Showing papers by "University of Nairobi published in 1995"

Human immunodeficiency virus type 1-infected cells in breast milk: association with immunosuppression and vitamin A deficiency.

Abstract: Breast milk samples from human immunodeficiency virus type 1 (HIV-1)-seropositive women were analyzed by polymerase chain reaction to determine the prevalence and determinants of HIV-1-infected cells in breast milk. Breast milk samples (212) were collected from 107 women, and 58% of the samples had detectable HIV-1 DNA. The proportion of HIV-1-infected cells in the milk samples ranged from 1 to 3255/10(4) cells. Breast milk samples with detectable HIV-1 DNA were more likely to be from women with absolute CD4 cell counts of < 400 (odds ratio, 3.1; 95% confidence interval [CI], 1.5-7.0). Severe vitamin A deficiency (< 20 micrograms/dL) was associated with a 20-fold increased risk of having HIV-1 DNA in breast milk among women with < 400 CD4 cells/mm3 (95% CI, 2.1-188.5). Women with CD4 cell depletion, especially those with vitamin A deficiency, may be at increased risk of transmitting HIV-1 to their infants through breast milk.

Products derived from the leaves of Ocimum kilimandscharicum (Labiatae) as post-harvest grain protectants against the infestation of three major stored product insect pests

Abstract: The bioactivity of materials from the leaves of Ocimum kilimandscharicum was tested against Sitophilus zeamais Mots chulsky (Coleoptera: Curculionidae), Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) and Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) in maize and sorghum grains in the laboratory. Exposure of adults of the three insect species to dried ground leaves and essential oil extract of O. kilimandscharicum induced 100% mortality after 48 h. Fresh and dried whole leaves were not toxic to Sitophilus zeamais or R. dominica. Grains treated with dried ground leaves and essential oil extract caused significant reductions in the number of progeny and survival rate of all three pest species tested. There was no adult survival or progeny production in grains treated separately with each of the two materials at doses of 25.0 g (dried ground leaves) and 0.3 g (essential oil) per 250 g of grain, respectively. Unlike R. dominica and Sitotroga cerealella, grains treated with fresh leaves enhanced the feeding activity of Sitophilus zeamais. Ground leaves and the essential oil, however, protected the grains against feeding by all three species, resulting in lower weight loss and number of damaged seeds compared with untreated grains. All the plant materials were repellent to S. zeamais with the essential oil extract applied at 0.3 g/250 g of grain evoking the highest repellent action. There was, however, considerable variation in the repellency of the materials against R. dominica and Sitotroga cerealella. The results are discussed in terms of the efficacy of O. kilimandscharicum for protection against loss due to insects in traditional grain storage in developing countries.

Rapid Progression To Disease In African Sex Workers With Human Immunodeficiency Virus Type 1 Infection

Abstract: From a cohort of female sex workers in Nairobi, Kenya, 163 women were observed to seroconvert to human immunodeficiency virus type 1 (HIV-1) and followed to study progression to HIV-1-related disease. The effect of several covariables on disease progression was studied using a Weibull proportional hazards model. The Weibull survival model was fitted to the observed incubation times. Estimates of the median duration to CDC stage IV-A and IV-C disease were 3.5 and 4.4 years, respectively. Condom use before seroconversion was associated with a reduced risk of CDC stage IV-A disease (relative risk = .64, P < .05). The incubation time of HIV-1-related disease is extremely short in this population.

Delineation of Uganda into climatological rainfall zones using the method of principal component analysis

Abstract: This paper attempts to delineate Uganda into climatological rainfall zones using the method of principal component analysis (PCA). Monthly rainfall records from 102 Uganda rain-gauge stations for the years 1940–1975 inclusive are used in the study. The rotated dominant PCA modes were used to delineate the temporal rainfall characteristics into homogeneous spatial regions. Statistical and other methods were then used to determine the physical reality of the spatial patterns of the delineated zones of the rainfall network in describing the climatological rainfall patterns of Uganda. The PCA varimax rotated solutions showed that for the climatological data a maximum of four PCA modes, accounting for about 65 per cent of annual rainfall variance, were significant. However, a maximum of 16 PCA modes, accounting for over 81 per cent of the rainfall variance were obtained with the seasonal/monthly records. The PCA regional patterns delineated Uganda into 14 homogeneous climatological zones, which were also indicated by the spatial patterns of the physical features of Uganda and other tests. The derived rainfall zones would be useful in the planning and management of rainfall dependent activities in the country.

Nutrient losses from cropland in the Central Highlands of Kenya due to surface runoff and soil erosion

Abstract: Soil loss, runoff and nutrient losses were measured on runoff plots during the rainy season from November 1992 to January 1993. Crops grown were maize ( Zea mays L.), beans ( Phaseolus vulgaris L.) and an intercrop of maize and beans. The control treatment was bare fallow. The total loss of C, N, P, K and plant-available P and K in the eroded soil as well as P and K dissolved in the surface runoff water were not dependent on the nutrient concentration of the eroded soil and water, but rather on the total amount of runoff and eroded soil. Compared to bare fallow, P (and K) losses under maize were reduced to 24.2% (28.3%), under beans to 15.3% (15.4%) and under intercrop to 9.3% (10.7%).

The aquatic plant communities of the Lake Naivasha wetland, Kenya: pattern, dynamics and conservation

Abstract: The spatial and temporal patterns of the wetland plant communities at Lake Naivasha over the past decade, and the past five years in particular, are discussed in relation to the major controlling factors. The four communities are:- the emergent swamp, dominated by Cyperus species; the floating raft, dominated by the aliens Salvinia molesta and Eichhornia crassipes; the floating-leaved plants, represented only by Nymphaea caerulea; and the submerged angiosperms, consisting of three species of Potamogetons — P. pectinatus, P. schweinfurthii, P. octandrus — together with Najas pectinata. The major factors affecting their dynamics are:- water level changes which influence agricultural clearance, introduced crayfish Procambarus clarkii, and interactions between communities such as the physical effects of mobile floating rafts. The value of the different communities to the ecological and economic value of the lake is highlighted, and the possible damage from future activities discussed.

The duration of breastfeeding by HIV-1-infected mothers in developing countries: balancing benefits and risks.

Abstract: How to best advise mothers infected with human immunodeficiency virus type 1 (HIV-1) in developing countries regarding breast feeding is an important issue that has generated considerable debate. Previous studies have addressed this problem by means of mathematical models but without considering the issue of the duration of breast feeding. A mathematical model was developed to compare the age-specific risks of mother-to-child HIV transmission versus the excess mortality due to not breast feeding. In this model it is assumed that both the risk of mother-to-child transmission of HIV through breast milk and the relative risk of not breast feeding do not vary with age. The model indicates that in HIV-1 seropositive mothers the decrease in child mortality afforded by breast feeding may exceed the risk of mother-to-child HIV-1 transmission only during the first 3-7 months of life. Thereafter the risk of HIV-1 transmission probably exceeds the mortality benefit of breast feeding. Experimental studies of counseling HIV-1 infected mothers to limit their duration of breast feeding should be considered in the setting of developing countries. (authors)

Removal of deciduous canine tooth buds in Kenyan rural Maasai

Abstract: The removal of deciduous canine tooth buds in early childhood is a practice that has been documented in Kenya and in neighboring countries. This paper describes the occurrence, rationale and method of this practice amongst rural Kenyan Maasai. In a group of 95 children aged between six months and two years, who were examined in 1991/92, 87% were found to have undergone the removal of one or more deciduous canine tooth buds. In an older age group (3-7 years of age), 72% of the 111 children examined exhibited missing mandibular or maxillary deciduous canines. It was found that the actual removal of a deciduous tooth bud is often performed by middle-aged Maasai women who enucleate the developing tooth using a pointed pen-knife. There exists a strong belief among the Maasai that diarrhoea, vomiting and other febrile illnesses of early childhood are caused by the gingival swelling over the canine region, and which is thought to contain 'worms' or 'nylon' teeth. The immediate and long-term hazards of this practice include profuse bleeding, infection and damage to the developing permanent canines. A multi-disciplinary approach involving social anthropologists in addition to dental and medical personnel, is recommend in order to discourage this harmful operation that appears to be on the increase.

Maize flour contaminated with toxigenic fungi and mycotoxins in Kenya

Abstract: The majority of the Kenyan human population may be exposed to regular doses of a wide spectrum of highly toxic, carcinogenic, immunosuppressive, mutagenic, and hepatotoxic mycotoxins through the consumption of maizemeal. Maizemeal is consumed in Kenya at the rate of about 0.4kg/person/day, therefore, even the lowest amount of toxins consumed can cause significant effects as some are cumulative. Maize is also a major component in livestock and poultry feed, and the therefore regular indirect human exposure through the consumption of animal products that contain mycotoxin residues could be common. Due to these suspected risks, it is imperative to establish whether consumers in Kenya are actually exposed to dangerous mycotoxins in maize products hence this survey. Forty samples of flour packed in 90kg bags, 58 samples of "Ugali" brand (milled and packed by the Milling Corporation of Kenya Ltd), and 74 samples of "Jogoo" brand ( Unga Maize Millers) were collected from the Nairobi area. The samples were analysed for resident mycoflora, and some mycotoxins associated with key fungal species. Important fungal species isolated from the flour included Aspergillus flavus, A. sulphureus, Fusarium moniliforme, Penicillium stoloniferum, and P. cyclopium. All the three brands of flour were contaminated with Aflatoxins B1 and B2 (0.4-20 ug/kg), Ochratoxin A(50-1,500 ug/kg), and Zearalenone (2,500 - 5,000 ug/kg). Ochratoxin A was the most prevalent mycotoxin. These data provide a warning that the mycotoxin contamination problem in maizemeal is critical and consumers' health is at risk. Therefore, rigorous countrywide monitoring of mycotoxins in this staple food should be pursued. If possible, maize products should be subjected to stiff microbial quality control from the farm gate to the market shelf.

Agrochemicals exposure and health implications in Githunguri location, Kenya.

Abstract: A study conducted in a rural agricultural community (Githunguri location) in Kenya between 1987 and 1990 investigated the extent of use of agrochemicals, especially pesticides, by the farmers ; their level of awareness of the dangers posed by these chemicals and their attitudes towards agricultural chemicals in general. The findings showed that more than 95% of the farmers used pesticides extensively. More women than men were found to be at risk of agrochemicals exposure, while babies and children were at more risk of agrochemicals exposure than the women. In this community, knowledge and awareness regarding safety in handling and storage of agrochemicals was to some extent limited. For instance, many had no knowledge of an antidote in case of accidental poisoning. Additionally, suicidal attempts by ingestion of agrochemicals was prevalent. Improper handling of the agrochemicals by the community members was implicated to have adverse health effects. These health effects were reported in form of complaints. They ranged from acute to chronic conditions. Consequently, an intervention programme was launched with the women as the key players. It is envisaged that community participation in the on going intervention programme is saving babies, children, women and the community at large from agrochemicals hazards.

Logistic regression in case-control studies: The effect of using independent as dependent variables

Abstract: In case-control studies, cases are sampled separately from controls. In such studies the primary analysis concerns the estimation of the effect of covariables on being a case or a control. To explore causal pathways, further secondary analysis could concern the relationships among the covariables. In this paper the validity of such secondary analysis is addressed. In particular, the use of multiple logistic regression in case-control studies where the dependent variable is not the case/control indicator is explored. It is shown that only under very restrictive conditions will sample regression coefficients correctly estimate their true value. In many situations, it may be valid to regress one covariable on others in the control group, but not in the case group or the combined sample. This principle is illustrated by a study of sexually transmitted disease in Kenya.

The negotiating strategies determining coitus in stable heterosexual relationships.

Abstract: Heterosexual behaviour is a complex subject and one which is aggravated by confounding variables. Few studies have investigated the way in which one variable, namely coitus, is initiated and negotiated in stable marital relationships. As the HIV/AIDS pandemic spreads in sub-Saharan Africa, the subject of marital coitus becomes of increasing concern. This study tests a methodology of semi-structured interviews and diary-keeping techniques to investigate how the activity is initiated and negotiated. A research team monitored the study and evaluated the research techniques. The study concluded that the HIV/AIDS pandemic is affecting the initiation and negotiation of coitus between marital partners and that the partners wish to renegotiate the relationship, but the mechanisms for renegotiation are not at present available. In the second decade of the HIV/AIDS pandemic certain trends have become noticeable. In developed countries the main HIV high-risk groups are intravenous drug users and homosexuals, while in developing countries, particularly sub-Saharan Africa, the main transmission routes are through perinatal and heterosexual activity. Heterosexual behaviour has been recognized as a transmission route since 1987 and studies which investigated it have tended to focus upon prostitution. Sexual networking has also been investigated in West Africa and it is an important determinant in the transmission of the virus (Caldwell et al. 1993). But these approaches tend to ignore heterosexual behaviour between couples in stable relationships, and as the pandemic continues to spread in sub-Saharan Africa, this is an area which is increasingly worthy of investigation. Heterosexual behaviour is a complex subject, but one which can be investigated despite its complexity. Part of the complexity stems from the number of variables involved and this study seeks to isolate one specific variable, namely coitus, and focus upon the way in which it is initiated and negotiated between marital partners. A qualitative methodology which uses semi-structured interviews and diary-keeping techniques, as complementary research instruments, is worthy of evaluation. Using this methodology the fieldwork is described and the findings discussed. With a better understanding of how coitus is initiated and negotiated it is possible to design intervention programs which will give marital partners new interpersonal skills, and, it is hoped, an increased sense of control. The subject of sexual behaviour is not well understood, partly because of its complexity. Part of the complexity stems from the number of variables which include social, biological, * The authors gratefully acknowledge the grant provided by the Network of AIDS Researchers in Eastern and Southern Africa (NARESA) which made this study possible.

Mass Antimicrobial Treatment in Pregnancy: A randomized Placebo Controlled Trial in a Population with High Rates of Sexually Transmitted Diseases

Abstract: Sexually transmitted diseases (STDs) are highly prevalent in pregnant women in many developing countries and have been associated with poor obstetric outcomes. Case detection and treatment of STDs in women is problematic and expensive, underscoring the need for other strategies. To explore the potential benefits of routine antimicrobial therapy on pregnancy outcome, we carried out a randomized, double-blind, clinical trial in one of the antenatal clinics in Nairobi, Kenya. Four hundred pregnant women between 28 and 32 weeks' gestation were given a single dose of 250 mg ceftriaxone intramuscularly or a placebo. There was a significant difference between ceftriaxone and placebo-treated women in infant birth weight (3,209 versus 3,056 g, P = .01). In addition, there was a trend toward lower rates of birth weight < 2,500 g (4.0% versus 9.2%, P = .08) and postpartum endometritis (3.8% versus 10.4%, P = .05) in the intervention than in the placebo group. Neisseria gonorrhoeae was isolated from the cervixes of postpartum women in 1.8% of the intervention group as compared to 4.2% of the control group. These data suggest a beneficial effect of antimicrobial prophylaxis on pregnancy outcome. Larger studies should be carried out to examine the public health impact of this intervention.

Temporal variability of the 40–50-day oscillation in tropical convection

Abstract: The temporal variability of the structure and two-dimensional phase propagation of the 40–50-day oscillation in tropical convection are diagnosed using complex empirical orthogonal function (CEOF) analysis of the 1974–1988 outgoing longwave radiation (OLR) data. Results from autoregressive spectrum analysis of the OLR time series indicate that apart from the well-known 40–50-day peak, there are other significant spectral peaks near 20–30 and 17 days. In much of the tropics, excluding the equatorial Indian and western Pacific Oceans, these higher frequency peaks appear to be distinct from the 40–50 day spectral peak. The dominant spatial mode of the 40–50-day oscillation consists of the well-known equatorial dipole and associated eastward propagation. Interactions between this mode and the extratropical 40–50-day oscillation are manifested through the propagation of convection anomalies to and from the tropics via the North Pacific, north-east Atlantic and north-east African subtropics. The sense of this propagation varies from season to season and year to year. Analysis of the oscillation during individual summers and winters and each of the 1976–1977, 1982–1983 and 1986–1987 El Nino-Southern Oscillation (ENSO) events revealed marked variability in the oscillation's characteristics. The characteristic dipole and associated eastward propagation were suppressed during the winter of 1980–1981 and the entire 1982–1983 ENSO episode. In 1975–1976 and 1983–1984, convection anomalies were confined to the Indian Ocean and Australia sector and the spatial pattern differed from the characteristic equatorial dipole. The equatorial dipole was most pronounced in February-May 1981, December 1984 to May 1985 and during the 1976–1977 ENSO. During certain occasions, such as the 1981–1982 and 1983–1984 winters, there was westward as well as eastward propagation from an apparent heating source in the east Indian Ocean.

The metazoan ecto‐ and endoparasites of the rabbitfish, Siganus sutor (Cuvier & Valenciennes, 1835) of the Kenyan coast. I

Abstract: Summary In a survey of the metazoan ecto- and endoparasites of Siganus sutor (Cuvier & Valenciennes, 1835), a commercially important herbivorous fish from the Kenyan coast, sixteen species of parasites are found. The gill parasites include Monogenea (Tetrancistrum sigani Goto & Kikuchi, 1917; Microcotyle mouwoi Ishii & Sawada, 1938; Pseudohaliotrema sp. 1 and sp. 2, and an unidentified Microcotylidae species); Copepoda (Caligus sp. and Hatschekia sp.); and Isopoda (one Gnathiidae species). The intestinal parasites found are Digenea (Opisthogonoporoides cf. hanumanthai Madhavi, 1912; Gyliauchen papillatus Goto & Matsudaira, 1918; Hexangium sigani Goto & Ozaki, 1929; and three other unidentified digeneans); Acanthocephala (Sclerocollum rubrimaris Schmidt & Paperna, 1978); and Nematoda (Procamallanus sigani Yamaguti, 1935). The species listed are first records for the Kenyan coast. Infection prevalence, mean intensity and site specificity are determined for the different parasite species. The parasites have an aggregated frequency distribution in the host population: some individuals of the siganid population are more heavily infected than expected in a random distribution, while others are very little or not at all infected. Resume On a decouvert seize especes de parasites lors d'une etude des metazoaires ecto-et endoparasites de Siganus sutor (Cuvier & Valenciennes, 1985), un Poisson herbivore commercialement important de la cote keyane. Les parasites des branchies comprennent des Monogeneae (Tetrancistrum sigani Goto & Kikuchi, 1917; Microcotyle mouwoi Ishii & Sawada, 1938; Pseudohaliotrema sp.1 & sp.2, et une espece non identifiee de Microcotylideae); des Copepodes (Caligus sp. et Hatschekia sp.) et un Icopode (une espece de Gnathiideae). Les parasites intestinaux trouves appartenaient aux Digeneae (Opisthogonoporoides cf. hanumanthai Madhavi, 1972; Gyliauchen papillatus Goto & Matsudaira, 1918; Hexangium sigani Goto & Ozaki, 1929; et trois autres Digenaeae non identifies); aux Acanthocephaleae (Sclerocollum rubrimaris Schmidt & Paperna, 1978), et aux Nematodes (Procamallanus sigani Yamaguti 1935). Ces especes sont rapportees pour la premiere fois sur la cote kenyane. Le degre, l'intensite

Visceral leishmaniasis in vervet monkeys: immunological responses during asymptomatic infections.

Abstract: Nine vervet monkeys (Cercopithecus aethiops) were infected intradermally with 8 x 10(7) virulent L. donovani promastigotes. Four animals developed clinical visceral leishmaniasis and died over a period of 18 months. The remaining five animals have remained asymptomatic for a period of 3 years now. Attempts to isolate parasites from spleen and liver through biopsies were fruitless. Immunological responses of these subclinically infected animals were examined. Enzyme-linked immunosorbent assay (ELISA) and western blot analyses demonstrated Leishmania specific antibodies in these animals, but the antibody titres were low. When proliferation of peripheral blood monocytes (PBMC) to Concanavalin A (Con A) of these animals was compared with control 'disease free animals' there were no significant differences in response. However, L. donovani antigen (fixed promastigotes) specific proliferation was demonstrated in the five subclinically infected animals. High and varying levels of interferon gamma (IFN-gamma) were secreted in PBMC cultures from the five vervet monkeys when stimulated with either Con A or L. donovani antigens. In control animals, IFN-gamma was only detected when PBMC were stimulated with Con A. Marked delayed-type hypersensitivity (DTH) responses were demonstrated in the five subclinically infected animals 48 h after injection with formalin fixed promastgotes. It was concluded that the visceral Leishmania disease spectrum due to L. donovani observed in humans could be induced in vervet monkeys and that L. donovani asymptomatic/cryptic infected animals have competent humoral and cellular responses to homologous parasites.

Scaling of oxygen consumption of Lake Magadi tilapia, a fish living at 37°C

Abstract: Rates of oxygen consumption were measured in the geothermal, hot spring fish, Oreochromis alcalicus grahami by stopped flow respirometry. At 37° C, routine oxygen consumption followed the allometric relationship: V o2=0.738 M0.75, where V o2 is ml O2 h −1 and M is body mass (g). This represents a routine metabolic rate for a 10 g fish at 37° C of 0.415 ml O2 g−1 h −1 (16.4 μmol O2 g −1 h −1). Acutely increasing the temperature from 37 to 42° C significantly elevated the rate of O2 consumption from 0.739 to 0.970 ml O2 g −1 h −1 (Q10=l.72). In the field, O. a. grahami was observed to be ‘gulping’ air from the surface of the water especially in hot springs that exceeded 40° C. O. a. grahami may utilize aerial respiration when O2 requirements are high.

Typhim Vi vaccine against typhoid fever: a clinical trial in Kenya.

Abstract: Safety, tolerance and immunogenicity of the purified Vi polysaccharide vaccine (Typhim Vi) against typhoid fever was evaluated in primary school children aged 5-15 years. A total of 435 children were vaccinated, each with a single intramuscular injection in the left deltoid muscle. One hundred and ten children were randomly selected for blood samples on day 0 (pre vaccination) and day 30 (post vaccination). Vi antibodies studied by Radio immuno assay (RIA) on 97(88%) paired sera showed a seroconversion rate of 76.2% and seroprotection rate after vaccination was 74.2%, while 6.2% of children already had protective immunity before vaccination. The vaccine was well tolerated. Most commonly reported reactions were mild pain at site of injection (83%), and a few complained of mild swelling (4.6%), induration (1.1%), itching (1.1%) and headaches (1.4%). All reactions were of mild severity and disappeared within 24 to 48 hours.