Infectious diseases: September 2010 Archives
An ongoing epidemic of pertussis, or whooping cough, in California has now claimed the lives of 9 infants and sickened at least 4017 children, according to state health officials. If the epidemic continues as expected, the number of reported cases this year could surpass the yearly spikes of the highly contagious disease that occurred during the 1950s.
All recent pertussis-related fatalities in California affected infants, most of whom were Hispanic and too young (ie, <3 months) to be fully immunized. These babies acquired illness because of an apparent lapse in herd immunity (although the latest data from the CDC indicate that California toddlers underwent vaccination in 2009 at rates* that were comparable to or higher than those for the rest of the country).
Currently the number of pertussis cases in California account for about one third of the reported number of US cases for this year.
The CDC recommendeds DTaP vaccination (under routine circumstances) at 2, 4, and 6 months, with boosters at 15-18 months (or as early as 12 months) and at 4-6 years of age.
DTaP = diptheria, tetanus, and acellular pertussis.
* State rates for DPT vaccination were not provided, however.
Photo of symptomatic child with pertussis from pertussis.com.
Facilities at Iowa's Wright County Egg, the apparent origin of the recent egg-borne salmonella outbreak, tested positive for the disease-causing bacteria, Salmonella enteritidis, at least as far back as 2 years ago. The revelation is made in a letter sent Tuesday by Congressmen Henry Waxman and Bart Stupak, chairmen of the House Investigations and Oversight Subcommittee, to Austin "Jack" DeCoster, CEO of Wright County Egg. Waxman and Stupak cite 28 sample reports, obtained by unclear means,* that reveal at least 73 instances in which Salmonella serogroup D was detected on chickens, egg belts, or "pit rows" in DeCoster's hen houses. The most recent sample report, dated July 26, 2010, revealed that DeCoster's poultry tested positive for serogroup D and ultimately S. enteritidis.**
The publicized testing records, which are incomplete and heavily redacted, show more than 400 instances in which environmental swabs (ie, "sponges") at DeCoster's egg farms were contaminated with various serogroups of Salmonella—B, CI, C2, D, "untypeable," and polyvalent. Isolates revealing serogroups D, untypeable, and polyvalent, detected on samples by the Veterinary Diagnostic Laboratory at Iowa State University (which were presumably taken as a part of routine surveillance testing performed by the company), were then forwarded for species identification to the NVSL, or the National Veterinary Services Laboratory. However, only about half, or 10, of these NVSL results are included in the publicized testing records. Of the available NVSL reports, 8 (80%) revealed S. enteritidis. (The NVSL is a part of the USDA—a fact that raises questions about the government lab's responsibility for further scrutinizing facilities that repeatedly test positive for infectious pathogens.)
The Subcommittee's information gathering, which is ongoing, is in anticipation of the DeCoster's voluntary appearance before Congressional members on Tuesday, September 21 (Hearing on Salmonella Outbreak and Egg Recall, beginning at 12 noon EDT). "Habitual violator" DeCoster, up until now, has been almost Howard Hughes-like in his ability to avoid direct media scrutiny and public accountability for the recent outbreak, the eyebrow-raising conditions at his egg farms, and several past infractions.
Whether DeCoster's S. entertidis isolates are related to the recent salmonella outbreak is currently unknown (or at least unpublicized). DNA characteristics of DeCoster's bacterial samples, including recent samples detected by the FDA, would have to be compared with those of bacteria cultured from infected individuals. The CDC reports that this egg-borne salmonella outbreak is distinct in that DeCosters' eggs are infected internally—meaning through the infection of his chickens' ovaries.
* Waxman's and Stupak's letter indicates that DeCoster provided, on request, documents to the Subcommittee on September 11, but that these did not contain the "potentially positive Salmonella Enteritidis test reults." The congressmen want to know why these reports weren't provided by DeCoster.
** Serogroup D includes the bacterial species S. enteritidis.
Another study showing that thimerosal—the ethylmercury-containing vaccine preservative—does not increase the risk of autism hardly seems necessary. For the rational majority, who are inclined to believe the results of credibly authored reports, there are at least 5 studies that fail to show a link between pre- or postnatal exposure to thimerosal and poor neuropsychologic outcomes or autism. (Moreover autism rates continue to rise despite the removal of thimerosal from childhood vaccines in 1999.) For the small group of irrational and very vocal citizens who maintain a causal connection between thimerosal and autism, no amount of negative data appears sufficient.
Nevertheless the results of a new case-control study, published in Pediatrics, are now available. And not only do they deny an increased risk of autism with thimerosal exposure (either in utero or later); they actually indicate that postnatal exposure to thimerosal significantly reduces the risk of autism—by about 40%. The authors (perhaps wisely) avoided speculating as to the reason for the reduced risk, however.
The case-control data were collected from children* enrolled continuously in 3 managed care organizations that participate in the CDC's Vaccine Safety Datalink. The study methods are distinctive in that the authors, in addition to mining electronic databases and medical charts, validated autism diagnoses in person and conducted parent interviews.
* 256 with autism spectrum disorder and 752 controls matched for birth year, sex, and MCO.
According to today's WSJ,* the US Department of Agriculture failed to inform the FDA of deteriorating conditions at Wright County Egg, the presumed center of the recent egg-borne salmonella outbreak. (For background, visit here and here.) While trash and bugs began to pile up at the Iowa plant last spring, blinkered USDA workers continued to ensure that Wright County's eggs were appropriately graded.
*Bleech. I cite the story, despite the fact that it was cowritten by Alicia Mundy, whose work I've found sensationalist and irresponsible.