manufactured by Olympus Corporation in Center Valley, Penn.
Health officials believe contamination is related to a design flaw in the duodenoscope, which makes the tip of the device difficult to clean. As a preliminary safety measure, Huntington has begun to quarantine disinfected scopes for 48 hours and check them for bacterial growth before use.
The US Food and Drug Administration issued warning letters in mid-August to three duodenoscope manufacturers, including Olympus, for safety and reporting violations.
Aug 19 Los Angeles Times story
Aug 18 CIDRAP News scan on FDA letters