Biology of Aids and Stds - Assignment Example

BIOLOGY OF AIDS AND STDS BACKGROUND Question No According to the Review article by Kourtis, et al, (2006: p.726), paediatric HIV is still a major pandemic, despite the reductions in transmission from mother to child that have been achieved. It is estimated that more than two million children are infected with HIV worldwide, and that more than 1800 new HIV infections are transmitted daily from mothers to infants. Mother to child transmission can take place during pregnancy, labor, delivery and post-partum through breast feeding. The exact timing and mechanisms of transmissions are still speculative, but important for refining perinatal HIV-1 prevention strategies. The estimated transmission rates during the different stages stages of pre-, during, and post-delivery: The results of several studies taken together support the notion that the risk for mother to child HIV-1 transmission increases rapidly as the pregnancy reaches its later stages. This inference is supported by evidence demonstrating the absence of HIV-1 infection in early and second trimester foetuses of HIV-1 infected mothers. Data from two African trials in breastfeeding populations lend further support to these estimates. Transmission rates of 6.5% and 5.3% respectively, were achieved when single-dose mother-infant nevirapine was added to zidovudine, started at 36 or 34 weeks of gestation, and continued for a week to a month in the infant, respectively. This cut the transmission rate by about half: to 11.9%. The results of studies are consistent with the hypothesis that a very high proportion of HIV-1 transmissions occur between 36 weeks and delivery. Transmission rates for women receiving high active antiretroviral therapy during pregnancy are less than 2%.The postnatal transmission rate is estimated to be as high as 15%, if women engage in prolonged breastfeeding for about 2 years. Transmission risk is higher during early lactation because of viral load in colustrum. Using the estimates from studies, if breastfeeding for only 6 months became a widely adopted policy, the transmission risk during breastfeeding would drop from 16% to 11%, and if breastfeeding was used exclusively for 6 months, this risk might be further reduced to about half: 6%. Breastfeeding would then account for 18% of all transmissions. An important area for future research recommended by the review: Addressing the challenge of breastfeeding transmission should be a top research priority, in order to prevent millions of new paediatric HIV-1 infections worldwide. Question No.2. a) The major concern regarding breastfeeding in HIV-1 infected women is that postnatal transmission via breastfeeding is high, especially in settings where safe feeding alternatives are not available. The postnatal transmission rate is estimated to be as high as 15% if women engage in prolonged breastfeeding of about 2 years. Risk is higher during early lactation because of increased breast milk viral load in colostrum. The risk which continues throughout breastfeeding is associated with low maternal CD4 count, duration of feeding, maternal virus load, mastitis and mixed feeding. It is derived that approximately 40% of all infected children become infected during breastfeeding. b) Promotion of exclusive breastfeeding for the first 6 months of life followed by rapid weaning has been advocated as a strategy to decrease mother to child HIV transmission, and is currently promoted by the World Health Organization. c) According to the Jones review, the number of deaths globally that can be prevented through breastfeeding is 1301 (x 1000), which constitues 13% of the proportion of all deaths. For 90% of global child deaths, a group of effective nutrition interventions including breastfeeding, complementary feeding, vitamin A and zinc supplementation could save about 25% of total deaths (Jones Review, 2003: p.69). Through breastfeeding, infant deaths can be prevented, because it has been confirmed that the highest rate of transmission of the infection from mother to child occurs during breastfeeding. If change in breastfeeding strategies ensure that the infant gets the benefit of its mother’s breast milk, but will not receive the HIV infection from its mother, infant deaths can be prevented through breastfeeding (Jones et al, 2003: p.67) Question No.3. a) A partial solution to the problem of HIV transmission, was suggested by the preliminary observation that exclusive breastfeeding (EBF) conferred less risk of HIV transmission than mixed feeding. This has led to calls for early cessation of exclusive breastfeeding to provide the young infant with some of the healthful, immune and nutritive benefits of breast milk while minimizing the duration of exposure to HIV. b) The risk of HIV transmission in exclusive breast feeding (EBF) is less than through mixed feeding. It is speculated that pathogen or allergen containing foods taken with mixed feeding may increase gut permeability or mucosal inflammation. . Incomplete breast emptying may lead to subclinical mastitis, and increased breast milk viral load. c) According to Thea et al (2006: p.1540) the rationale behind early complete cessation of breastfeeding is that, the young infant will receive some of the healthful and nutritive benefits of breast milk, while minimizing the duration of exposure to HIV. Question No. 4. ZEBS is the Zambia Exclusive Breastfeeding Study, which aims to assess the risks associated with early and rapid weaning, compared to the potential benefit of reduced late postnatal transmission. The researchers compared or measured viral load in breast milk obtained two weeks after rapid and complete weaning, versus breast milk from women at the same postnatal age, who continue to exclusively breastfeed. To assess the compliance of self-reported breastfeeding cessation, they used plasma prolactin levels and breast milk volume as biologic confirmation of the decrease or cessation of lactation (Thea, et al, 2006: p.1540). METHODS Question No.5. a) Enrolment criteria for the study: HIV positive women intending to breastfeed were recruited and a small number of HIVnegative women were also enrolled. b) Study population: Data reported here are from a planned subset analysis of women enrolled in ZEBS. It was designed to determine whether short exclusive breastfeeding with abrupt cessation at 4 months is feasible and can reduce postnatal HIV transmission and child mortality at 24 months postpartum. c) Comprehensive lactation counseling promoted exclusive breastfeeding in all women up to four months. Half of the women were randomized to a counseling programme, encouraging abrupt breastfeeding cessation (within 24 hours) , to occur at the four month visit (Group A). Half were randomized to the WHO recommendation to continue exclusive breastfeeding to six months, and then introduction of weaning foods.(Group B). Question No.6. After weaning, women in group A were counseled to manually express milk for relief of discomfort. Both groups of women were seen again in the clinic two weeks later, when breast milk volume was measured by timed pumping, 10 minutes per breast, using a Madela Lactina pulsatile electric breast pump, set at a standard rate. Blood for prolactin was obtained before and after pumping. All mothers were asked to refrain from breastfeeding for one hour prior to the baseline prolactin and breast milk pumping. Breast milk collection and viral load measurements were done. RESULTS Question No.7. a) Among the 97 HIV-positive women assigned to the early weaning group, 92 (95%) reported having stopped all breast-feeding before the post-weaning measurements were taken. Post-weaning samples were obtained for 83 (85.6%) women at the scheduled 4.5 month visit, for 11 at the 5-month visit, and for 3 at a later time point. For clarity, the analysis was based on actual reported practice rather than group assignment. b) There were no significant differences in maternal age, parity, plasma viral load, CD4 cell count or body mass index between the HIV-positive women who had weaned and those who were still breastfeeding at the time of measurement. c) Subset analyses that were done, and results of the study: Prolactin and pumped breast milk volume as a measure of weaning compliance: Baseline plasma prolactin levels (just prior to pumping) were significantly lower in women who claimed to have weaned, in comparison with women who reported continued breastfeeding, providing confirmation that weaning had occurred. Prolactin levels measured after breast milk pumping increased to a similar extent in both groups, but the percentage of women with very high prolactin levels was far greater among the breastfeeding women, presumably in response to the suckling stimulus of breast milk pumping. There were no differences between HIV-positive and HIV-negative women who were still breastfeeding. The volume of breast milk pumped in ten minutes was significantly less among women who had weaned than in those still breastfeeding. Clinical signs and duration of weaning: There were no significant differences in prolactin or breast milk volume by duration of time, since cessation of breastfeeding. There were also no significant differnces by the duration of the weaning period. Exclusive breastfeeding and prolactin levels: Post-pumping prolactin levels and pumped volumes were similar among exclusive and nonexclusive breastfeeding women. Resumption of menses: Resumption of menses by six months post-partum was significantly more common among women who stopped breastfeeding, than those who continued to breastfeed. Among those who had stopped all breastfeeding, basal prolactin levels post-weaning were significantly lower (mean 36.9ng/ml) among those who subsequently resumed menses by 6 months, than those who did not resume menses by this time (mean 75.3 ng/ml). DISCUSSION: Question No.8. a) According to the authors’ discussion the major finding in this study are: Breast milk viral load is an important determinant of postnatal HIV transmission, associated with high plasma viral load, advanced HIV disease and mastitis. Increases in mammary epithelial permeability which accompanies weaning in animals and humans may also increase breast milk viral load. This may lead to a substantially increased transmission risk among children partially weaned or in whom breastfeeding is resumed once stopped. b) In this study it is shown that breast milk obtained after complete cessation of breastfeeding had a substantially higher concentration of viral RNA than milk obtained from women who were still breastfeeding at the same post-natal age. There were no significant differences between the two groups at baseline in maternal CD4 cell count or plasma viral load and any slight differences between these two groups seem unlikely to explain the large differences observed. Additionally, the presence of low breast milk viral load 2 weeks prior to weaning strongly supports the concept that weaning itself accounted for the increase in viral load rather than some confounding factor. The biological markers used to confirm self-report of weaning, pumped breast milk volume and plasma prolactin, provide objective evidence that the mode of feeding in the two groups during the weeks prior to viral load measurement were, in fact, markedly different. In both conditions: milk fever and milk stasis, mammary gland permeability is enhanced, potentially allowing easier flow of virus into the milk. Systemic infections may also play a role in increasing breast milk viral load. It will be important to establish the role of high breast milk viral load in postnatal transmission during mixed feeding. Question No.9. a) Prolactin has a well-established role in human milk production and lactational amenorrhea. It has been shown to increase significantly in response to the stimulus of breastfeeding, diminish with the onset of non-exclusive breastfeeding and fall precipitously after suckling has ended. Hyperprolactinemia is also known to occur in up to one-fifth of HIV-infected non-lactating individuals but has not been assessed in lactating HIV-infected women. b) To increase the reliability of self-reported weaning information, they used both breast milk volume obtained during a structured pumping session and prolactin level as biologic confirmation that weaning had occurred. Low prolactin levels predict early (6 months) return of menses, regardless of the woman’s weaning status. Question No.10. a) The authors conclude that that prolactin and pumped breast milk volume were highly associated with reported weaning behavior. It is also clear that large increases in breast milk viral load occurred after rapid cessation of breastfeeding. This shows that infants’ risk for exposure to HIV is greater if relactation is started. b) Influence of mixed feeding on breast milk viral load: counseling of HIV infected women regarding transition from exclusive breast feeding. c) Recommendations: Using cow’s milk which is easily digestible by the infant. Question No.11. The term intervention refers, according to Jones, et al (2003: p.65), any biological agent or action intended to reduce morbidity or mortality. Interventions that can be delivered mostly through the health sector are considered here, for universal coverage. Interventions include preventive approaches that may reduce the exposure to the infection or conditions, and uses both preventive and treatment approaches. Success in achieving high coverage levels with effective interventions leads over time to reductions in deaths,with associated reductions in estimates of preventable deaths. Measles vaccination provides a good example of an effective programme that has achieved high coverage levels and has reduced child mortality, and must continue to be supported within the context of child survival programmes. Question No.12. Culture plays a significant role in the decision to breastfeed. This is especially so in developing countries, where it is considered to be a part of the mother-child bond, and is also seen as an economically sound measure. The health benefits are also well-known, and it would be considered sacrilege to deprive an infant of its mother’s milk. Under such circumstances, it would be difficult to counsel HIV affected women to cease breastfeeding abruptly after the initial four months of exclusive breastfeeding. However, since awareness levels are higher in current times, the mother may be amenable to heed the advise, to avoid putting her child at risk to HIV. Even then, providing alternative food for the infant would be difficult economically. Weaning foods would have to be introduced, which are low-cost and suitable for consumption by infants. The Government health department can set into motion a service to help HIV infected low-income mothers in cash or kind, working on a policy framework with suitable limits. Question No.13. (Iliff, et al, 2005: p.699): Research has shown that prophylactic doses administered to HIV infected pregnant mothers, and later to the newborns considerably reduces the rate of transmission of the infection from mother to child. The administering of drugs to the neonate’s system may cause harmful side-effects later, which may not be obvious immediately. In third-world countries, where the incidence of HIV is slowly rising, it would be difficult to teach HIV infected parents to give alternative foods to their infant, as the mother would transmit her infection to the child. Though there may be regular advertisements in the media, supporting the breastfeeding of infants, it is the essential culture of the county, rather than the government which will decide the course of action. Question No.14. Discussion Question: Can parental education benefit the quality of life of their children? REFERENCES Jones, Gareth; Steketee, Richard W; Black, Robert E; Bhutta, Zulfikar A; Morris, Saul S; and the Bellagio Child Survival Study Group. (2003). “How Many Child Deaths Can We Prevent This Year?” Journal: The Lancet, Vol.362, pp.65-71. Iliff, Peter J; Piwoz, Ellen G; Tavengwa, Naume V; Zunguza, Clare D; Marinda, Edmore T; Nathoo, Kusum J; Moulton, Lawrence H; Ward, Brian J; the Zvitambo Study Group; and Humphrey, Jean H. (2005). “Early Exclusive Breastfeeding Reduces the Risk of Postnatal HIV-1 Transmission and Increases HIV-free Survival”. Journal: AIDS, Vol.19, pp.699-708. Kourtis, Athena P; Lee, Francis K; Abrams, Elaine J; Jamieson, Denise J; Bulterys, Marc. (2006). “Mother-to-Child Transmission of HIV-1: Timing and Implications for Prevention”. Journal: The Lancet, Infection. Vol. 6, pp.726-732. Thea, Donald M; Aldrovandi, Grace; Kankasa, Chipepo; Kasonde, Prisca; Decker, W.Donald; Semrau, Katherine; Sinkala, Moses; Kuhn, Louise. (2006). “Post-Weaning Breast Milk HIV-1 Viral Load, Blood Prolactin Levels and Breast Milk Volume”. Journal: AIDS, Vol.20, pp.1539-1547. Read More