Prevalence of SARS-CoV-2 infection in Baja California, Mexico: Findings from a community-based survey in February 2021 in the Mexico-United States border.

Between March 2020 and February 2021, the state of Baja California, Mexico, which borders the United States, registered 46,118 confirmed cases of COVID-19 with a mortality rate of 238.2 deaths per 100,000 residents. Given limited access to testing, the population prevalence of SARS-CoV-2 infection is unknown. The objective of this study is to estimate the seroprevalence and real time polymerase chain reaction (RT-PCR) prevalence of SARS-CoV-2 infection in the three most populous cities of Baja California prior to scale-up of a national COVID-19 vaccination campaign. Probabilistic three-stage clustered sampling was used to conduct a population-based household survey of residents five years and older in the three cities. RT-PCR testing was performed on nasopharyngeal swabs and SARS-CoV-2 seropositivity was determined by IgG antibody testing using fingerstick blood samples. An interviewer-administered questionnaire assessed participants' knowledge, attitudes, and preventive practices regarding COVID-19. In total, 1,126 individuals (unweighted sample) were surveyed across the three cities. Overall prevalence of SARS-CoV-2 infection by RT-PCR was 7.8% (95% CI 5.5-11.0) and IgG seroprevalence was 21.1% (95% CI 17.4-25.2). There was no association between border crossing in the past 6 months and SARS-CoV-2 prevalence (unadjusted OR 0.40, 95%CI 0.12-1.30). While face mask use and frequent hand washing were common among participants, quarantine or social isolation at home to prevent infection was not. Regarding vaccination willingness, 30.4% (95% CI 24.4-3 7.1) of participants said they were very unlikely to get vaccinated. Given the high prevalence of active SARS-CoV-2 infection in Baja California at the end of the first year of the pandemic, combined with its low seroprevalence and the considerable proportion of vaccine hesitancy, this important area along the Mexico-United States border faces major challenges in terms of health literacy and vaccine uptake, which need to be further explored, along with its implications for border restrictions in future epidemics.

Surveillance or support: The experience of direct observation during tuberculosis treatment.

Directly observed therapy (DOT) is a cornerstone of tuberculosis (TB) control. DOT has been criticised as paternalistic, but it has also been argued that the interaction with healthcare workers (HWs) can be a source of support for patients. We explored the experience of patients in antituberculosis treatment, with the aim of understanding the balance between surveillance and support from the recipient's point of view. We interviewed 27 patients in Tijuana, Mexico, employing narrative analysis to understand how participants made sense of their illness and their experience of DOT. We found a core narrative of biographic disruption and self-reconstruction, in which HWs helped participants to attribute a less negative meaning to TB. Interviewees accepted DOT's as necessary for other people to avoid treatment abandonment, but felt that in their case it was unnecessary. Only a few felt that DOT represented mistrust on the part of the HWs. We conclude that DOT can be a source of support when it is enacted in a patient-centred way. We discuss whether participants' lack of criticism of DOT is a case of adaptive preference, in the context of a power differential between patient and health system.

Multidrug-resistant tuberculosis among patients in Baja California, Mexico, and Hispanic patients in California.

OBJECTIVES: We sought to compare prevalence and determinants of multidrug-resistant tuberculosis (MDR-TB) between tuberculosis patients in Baja California, Mexico, and Hispanic patients in California. METHODS: Using data from Mexico's National TB Drug Resistance Survey (2008-2009) and California Department of Public Health TB case registry (2004-2009), we assessed differences in MDR-TB prevalence comparing (1) Mexicans in Baja California, (2) Mexico-born Hispanics in California, (3) US-born Hispanics in California, and (4) California Hispanics born elsewhere. RESULTS: MDR-TB prevalence was 2.1% in Baja California patients, 1.6% in Mexico-born California patients, 0.4% in US-born California patients, and 2.7% in Hispanic California patients born elsewhere. In multivariate analysis, previous antituberculosis treatment was associated with MDR-TB (odds ratio [OR] = 6.57; 95% confidence interval [CI] = 3.34, 12.96); Mexico-born TB patients in California (OR = 5.08; 95% CI = 1.19, 21.75) and those born elsewhere (OR = 7.69; 95% CI = 1.71, 34.67) had greater odds of MDR-TB compared with US-born patients (reference category). CONCLUSIONS: Hispanic patients born outside the US or Mexico were more likely to have MDR-TB than were those born within these countries. Possible explanations include different levels of exposure to resistant strains and inadequate treatment.

Tuberculosis testing among populations with high HIV risk in Tijuana, Baja California, Mexico.

OBJECTIVE: To assess the prevalence of prior tuberculin skin testing (TST) among populations at risk for HIV infection in Tijuana, Mexico, and to identify factors associated with TST. METHODS: Sex workers, injection drug users, noninjecting drug users, and homeless persons > 18 years old were recruited by using targeted sampling for risk assessment interviews and serologic testing for HIV and Mycobacterium tuberculosis infection. Univariate and multivariate logistic regression were used to identify correlates of self-reported TST history. RESULTS: Of 502 participants, 38.0% reported prior TST, which was associated with previous incarceration in the United States of America [odds ratio (OR) = 13.38; 95% confidence interval (CI) = 7.37-24.33] and injection drug use (OR = 1.99; 95% CI = 1.27- 3.11). Positive results on serologic tests for M. tuberculosis infection (57%) and HIV (4.2%) were not associated with a prior TST. CONCLUSIONS: A history of TST was lower in HIV-positive participants even though TST is indicated for persons with HIV in Mexico. Fewer than half the individuals at high risk for HIV in this study had a history of TST; however, TST was fairly common among those individuals with a prior history of incarceration. Increased tuberculosis screening is needed for populations at risk of contracting HIV in Tijuana, particularly those outside of criminal justice settings.

Tuberculosis testing among populations with high HIV risk in Tijuana, Baja California, Mexico / Prueba de tuberculosis en poblaciones con riesgo alto de VIH en Tijuana, Baja California, México

OBJECTIVE: To assess the prevalence of prior tuberculin skin testing (TST) among populations at risk for HIV infection in Tijuana, Mexico, and to identify factors associated with TST. METHODS: Sex workers, injection drug users, noninjecting drug users, and homeless persons > 18 years old were recruited by using targeted sampling for risk assessment interviews and serologic testing for HIV and Mycobacterium tuberculosis infection. Univariate and multivariate logistic regression were used to identify correlates of self-reported TST history. RESULTS: Of 502 participants, 38.0% reported prior TST, which was associated with previous incarceration in the United States of America [odds ratio (OR) = 13.38; 95% confidence interval (CI) = 7.37-24.33] and injection drug use (OR = 1.99; 95% CI = 1.27- 3.11). Positive results on serologic tests for M. tuberculosis infection (57%) and HIV (4.2%) were not associated with a prior TST. CONCLUSIONS: A history of TST was lower in HIV-positive participants even though TST is indicated for persons with HIV in Mexico. Fewer than half the individuals at high risk for HIV in this study had a history of TST; however, TST was fairly common among those individuals with a prior history of incarceration. Increased tuberculosis screening is needed for populations at risk of contracting HIV in Tijuana, particularly those outside of criminal justice settings.

OBJETIVO: Evaluar la prevalencia de la prueba de la tuberculina previa, e identificar los factores asociados con ella, en poblaciones con riesgo de infección por el VIH en Tijuana, México. MÉTODOS: Se reclutó a profesionales del sexo, consumidores de drogas inyectables y no inyectables y personas sin hogar > 18 años de edad mediante un muestreo dirigido a fin de efectuar entrevistas para evaluar el riesgo y pruebas serológicas para la infección por el VIH y Mycobacterium tuberculosis. Para identificar la correlación de los antecedentes de la prueba de la tuberculina proporcionados por el propio individuo se usó regresión logística de una sola variable y con múltiples variables. RESULTADOS: De 502 participantes, 38,0% informaron una prueba de la tuberculina previa, que se asoció con encarcelamiento anterior en los Estados Unidos de América (razón de posibilidades [OR] = 13,38; intervalo de confianza de 95% [IC] = 7,37-24,33) y consumo de drogas inyectables (OR = 1,99; IC de 95% = 1,27-3,11). Los resultados positivos en las pruebas serológicas para la infección con M. tuberculosis (57%) y VIH (4,2%) no se asociaron con una prueba de la tuberculina previa. CONCLUSIONES: Los antecedentes de una prueba de la tuberculina fueron menores en los participantes seropositivos para el VIH, a pesar de que en México esta prueba está indicada en las personas con VIH. En este estudio menos de la mitad de los individuos con alto riesgo de VIH tenían antecedentes de la prueba de la tuberculina; sin embargo, esta fue bastante frecuente en los individuos con antecedentes de encarcelamiento. En las poblaciones en riesgo de contraer el VIH en Tijuana se requiere un mayor tamizaje de tuberculosis, en particular en aquellas no relacionadas con el ambiente de la justicia penal.

Pandemic (H1N1) 2009 Surveillance in Marginalized Populations, Tijuana, Mexico.

To detect early cases of pandemic (H1N1) 2009 infection, in 2009 we surveyed 303 persons from marginalized populations of drug users, sex workers, and homeless persons in Tijuana, Mexico. Six confirmed cases of pandemic (H1N1) 2009 were detected, and the use of rapid, mobile influenza testing was demonstrated.

Latent tuberculosis among persons at risk for infection with HIV, Tijuana, Mexico.

Because there is little routine tuberculosis (TB) screening in Mexico, the prevalence of latent TB infection (LTBI) is unknown. In the context of an increasing HIV epidemic in Tijuana, Mexico, understanding prevalence of LTBI to anticipate emergence of increased LTBI reactivation is critical. Therefore, we recruited injection drug users, noninjection drug users, female sex workers, and homeless persons for a study involving risk assessment, rapid HIV testing, and TB screening. Of 503 participants, the overall prevalences of TB infection, HIV infection, and TB/HIV co-infection were 57%, 4.2%, and 2.2%, respectively; no significant differences by risk group (p>0.05) were observed. Two participants had TB (prevalence 398/100,000). Incarceration in Mexico (odds ratio [OR] 2.28), age (OR 1.03 per year), and years lived in Tijuana (OR 1.02 per year) were independently associated with TB infection (p<0.05). Frequent LTBI in marginalized persons may lead to increases in TB as HIV spreads.

Tracing the origins of Mycobacterium bovis tuberculosis in humans in the USA to cattle in Mexico using spoligotyping.

OBJECTIVES: To compare genotypes of Mycobacterium bovis strains from humans in Southern California with genotypes of M. bovis strains in cattle in Mexico and the USA to explore the possible origins of human infections. METHODS: We conducted a descriptive analysis of M. bovis genotypes from a binational population of humans and cattle using spacer oligonucleotide typing (spoligotyping). RESULTS: One hundred six human M. bovis spoligotypes were compared to spoligotypes from 496 Mexican cattle and 219 US cattle. Twelve spoligotype patterns were identified among human cases and 126 spoligotype patterns were detected in cattle. Over 91% (97/106) of the human M. bovis isolates had spoligotypes that were identical to those found in Mexican cattle. Four human cases had spoligotypes that matched both cattle born in Mexico and in the USA. Nine human cases had spoligotypes that did not match cattle born in Mexico or the USA. CONCLUSIONS: Our data indicate that the population of M. bovis strains causing human TB disease in Southern California is closely related to the M. bovis strain population found in Mexican cattle and supports existing epidemiological evidence that human M. bovis disease in San Diego likely originated from Mexican cattle.

Influences of cross-border mobility on tuberculosis diagnoses and treatment interruption among injection drug users in Tijuana, Mexico.

OBJECTIVES: We sought to identify correlates of reported lifetime diagnoses of TB among injection drug users in the border city of Tijuana, Mexico. METHODS: Injection drug users in Tijuana were recruited into a prospective cohort study during 2006 and 2007. We used weighted multivariate logistic regression to identify correlates of TB diagnoses. RESULTS: Of the 1056 participants, 103 (9.8%) reported a history of TB, among whom 93% received anti-TB medication and 80% were diagnosed in the United States. Treatment was prematurely halted among 8% of patients; deportation from the United States was the cause of half of these treatment interruptions. History of travel to (odds ratio [OR] = 6.44; 95% confidence interval [CI] = 1.53, 27.20) or deportation from (OR = 1.83; 95% CI = 1.07, 3.12) the United States and incarceration (OR = 2.20; 95% CI = 1.06, 4.58) were independently associated with a reported lifetime diagnosis of TB. CONCLUSIONS: Mobility and migration are important factors in identifying and treating TB patients diagnosed in the US-Mexico border region. Strengthening capacity on both sides of the border to identify, monitor, and treat TB is a priority.

Tuberculosis from Mycobacterium bovis in binational communities, United States.

The epidemiology of tuberculosis (TB) in the United States is changing as the incidence of disease becomes more concentrated in foreign-born persons. Mycobacterium bovis appears to be contributing substantially to the TB incidence in some binational communities with ties to Mexico. We conducted a retrospective analysis of TB case surveillance data from the San Diego, California, region from 1994 through 2005 to estimate incidence trends, identify correlates of M. bovis disease, and evaluate risk factors for deaths during treatment. M. bovis accounted for 45% (62/138) of all culture-positive TB cases in children (<15 years of age) and 6% (203/3,153) of adult cases. M. bovis incidence increased significantly (p = 0.002) while M. tuberculosis incidence declined (p<0.001). Almost all M. bovis cases from 2001 through 2005 were in persons of Hispanic ethnicity. Persons with M. bovis were 2.55x (p = 0.01) as likely to die during treatment than those with M. tuberculosis.