What’s Up in San Diego?

Disease reporting is a very valuable tool in the control and prevention of recognized illnesses, as well as newly identified ones. A report from a physician often triggers an epidemiologic investigation to determine if the case is in a sensitive occupation — such as a food handler, a daycare provider or attendee, or a healthcare provider — and if a public health intervention is needed.

The goal of this article is to highlight several key disease categories and to provide the medical community with an understanding of their important role in initiating the epidemiological investigative process and the impact on the public health of the community. A complete list of communicable diseases reported in San Diego County from 1996 to 2005 is available at: www2.sdcounty.ca.gov/hhsa/ServiceDetails.asp?ServiceID=147.

Enteric Infections

From 2003 through 2005, 4,054 cases of enteric infections were reported in San Diego County. The reporting form (available through the EMAN website at www.EMANSanDiego.com) provides a space to report this information. Patients are interviewed to determine if others developed illness.

Salmonella, shigella, listeria, and E. coli 0157 isolates are Pulsed Field Gel Electrophoresis (PFGE) typed from specimens submitted to the public health laboratory, and results are posted on the Centers for Disease Control and Prevention-sponsored Secure National Web board where PFGE patterns can be compared. Two recent investigations revealed the following:

Investigation 1:

A cluster of salmonella cases with an identical PFGE pattern was recognized among patrons acquiring illegal cheese. All cases were Hispanic.

A case control study was conducted, and illness was associated with consuming fresh, unpasteurized Mexican-style cheese, or queso fresco. The cheese was purchased from illegal street vendors and from several local markets. This case control study ultimately led to actions by the California Department of Food and Agriculture, the San Diego County District Attorney, and the San Diego County Department of Environmental Health’s confiscating the illegal food items, and penalties were brought against markets participating in the sale of illegal, unpasteurized cheese. Educational materials about the risks associated with raw cheese consumption were developed in English and Spanish and are distributed in multiple sites throughout the county, including WIC clinics. These documents are available at www.sdcdeh.org/deh/fhd/publications.html#food.

Investigation 2:

Salmonella cases were also associated with water dragon lizards. Locally, in San Diego County, an infant was bathed in a tub previously used for a water lizard. A routine public health investigation of this case determined the exposure risk associated with the lizard. Additional testing of the patient and lizard confirmed the link. The unusual salmonella serotype isolated from the child matched other cases in other states that were likewise associated with exposure to these lizards. Once again, public health follow-up and laboratory testing confirmed the successful PFGE matching with other cases.

When a case of salmonella is reported to Public Health, the report, subsequent patient interview, and laboratory evaluation initiate an active search for the source of infection. The ultimate goal is to eliminate the source of additional infections. It all begins with the physician’s report.

Central Nervous System (CNS) Diseases

Meningococcal meningitis and meningococcemia occur in all age groups. The local public health jurisdiction requests notification from the medical community when the diagnosis is suspected, prior to laboratory confirmation. Investigation to identify contacts eligible for post-exposure prophylaxis is initiated immediately.

A recent case in a college student presented a unique challenge:

A local physician reported a case of meningococcemia in a college student. It was determined that post-exposure prophylaxis should be administered to all close contacts. The family received prophylaxis but was unable to provide the names of the student’s close friends. Although the family gave permission for the college to provide the class schedule and provided the case’s cell phone, the cell phone was locked. Public health staff worked with the phone company to obtain recent phone numbers called, resulting in over 300 numbers. Interview of these contacts identified a group of close friends with extensive exposure. A total of 18 persons were prophylaxed and no contacts became ill. This example demonstrates how County Public Health Services partners with you, the physician, in identifying contacts who may be at risk, and ensures access to prophylaxis for contacts of an identified case.

Vector-borne Diseases

Outdoor activity is year-round in San Diego. Vector-borne illnesses can be acquired locally. Local vectors can transmit St. Louis encephalitis, western equine encephalitis, West Nile virus, malaria, lyme disease, and plague. In 2004, a local resident developed the Hanta respiratory syndrome. The individual cleaned rodent-infested enclosed structures at three sites, two of which had been closed for extended periods of time. The individual neglected to take appropriate precautions, such as airing the area for over 30 minutes, dampening surfaces with dilute bleach solution, and wearing rubber gloves. Likely, the patient became exposed to the aerosolized material (i.e., rodent droppings and urine containing the Hanta virus). The initial presentation is non-specific: fever, non-productive cough, malaise, headache, and GI symptoms. Early findings may include a platelet count below 150,000. Rapid progression to pulmonary edema and hypoxia may follow. Obtaining an exposure history is key. Rodent trapping was conducted at the sites where the patient had worked. Hanta virus was identified in field mice trapped at one of the three sites.

Enroll in EMAN

The Emergency Medical Alert Network (EMAN) provides alerts about potential public health threats and is a resource for disease reporting information, including the confidential morbidity report form. Enrolling is easy at www.EMANSanDiego.com by clicking on “Subscribe to EMAN.” Additional information about disease reporting and EMAN is available by calling 619/515.6620. The San Diego County Community Epidemiology Branch thanks you for your prompt disease reporting. It facilitates investigation and overall reduction in disease.

The County Public Health Services Division works with other county offices and state and federal officials to reduce the burden of illness in the community. However, practitioners in the community are the vital link. Prompt reporting of disease and unusual illness allow for efficient investigation and intervention to proceed.

San Diego County Health Statistics:

Reportable Diseases and Conditions

• There are over 90 reportable diseases and conditions, including occurrence of unusual diseases and outbreaks of any diseases (1).
• Currently, there are 459 physicians in San Diego County enrolled in the EMAN system (1).

To request additional health statistics describing health behaviors, diseases, and injuries for specific populations, health trends and comparisons to national targets, please call the County’s Community Health Statistics Unit at 619/285.6479. To access the latest data and data links, including the Regional Community Profiles document, go to SDHealthStatistics.com.

References:

1. County of San Diego, Health and Human Services Agency, Community Epidemiology.