To the Editors:
HIV infection is a major health problem. In adults, the main routes of transmission include unprotected sexual activity with an infected person and parenteral through transfusion with infected blood and sharing of contaminated sharp objects.1 In children, on the other hand, the predominant mode of transmission is vertical, from an infected mother to the child.1–6 In some HIV-infected children, however, the mother is HIV negative, suggesting a nonvertical (horizontal) mode of transmission.7–10 The objective of this study was to determine the horizontal mode of transmission of pediatric HIV infection in Port Harcourt.
This was a prospective study of HIV-infected children receiving care and treatment at the Pediatric Infectious Disease Unit from January 2008 to December 2012. Information obtained included the gender, age at presentation, clinical manifestation, World Health Organization clinical stage and CD4 count at presentation, and the presence of risk factors like blood transfusion, surgery, exposure to sexual activity, and use of unsterilized sharp objects. For those who received blood transfusion, the age of receiving the blood transfusion, the indication for the blood transfusion, the source of blood, and the place of the transfusion were also documented. HIV infection was confirmed using DNA polymerase chain reaction in children less than 18 months and by antibody tests (rapid diagnostic test using Determine and Unigold or by enzyme-linked immunosorbent assay) in those greater than 18 months. All the mothers were also tested using rapid diagnostic test. HIV-infected children who were adopted or those whose mothers had died with unknown HIV status were excluded from the study. The mode of transmission was arrived based on the maternal HIV status and history of blood transfusion, sexual history, use of sharp objects, and surgical treatment in the child. Children of HIV-positive mothers without other risk factors were considered to have acquired their infection vertically. Children of HIV-negative mothers were considered to have been horizontally infected. Data were entered in an Excel spreadsheet and analyzed using Epi Info version 3.5.1. Categorical data were analyzed using the χ2 test, and a P value ≤0.05 was regarded as significant.
Out of a total of 620 [304 (49%) males and 316 (51%) females] confirmed HIV-infected children, 549 (88.5%) acquired the infection vertically and 71 (11.5%) by horizontal route made up of 42 (59%) males and 29 (41%) females. There was no statistically significant difference between both genders (χ2 = 1.50, df = 1, P = 0.22). Of those infected by the horizontal route, 47 (66.2%) were through blood transfusion and 13 (18.3%) were through the use of contaminated sharp objects (Table 1). In 5 (7.0%) children of the HIV-uninfected mothers, the actual mode of transmission could not be determined because of either no identifiable risk factor or exposure to multiple risk factors.
Children who acquired their infection by the horizontal route were significantly older than those with vertical mode of transmission (χ2 = 60.46, df = 1, P = 0.0000). Fifty-four (76.1%) children were in World Health Organization clinical stage 4, 14 (19.7%) were in stage 3, and 3 (4.2%) were in stage 2 disease. None of them were in stage 1. The mean CD4 count was 265 ± 175 cells per mm3 (range 23–830). The commonest presenting clinical features were progressive weight loss in 53 children (74.6%), persistent or recurrent fever in 51 (71.8%), chronic cough in 46 (64.8%), and generalized persistent lymphadenopathy in 42 (59.2%). Other features were various skin manifestations in 21 children (29.6%), oral candidiasis in 15 (21.1%), chronic suppurative otitis media in 12 (16.9%), encephalopathy in 6 (8.5%), parotid swelling in 5 (7.0%), and chronic kidney disease in 3 (4.2%).
Among those who acquired their infection through blood transfusion (n = 47), the indications for the blood transfusion were severe anemia from severe malaria in 36 children (76.6%), sickle cell anemia in 6 (12.8%), during surgery in 3 (6.4%), nephrotic syndrome with severe hypoproteinemia in 1 (2.1%), and exchange blood transfusion for severe neonatal jaundice in 1 (2.1%). Three of the transfused children also had hepatitis B coinfection, whereas another was positive for hepatitis B surface antigen and hepatitis C antibody. The source of blood was from a commercial donor in 44 children (93.6%). Two children (4.3%) were from the fathers (who later turned out to be seropositive), and 1 (2.1%) was from an uncle who was said to have died later from a chronic disease. Two (4.3%) children received the blood transfusion in a government tertiary hospital, whereas 45 (95.7%) received in private hospitals. The mean duration between the transfusion with the infected blood and the diagnosis was 15.02 ± 8.4 months (range 7–39 months).
Of those in whom the only identified risk factor was contaminated sharp objects (n = 13), 5 (38.4%) were from scarification marks, 3 (23.1%) from herniorrhaphy, 3 (23.1%) from circumcision, 1 (7.7%) from sharing of toothbrush with an infected house help, and 1 (7.7%) from sharing of hair clipper with an infected brother who acquired his own infection from blood transfusion. Of those with sexual route of transmission (n = 6), 3 (50%) were rape cases and 3 (50%) were adolescents from early sexual debut, and they were all females. On outcome, 41 (57.7%) are still alive and in care, 17 (23.9%) have been lost to follow-up, 5 (7%) have been transferred out, and 8 (11.4%) have died.
HIV is a preventable disease. Most HIV infections in children are vertically transmitted from infected mothers. This study and other reports2–6 also support the fact that vertical transmission remains the commonest route of HIV infection in children. Children, however, may also be infected from a source other than their mothers.
In this study, the prevalence of horizontal transmission was 11.5%. This was comparable with the findings of 10% in Uganda11 and 13.3% and 16% in India.2,3 It was, however, lower than 19% in another Ugandan study,9 20% in Rwanda,12 21% in Cote d'Ivoire,8 23% in Burkina Faso,7 28.1% in Brazil,13 and 39% in Zaire.14 In one South African study, up to three quarters (75%) of HIV-infected 2- to 11-year olds were identified as having become infected from a source other than their mothers.15 The higher prevalence in these studies may, however, be because they studied very small groups of children.
Blood transfusion was the commonest horizontal mode of transmission accounting for 66.2% of all those with this mode of transmission. It was also the commonest nonvertical route in several other studies.3–5,16–18 Blood and blood products remain an important source of HIV infection. Blood transfusion–transmitted HIV infection may be a result of transfusion with unscreened or improperly screened blood,18 and most recipients (90%–95%) of HIV-positive unit of blood/blood product will develop HIV infection.19 Transfusion with unscreened or improperly screened blood also carries the risk of transmission of other blood-borne infections as seen in this study where 4 of the transfused children in addition to HIV also acquired hepatitis. The possibility of transfusing infected blood collected during the donor's seronegative window period (during which the blood of a newly infected person does not show up as positive on screening tests) cannot be ruled out.20 This may have been the case in 2 of the children who received blood from their fathers who later turned out to be HIV positive.
Over 8% of the children acquired their infection by the sexual mode. This mode of transmission has also been reported in other studies in southern parts of Nigeria.21,22 In studies from the northern parts of Nigeria, however,23,24 sexual mode of transmission was not reported. Sexual mode of transmission cannot be ignored in adolescents as they are prone to sexual exploitation. Girls in many African settings become sexually active at younger ages, and sexual debut frequently occurs with men who are some years older and likely to have multiple sexual partners and/or be HIV infected. This places adolescent girls at higher risk than adolescent boys. All those who acquired their infection by the sexual route in this study were all females. In a review of the sexual behavior of South African youths, it was found that at least 50% of young people were sexually active by the age of 16 years.25
Use of unsterilized sharp objects was the identified mode of transmission in 18.3% of the children. Cultural practices like circumcision and scarification are quite commonly performed in children and involve the use of shared and nonsterile instruments by traditional healers, and because these practices result in exposure to blood, they present avenues for the transmission of HIV to children.26 Scarifications may also be a significant source of transmission of HIV in adolescents, especially with the rising increase of blood oaths in cult activities and beauty tattoo marks.
Although the predominant mode of transmission of HIV in children is vertical, a horizontal mode of transmission of 11.5% cannot be ignored, especially as severe anemia is common in children in our environment. As a way of preventing HIV infection in children, intervention efforts are also needed to address these other modes of transmission. Transfusion with properly screened blood and health education and legislature against scarification and child sexual abuse are needed to prevent horizontal transmission.
The authors wish to thank the nurses and the doctors who are directly involved in providing care and treatment to the HIV-infected children.
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