| Epidemiological Bulletin (Part 2 of 2)
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Syphilis Update
Both the Los Angeles County Area and the Bay Area have been experiencing a resurgence in syphilis over the past 2 years, and this trend is now spilling over into San Mateo County. Sixteen cases of infectious 1°, 2°, or early latent syphilis have been reported in 2001, reflecting a four-fold increase from 2000. All cases were between 20 and 40 years old. Fifteen of these patients were male, 9 (60%) of whom reported sex with other men. Only one case of the sixteen self-reported as being HIV-positive. Ten percent of cases live in the mid- county region, while the remaining were split equally in north county and south county.
We urge practitioners to keep in mind the risk for and symptoms of syphilis in high-risk patients (especially MSM, patients with multiple sexual partners and/or anonymous partners, and anyone with a diagnosis of any STD). Not only is prompt treatment of infectious syphilis essential in stopping the spread of the disease, but equally important is the rapid prophylactic treatment of partners. Furthermore, genital sores caused by syphilis are associated with a 2- to 5-fold increase in risk of acquiring HIV infection.
Beginning in early 2002, San Mateo County will be offering syphilis testing at its HIV Testing Van Sites, in addition to Mobile Clinic Sites, Evening STD Clinic, and Primary Care Clinics. Times and locations of test sites and county clinics can be accessed on our website at http://www.smhealth.org.
MANAGEMENT OF PARTNERS OF PATIENTS WITH SYPHILIS
Sexual transmission of Treponema pallidum occurs only when mucocutaneous syphilitic lesions are present; such manifestations are uncommon after the first year of infection. However, persons exposed sexually to a patient who has syphilis in any stage should be evaluated clinically and serologically according to the following recommendations:
- Persons exposed during the 90 days preceding diagnosis of 1°, 2°, or early latent syphilis in a sex partner may be infected even if seronegative and should be treated presumptively.
- Persons exposed >90 days before diagnosis of 1°, 2°, or early latent syphilis in a sex partner should be treated presumptively if serologic test results are not available immediately and the opportunity for follow-up is uncertain.
- For other situations where diagnosis or treatment is unclear, please call the STD unit at (650) 573-2346.
- Standard treatment of sex partners is typically 2.4 million units of IM benzathine penicillin in a single dose. See http://www.cdc.gov/nchstp/dstd/1998_STD_Guidlines/98m1633.pdf for more information. Syphilis Fact Sheet online: http://www.cdc.gov/nchstp/dstd/Fact_Sheets/ Syphilis_Facts.htm
FDA Panel Supports New Test for Diagnosing Latent TB Infection (LTBI)
If the FDA follows the October 12, 2001 recommendation of its Microbiology Devices Panel, QuantiFERON-TB, a one-step whole-blood interferon gamma assay for LTBI, could be one of the most valuable new tools to fight TB in decades. Gamma interferon is believed to be an indicator of a cellular response to TB infection. The panel's decision was based largely on a recent study reported by Mazurek et al in which quantitative results of both the QuantiFERON-TB assay and tuberculin skin testing (TST) for 1,226 adults were analyzed. In addition to eliminat-ing the need for a second clinical visit and subjectivity of TST placement and reading, the researchers concluded that QuantiFERON-TB was also less affected by BCG vaccination and cross-reactivity with non-TB mycobacteria. QuantiFERON-TB is already available in Australia and New Zealand.
References
1. Mazurek, GH, et. al. Comparison of whole-blood interferon gamma assay with tuberculin skin testing for detecting latent M. tuberculosis infection. 2001: JAMA. 286(14):1740-7.
2. Brock, I, et. al. Performance of whole blood IFN-gamma test for tuberculosis diagnosis based on PPD or the specific antigens ESAT-6 and CFP-10. 2001: Int J Tuberc Lung Dis. 5(5):462-7.
3. Johnson, PD, et. al. Tuberculin-purified protein after M. bovis BCG vaccination and in patients with derivative-, MPT-64, and ESAT-6-stimulated gamma interferon responses in medical students before and tuberculosis. 1999: Clin Diagn Lab Immunol. 6(6):934-7.
4. Pottumarthy, S, et. al. Evaluation of the tuberculin gamma interferon assay: potential to replace the Mantoux skin test. 1999: J Clin Microbiol. 37(10):3229-32.
State Department of Health Services Year 2000 Annual Vector-Borne Disease Report
The State Department of Health Services has released the 2000 report on vector-borne diseases in California. Visit http://www.dhs.cahwnet.gov/ps/dcdc/html/cdtables.htm for monthly reports for 2001. A summary of highlights for 2000 follows.
Hantavirus Pulmonary Syndrome (HPS)
There were eight cases of HPS, two of which were fatal. Three cases may have been exposed out of state. Seven of the eight cases were residents of Southern California. The one patient from Sacramento County had likely been exposed during a camping trip to Yosemite National Park. Fourteen (64%) of 22 counties surveyed found seropositive rodents, including SMC.
Arenavirus
Whitewater Arroyo Arenavirus (WWA), not previously recognized as a human pathogen, resulted in 2 deaths in Riverside and Alameda Counties. Death resulted from respiratory and hepatic failure. WWA infection has been documented in rodent populations in Southern California, and a statewide surveillance campaign has been initiated.
Plague
One case of human plague occurred in Kern County. Seropositive wild carnivores (especially coyotes) and feral pigs were identified in 19 counties (including one in the Bay Area). Wild rodents were seropositive for plague in 6 (28.6%) of 21 counties - either in Southern California or rural counties. Flea eradication efforts were conducted in a number of these counties.
Lyme Disease
95 cases from 32 counties. Highest rates were in Nevada, Humboldt, Mendocino, and Trinity Counties (5 to 10/100,000 person-years). An estimated 78% of cases were exposed in California. Erythema Migrans was noted in 57% of cases, with the majority of rashes seen in May- August. SMC's Health Officer Dr. Scott Morrow currently serves on the state advisory committee on Lyme Disease. SMC typically averages 1-4 cases each year, and has a very low positivity rate for tick surveillance. Visit http://www.dhs.cahwnet.gov/ps/dcdc/pdf/ dhs_lyme_medbd_news_10_2001.pdf for maps and further information.
Babesiosis & Rocky Mountain Spotted Fever
1 confirmed case of each
Ehrlichiosis
No confirmed cases. Tick testing in 4 counties all negative.
Tick-Borne Relapsing Fever
Seven cases were recorded, including some Bay Area residents likely infected in rural counties.
Mosquito-Borne Encephalitides
West Nile Virus Dead bird surveillance has begun in California; all negative to date. WNV is known to have spread as far west as Illinois and Arkansas and as far south as Florida. Up-to-date maps are available online at http://cindi.usgs.gov/hazard/event/west_nile/west_nile.html
St. Louis Encephalitis Occasional positive test results in mosquitoes and sentinel chicken flocks.
Head Lice
Head lice control products containing the pesticide Lindane are prohibited from sale in California beginning in 2002 under legislation signed into law in 2000 by Governor Gray Davis. Head lice guidelines can be found online at http://www.applications.dhs.ca.gov/pressreleases/store/pressreleases/60-01.html
Rabies Preexposure Prophylaxis Guideline Reminders
Animal bites are a frequently encountered public health problem. Preexposure prophylaxis, given intradermally (ID) or intramuscularly (IM) plays an important role in certain groups at risk, and is justified for three of four risk groups (Table I). The rationale behind preexposure prophylaxis is the bestowal of primary immunity that is boosted readily at a later date after exposure to a rabid animal. The immune response to booster injections occurs within several days and confers protection, thus eliminating the need for RIG (rabies immunoglobulin). This is particularly important for travel to remote areas, where access to appropriate wound care and modern biological materials are limited or nonexistent. Currently, there are three rabies vaccines licensed in the United States: IM purified chick embryo cell culture vaccine (PCECV), IM or ID human diploid cell vaccine (HDCV), and IM rabies vaccine adsorbed (RVA). Although preexposure prophylaxis is generally very safe, HDCV may be associated with an immune complex-like reaction in 7% of persons receiving it as a booster. Table I. Rabies preexposure prophylaxis guide, United States, 1999 (Source: CDC)
| Risk Category |
Nature of Risk |
Typical Populations |
Recommendations |
| Continuous |
Virus present continuously, often in high concentrations. Specific exposures likely to go unrecognized. Bite, non-bite, or aerosol exposure. |
Rabies research lab workers, rabies biologic agents production workers. |
Primary course, serologic testing every 6 months. Booster vaccination if antibody titer is below acceptable level. |
| Frequent |
Exposure usually episodic, with the source recognized or unrecognized. Bite, non-bite, or aerosol exposure. |
Rabies diagnostic lab workers, veterinairans and staff, spelunkers, animal control and wildlife workers in rabies enzootic areas. |
Primary course, serologic testing every 2 years. Booster vaccination if antibody titer is below acceptable level. |
| Infrequent, greater than general population |
Exposure is nearly always episodic with a recognized source. Bite or non-bite exposure. |
Veterinarians, animal control and wildlife workers in areas with low rates, veterinary students, travelers to rabies enzootic areas. |
Primary course only. No serologic testing or booster vaccination. |
| Rare, general population |
Exposure always episodic with a recognized source. Bite or non- bite exposure. |
U.S. population at large, including people in rabies epizootic areas. |
No vaccination necessary. |
Although not specified above, preexposure prophylaxis should be considered for international travelers who are likely to come into contact with animals in areas where canine rabies is present and where immediate access to appropriate medical care may be difficult. A good source of information on rabies in various geographic locations is the Centers for Disease Control and Prevention Traveler's Health website at http://www.cdc.gov/travel. Guidelines for optimizing preexposure prophylaxis are:
1. Classify travelers going to developing countries by their risk of rabies exposure. Include those with a higher risk in the frequently exposed group, and conduct RVNA testing and boosting accordingly.
2. Use IM immunization in preference to ID immunization.
3. Use PCECV or RVA in preference to HDCV to prevent immune complex reactions Below is a list of Bay Area clinics where rabies preexposure prophylaxis can be obtained:
Palo Alto Medical (Urgent Care): 795 El Camino Real, Palo Alto (650) 853-2958
Mills/Peninsula Hospital: 1720 El Camino Real, Suite 225, Burlingame (650) 696-5838
Santa Clara County Health Department: 976 Lenzen Avenue, San Jose (408) 792-5200
Travel Health Clinics: 450 Sutter, Room 1723, San Francisco (415) 362-7177
San Francisco International Airport Clinic: (650) 821-5601
SF Health Department Travel Clinic: 101 Grove, Room 405, San Francisco (415) 554-2625
References
1. Centers for Disease Control and Prevention. Human rabies prevention - United States, 1999. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Morb Mortal Wkly Rep. 1999; 48(RR-1):1-21.
2. Gibbons, Robert V., Rupprecht, Charles. Twelve common questions about human rabies and its prevention. Infectious Dis in Clinical Practice. 2000; 9:202-207.
3. Shoff, William H. Preexposure prophylaxis: optimizing protection. Rethinking Rabies Risks: Sharpening Clinical Skills for a Reemerging Threat. SCIENS Worldwide Medical Foundation, 2000:35-36
Epidemiology of Tuberculosis in San Mateo County: Drug Resistance, 1993-2000
Scott Nabity, MPH, Epidemiologist
This is the third in a series of articles dedicated to the epidemiology of TB in San Mateo County. Because a few cases for 2001 are still in the process of being verified, incidence trends including 2001 cases will be reviewed in the next issue of the Bulletin.
During 1993-2000, 611 cases of TB were reported in San Mateo County. During this period, 472 (77.3%) cases had both a positive culture result and drug resistance data available. Among these cases, 325 (68.9%) were susceptible to all first- line drugs (isoniazid-INH, rifampin-RIF, pyrazinamide-PZA, ethambutol-ETH, streptomycin-STR). Forty-five (13.8%) were INH-resistant, 7 (4.5%) were RIF-resistant, and 5 (1.1%) were MDR. There were 46 (9.7%) cases resistant to at least one other first-line drug, with 39 (84.8%) of these resistant to streptomycin. The majority of SM-resistant cases were foreign-born (n=36; 92.3%), presumably because streptomycin as a primary TB drug is used infrequently in the U.S.
Drug-resistant cases are more frequently foreign-born than pan-sensitive cases. One reason is the misuse of anti-TB medications in developing regions of the world. In San Mateo County during 1993-2000, 41/382 (10.7%) of foreign-born cases were INH-resistant compared to 4/90 (4.4%) of US-born cases (p=0.07). Cases resistant to at least one non-INH/ RIF first-line drug showed a similar trend (data not shown). Because previously treated TB cases are at risk for drug resistance either due to incomplete or improper treatment or during a recurrent episode of TB, it is not surprising that 3/ 12 (25%) of cases with a history of TB disease were INH-resistant while 42/460 (9.1%) of those with no previous episode of TB disease were INH-resistant (p=0.19). Again, the same trend is evident for resistance to at least one first-line drug other than INH and RIF (data not shown).
Drug resistant TB is a worldwide problem. The WHO/IUATLD Global Project on Anti-TB Drug Resistance Surveillance sampled culture specimens from 72 locations, and found drug resistant specimens at each geographic site. Between 1996 and 1999, the prevalence of resistance to at least one drug among cases never before treated for TB ranged from 1.7% in Uruguay to 36.9% in Estonia (median=10.7%). MDR-TB among cases not previously treated ranged from 0% in 8% (median=1%). High prevalence of MDR-TB was observed at sites in China (10.8%), Latvia (9%), Russia (6.5% and 9%), and Iran (5%). Resistance among previously treated cases was more troubling: resistance to at least one drug ranged from 0% in Finland to 94% in Uruguay (median=23.3%), and MDR-TB ranged from 0% in four geographic settings to 48.2% in Iran (median=9.3%). The full WHO/IUATLD report including maps can be downloaded online at http://www.who.int/gtb/publications/drugresistance/index.htm.
Widely accepted as the best method for preventing the development of drug resistance, and perhaps the most cost- effective public health intervention, directly observed therapy (DOT) programs have expanded substantially in the US since being introduced in the 1980s. The proportion of San Mateo County patients who received DOT has doubled from 26% in 1993 to 50% in 1998, averaging more than 26 weeks of DOT. Currently, about ? of all TB patients receive DOT.
DOT is a service available to all TB patients and medical providers in San Mateo County at no charge. Dedicated TB staff work directly with patients, their families, and their physicians to ensure that each dose is taken appropriately, adherence to therapy and completion verified, and every patient completing therapy is cured. In addition, DOT workers are invaluable in helping to provide information to patients and bringing possible medication side effects to the attention of providers. Clinicians should be aware that any patient can be non-adherent. Research has shown that clinical predictions regarding adherence to therapy are correct only 50% of the time, which is no greater than chance. For more information on DOT services in San Mateo County, please contact Lois Korhonen, Sr. PHN, at (650) 573-2231.
Taken together, these data indicate that TB control practices abroad combined with international migration have an impact on local TB control practices in the US, and stress the importance of DOT.
References
1. US Dept. of Health & Human Services. Core Curriculum on Tuberculosis, 4th Ed. CDC (2000). pp. 120-4.
2. The WHO/IUATLD Global Project on Anti-Tuberculosis Drug Resistance Surveillance. Anti-Tuberculosis Drug Resistance in the World, Report 2: Prevalence and Trends. WHO:2000.
3. Selvin, S. Statistical Analysis of Epidemiologic Data, 2nd Ed. Oxford: Oxford University Press (1996). pp. 237-8.
4. Haynes, RB, et. al. Compliance in health care. Baltimore: The Johns Hopkins University Press (1979).
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