Shift in the buoyant density of hepatitis C virus particles in infants infected by mother-to-infant transmission

BACKGROUND: Hepatitis C virus (HCV) particles in sera can be divided into two classes: low-density free particles and high-density immune complex particles. Previous studies have revealed that the clinical progression of HCV infection is closely associated with the occurrence of the former class, rather than the latter, in an experimental chimpanzee model and in HCV-infected adult cases. METHODS: To verify this concept in infantile cases, we prospectively analysed HCV particle populations, fractionated according to buoyant density, in serum samples from five infants infected by mother-to-infant transmission. RESULTS: In all five cases, HCV particles were predominantly high density at the age of one month. In four of five cases, low-density HCV particles became predominant in association with a decrease in maternally transmitted antibody levels. In one case, in which high serum levels of alanine aminotransferase persisted, low-density particles were predominant between the ages of 3 and 9 months, in three consecutive samples. In other cases, in which infants were asymptomatic or had transient hepatitis, low-density HCV particles were predominant at only one sampling point or not at all throughout the follow-up period. CONCLUSIONS: Maternal antibody transmitted via the placenta reacts with the HCV particles in infants infected through vertical transmission. A decrease in maternal antibody levels results in an increase in low-density free virions. It is suggested that low-density particles play an important role in liver inflammation.     

Evolution in the hypervariable region of the hepatitis C virus in two infants infected by mother-to-infant transmission

BACKGROUND: There is little data on the evolution of hepatitis C virus (HCV) quasispecies in infants infected by mother-to-infant transmission during long-term follow up. The hypervariable region 1 (HVR1) of the HCV genome was investigated in two mother-infant pairs from birth to 7.6 and 10.2 years, respectively. METHODS: Ten cDNA clones of HVR1 generated from HCV-RNA and extracted from serum samples of both pairs were analyzed. The sequences were compared with regard to variability, identity, and hydrophobia profile, and analyzed by phylogenetic studies. RESULTS: The alanine aminotransferase (ALT) level was high with fluctuation in infant A and almost within the normal range in infant B. Sequence diversity was higher in infant A at 7.6 years than in infant B at 9.3 years (sequence identity with the mothers'; 69.3-70.7% vs 85.3-90.7% for nucleotides, and 48% vs 68-72% for amino acids, respectively). Compared to the first samples, amino acid changes greatly increased in infant A (35.2% at 4.9 years and 52% at 7.6 years), but not in infant B (4% at 5.6 years and 27.5% at 9.3 years). Phylogenetic studies revealed that quasispecies in infant A evolved to a greater extent than that in infant B. Hydrophobia profile analyses revealed that dynamic shifts between hydrophilia and hydrophobia occurred in both infants. CONCLUSIONS: As in adults, the evolution of HVR1 and variability of quasispecies increased in infants infected through mother-to-infant transmission for 10 years after birth. A large episode of ALT elevation suggested the emergence of escape mutants and the evolution of new quasispecies.     

感染丙型肝炎病毒的孕妇及其新生儿随访观察

目的了解丙型肝炎病毒(HCV)母婴垂直传播情况及HCV感染后对新生儿体格发育的影响。方法用ELISA法对1023名孕妇静脉血做抗HCV检测,阳性者对其新生儿脐带血做抗HCV检测。阳性者(包括产妇及其新生儿)进一步做HCVRNA检测;对抗HCV阳性新生儿做10～12个月随访,观察HCV感染指标及新生儿喂养、患病、生长发育情况。结果产妇HCV感染率为2.74％(28/1023);抗HCV阳性产妇中HCVRNA检出率为75％(21/28);抗HCV阳性产妇的新生儿脐血中抗HCV检出率为46.43％(13/28),其中检出HCVRNA阳性5例。对抗HCV阳性新生儿1年随访,抗HCV阴转率为69.23％(9/13),实验组新生儿母乳喂养率57％明显低于对照组85％,实验组儿童人均患病1.25次,而对照组儿童为0.5次,有非常显著性差异,身长、体重指标明显落后于对照组。结论母婴间存在着HCV的垂直传播;HCVRNA的存在不但增加了母婴垂直传播的比率,而且延缓了抗HCV的阴转;HCV的感染非常明显地影响了新生儿的体格发育。     

When does mother to child transmission of hepatitis C virus occur?

OBJECTIVE: To investigate when hepatitis C virus (HCV) infection from mother to child occurs, and evaluate possible associated factors. DESIGN: Prospective cohort study. PATIENTS: Fifty four HCV infected children tested within three days of birth and their mothers. MAIN OUTCOME MEASURES: HCV RNA polymerase chain reaction (PCR) results. RESULTS: Seventeen of the children (31%, 95% confidence interval 19% to 46%) were positive in the first 3 days of life and could be assumed to have acquired infection in utero. Testing PCR positive was not associated with sex (53% v 49% boys; p=0.77) or mode of delivery (29% elective caesarean section in both groups; p=0.98). Children with evidence of intrauterine infection were significantly more likely to be of lower birth weight and infected with genotype 1 (58% v 12%, p=0.01). Although a higher proportion of infants born to HCV/HIV co-infected women were PCR positive in the first 3 days of life, this difference did not reach statistical significance; excluding infants born to co-infected women did not affect the results. Thirty seven of the children (68%) were negative in the first 3 days of life, 27 of whom were positive when tested again at 3 months, and nine were first PCR positive after 3 months (one child had no further tests). CONCLUSIONS: These results suggest that at least one third and up to a half of infected children acquired infection in utero. Although postpartum transmission cannot be excluded, these data suggest that it is rare. The role of HCV genotypes in the timing and mechanism of infection should be explored further.     

乙型肝炎病毒母婴传播影响因素探讨

目的：探讨乙型肝炎病毒(HBV)母婴传播的影响因素,寻求降低婴儿HBV感染率的方法。方法：HBV携带及慢性乙型肝炎孕妇共635例,分别比较不同血HBV DNA滴度,不同分娩方式（剖宫产或自然分娩）,以及不同肝功能状态孕妇所生婴儿出生时及3月龄时HBV的感染率。新生儿生后12 h内肌注乙肝免疫球蛋白200 U 及重组酵母乙肝疫苗10 μg;生后即刻显示血清HBV感染存在者,14 d时再肌注乙肝免疫球蛋白200 U。结果：孕妇高滴度组（HBV DNA>105拷贝/mL）所生新生儿出生时（14.4% vs 4.1%,P<0.01）与3月龄时（4.7% vs 0,P<0.01）HBV感染率均高于低滴度组（HBV DNA ≤105拷贝/mL）。两组新生儿3月龄时HBV感染率均低于出生时（P<0.05）。自然分娩的孕妇其婴儿出生时HBV感染率明显高于剖宫产组（P<0.01）,但3月龄时,两组感染率接近。HBV携带孕妇所生婴儿出生时HBV感染率明显高于慢性乙型肝炎孕妇所生婴儿（P<0.01）,但3月龄时两组婴儿HBV感染率亦接近。结论：孕妇血清HBV DNA水平与新生儿HBV宫内感染密切相关,故降低孕妇血清HBV DNA水平可能成为减少新生儿HBV感染的一种有效途径。在乙肝免疫球蛋白及重组酵母乙肝疫苗的双重保护下,孕妇的分娩方式与肝功能状态对HBV母婴传播无影响。     

丙型肝炎病毒母婴宫内传播的研究

目的为研究丙型肝炎病毒（ＨＣＶ）的母婴宫内传播，评估ＨＣＶ母婴传播的危险性。方法应用酶联免疫吸附试验（ＥＬＩＳＡ）法检测ＨＣＶ，以逆转录－聚合酶链反应（ＲＴ－ＰＣＲ）检测ＨＣＶ－ＲＮＡ。结果检测的４２７７例孕晚期孕妇血清抗－ＨＣＶ，其中６例阳性，进一步检查ＨＣＶ－ＲＮＡ，结果６例中有５例阳性，且均有受血史，５例阳性孕妇其配对婴儿脐血抗－ＨＣＶ均阳性，其中２例ＨＣＶ－ＲＮＡ阳性，肝功能异常；１例出生时ＨＣＶ－ＲＮＡ阴性，到２４个月时ＨＣＶ－ＲＮＡ阳转。ＨＣＶ母婴宫内传播率为２／５。结论表明上海地区存在ＨＣＶ母婴宫内传播，应重视有受血史的生育妇女孕期及孕前的ＨＣＶ检查及ＨＣＶ感染儿的随访。     

Prospective study of mother-to-infant transmission of hepatitis C virus

BACKGROUND: Mother-to-infant transmission of hepatitis C virus (HCV) could become the main route of HCV infection in the future because there are no methods available to prevent vertical infection. The aim of this study was to determine the incidence of mother-to-infant transmission in infants born to mothers who tested positive for anti-HCV antibodies and to elucidate associated risk factors for transmission. METHODS: Screening was conducted for 16,800 pregnant women with an anti-HCV antibodies test, and 154 mothers were positive. From the positive group 141 mothers were enrolled in the study and their 147 infants were followed from birth for serum alanine aminotransferase activity, anti-HCV antibodies and HCV RNA. HIV infection was tested in 73 of 141 mothers, all of whom were negative. RESULTS: Thirty-three infants were dropped from the study because they were followed for <6 months or were not tested adequately. Of the 114 infants finally evaluated 9 (7.8%) had detectable HCV RNA. The transmission rate was not influenced by the mode of delivery [vaginal delivery, 8 of 90 vs. cesarean section, 1 of 24 (P = 0.396)] or by the type of feeding [9 of 98 for breast-fed infants vs. 0 of 16 for formula-fed infants (P = 0.243)]. All infected infants were born to mothers who had HCV viremia at the delivery (P = 0.040) and to those with a high viral load (P = 0.019). CONCLUSIONS: Our prospective study showed that the transmission rate of mother-to-infant HCV infection was 7.8% in anti-HCV antibody-positive mothers. Risk was related to the presence of maternal HCV viremia at delivery and a high viral load in the mothers.     

Serum levels of hepatitis C virus RNA in infants and children with chronic hepatitis C.

BACKGROUND: The role of serum hepatitis C virus (HCV) load in infectivity, disease activity, and response to interferon treatment has been investigated in adults, and controversial results have been obtained. Little is known about HCV load in infants and children with HCV infection. PURPOSE: To investigate the relation between HCV load in serum and features of associated liver disease in infants and children with HCV infection. METHODS: Hepatitis C viral load was investigated in serial samples in 43 children with chronic HCV infection, including 32 patients aged 4 to 16 years infected by different routes and 11 vertically infected infants observed prospectively since birth. RESULTS: Overall viremia ranged between 2.7 and 6.9 log copies/ml (median, 5.56 log/ml) and fluctuated slightly during the follow-up. Median HCV RNA levels did not significantly differ among infants, children, and adolescents. Viral load was also independent of sex, route of infection, clinical manifestation, alanine aminotransferase levels, and liver histology. All 11 perinatally infected children became chronic HCV carriers, whatever their initial viral load; retrospective testing of sera taken in the first day of life in three infants showed high viremia levels. CONCLUSIONS: Viremia levels observed in children were similar to those reported in adults, were independent of age, biochemical activity of liver disease, and chronicity of infection. They were also relatively stable, suggesting that serial measurement of viral load is useless in untreated infants and children. The detection of viremia at birth in children in whom chronic hepatitis developed later suggests the possibility of in utero infection.     

Mother-to-infant transmission of hepatitis C virus: A prospective study

To investigate the risk of mother-to-infant transmission of hepatitis C virus (HCV) and the natural course of HCV-infected infants, we prospectively studied 31 offspring of pregnant women who were anti-HCV positive and anti-HIV negative. Sera were serially tested for anti-HCV by the second-generation ELISA-test (ELISA-2) and for HCV-RNA by the polymerase chain reaction procedure. The mean period of follow up was 19 months (range 6–41 months). The presence of HCV-RNA in the mothers was associated with a high titre of anti-HCV by ELISA-2 or a positivity of the second generation recombinant immunoblot assay. At birth, 26 babies were positive for anti-HCV. Passively transferred maternal antibodies became undetectable within 2–15 months. HCV-RNA was detected in only 3 infants (9.7%) within 1–4 weeks after birth and persisted there-after. The genotype of HCV-RNA in each of the infants was consistent with that of their mother. These 3 showed chronic transaminase elevation during the follow up that started at 1–2 months of age, although they revealed no clinical symptoms. Re-elevation of anti-HCV titre was observed in the HCV-infected infants within 10 months of age, suggesting an endogenous production of anti-HCV. The mean titre of HCV-RNA in three mothers of infected infants was higher than that in the mothers of uninfected infants (10^5.3±0.3 vs 10^4.4±0.2/ml).Conclusion Our findings indicate that HCV was most likely to have been transmitted from mothers to infants at the time of delivery and that it was capable of evoking the chronic carrier state.     

广东地区婴肝患儿的HCV感染

目的探讨广东地区婴儿肝炎综合征中丙型肝炎病毒感染及其传播途径。方法采用酶联免疫吸附法（ELISA法）检测血清中丙型肝炎病毒（HCV）抗体，多聚酶链反应（PCR）检测血清中HCVRNA。结果90例婴肝中有11例HCV标志阳性，阳性率为12．2％（11／90），其中抗HCV以及HCVRNA均阳性4例，单项抗HCV阳性3例，单项HCVRNA阳性4例。母亲抗HCV阳性2例。结论HCV感染是广东地区婴儿肝炎综合征中一个不可忽视的病因，本组11例阳性患者的传播途径主要与输注血制品有关，其次为母婴传播。     

Risk factors for late postnatal transmission of human immunodeficiency virus type 1 in sub-Saharan Africa

BACKGROUND: We conducted secondary data analyses of a clinical trial (HIVNET 024) to assess risk factors for late postnatal transmission (LPT) of human immunodeficiency virus type 1 (HIV-1) through breast-feeding. METHODS: Data regarding live born, singleton infants of HIV-1-infected mothers were analyzed. The timing of HIV-1 transmission through 12 months after birth was defined as: in utero (positive HIV-1 RNA results at birth), perinatal/early postnatal (negative results at birth, positive at 4-6 week visit), or LPT (negative results through the 4-6 week visit, but positive assays thereafter through the 12-month visit). HIV-1-uninfected infants were those with negative HIV-1 enzyme immunoassay results at 12 months of age, or infants with negative HIV-1 RNA results throughout follow-up. RESULTS: Of 2292 HIV-1-infected enrolled women, 2052 mother/infant pairs met inclusion criteria. Of 1979 infants with HIV-1 tests, 404 were HIV-1-infected, and 382 had known timing of infection (LPT represented 22% of transmissions). Further analyses of LPT included infants who were breast-feeding at the 4-6 week visit (with negative HIV-1 results at that visit) revealed 6.9% of 1317 infants acquired HIV-1 infection through LPT by 12 months of age. More advanced maternal HIV-1 disease at enrollment (lower CD4 counts, higher plasma viral loads) were the factors associated with LPT in adjusted analyses. CONCLUSIONS: In this breast-feeding population, 6.9% of infants uninfected at 6 weeks of age acquired HIV-1 infection by 12 months. Making interventions to decrease the risk of LPT of HIV-1 available and continuing research regarding the mechanisms of LPT (so as to develop improved interventions to reduce such transmission) remain essential.     

Follow-up of transmission of hepatitis C to babies of human immunodeficiency virus-negative women: the role of breast-feeding in transmission

BACKGROUND: The studies on hepatitis C virus (HCV) vertical transmission, the effect of potential risk factors and the role of breast-feeding have reported conflicting results. PATIENTS AND METHODS: Seventy-three infants of 63 anti-HCV-positive and anti-HIV-negative mothers were studied from 1993 to 1999 in the south of Spain. The mean period of follow-up in children was 29.2 +/- 19 months (range, 8 to 76 months); 6 (8%) children were lost to follow-up. Breast milk was studied for HCV-RNA in 68 samples of 35 mothers. RESULTS: Alanine aminotransferase was high in 19 (26%) and HCV-RNA was positive in 46 (63%) pregnant woman. Breast milk HCV-RNA was negative in nonviremic mothers and positive in 20% of the viremic mothers. The overall rate of vertical HCV transmission was 11.9% (n = 8) (95% confidence interval, 6 to 23%) if HCV-RNA was positive one or more times, but only 1.5% (n = 1) (95% confidence interval, 0.1 to 9%) if HCV-RNA was permanently positive. Seven HCV-infected children did not develop antibodies to HCV, and they had a spontaneous clearance of the virus. A 10-month-old baby was HCV-RNA-positive from birth to the end of the follow-up. The genotype in each of the infants was consistent with that of their mother. The rate of HCV transmission was higher for infants of mothers with higher HCV viremia (P < 0.01) and also for infants whose mothers were HCV-RNA-positive in breast milk (P < 0.05). There were no statistically significant differences between other risk factors. CONCLUSION: The presence of transitory viremia without seroconversion indicates that the vertical transmission of HCV is not important. This could be related to the viral charge and ingestion of milk of HCV-RNA-positive mothers. However, to advise avoidance of maternal breast feeding, it would be necessary to conduct larger studies.     

Hepatitis C virus infection in infants whose mothers took street drugs intravenously.

To assess the risk of transmission of hepatitis C virus from mother to infant during pregnancy or at delivery, we measured the antibody to hepatitis C virus (anti-HCV) by an enzyme-linked immunosorbent assay (ELISA) and a recombinant immunoblot assay (RIBA) in serum from 43 infants whose mothers took illicit drugs intravenously. Passively transmitted maternal anti-HCV was detected in 17 (40%) of the 43 infants tested with the ELISA during the first 4 postnatal months. Ten of these initially seropositive infants were followed to 15 months of age or beyond; anti-HCV cleared from nine infants and persisted in one. Among 24 initially seronegative infants, three (12.5%) showed persistent anti-HCV at 6, 11, and 18 months of age, respectively. The remaining two infants were initially tested with ELISA at 6 and 15 months of age; both were transiently seropositive, but anti-HCV disappeared by 12 and 24 months of age, respectively. Among the 17 infants with maternal antibody, nine with ELISA reactions greater than 2.5 optical density units were reactive by RIBA: the eight with weaker reactivity by ELISA were nonreactive by RIBA. When serum samples from the four infants who showed persistent reactivity by ELISA were tested with RIBA, one reacted to both antigens displayed by RIBA (C-100 and 5-1-1), one reacted to the 5-1-1 antigen only, and two were nonreactive. Serum transaminase values were elevated in three of these four infants; all four were also infected with human immunodeficiency virus. The results indicate that vertically transmitted hepatitis C virus may be a cause of hepatitis in infants, especially those coinfected with human immunodeficiency virus. Neonates at risk of hepatitis C virus infection should be monitored beyond 12 months of age. The interpretation of tests for anti-HCV antibody during infancy requires further investigation.     

Transmission of hepatitis C virus from infected mother to offspring during subsequent pregnancies

BACKGROUND: Several studies have demonstrated that hepatitis C virus (HCV) may be transmitted from mother to offspring. To date, however, little is known about the risk of vertical transmission during subsequent pregnancies. The purpose of this study was to evaluate the risk of vertical HCV transmission in offspring in subsequent pregnancies of HCV infected women. METHODS: In a multicenter study, two groups of index cases were selected. Group 1 included 75 children investigated for HCV infection during prospective studies of vertical transmission. Group 2 included children born to HCV-infected mothers and found to be HCV infected, independent of studies on vertical transmission. All children in the index cases had one or more siblings. Anti-HCV, HCV-RNA (determined by polymerase chain reaction), and HCV genotype were evaluated in all the infected children, their mothers, and siblings. RESULTS: The results indicate that a mother who has already delivered an HCV-infected baby is not at greater risk of infecting her second child. Duration of maternal infection does not seem to be a risk factor in offspring infection, because HCV infection is equally distributed among first-born infants and infants of subsequent births. Because clustering of HCV infection among siblings appeared to be rare in this study, data also indirectly confirm that the risk of horizontal transmission of HCV among siblings is low. CONCLUSION: For practical purposes, the current observations indicate that mothers who have already delivered an HCV-infected child can be advised that this event does not increase the probability of infecting the second child.     

1~24月婴幼儿胰岛素样生长因子-1水平及与生长发育的关系

目的：分析1~24月龄婴幼儿血清胰岛素样生长因子-1（IGF-1）水平及其与生长发育的关系。方法：525名健康婴幼儿入选本研究（早产儿125名,足月儿400名）,测量体重/身长,酶联免疫吸附法检测血清IGF-1水平。结果：早产组婴儿期血清IGF-1水平在生后1.5月为最低（86±60 ng/mL）,此后一直维持较高水平,生后4~12月显著高于足月组。足月组婴儿期血清IGF-1水平在生后1.5月为最高(116±52 ng/mL),此后缓慢下降,生后8月时降至最低（69±58 ng/mL）。不论是早产儿还是足月儿体重/身长SDS与血清IGF-I水平均存在着正相关关系。结论：血清IGF-1水平均与婴幼儿期生长发育速度密切相关。［中国当代儿科杂志,2010,12（6）：459-461］     

Mother-to-Infant transmission of hepatitis C virus (HCV) in Brazil

Sixty-one women with anti-HCV antibodies, detected by a third-generation enzyme immunoassay (EIA3), were prospectively recruited for investigation of vertical HCV transmission during child-birth, at the University Hospital of the Catholic University of Campinas, Brazil, between January 1994 and July 1998. Six of the women presented coinfection with the human immunodeficiency virus type 1 (HIV-1). All of the 72 children born in this period were followed at least until they were 18 months of age. Analyses of anti-HCV, HCV RNA, and alanine aminotransferase were performed in a minimum of two blood samples during follow-up. One (2.4 per cent; 95 per cent CI, 2.2-7) of the 42 children born to HCV viremic mothers was both anti-HCV and HCV RNA-positive, with altered ALT levels. Passively transferred maternal anti-HCV antibodies became undetectable within 9-12 months. None of the nine infants born to HIV-1 infected mothers were infected either by HIV or HCV. Thus, the mother-infant HCV transmission rate is low and seems to be associated with maternal HCV RNA positivity.     

Immunogenicity and reactogenicity of DTPa-HBV-IPV/Hib vaccine as primary and booster vaccination in low-birth-weight premature infants

AIM: To assess suitability of a combined DTPa-HBV-IPV/Hib vaccine (Infanrix hexa) for immunization of low-birth-weight (<2.0 kg) preterm infants, with particular focus on the hepatitis B response. METHODS: Open-label study in 170 preterm infants receiving primary vaccination at 2, 4 and 6 months of age and booster vaccination at 18-24 months. Enrollment and analysis were stratified in two groups: infants with birth weight between 1.5 kg and 2.0 kg (low birth weight: LBW), infants with BW <1.5 kg (very low birth weight: VLBW). RESULTS: One month after the three dose primary vaccination, 93.7% and 94.9% of infants in VLBW and LBW groups, respectively, had anti-HBs antibody concentrations > or = 10 mIU/mL. High seroprotection and response rates (92.4-100%) to all vaccine antigens were observed. Those were reinforced (>98%) by booster vaccination for all antigens except for HBs in VLBW children: only 88.7% of those had anti-HBs antibody concentrations > or = 10 mIU/mL, compared with 96.5% of LBW children (difference statistically not significant). The vaccine was well tolerated in both groups of infants. CONCLUSION: Preterm infants will benefit by the administration of a primary and booster vaccination with DTPa-HBV-IPV/Hib vaccine.     

Vertical transmission of hepatitis C virus in a cohort of 2,447 HIV-seronegative pregnant women: a 24-month prospective study.

BACKGROUND: Mother to infant transmission of hepatitis C virus (HCV) has been extensively studied in mothers with human immunodeficiency virus (HIV) infection, whereas fewer data are available on the vertical HCV transmission in HIV-negative women. METHODS: Between January 1995 and June 1997, 78 consecutive HCV-positive/HIV-negative women with their offspring entered this prospective study aimed to define the prevalence of and risk factors for HCV vertical transmission. Risk factors for HCV were carefully sought, and HCV viral load and genotype were determined in all positive mothers. The infants were tested for alanine aminotransferase (ALT) and HCV-RNA at birth and at 4, 8, 12, 18, and 24 months of age. RESULTS: Eight of 60 (13.3%) infants born to HCV-RNA positive mothers acquired HCV infection, but only 2 (3,3%) were still infected by the end of follow-up. Infants' genotypes matched that of the mothers. ALT levels were in the normal range in all study subjects throughout the follow-up. High maternal viral load (P < 0.05), possession of HCV risk factors (P < 0.004), and history of blood transfusion (P < 0.05) were associated with increased risk of HCV vertical transmission. CONCLUSIONS: This long-term prospective study shows that, although vertical transmission from HIV-negative mothers occurs in 13% of cases, there is a high rate of spontaneous viral clearance (75%). High maternal viral load and mothers belonging to HCV risk categories were the only variables predictive of the vertical transmission.     

Diagnosis of HIV infection in children

Many advances have been made in the area of HIV diagnostics. Commercially available virologic assays are sensitive and specific for the early detection of HIV in perinatal infection. The timing of the transmission of HIV from mother to child (in utero, at the time of birth, or postnatally by breast-feeding) is a critical consideration in the appropriate diagnosis of infants. Several algorithms can be used to define early infection and the potential timing of acquisition of infection that combine different assays and timing of specimens. The use of virologic assays, including HIV DNA PCR and HIV RNA detection methods and culture, can define and rule out infection in infants less than 18 months of age. Serologic diagnostic methods, including HIV ELISA, immunofluorescence, and western blot assays, can be used to diagnose infants more than 18 months of age, when transplacental antibody has disappeared in uninfected HIV-exposed infants. The challenge of the early and accurate diagnosis of perinatally HIV-exposed infants is the use of new assays to detect different HIV subtype infections that are prevalent in developing countries. Rapid, simple, and inexpensive serologic and virologic assays are being developed for worldwide use.