Examine a dynamic of mother-to-child transmission of HIV in the population-based surveys

doi:10.4236/ojpm.2011.13021

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Vol.1, No.3, 164-166 (2011)

doi:10.4236/ojpm.2011.13021

Open Journal of Preventive Medicine

Examine a dynamic of mother-to-child transmission of

HIV in the population-based surveys

Rathavuth Hong1*, Rathnita Them2

1Measure Demographic and Health Survey, ICF Macro, Calverton, USA;

*Corresponding Aut h o r : [email protected]

2College of Health and Human Services, George Mason University, Fairfax, USA.

Received 29 June 2011; revised 23 September 2011; accepted 14 October 2011.

ABSTRACT

The main source of HIV infection in young chil-

dren is of their mothers, during pregnancy, la-

bor and delivery, or by breastfeeding. The rate

of HIV transmission from infected mothers to

their newborn children varies from 15% to 40%

with one-thirds of these infections was through

breastfeeding. This paper examines cross-sec-

tional population-based survey data of HIV test

results among mothers and their children in

Uganda, Swaziland to estimates of mother-to-

child transmission (MTCT) rate of HIV infection.

The prevalence of HIV among women aged 15 -

49 who gave birth in the past 5 years in Uganda

is 7.3%, and in Swaziland is 37.9%. The HIV

prevalence of children who mothers were HIV

positive were very similar: 10.3% in Uganda and

11.5 % in Swaziland. This association represents

the crude rate of MTCT in these two countries at

the time of the survey. Presence of HIV antibody

in early age (0 - 11 months) is due to both true

infection and passive antibody from mothers.

The seroconversion dropped nearly half in the

second year of age which was likely that many

of these children died before reaching the age

of 12 - 23 months and passive antibody were

gradually cleared at this point. This analysis

demonstrated that cross-sectional data can be

used to estimate indirectly the magnitude and

dynamic of MTCT.

Keywords: HIV/AIDS; Mother-to-Child;

Transmiss ion; Demographic and Health Survey;

Uganda; Swaziland

1. INTRODUCTION

The source of HIV infection in young children is

overwhelming of their mothers, during pregnancy, labor

and delivery, o r by breastfeeding. In the region where the

rate of HIV infection among pregnant women is very high,

for example exceeds 35%, HIV/AIDS infection contrib-

utes to as high as 42% of child mortality [1]. In develop-

ing countries, the rate of HIV transmission from infected

mothers to their newborn children varies from study to

study, and is estimated from about 15% to 40%. Among

those children who are infected HIV through the trans-

mission from their mothers, one-third received the virus

through breastfeeding [2].

We examine whether data on HIV testing in the

cross-sectional data such as population-based survey

provide good estimates of mother-to-child transmission

(MTCT) rate of HIV infection. The testing procedure

used two ELISAs parallel testing algorithm according to

WHO testing algorithm. All discordant samples were

subjected to a second round of testing using both tests.

The discordances from the second round are “indeter-

minate” and were then subjected to a third confirmatory

Western-Blot test. The Western-Blot result was consid-

ered final for the indeterminate samples.

2. METHODS

2.1. Data

We used data from the 2004-2005 Uganda HIV/AIDS

Sero Behavioural Survey (UHSBS) and from the 2006

Swaziland Demographic and Health Survey (SDHS).

These are national representative household surveys that

include HIV testing among children and adults. UHSBS

tested HIV among 8,374 children aged 0 - 59 months,

10,227 women age 15 - 59 years, and 8,298 men age 15 -

59 years in a random sample of 9,529 households across

the country. Information on birth history from the women

questionnaire was used to establish the link between

mothers and her biological children for the analysis of

this study.

2.2. Statistical Methods

Statistical analysis was performed using Stata 10.0

R. Hong et al. / Open Journal of Preventive Medicine 1 (20 11) 164-166

165

Table 1. Association of children’s HIV status with mother’s HIV status, Uganda AIS 2004-2005 and Swaziland DHS 2007.

Uganda (0 - 59 months) Swaziland (24 - 59 months)

Variable Percentage HIV positive Number of children Percentage HIV positive Number of children

Mother’s HIV status

Negative 0.14 6607 0.79 345

Positive 10.25 364 11.52 176

Not tested/missing 0.76 1403 6.57 306

Total 0.68 8374 5.20 827

Table 2. Association of children’s HIV status with mother’s HIV status, by age of the child, Uganda AIS 2004-2005.

Mother HIV's status

Child's age (month) HIV negative HIV positive Unknown, died Unknown, survived Number

0-11 0.00 19.44 0.00 3.02 1631

12-23 0.47 10.24 0.00 0.00 1484

24-35 0.26 14.52 6.33 0.46 1667

36-47 0.00 6.37 6.35 0.43 1742

48-59 0.00 2.51 3.35 0.37 1849

Total 0.14 10.25 4.40 0.54 0.68

Number 6607 364 80 1323 8374

(Stata Corp., College Station, TX). Bivariate analyses

were conducted to identify the relationship of the

HIV-positive status between the children and the moth-

ers at the time of the survey, and the HIV prevalence

among the children by age group.

3. RESULTS

In the 2004-2005 Uganda HIV/AIDS Sero-Behav-

ioural Survey (UHSBS), 8,374 children age 0 - 59

months from a random sample of 9,529 households were

tested for HIV virus with valid test results [3]. The

prevalence of HIV infection in women aged 15 - 49 is

7.5%, in women aged 15 - 49 who gave birth in the 5

years before the survey is 7.3%, and in children age 0 -

59 months was 0.7%. In the 2006 Swaziland Demo-

graphic and Health Survey (SDHS), only 827 children

age 24 - 59 months were tested for HIV [4], of whom

5.2% were positive. In Swaziland the HIV prevalence is

31.1 percent among all women aged 15 - 49: 37.9%

among women who gave birth in the last 5 years and

26.0% among those who did not.

In UHSBS, 83% of HIV tested children, their bio-

logical mothers were also tested for HIV with valid test

results; 16% of the children, their mothers were not

tested or results were missing, or they were absent at the

time of testing; and abou t 1 percent of the children, their

mothers died before the survey. In Swaziland, 63% of

HIV tested children; their biological mothers were also

tested for HIV with valid test results available. In spite

of differences in prevalence of adult women and children

less than 5 founded in the two surveys, the HIV preva-

lence of children who mothers were HIV positive were

very similar: 10.3% in Uganda and 11.5% in Swaziland.

Results in Table 1 show strong relationship between HIV

positive status of the ch ildren and HIV positive status of

their biological mother. Nonetheless, there were a small

number of children (0.14% in Uganda and 0.79% in

Swaziland) who were tested positive for HIV, whereas

their biological mothers were tested negative for HIV.

This observed discordance could caused by false posi-

tive (among the children) and false negative (among the

mothers); or by HIV infection afterbirth in children, for

example by unsterile or used syringes and needles. The

association between HIV positive mother and HIV posi-

tive children repr esents the crude rate of MTCT in these

two countries at the time of the survey. At the time of

study the preventive MTCT (PMTCT) programs were

implemented only in some part of these two countries.

However, data on breastfeeding and on PMTCT program

is not available in these surveys; and attrition of breast-

feeding and impact of PMTCT on the transmission rate

are unknown.

R. Hong et al. / Open Journal of Preventive Medicine 1 (20 11) 164-166

166

4. DISCUSSION

In these cross-sectional data, it is usually not possible

to establish a longitudinal association of HIV infection

in children and their mothers. Nonetheless, in Uganda

where the sample is quite large and includes children age

from 0 - 4 years old, the HIV test results among these

children can be estimated by age group of 0 - 11, 12 - 23,

24 - 35, 36 - 47, 48 - 59 months (age in single month is

not available) in order to understand some dynamic of

the infection.

About 19.4% of children aged 0 - 11 months of the

HIV positive mothers were tested positive. Presence of

HIV antibody in early age is due to both true infection

and passive antibody from mothers. The seroconversion

among children aged 12 - 23 months dropped nearly half

to only 10.2 %. It was very likely that these children had

the same positive rate as those aged 0 - 11 months, when

they were at that age group. Therefore this drop in sero-

conversion could be a result of (1) many infected chil-

dren were died before reaching the age of 12 - 23

months and (2) children were tested positive due to pas-

sive antibody from the mothers were gradually cleared

of this passive antibody. Study elsewhere also indicates

that children who are HIV positive after birth, about

23% became seronegative when they are nine months

old [5]. The proportion of children aged 24 - 35 months

tested positive increased to 14.5%, indicating that some

children newly infected at this age, most likely through

breast feeding. The prevalence decreased to 6.3% then to

4.4% among children age 36 - 47 months and 48 -59

months respectively as infected children continued to die

and exit the cohort. It is very unlikely that the passive

antibody presence a fte r 24 months of age.

The lack of information on breastfeeding and PMTCT

program dwindle the ability to analyze the attrition of

breastfeeding and the impact of PMTCT on MTCT of

HIV virus; and the lack data on age in single month im-

pede the prospect of decomposing positive rate by

smaller age group or performing survival analysis of

infected children. Nonetheless, this analysis demon-

strated that cross-sectional data can be used to estimate

indirectly the magnitude and dynamic of MTCT.

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