This study was undertaken to investigate the relationship between Natural Killer cells and HLA-G at the placental barrier in HIV-I infected pregnant women and to establish the significance, if any, to in utero infection. Fifty-five HIV -I infected pregnant women were recruited into the study after consent was obtained. Blood samples were collected from both mothers and babies for viral loads and CD4+ cell counts. Placental samples were obtained from pregnancies at delivery and examined by immunoperoxidase immunohistochemistry methods using monoclonal antibodies to p24 antigens and Natural Killer (CD56+) cells. HLA-G expression was quantified using real-time polymerase chain reaction. Analysis of viral loads and CD4+ cell counts were undertaken in categories. No significant association was observed between the viral load of mothers and their CD4+ cell counts. Eighteen percent of the women in this study population had 5 log viral loads with a transmission rate of 0.27(95% Cl, 0.15 - O. 39). Maternal viraemia was significantly associated with transmission of infection to babies (p = 0.047). The odds ratio indicated that for every 1 log increase in maternal viral load the babies were 3.1 times more likely to acquire the infection (Exp (B) = 3.137 (95%CI, 1.015-9.696). Furthermore, the study found that a higher number of female babies were infected than males. Although not statistically significant the odds ratio indicated that female babies were 3.1 times more likely to become infected than males (Exp (B) = 3.110 (95%CI, 0.819-11.808). We report here the results of immunohistochemistry for p24 antigens and NK (CD56+) cells and compare them to the immunological responses of both mothers and babies at birth. HIV-1 antigens were detected in 94.5% of all placentas by immunohistochemistry. Infiltration of CD56+ was found in 98% of placental tissue. The analysis revealed that the presence of p24 antigens in placental tissue was not influenced by maternal viral load or CD4+ cell counts. Lower median NK cell values were observed in placentas of mothers with infected babies as compared with the uninfected cluster. Although not statistically significant, the risk of vertical transmission was increased 3.4 times more in placentas which had lower NK cell values. According to the odds ratio, babies CD4+ counts were affected by every 1 log increase in mother's viral load. Overall, maternal viral load emerged as a strong predictor for risk of infection from infected mothers to their infants. Our analysis indicated that female babies were 3.7 times more likely to acquire the infection than males. Using data obtained from real-time PCR we investigated the relationship between maternal viral load and the quantity of HLA-G expression (p = 0.045; 95%CI 1.029- 11.499). Logistic regression models revealed that mother's viral load was the strongest risk factor for vertical transmission. No statistically significant correlation was noted with HLA-G and viral transmission. However, the odds ratio indicated that the risk of infection increased by 1.3 with every 1 fold increase in HLA-G expression. An analysis of mother-to-child transmission rates by gender revealed that the odds ratio for transmission was 3.4 times more in female babies than in males. We then investigated the relationship between maternal viraemia and HLA-G expression. A positive correlation between maternal viral load and placental HLA-G was observed (p = 0.038). When gender susceptibility to HLA-G expression was explored a statistically significant association was observed in placental tissue of mothers with infected and uninfected male babies and HLA-G expression (p = 0.013). To conclude, the analysis found that HLA-G was up regulated 3.95 times more in placental tissue of mothers with infected babies than in mothers with uninfected babies. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2007.

This dissertation elicits focuses on sexual misconceptions which pose challenges to HIV/AIDS prevention and control among African adolescent girls in Umlazi Township, Durban. The study springs from the realisation that mere misconceptions related to sexuality could instigate risky behaviour resulting in HIV infection, and ultimately, result in premature death related to AIDS-related illnesses. Due to their physiological vulnerability, adolescent women are among a group at highest risk for contracting HIV in South Africa The study seeks, therefore, to understand how sexual misconceptions predispose girls to HIV infection against the context of gender, sexuality and reproductive health. The latter three issues are shaped by myriad forces working against the adolescent group. The study concludes with recommendations focused on challenging and removing sexual misconceptions with gender-sensitive interventions. / Thesis (M.A.)-University of KwaZulu-Natal, 2006.

HN/AIDS in South Africa has grown to very serious proportions. An estimated number of 5.3million South Africans are infected with HIV and the majority of these infections are in the reproductive age group. Based on Annual Antenatal survey 2002,of the total 2.95 million were women aged 15-49, with an estimation of 91271 babies infected through mother to child transmission. Breastfeeding is said to be an ideal food for growth and development of a child. Given that HIV is transmissible through breastfeeding, the paper aims at examining patterns and attitudes towards breastfeeding in the era of HIV/AIDS. A total of 400 respondents drawn from Mafikeng district were interviewed. The majority were aged 20-39, never married, rural, unemployed with high school level of education. Areas of interest were knowledge about HIV/AIDS, patterns of breastfeeding and attitudes towards alternative methods of infant feeding for an HIV positive mother. Previous reports gave clarity to HIV transmission rates at various stages of life. Evidence has shown that rates of transmission are higher in early stages than late stages of life. Few weeks of life from 6-8 weeks may particularly be a period of high risk than ages above three months. Transmission might have occurred during pregnancy, labor or through breastfeeding, whereby data has shown that colostrums have high concentration of Human Immune Virus than mature milk. The study shows that breastfeeding is still regarded as an important infant feeding method that is ideal for child's growth and development but HIV infection is seen as a disturbing factor to successful breastfeeding. Fifty four percent of respondents did not breastfeed exclusively as promoted by UNICEF and WHO; mean duration for exclusive breastfeeding is two months, support is given by SADHS 1998, mean duration for complementary feeding is two months which gives an indication that more infants are at higher risk of contracting the virus should their mothers test positive which in turn gives rise to high infant /childhood morbidity and mortality rates. There is a need to strengthen and expand programmes such as VCT and PMTCT in all communities especially in rural setting where there is lack of pure water supply and proper sanitation. Efforts to reduce the risk of transmission should therefore be centered on promoting the understanding that mixed feeding or breastfeeding with supplementary feeding carries the highest risk of HIV transmission compared to exclusive breastfeeding or exclusive formula feeding. / Thesis (M.Soc.Sc. (Population Studies) North-West University, Mafikeng Campus, 2004

Eight studies of the epidemiological dynamics of avian influenza viruses were conducted on poultry in Hong Kong, with special focus on the movement of birds through the live poultry marketing system, and the implications for avian influenza transmission. The first involved analysis of virus isolation data from faecal samples obtained from cooperating stalls in live poultry markets in Hong Kong in a routine sampling program undertaken between 1999 and 2001. This showed that two subtypes of avian influenza viruses, H9N2 and H6N1, have become well established in the Hong Kong live poultry markets, especially in chickens (mainly H9N2) and quail (mainly H6N1). In addition, a wave of H5N1 virus infection occurred in 2001 after it had been absent through the earlier period of the study. The second study was an evaluation of long term changes in the marketing systems for live poultry in Hong Kong, their likely effects on avian influenza epidemiology, and documented evidence of the prevalence of various H subtypes of avian influenza in sampling undertaken during three periods from 1975 to 2001. The third project involved two cross-sectional studies and one longitudinal study on local quail farms in Hong Kong. Results showed that quail could act as a reservoir host for H9N2 and H6N1 subtype viruses, but each subtype differed in its epidemiology. H9 virus usually infected quail at around 10 days of age, whereas H6 infected quail at 15-20 days of age. At 35 days of age (usual market age in Hong Kong), a proportion of market quail were likely to be susceptible to H6 (50%) and H9 viruses (20%), and were able to transmit the virus in the markets. Due to these findings, the Hong Kong Government closed the quail farming operations and restricted the sale of quail in live poultry markets. A longitudinal study was conducted on three live poultry market stalls to assess the time from stall entry to sale, and evaluate the influence of this delay on avian influenza virus transmission to other poultry in the same stall. Participating stalls varied from high volume/rapid turnover to low volume/slow turnover. Turnover for tagged poultry was rapid, although some chickens became infected with H9 virus before sale. Birds which stayed longer, such as quail, became infected and maintained infection in the stall. As well as spread by direct contact and on typical fomites, keeping of pet roosters and re-use of washing water were identified as factors increasing the ability of avian influenza strains to persist in market stalls. An experimental replica of a market stall was created to study the transmission of low pathogenic avian influenza virus (H9N2) in a controlled environment, with different rates of population turnover and different immune status with respect to both H5 and H9 subtypes. Transmission was influenced by distance between birds, the proportion of birds carrying antibody to H9 and the rate of introduction of susceptible birds, but not by the use of H5N2 vaccine. In order to assess the effectiveness of temporary depopulation of stalls, a study was conducted to compare the prevalence of avian influenza virus and Newcastle disease virus before and shortly after the monthly rest day in live poultry markets in Hong Kong, by virus isolation. Prevalence of H9N2 avian influenza virus was reduced by the rest day, but Newcastle disease virus prevalence was unaffected. During the 2002 avian influenza H5N1 outbreak in local chicken farms, a case-control study was undertaken to identify risk factors that may have contributed to this outbreak. A questionnaire was administered by interview to collect the data for this study. Multivariate logistic regression models showed that movement of people and fomites from live poultry markets to farms were important influences on transmission, and that the live bird markets were the likely source of virus for farms. A spatial stochastic computer model was constructed to predict the spread of avian influenza virus in local chicken farms and live poultry markets in Hong Kong, and the effectiveness of control measures. The data used in model parameter setting was derived from the case-control study. The reference model produced an epidemic curve which was similar to the true epidemic curve in the 2002 outbreak. Control strategies such as rest day and vaccination were evaluated within the model, and found to produce results comparable with field experience. Results from these studies clarify various aspects of the epidemiological features and transmission dynamics of avian influenza viruses, and provide guidance on appropriate control and prevention strategies for highly pathogenic avian influenza viruses within poultry marketing systems in Asia.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2006. / Härtill 5 uppsatser.

Thesis (M.Sc.) Uppsala : Sveriges lantbruksuniv. / Härtill 1 uppsatser.

Source: Dissertation Abstracts International, Volume: 70-07, Section: B, page: 4122. Adviser: John Michael Swint. Includes bibliographical references