Epidemiological Bulletin: Summer 2001 (Part 2 of 2)
Activities of the County Asthma Coalition
Gloria Tzuang, MPH (Epidemiologist)
A small group of professionals - including representatives from the American Lung Association, the Health Plan of San Mateo, county agencies, and community based programs - have started meeting regularly in an effort to establish an asthma coalition for San Mateo County. This effort is being coordinated by the San Mateo County Health Services Agency, which was awarded a grant through the Children and Families First Commission to develop a working group to set priorities for addressing asthma in children ages 0 to 5. As work on the grant has commenced, it is clear that the foundations for addressing asthma at a countywide level do not yet exist. Thus, the initial focus is on bringing together the major players and developing organizational relationships. Once the coalition is organized, a next step is to develop working groups for specific issues such as: identifying and evaluating existing data and resources; identifying the needs of particular populations such as children 0 to 5, daycare centers, schools, clinicians, or parents; and developing educational programs & health policy. At this stage of the process, many ideas have been set forth; the next few months promise to be challenging as the coalition gels and begins to define its priorities. Ideally, this work will lead to better coordination of asthma programs and services throughout the county and, ultimately, better health for asthma sufferers. For more information about the San Mateo County Asthma Coalition, please contact Gloria Tzuang at (650) 573-2547 or email gtzuang@co.sanmateo.ca.us.
MMR and Autism: A review of the Literature
Assessing the Proposed MMR-Autism Connection: A Summary from the Literature Colin McCreight, DCPU Intern, MS I
The media has recently run numerous stories on a supposed link between measles-mumps-rubella (MMR) vaccination and the development of childhood autism. DCPU staff have been contacted by local parents who are have questions and are concerned about their children's health after receiving MMR -- even after those children were exposed to confirmed measles cases. A 1998 British study by Dr. Andrew Wakefield 1 initiated much of this controversy. Dr. Wakefield's anecdotal report stated that in 9 of 12 children with autism and bowel disease, the parents or pediatricians speculated that MMR vaccination might have contributed to the child's later autism. This article has glaring limitations, however, including a very small sample size (n=12), and an inadequate control group.
Nonetheless, anti-vaccination groups, news media, and United States Congressmen have frequently cited this article as evidence for an MMR-autism link. The Centers for Disease Control (CDC) and the National Immunization Program (NCIP) have conducted follow-up studies to examine this concern more thoroughly and scientifically. A retrospective, case-control analysis of approximately 14,000 California children immunized with MMR over a 14- year period found no statistically significant link between MMR and autism.2
The study noted that between 1980-94, the MMR coverage rate increased modestly from 72 to 82%, while during the same time period, autism incidence increased dramatically from 44/ 100,000 live births to 208/ 100,000 live births Ð a 373% relative increase. A similar British study found the same result: MMR vaccination coverage remained relatively constant while autism incidence increased seven-fold.3 If MMR were indeed promoting autism, the increased autism incidence would be comparable to the change in MMR vaccination rates, but this is clearly not the case. Other large, controlled studies in the US and UK have consistently found no link between MMR vaccination and autism.4 There has been concern over the past several years about organic mercury exposure due to the thimerosal preservative in some vaccines, and thimerosal is currently being phased out of the vaccine supply.
MMR vaccine, however, has never contained thimerosal.5
MMR vaccination continues to be highly effective in preventing measles in the United States. Prior to MMR, measles was ubiquitous, with 800,000 cases reported in 1962 and about 430 measles-related deaths reported each year between 1958 and 1962. 5 In 1999, all of the 100 reported measles cases were imported; endemic measles has been successfully eliminated in the United States.
As the CDC stresses, "getting MMR vaccine is much safer than getting [measles, mumps, or rubella]."6 And as the literature consistently shows, there is no reliable evidence to support claims of a MMR-autism link. For more information on this issue, and for answers to frequently asked questions about MMR and autism, we suggest that you look at: www.cdc.gov/nip/vacsafe/concerns/autism/autism-mmr. htm
References:
1. www.cdc.gov/nip/vacsafe/concerns/autism/ autism-mmr. htm
2. JAMA. 2001;285:1183-1185
3. BMJ 2001;322:460Ð3
4. www.mrc.as.uk/autism_report.html
5. www.cdc.gov/nip/vacsafe/concerns/thimerosal/ joint_statement_00.htm
6. MMWR, April 02, 1999 / 48(12); 243-248 (www.cdc.gov/epo/mmwr/preview/mmwrhtml/000568 03.htm)
7. www.cdc.gov/nip/publications/VIS/vis-mmr.pdf
A Busy Winter of Foodborne Outbreaks
A Busy Winter for Food-borne Outbreak Investigations in San Mateo County Francis Wiser, MSPH (Epidemiologist)
Between 7/1999 and 10/2000, the Disease Control and Prevention Unit (DCPU) was not called upon to investigate any food-borne outbreaks in the county. This was the longest stretch without such an outbreak in the recent history of the Unit, and it ended in late October with a very large outbreak of shigellosis at the Viva Mexico restaurant in Redwood City (as summarized in the last EpiBulletin - Spring 2001). In the eight months since that outbreak, the unit has conducted investigations on varying scales for 11 different outbreak incidents, all of which are summarized in Table 7, below. It appears that the media coverage in the Viva Mexico incident may have raised awareness in the community and among providers about cluster reporting and the investigatory role of the health department.
Of the 8 incidents that have been fully investigated, 2 were confirmed as involving Norwalk-agent (or calicivirus) gastroenteritis, with several other similar incidents appearing to stem from the same type of viral pathogen. Testing for Norwalk is slow, is only done at selected labs and requires stool collected within a day of the onset of symptoms. Since most incidents are only reported a week or more after the fact, most of the local likely Norwalk incidents cannot be confirmed.
Regardless, while most of the outbreaks appeared to be viral in nature, the largest occurrence Ð Viva Mexico Ð was caused by a multiply drug-resistant strain of the bacteria Shigella sonnei. Another restaurant outbreak on the list appeared to be caused by (was not confirmed as) Vibrio parahaemolyticus, a bacterial pathogen commonly associated with shellfish.
All but one of the events were localized to dining events or restaurants, the one exception being an episodic outbreak of Norwalk gastroenteritis at a nursing home, fairly typical for a viral outbreak in such a setting, which may well have stemmed from food and/or staff contact with residents.
HIV Infection Reporting in Development
HIV Infection Reporting: The State-Mandated Procedures Become Clearer Sarah Cottrell, MPH (Epidemiologist)
With the anticipation of mandatory HIV reporting in California, the DCPU would like to stress the necessity for such reporting and explain how it will be structured. The CDC recommends that all states implement a system for reporting HIV infection, either by name or by unique identifier. To date, California is one of only three remaining states without mandatory HIV reporting. With the face of changes in the HIV/AIDS epidemic and with HIV antiretroviral therapies reducing the incidence of AIDS and related mortality it has become difficult to epidemiologically profile HIV trends from AIDS case data alone. Statewide reporting of HIV infection will not only allow an accurate epidemiological picture of HIV but also provide communities with a basis for prioritizing services and prevention plans, estimating future resource needs, following disease trends, and planning prevention strategies. It will also allow evaluation of the effectiveness of HIV prevention and treatments. In light of these benefits, California is instituting a unique identifier * system for HIV reporting. This unique identifier will establish a confidential system that would hopefully provide unduplicated data while not driving individuals away from HIV testing and treatment.
HIV reporting in California will involve of the following entities: health care providers, laboratories, the San Mateo County Disease Control and Prevention Unit (DCPU) and California DHS Office of AIDS. Health care providers will be required to report to the DCPU all positive HIV antibody tests, all viral loads, and CD4 tests which indicate HIV infection. Within seven days of the confirmatory test, the health care provider will generate a unique identifier for each client and subsequently fill out an HIV Infection Report form on the client. Individual names will not be reported to the San Mateo County DCPU and the DCPU will not complete the infection report in-house (as is done with active AIDS case reports). The DCPU will be able to provide assistance with how to generate the unique identifier and to answer questions about how to complete the form. Laboratories will also submit positive test results with non-identifying client information and the name, address, and telephone number of the health care provider/facility who submitted the specimen. The DCPU will match laboratory tests with case reports submitted by the provider to ensure there is no duplication in reporting. Laboratories and providers are still required to report active AIDS cases by name within seven days of the case meeting the AIDS surveillance case definition of CD4 count < 200 µl or < 14 % or the presence of specified opportunistic infections (1987 definition MMWR 1987 36(suppl 1S); 1993 definition ( MMWR 41(RR-17).
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