The rates of vertical transmission of HIV have steadily declined over the last 10 years in developed countries because of wide implementation of mother-to-child transmission prophylaxis. The CDC has estimated that as of 2002, there have been 144–236 HIV-infected children born in the United States per year.1 Recent Canadian and European studies demonstrate that in countries of low pediatric HIV incidence, migration-related HIV infection in children contributes to the epidemic.2–4
The estimated rate of AIDS cases in the District of Columbia is one of the highest in the nation, reaching 128.4 per 100,000 population in 2005.5–7 Concurrently, the Washington metropolitan area has become a popular destination for immigrants in the United States. By 2000, immigrants comprised 17% of the region's population, making the area the 7th largest immigrant gateway in the United States.8 This study was conducted to assess the proportion of immigrant mothers among new cases of pediatric HIV infection at Children's National Medical Center (CNMC) in Washington, DC from 2000 through 2005 and to compare characteristics of the children born to mothers of U.S. origin and immigrant mothers.
PATIENTS AND METHODS
The Special Immunology Service (SIS) at CNMC provides counseling, testing, and clinical care for the majority of HIV exposed and infected children in the metropolitan Washington DC area. Since 1985, the SIS has diagnosed and cared for more than 600 HIV-infected children.
We conducted a retrospective, observational cohort analysis of new pediatric (birth to 13 years of age) HIV cases from 2000 through 2005. New cases were defined as HIV-positive children referred to the SIS for diagnostics and medical care including those with established HIV infection who were new to the SIS. Medical records were reviewed using a standardized questionnaire. No subject contact was involved. The mothers were defined as immigrant if they were born outside of the United States (non-U.S. origin). Information regarding immigration status was not collected. The study was reviewed and approved by the CNMC Institutional Review Board (IRB).
The child's date and country of birth, gestational age, race, gender, age and place of HIV diagnosis, postnatal antiretroviral therapy (ART), clinical and immunologic (CD4+ T-cell percentage, CDC classification), and virologic (Log10 viral load and HIV clade) parameters at the time of initial presentation at CNMC were recorded. Maternal data included the country of origin, age at the time of HIV diagnosis, age at delivery, mode of delivery, history of breast-feeding, illicit drug use, history of ART before pregnancy and mother-to-child transmission (MTCT) prophylaxis.
Descriptive statistics were used to analyze the patient and mother populations, and t tests were used to compare the mean age, CD4+ cell percentage, and Log10 Viral load (VL) with the maternal immigrant history (U.S. origin/immigrant), and child's place of birth (United States versus non-United States). Fisher exact test andχ2 test were performed to compare proportions across places of origin and birth.
From 2000 through 2005, 84 pediatric cases (<13 years of age) of HIV infection were referred to CNMC. Sixty-five children were diagnosed with HIV at CNMC, and 19 established HIV infections were confirmed. Twenty-eight (33.3%) of the children were born to immigrant mothers. Among the HIV positive children of immigrant mothers, 10 children were born in the United States. The number of new HIV cases ranged from 12 to 15 cases per year, and the proportion of children of immigrant mothers was between 30% and 47% per year. All cases were caused by type HIV-1 infection and 83 were due to vertical transmission. In 1 case of child born abroad, a neonatal blood transfusion was believed to have caused the infection.
Fifty-six mothers (66.7%) were born in the United States, 25 (29.7%) were from African countries and 3 (3.6%) from Latin American countries (Honduras, El Salvador, and Trinidad). African countries of origin included Nigeria (n = 5), Ethiopia (n = 3), Tanzania (n = 3), Zambia (n = 3), Zimbabwe (n = 2), Cameroon (n = 2), Sierra Leone (n = 2), Ivory Coast, Kenya, Senegal, South Africa, and Togo (each n = 1).
The recovery rate of data on maternal health, ART, and perinatal histories varied from 60% to 80%. Demographic, clinical, and prevention of mother-to-child transmission (PMTCT) profiles of the mothers of U.S. origin and immigrant mothers and their children are represented in Table 1 (available online only). The table also compares the characteristics of children of immigrant mothers based on place of birth.
Maternal age at the time of delivery, rates of cesarean-section, and the mean time between HIV diagnosis and delivery were similar for immigrant and nonimmigrant mothers. Seventeen mothers of U.S. origin (30.4%) had a history of illicit drug use, including intravenous injections, while none of the immigrant mothers used drugs (P < 0.001). None of the immigrant mothers and only 7.1% of mothers of U.S. origin received ART before pregnancy. Significantly more immigrant mothers who delivered their children in the United States (70%) received ART ever before, during the pregnancy, and during and after birth compared with immigrant mothers who delivered abroad (11.1%). None of the immigrant mothers who gave birth outside of the United States received PMTCT. The rates of antiretroviral (ARV) prophylaxis during pregnancy, labor, and delivery were equally low in immigrant mothers and mothers of U.S. origin.
All children born to mothers of U.S. origin received their HIV diagnosis in the United States, while 3 children born to immigrant mothers were diagnosed in Nigeria2 and Ethiopia.1 Ninety-five percent of children were black, and the mean age at HIV diagnosis was comparable between the children of mothers of U.S. origin and immigrant mothers. Of the children born to immigrant mothers, those born abroad were diagnosed at a significantly later age (5.5 ± 3.2 years) as compared with U.S.-born children (2.0 ± 3.7 years) (P = 0.014). The children of immigrant mothers born in the United States had significantly higher Log10 viral loads than children born outside of the United States, which corresponds with an earlier age at the time of diagnosis. There were no significant differences in CD4+ T-cell percentage and CDC clinical category between the children of immigrant mothers and mothers of U.S. origin.
HIV clade information was available for 30 children. All children born to mothers of U.S. origin had HIV clade B, while 6 African children had Clade C (2-Ethiopia, 1-Ivory Cost, 1-Zambia), Clade CRF02-AG (1-Zambia) and Clade A1 identified (1-Cameroon). Significantly fewer non-U.S.-born children received postnatal ARV prophylaxis as compared with U.S.-born children (11.1% versus 60% respectively, P = 0.032). Fourteen (50%) children of immigrant mothers were breast-fed including 2 children born in the United States, and all children of mothers of U.S. origin received exclusive formula feeding (P < 0.001). The rates of prematurity (<37 weeks gestation) were significantly higher for U.S.-born (50%) when compared with non-U.S.-born children (11.1%) of immigrant mothers (P = 0.06). No comorbidities with tuberculosis or malaria were reported in the children of immigrant mothers.
Our findings of a significant proportion of cases of HIV infection among children of immigrant mothers (33.3%) are similar to data from Canada and Europe.2–4 Although the majority of the metropolitan DC immigrants come from Latin America,8 the children of mothers of African origin constituted the largest proportion of new HIV cases among children of immigrant mothers. This difference might be explained by the representative rates of HIV infection in the countries of origin.9
The low rates of PMTCT (not taken, insufficient, or taken too late) were similar between the immigrant mothers and mothers of U.S. origin. The review of the charts provided limited information regarding the cause of missed ARV prophylaxis, primarily because of the fact that many children presented to the clinic with a foster parent or legal guardian, and not the mother. Lack of prenatal care and late diagnostics of HIV infection seem to be the most plausible explanations of PMCTC failure. The higher rate of prematurity among the U.S.-born children observed in our study is most likely related to the fact that premature children born in resource-limited countries have higher mortality rates, and therefore, did not enter the study cohort.
With both U.S.-origin and immigrant mothers represented primarily by black minority population, the rates of the maternal illicit drug use were significantly different between both groups, with all the cases reported in the mothers of U.S. origin. Two of the 10 (20%) immigrant mothers that gave birth in the United States were breast-feeding their infants despite recommendations to use exclusive formula feeding. This difference in risk behavior needs to be recognized to focus effective prevention messages to black women of different cultural and behavioral background.
1.Center for Disease Control and Prevention (CDC). Achievements in public health: reduction in perinatal transmission
of HIV Infection
—United States, 1985–2005. MMWR Morb Mortal Wkly Rep.
2.MacPherson DW, Zencovich M, Gushulak BD. Emerging pediatric HIV epidemic related to migration. Emerg Infect Dis
3.Macassa E, Burgard M, Veber F, et al. Characteristics of HIV-infected children
recently diagnosed in Paris, France. Eur J Pediatr
4.Cortina-Borja M, Cliffe S, Tookey P, Williams D, Cubitt WD, Peckham C. HIV prevalence in pregnant women in an ethically diverse population in the UK: 1998–2002. AIDS
5.HIV/AIDS Epidemiological Profile for Washington, DC. Supplemental Report. Washington, DC: Department of Health; 2004. Available at: http://doh.dc.gov/doh/site/default.asp
. Accessed August 26, 2007.
7.AIDS Cases, by Geographic Area of Residence and Metropolitan Statistical Area of Residence, 2004. Centers for Disease Control and Prevention. HIV/AIDS Surveillance Report, 2005. Vol. 12. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention. Available at: http://www.cdc.gov/hiv/topics/surveillance/resources/reports
. Accessed August 26, 2007.