This alert is to notify providers of an outbreak of isoniazid-resistant tuberculosis (TB) among Oaxacan persons in the northern region of Santa Barbara County. To date, nine active TB cases have been identified within this community; 5 of the cases have epidemiologic links and the same genetic pattern on their TB isolate, suggesting the same chain of TB transmission. All case-patients are residents of Santa Barbara County, aged 1-79 years old, and all are ethnically Oaxacan (persons from a region in Mexico who often speak Mixteco and do not speak Spanish.) The Santa Barbara County Public Health Department has been conducting an ongoing investigation of this outbreak and is asking medical providers within North County to have an increased suspicion for TB in patients from the Oaxacan community who present with TB symptoms, both in children and adults.

Pediatric Cases

There have been multiple pediatric TB cases as a result of this outbreak. TB in children, both pulmonary and extra-pulmonary, can present in a variety of ways: failure to thrive, poor appetite or weight loss, lethargy, lymph node swelling, cough, fever, or night sweats. The most common form of TB occurs in the lungs, but TB disease can affect other parts of the body as well (organs, bones, lymph nodes.) Importantly, abnormal chest x-rays in children with active pulmonary TB may only show hilar or mediastinal lymphadenopathy. We recommend pediatric providers have a low threshold for TB testing in children from the Oaxacan community.

TB Screening: We are recommending TB screening using the Tuberculin Skin Test (TST) in all Oaxacan patients living in North County who do not have a history of a positive TB test. The Quantiferon-Gold blood test (QFT) may be used in lieu of the TST in persons aged 5 years or older.

If a screening test is positive, a chest x-ray (CXR) should be done. Chest radiography findings in TB disease include, but are not limited to, the following:

•     Abnormalities in the apical or posterior segments of the upper lobes, or superior segments of the lower lobes

•     Cavitary lesions

•     Miliary pattern (i.e., fine, rounded opacities, that may have shape of millet seeds)

•     Reticulonodular infiltrates

•     Hilar or mediastinal lymphadenopathy (note: this may be the only radiographic abnormality detected among children)

Patients with HIV and TB disease commonly have normal chest radiography findings, and children often have subtle radiographic abnormalities.

Drug Resistance

Of the nine active TB cases within the Oaxacan Community, 4 (44%) are resistant to Isoniazid (INH). Accordingly, patients determined to have Latent TB Infection (LTBI) as a result of exposure to a drug resistant case must be placed on an alternative LTBI treatment regimen, such as Rifampin.

LTBI Treatment

For persons from a Oaxacan background who have LTBI but are not known to be contacts to outbreak case-patients, treatment with isoniazid (INH) is still appropriate.

Public Health Outbreak Response Plan: The SBCPHD, in consultation with the California Department of Public Health (CDPH), is formulating a strategic response plan to interrupt TB transmission and stop the outbreak. We will be asking community stakeholders to partner with us in this effort.

Reporting TB Suspects: Any person suspected of having active TB should be reported immediately to Disease Control. For further clinical guidance please call the Santa Barbara County Public Health Department Disease Control and Prevention at (805) 681-5280.

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Author: Jeremy Farnum, Information Systems

Jeremy works for Lompoc Valley Medical Center.

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