Borderline: Cross-border Mobility and its Link to Transmission of HIV,

Syphilis and TB in the Mexico-US Border Region

Steffanie A. Strathdee, Ph.D.Associate Dean of Global Health Sciences,Harold Simon Professor; Chief, Division of Global Public Health, Department of Medicine, University of California, San Diegosstrathdee@ucsd.edu

Overview

• Unique features about the context of HIV risks along the Mexico/U.S. border

• Recent border studies– HIV– Syphilis– TB

• Influencing policy

U.S.MEXICO

MEXICOU.S.

What makes the Mexico-US border region different?

• Volume of cross-border traffic ~60 million crossings per year

• Major drug trafficking route

• Sex work is quasi-legal

• Main corridor for migration fueled by huge economic disparities

>>Confluence of risk factors for infectious diseases (e.g. HIV, STIs, TB)

Major U.S. Drug Trafficking Routes

Source: National Drug Intelligence Center, National Drug Threat Assessment 2006

Tijuana

Major US Drug Trafficking Routes

Cd. Juarez

Tijuana has one of the fastest Tijuana has one of the fastest growing populations of growing populations of injection drug users (IDUs) in injection drug users (IDUs) in Mexico, with ~21,000 drug Mexico, with ~21,000 drug users, and ~10,000 IDUsusers, and ~10,000 IDUs

Most frequent drug injection sites in Tijuana (n=995)

2/3rds born Outside of Baja California

Place of Birth among Tijuana’s Injection Drug Users

Number of

subjects

HIV and Migration:What is the link?

• Family separation, changes in cultural environment, homelessness, poverty, social isolation, greater sense of anonymity (Deren, 2003; Lagarde, 2003; Organista et al, 2004; Parrado, 2004)

• Mobility can increase the chance of encountering HIV-positive persons (Kottiri et al, 2002)

• Mobile persons can act as bridge populations between groups that normally wouldn’t interact (Paschane, 2000)

• Mobility can change sexual networks in the sending or receiving community (Aral, 2007)

San Diego Tribune, Reuters, CNN, March 1, 2006

ADAPTED FROM: Report on the Global AIDS Epidemic, UNAIDS, 2008

Tijuana

Reasons for moving to Tijuana, by gender

Deportation Economic Opportunities

Family Moved Here

Intended to Cross the Border

to U.S.

Born in the Area

0

5

10

15

20

25

30

35

40

45

50

55

60

%

Gender

Male

Female

Note: 15 males and 7 females listed other reasons.

Factors Independently Associated with HIV infection by Gender

VariableAdjusted

Odds Ratio (Females)

Adjusted Odds Ratio

(Males)

Age 0.84 --

# of arrests for track marks (per 5 arrests)

-- 1.1

Syphilis 4.8 6.2

# of different people usually injects with* (per 5 people)

-- 1.3

Number of years lived in Tijuana (per 10 year increase)

1.9 --

Deportation -- 4.0 All p<0.05

Explanation #1: Is Deportation a marker for a high risk subgroup of male IDUs who acquired HIV

in the US?

Courtesy of La Frontera, 2008

Explanation #2: Is Deportation a Risk Factor for HIV Acquisition?

All photos shared with permission

Impact of deportation on families

HIV Prevalence and Incidence among IDUs in Tijuana: 2006-2008

Pre

vale

nce

Mal

e ID

U

HIV Prevalence

Sex Work in Mexico• Quasi legal in Mexico

– Zone of tolerance (zona roja)– Work permit

• Up to 9000 FSWs in Tijuana,

~4000 in Ciudad Juarez

• Many women/girls from

S. Mexico/Central America

• ‘Sex tourism’ is common

Sex work in the Mexico-US Border Region

• 70% of FSWs in Tijuana and Cd. Juarez are migrants

• Migrant FSWs have:– Lower HIV and STI

prevalence– Less drug use– More condom use

Over time, protective factors associated with being a migrant appear to erode

Ojeda et al, Sex Transm Infect 2009

Factors associated with HIV infection in FSWs in Tijuana and Ciudad Juarez (n=924)

Baseline Characteristics Adjusted Odds Ratio, 95% CI

Injected cocaine past month 2.96 (1.29, 6.80)

Smoked, inhaled, or snorted methamphetamine past month

3.32 (1.85, 5.95)

Syphilis titer >1:8 4.16 (2.28, 7.59)

Patterson et al, J Inf Dis (2008)

**

HIV prevalence: 6%* Consistent with active infectionHIV prevalence: 6%* Consistent with active infection

Male Clients of FSWsin Tijuana and Ciudad Juarez

• 70% of FSWs have U.S. clients

• FSWs with U.S. clients more likely to have:– Syphilis titers ≥ 1:8– Injected drugs– High client volumes– Been paid more for

unprotected sex

Strathdee et al, Sex Trans Dis 2008

Prevalence of HIV testing and HIV/STIs among Mexican (N=200) and U.S. clients (N=200) of Tijuana FSWs

Pre

vale

nc

e

Patterson et al, AIDS 2009

Factors Independently Associated with HIV Infection among Male Clients of

FSWs in Tijuana, Mexico (N=400)

VariableAdjusted Odds

Ratio95% Confidence

Interval

Resides in Mexico (vs. United States)

2.26 0.91–5.58

Lives alone 2.88 1.23–6.71

Ever used methamphetamine 4.34 1.31–14.36

Tested positive for syphilis 9.36 2.41–36.42

Patterson et al, AIDS 2009

CA

AZ NM

TX

SONCHI

COH

TAM

NL

B.C.

3.8

7.4

United StatesNational syphilis incidence: 4.5 (2008)

MexicoNational Syphilis Incidence: 1.2 (2007)

Syphilis Incidence on the U.S.-Mexico Border (Per 100,000)

Sources: CONASIDA, US Centers for Disease Control, SD County Health Dept

San Diego(increasedfrom 3.8 to 11.8 from 2003 to 2007)

5.7

California – Primary and Secondary SyphilisRates by County, 2008

Source: California Department of Public Health, STD Control Branch

Mexico

Prevalence of HIV and lifetime syphilis infection among high risk groups in Tijuana and Cd. Juarez (2004-2009)

Proportion of Lifetime Syphilis Infections with current titers > 1:8* by Risk Group in Tijuana and Cd. Juarez

*Consistent with active infection

ADAPTED FROM: Report on the Global AIDS Epidemic, UNAIDS, 2008

Tijuana

TB - The forgotten epidemic

CA

AZ NM

TX

SONCHI

COH

TAM

NL

B.C.

25.4 18.7

11.7

31.1

57.3

21.9

7.5

4.8 2.6

6.3

United StatesNational TB Incidence: 4.4

MexicoNational TB Incidence: 15.7

TB Incidence on the U.S.-Mexico Border

Source: CDC, USA ,2007 & DGE Mexico, 2004. Incidence per 100,000 population

San Diego(9.0)

HIV and TB Co-infection: What’s the link?

• Of ~42 million people with HIV worldwide, one third also have TB.

• Among HIV+ people, risk of progressing from latent to active TB is 10% per year.

Trends in HIV-TB Co-infection in San Diego by Ethnicity (1993-2007)

Factors independently associated with HIV-TB co-infection in San Diego (1999-2007)*

Characteristic Adjusted* Odds Ratio 95% Confidence Interval

Age in years**30-39 years 3.23 2.11 - 4.95

Male sex 2.86 1.97 - 4.14

Hispanic ethnicity 3.90 2.79 - 5.45

Ever injected drugs 2.30 1.19 – 4.43

*Odds ratios are adjusted for all other variables in the table.**reference group: 20-29 years

Rodwell et al, AJPH 2010

Prevalence of Latent TB Infection (LTBI)* among High Risk Populations in Tijuana, Mexico

Pre

vale

nce

IDU

s(N

=232

)

Non

-IDU

s(N

=311

)

FSW

s(N

=115

)

Hom

eles

s(N

=280

)

LTB

I inc

iden

ce

amon

g ID

Us

(N=5

03)

*Tested through IGRA (Quantiferon Gold), Cellestis Inc; IDUs=injection drug users; FSWs= female sex workers. Garfein et al, Emerg Inf Dis (in press)

Factors associated with tuberculosis infection among high risk groups for HIV in Tijuana: 2007

Characteristic Adjusted* Odds Ratio (95% Confidence Interval)

Age in years 1.03 per yr (1.01 – 1.05)

Years lived in Tijuana 1.02 per yr (1.01 – 1.04)

Location of incarcerationNever jailed 1.00Jailed in US only 1.61 (0.98 – 2.63)Jailed in Mexico, or BOTH

US and Mexico2.28 (1.48 – 3.51)

* Odds ratios are adjusted for all other variables in the table.Garfein et al, in press

Characteristics of Active TB Cases among IDUs in Tijuana (n=103/1060)

Pre

vale

nce

Pre

viou

sly

Dx’

ed

with

Act

ive

TB

Act

ive

TB D

x’ed

in

US

Rec

eive

d A

nti-T

B

Med

s

TB tx

Pre

mat

urel

y

Sto

pped

TB tx

sto

pped

due

to d

epor

tatio

n

Deiss et al, AJPH 2009

Influencing Policy

• Donated a mobile vehicle for HIV prevention to our partner NGO which became the prototype for HIV service delivery across Mexico

The Prevemovihl

2010: Mexico to receive $76 M USD for HIV Prevention

Lessons Learned The Mexico-U.S. border region is vulnerable

to epidemics of HIV, syphilis and TB Cross-border infectious disease transmission

is bi-directional, and depends on factors such as:

Host Agent Environment (physical, social, economic, policy)

Implications Mobility can confer either protection or risk

shaping an individual’s risk of infection. Immigration policies and health policies

should not work at odds. Discrimination and blame represent

significant barriers to prevention and treatment of mobile populations in border regions.

Prevention and treatment for overlapping epidemics requires binational cooperation

Acknowledgements

• UCSD Center for AIDS Research , USAID• National Institutes of Drug Abuse and Mental

Health: K01 DA020364, R01 DA019829, RO1 MH065849 ; T32 DA023356

• Staff from the PrevenCasa, A. C., Patronato Pro-COMUSIDA, UCSD, and Programa Companeros

• San Diego County Public Health Dept• Most importantly, the participants who gave their

time