RP-Department of Biological Sciences

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Correlation of melting temperature and cesium chloride buoyant density of bacterial deoxyribonucleic acid.
(American Society for Microbiology, 1970) Igambi, L.; Mandel, M.; Bergendahl, J.; Dodson, M. L. Jr.; Scheltgen, E.
Samples of bacterial deoxyribonucleic acid from bacteria having guanine plus cytosine (GC) contents in the range of 27 to 72 moles per cent GC were analyzed by optical melting (T(m)) and equilibrium buoyant density methods. The relation between these properties is shown to be linear. The relative value of 1.99 moles per cent GC per degree C change in T(m) is calculated, and a reference method for the calculation of GC contents relative to a standard is derived.
Standing biomass and carbon distribution in a papyrus (Cyperus papyrus L.) swamp on Lake Naivasha, Kenya
(Cambridge University Press, 1997-05) Muthuri, F. M.; Jones, M. B.
The standing live biomass of papyrus swamps is high compared with most other communities dominated by herbaceous vegetation. For the first time, measurements of below-ground rhizome and root biomass are reported here, in addition to measurements of shoot biomass, for a papyrus swamp located on Lake Naivasha, Kenya. The ratio of rhizome and root to shoot dry weight was 1.38: 1 and the total standing live biomass was 7.8 kg(dry weight) m−2. Detritus, formed from slowly decomposing papyrus, is normally the most important sink for carbon in this ecosystem. The amount of detritus retained by swamps varies but at L. Naivasha it contained almost 20 times the carbon found in living biomass. The net primary production of the swamp was calculated to be 6.28 kg(dry weight) m−2 y−1, which is amongst the highest recorded productivities for natural ecosystems. Model estimates of carbon input into the system from photosynthesis are incorporated into a carbon flow diagram for the swamp and this emphasises the importance of detritus as a sink for carbon in this ecosystem.
Use of arbuscular mycorrhiza fungi for improved crop production in sub-Saharan Africa
(2002) Waceke, J.W.
Soil fertility depletion through crop removal, soil erosion and leaching is a major challenge to increased crop productivity in Sub-Saharan Africa. Whereas nitrogen can be replenished using Rhizobium inoculants and growing leguminous crops, P is difficult to replenish. This is due to the high fixing capacity of most soils in Africa and the high cost of inorganic fertilizers. Arbuscular mycorrhiza fungi (AMF), endophytic fungi reputed for their ability to enhance P uptake can be used to alleviate P deficiencies and improve crop productivity. Although the technology has been used in developed countries, it has not been applied in crop production systems in Africa to any significant level. This is due to poor management of indigenous AMF populations, high cost of inoculants and challenges associated with the inoculum production and efficacy. These challenges are discussed in detail in this paper. Possible and practical ways of impacting these challenges are discussed. They include production of inoculum in farmers' fields to reduce transport costs, development of multi-agent inoculants to reduce cost of inoculum and genetic manipulation to improve the quality of the symbionts.
Sacred groves (kibaga) of Mfangano Island, Lake Victoria, Kenya
(Kenyatta university, 2004) Ogol, Callistus KP.O.; Ogola, Patrick O.; Beatrice Khayota, Beatrice
A questionnaire method was used to obtain information about the sacred groves and identity of other protected and sacred plants ofMfangano Island. Some 36 sacred groves, locally known in the Suba language as Kibaga, were reported to have existed on Mfangano Island, of which some 19 still exist, and the other 17 were described as extinct. From the existing groves, 12 were identified as threatened with 7 being intact. They ranged in size from 30m2 , represented by a tree, while the largest was a forest patch covering approximately 15,000m2 (1.5 Ha.). Three broad classes of sacred groves were recognized: burial sites for elders, homesteads of pioneer immigrants, and leprosy victim burial grounds. Each clan is associated with a set of groves whose protection is the. responsibility of its members. Threats to the groves are mostly anthropogenic in nature, and include vegetation clearing for homesteads, agriculture, forest products and other developments. Furthermore, modem Christian faith and educational ideals conflict with these traditional beliefs, further endangering these groves. Several plant species, particularly trees, are considered special and are accorded differential treatment, based on their socio-cultural or utilitarian value. Using some of these for building or firewood is considered a taboo, a status that has provided such species protection.The study has demonstrated that the people of Mfangano have a good traditional ecological knowledge for natural resource use and conservation.
Life tables, key factor analysis and density relations of natural populations of the spotted maize stemborer, Chilo partellus (Lepidoptera: Crambidae), under different cropping systems at the Kenyan coast
(Cambridge University Press, 2005-06) Ogol, C.K.P.O.; Midega, C. A.O.; Overholt, W. A.
Studies were conducted at Mtwapa, in the coastal area of Kenya, during the long and short rains of 1999 and 2000 to evaluate interaction of mortality factors in lowering Chilo partellus (Swinhoe) populations in diverse agroecosystems. Treatments consisted of hedgerows of leucaena only, gliricidia only, alternating rows of leucaena and gliricidia, and three plots without trees. During the cropping seasons, maize was planted between the hedgerows while a row of cowpea was planted between the rows of maize. One of the plots without trees was planted to an intercrop of maize and cowpea. The remaining two plots without trees were planted to maize alone, one of which was mulched. The treatments were laid out in a randomized complete block design with four replications. There was no evidence of enhanced mortality in the more diverse systems indicating that the vegetation structure and cultural treatments studied did not enhance activity levels of C. partellus mortality factors. The highest mortality occurred in the early and medium larval stages in all treatments. This mortality was attributable to ‘disappearance’, which represented mortality from sources other than parasitism. The total real generation mortality showed that from the initial cohort of first and second instar larvae, less than 10% of C. partellus survived to adult stage under field conditions in all the treatments. Mortality by Cotesia sesamiae Cameron and Cotesia flavipes (Cameron) was very minimal, indicating the parasitoids were not important mortality factors of C. partellus under the cropping systems studied. Their effects were also not influenced by the cropping systems studied.
Dynamics of immature stages of Anopheles arabiensis and other mosquito species (Diptera: Culicidae) in relation to rice cropping in a rice agro-ecosystem in Kenya
(Wiley, 2006) Mwangangi, Joseph; Shililu, Josephat; Muturi, Ephantus; Gu, Weidong; Mbogo, Charles; Kabiru, Ephantus; Jacob, Benjamin; Githure, John; Novak, Robert
We determined changes in species composition and densities of immature stages of Anopheles arabiensis mosquitoes in relation to rice growth cycle in order to generate data for developing larval control strategies in rice ecosystems. Experimental rice paddies (6.3m x 3.15m) exposed to natural colonization of mosquitoes were sampled weekly for two rice growing cycles between February 2004 and March 2005. Overall, 21,325 Anopheles larvae were collected, of which 91.9% were 1st and 2nd instars and 8.1% were 3rd and 4th instars. An. arabiensis was the predominant species (84.1%) with other species, An. pharoensis (13.5%), An. funestus (2.1%), An. coustani (0.3%), and An. maculipalpis (0.1%) accounting for only a small proportion of the anophelines collected. Culex quinquefasciatus (65.7%) was the predominant species among the non-anopheline species. Others species collected included: C. annulioris (9.9%), C. poicilipes (7.3%), C. tigripes (7.2%), C. duttoni (0.6%), Aedes aegypti (5.3%), Ae. cumminsii (3.5%), and Ae. vittatus (0.7%). The densities of the major anopheline species were closely related to rice stage and condition of the rice field. An. arabiensis, the predominant species, was most abundant over a three-week period after transplanting. Low densities of larvae were collected during the late vegetative, reproductive, and ripening phases of rice. An increase in larval density ten days post-transplanting was found to correlate with the application of fertilizer (sulphate of ammonia). Culicine and aedine species densities were significantly higher during the post-harvesting period. Our results suggest that the transplanting stage is favorable for the growth of immature stages of An. arabiensis and provides a narrow window for targeted larval intervention in rice
Effects of Canavalia ensiformis and Mucuna pruriens intercrops on Pratylenchus zeae damage and yield of maize in subsistence agriculture
(Kluwer Academic Publishers, 2006-06) Arim, O. J.; Waceke, J.W.; Waudo, S. W.; Kimenju, J. W.
Host status of four leguminous cover crops [Canavalia ensiformis (L.) DC. (Jack bean), Crotalaria ochroleuca G. Don (Sunnhemp), Lablab purpureus L. (Hyacinth bean) and Mucuna pruriens (L.) DC. (velvet bean)] to Pratylenchus zeae Filipjev and effects of intercropping C. ensiformis and M. pruriens with Pan5195, H627 and Emap11 maize cultivars on P. zeae population and disease severity on maize were determined in greenhouse and field tests. Pratylenchus zeae significantly (P<0.05) reduced growth of C. ochroleuca by 36% but had no effect on C. ensiformis, M. pruriens and L. purpureus. While C. ensiformis, M. pruriens and L. purpureus reduced P. zeae population, C. ochroleuca increased it. In the greenhouse test, intercropping maize with C. ensiformis significantly (P<0.05) improved maize growth by up to 34%, Nematode populations in the roots of maize intercropped with either C. ensiformis or M. pruriens were significantly (P<0.05) reduced by up to 32% while nematode disease severity in these intercropping systems was reduced by up to 26%. In the field test, intercropping Emap11, Pan5195 and H627 with C. ensiformis significantly (P<0.05) increased maize grain yield by 190, 29 and 22%, respectively. Intercropping H627 with M. pruriens significantly (P<0.05) increased maize grain yield by 12%, but grain yields of Pan5195 and Emap11 declined by 79 and 40%, respectively. Root necrosis and soil nematode populations in the C. ensiformis–maize intercrop declined by up to 50 and 30%, respectively. Under pure maize stands, soil nematode populations increased by up to 35% in 90 days relative to the initial nematode population of three nematodes g−1 of fresh soil.
Susceptibility of Non-target Aquatic Macro-invertebrates and Vertebrates of Piper guineense (Piperceae) and Spilanthes mauritian (Asteraceae) Powder in Kilifi District, Kenya
(Academic Journals, New York, 2007) Ohaga, S.O.; Ndiege, I.O.; Kubasu, S.S.; Beier, J.C.; Mbogo, C.M.
Parental awareness of hearing impairment in their school-going children and healthcare seeking behaviour in Kisumu district, Kenya
(Elsevier, 2007-03) Otieno, S.; Ogol, C.K.P.O.; Omondi, D.; Macharia, I.
Background Hearing-impaired children who are identified early and appropriately managed have improved outcomes in speech, language, cognitive and social development. Enhanced parental awareness of their child's hearing disability, behavioral, developmental and psychosocial limitations is essential to sustaining timely detection and appropriate intervention. Additionally, availability of services for diagnosis, treatment and habilitation would improve the demand for pedaudiological care in this community. Objective To describe level of parental awareness of childhood HI and the pattern of access to and utilization of ambulatory care services. Subjects Thirty-three parents of lower primary school-going children who failed audiometric screening from sampled schools in Kisumu district, western Kenya. Main outcome measures First person to detect HI, age of child at first suspicion of HI, source of ambulatory health care and use of the health care facilities. Results The prevalence of HI was 2.48%. Most parents/guardians (69.7%) were aware of their child's hearing impairment. Of these, 63.6% were first to detect HI in the pupils, while 30.3% were detected by screen. Most children (57.2%) were first recognized with (HI) after age 2 years. The mean age at identification was 5.5 years. The median travel distance to the preferred health care facility was 2 km (IQR 1–2.5). Parents seldom sought or lacked help for their hearing-impaired children. Of 27.3% who asked for hearing assessment, 9.1% received some counsel on HI and 12.1% received medication, one (3%) was referred for audiological assessment and none used a hearing aid. Use of health facilities for maternal care was (65.7%) and immunization (62.9%). Conclusions Despite adequate parental awareness of chronic childhood disability, health facilities were underutilized. This indicates the need to further stimulate and maintain a desirable level of uptake of services for diagnosis, treatment and habilitation of childhood HI, while sustaining delivery of effective and acceptable high quality paediatric care.
Bionomics of the acarophagous ladybird beetle Stethorus tridens fed Tetranychus evansi
(Wiley, 2007-06-02) Ogol, C.K.P.O.; Fiaboe, K. K. M.; Gondim Jr, M. G. C.; De Moraes, G. J.; Knapp, M.
The bionomics of Stethorus tridens Gordon fed Tetranychus evansi Baker & Pritchard were studied in the laboratory. The number of prey consumed by S. tridens increased with increasing instar levels and the total mean number consumed during immature development was 184.1 ± 18.02 T. evansi nymphs per individual. For adult male and adult female, the daily consumption was 41.3 ± 0.80 and 67.8 ± 1.69 nymphs, respectively. Stethorus tridens successfully developed to adulthood between 20 and 30°C but failed at 10, 15 and 35°C. The lower thermal threshold for egg-to-adult development estimated via linear regression and the modified Logan model was 9.2 and 8.1°C, respectively. The optimum and maximum temperatures for egg-to-adult development were around 29–31 and 32.9°C, respectively. Egg to adult development time was 23.8 ± 0.24, 17.4 ± 0.22, 16.2 ± 0.22 and 12.1 ± 0.16 days at 20, 24, 27 and 30°C, respectively. At 27°C, the sex ratio, expressed as the proportion of females, was 0.54 and the mean preoviposition, oviposition and postoviposition periods were 10.3 ± 0.67, 31.2 ± 4.74 and 30.2 ± 5.24 days, respectively. The oviposition rate was 4.0 ± 0.16 eggs/female/day with a female mean longevity of 71.6 ± 6.19 days and an intrinsic rate of natural increase of 0.104. The potential of S. tridens as a candidate natural enemy of T. evansi is discussed.
Spatial distribution of cocoon nests and egg clusters of the silkmoth Anaphe panda (Lepidoptera: Thaumetopoeidae) and its host plant Bridelia micrantha (Euphorbiaceae) in the Kakamega Forest of western Kenya
(Cambridge University Press, 2007-12) Mueke, J. M.; Mbahin, N.; Raina, S. K.; Kioko, E. N.
A study on the spatial distribution of the silkmoth Anaphe panda (Boisduval) cocoon nests, egg clusters and the host plant Bridelia micrantha (Hochst) Baill. was conducted in two different habitats of the Kakamega Forest of western Kenya: Ikuywa (indigenous forest) and Isecheno (mixed indigenous forest). The mean densities of cocoon nests, egg clusters and B. micrantha were significantly different in the two blocks and were not semi-randomly distributed in the two habitats. The host plants were underdispersed in the indigenous forest, whereas they were overdispersed in the mixed indigenous forest. The cocoon nests were overdispersed and the silkmoth egg clusters were underdispersed in the two blocks of forest. This study reveals that A. panda tends to distribute its egg clusters uniformly over the lower and middle crown of B. micrantha with a preference to eastern localization and confirms the insufficient presence of populations of this silkmoth in a mixed indigenous forest compared with an indigenous forest. Consequently, indigenous forests should be managed in a sustainable way and more indigenous tree species should be used in reforestation campaigns.
Parasitoids of the African wild silkmoth, Gonometa postica (Lepidoptera: Lasiocampidae) in the Mwingi forests, Kenya
(Wiley, 2009-07) Mueke, J. M.; Fening, K. O.; Raina, S. K.
Gonometa postica Walker produces silk of high quality, but it is affected by parasitoids attack. A study on the parasitism of G. postica larvae and pupae on host and non-host plants were undertaken for the first and second generations, corresponding to the long (March–May) and short (October–December) rainy seasons in 2006 at six field sites, three each in the Imba and Mumoni forests of Mwingi, eastern Kenya. All freshly spun cocoons of G. postica were sampled at each site from a total of 100 trees of host plants and other non-host plants where they have migrated before pupation. The cocoons were kept individually in fine net-sealed plastic vials to determine percentage parasitism. Two dipterans and four hymenopteran larval–pupal parasitoids were identified from the two forests. The most common parasitoids were Palexorista sp. (Diptera: Tachinidae) and Goryphus sp. (Hymenoptera: Ichneumonidae) with parasitism ranging from 1.8 to 32.7% and 2.2 to 7.5%, respectively. Parasitism varied significantly according to host or non-host plants, seasons and sites. This study indicates that, of the six parasitoid species recovered, only two had a significant impact in reducing the quality of the cocoons.
Plant parasitic nematodes: a threat to vegetable production in Kenya
(African Crop Science Society, 2011) Maina, J. M.; Waceke, J. W.; Kariuki, G. M.
A survey of plant parasitic nematodes (PPN) associated with cabbage was carried out in selected agro-ecological zones (AEZs) in Kenya to determine PPN density, distribution and farmer’s awareness of nematodes associated problem. Sixty cabbage farms were sampled and nematode assays on root and soil samples were carried out. Nematode population density differed significantly (P<0.05) across all the AEZs with Upper highland 1 (UH1a) recording the highest PPN population and UM1 recording the lowest. Nematodes from cabbage roots also differed significantly (P<0.05) across AEZs with Upper highland 1 (UH1b) recording the highest population density of 60 nematode 10g-1 of dry roots and UM1 having 1.2 nematodes 10g-1 of dry roots. Pratylenchus was the most abundant nematode in all AEZs. Only 3% of sampled farmers were aware of nematodes associated problems and none of them applied any nematode management practice. Key words: Agro-ecological zones, cabbage, farmer’s awareness
Molecular Characterization of HIV Type 1 among HIV-Infected Respondents in a Cohort Being Prepared for HIV Phase III Vaccine Clinical Trials, Western Kenya.
(PubMed, 2011-03) Mbithi, J. N.; Oyaro, M.; Oyugi, F.; Laten, A.; Anzala, O.; Engelbrecht, S.
Kenya is one of the sub-Saharan African countries affected by HIV-1 infection and AIDS. We investigated HIV-1 genetic diversity in 130 individuals from Busia, Bungoma, and Kakamega in western Kenya as part of an HIV-1 vaccine feasibility study in preparation for Phase III efficacy clinical trials. After RNA extraction the partial gag (484 bp) and env (1297 bp) regions were amplified and directly sequenced. Phylogenetic analysis was done using MEGA version 4 and recombinants were identified using the jpHMM tool and phylogenetic analysis. HIV-1 sequences were amplified from 122 of the 130 samples, 118 (90.8%) from the gag region and 78 (60 %) from the env region and 74 samples (56.9%) from both the gag and env regions. Of these sequenced on both regions, 51.4% were subtype A, 9.4% subtype D, 1.4% subtype C, 4.1% subtype G, and 33.7% were discordant and thus possible recombinants, including A1/C, A1/D, A1/A2, and A2/C. The jpHMM tool indicated a further two samples with CD and BD breakpoints within the env gene and one within the gag gene (A1C). An additional sample had an A1D breakpoint in the gag gene, but the envelope was not amplified. HIV-1 subtype diversity in western Kenya should be considered in vaccines designed for clinical trials in this region and this genetic diversity should be continuously monitored.
Biotaxonomy of cassava green spider mites, Mononychellus spp. (Tetranychidae): “Life type” as a possible biological criterion for their identification
(Cambridge University Press, 2011-09-19) Ogol, C.K.P.O.; Oloo, G. W; Kambona, K.O.
The life patterns of cassava green spider mite populations were compared using characteristics of spinning behaviour and other associated biological parameters so as to determine the possibility of using these criteria for separating closely related forms or populations of Mononychellus complex of species. These included web structure and density, preferred site for oviposition, feeding, walking, defecation, quiescence, spinning behaviour during walking and type of egg cover. Of these, preferred site for feeding, walking, quiescence and spinning behaviour during walking were found to be consistent and could possibly be used in comparative studies on different mite populations. The surface structure of the leaves i.e. pubescence, and mite population density were found to affect some of the behaviour patterns. Detailed studies on the influence of other factors, such as host plant variety, stage of plant growth, age of leaf colonized, weather, etc. will be necessary to determine the usefulness of these biological criteria in separating sympatric and allopatric populations of the mite.
Biology of the Wild Silkmoth Anaphe panda (Boisduval) in the Kakamega Forest of Western Kenya
(Hindawi Publishing Corporation, 2012) Kioko, E. N.; Mueke, J. M.; Raina, S. K.; Mbahin, N.
A study on the life cycle of the silkmoth Anaphe panda (Boisduval) was conducted in two different habitats of the Kakamega Forest in western Kenya: Ikuywa, an indigenous forest, and Isecheno, a mixed indigenous forest. Eggs were laid in clusters, and the incubation period ranged from 40 to 45 days. Larvae fed on Bridelia micrantha (Hochst) and passed through seven instars. The developmental period took between 83 to 86 days in the dry season and 112 to118 days in the rainy season. The pupal period ranged between 158 and 178 days in the rainy season and, on the other hand, between 107 and 138 days in the dry season. But the later caught up in development with those that formed earlier. Moths emerged from mid-October until mid-May. Longevity of adult Anaphe panda moths took between 4 and 6 days, but generally females seemed to live longer than males. The moth also seems to have higher lifespan in the indigenous forest compared to the mixed indigenous forest.
Effect of Predation on Anopheles Larvae by Five Sympatric Insect Families in Coastal Kenya.
(Medknow Publications, 2013-03) Kabiru, Ephantus W.; Kokwaro, E. D.; Muiruri, S. K.; Mwangangi, J. M.; Carlson, J.; Githure, J.; Mbogo, C. M.; Beier, J. C.
BACKGROUND & OBJECTIVES: The use of insecticides to eliminate mosquito larvae from ground pools may disrupt atural predator-induced control of mosquito larvae. Detrimental effects on predators may be directly from toxicity or by eliminating prey organisms. Identifying the principal predators responsible for mosquito suppression is needed to select non-target indicator species for insecticide studies. In this study, we sought to determine trophic level interactions between predators and immature stages of Anopheles gambiae Giles mosquitoes under experimental conditions in the coastal region of Kenya. METHODS: To identify effective predation pattern, a series of prey choice experiments was conducted. The relative abilities of five common species of aquatic insects found in the malaria-endemic coastal region of Kenya were assessed in a series of experiments. Experiments were conducted in semi-field conditions at Jaribuni, near the sites of insect collection. RESULTS: In single predator experiments, notonectids consumed most of the mosquito larvae; hydrometrids consumed about half of the mosquito larvae in treatments. Veliids and gerrids had significant, but small effects on larval survivorship. Dytiscids did not have a significant effect on mosquito larvae survivorship. In a two-predator experiment, notonectids significantly decreased survivorship of dytiscids without a change in suppressive effects on mosquito larvae. Of the five common predators evaluated, notonectids were clearly the most voracious consumers of mosquito larvae. The predation pressure on mosquito larvae was not affected by the addition of additional prey items, consisting of small dytiscid beetles. The importance of this notonectid species in coastal Kenya suggests that it would be a valuable non-target indicator species for insecticide studies. Hydrometrids were also efficient at consuming mosquito larvae. INTERPRETATION & CONCLUSION: Of the five common predators from the Kenyan coast evaluated in this study, notonectids were the most voracious consumers of immature mosquitoes. Their predation pressure on mosquito larvae was not affected by the addition of additional prey items, consisting of small dytiscid beetles.
Physico-chemical Analysis, Microbial Isolation, Sensitivity Test of the Isolates and Solar Disinfection of Water Running in Community Taps and River Kandutura in Nakuru North Sub-county, Kenya
(Academic Journals, New York, 2015) Waithaka, Paul N.; Maingi, John Muthini; Nyamache, Anthony Kebira
Nakuru North sub-county is a peri-urban area which has both dry and wet seasons. Its residents rely mostly on untreated water sources for daily water needs due to unreliable water supply from the urban council. However, this water has not been evaluated on its quality despite residents solely depending on it. This study was aimed at determining the physico-chemical and bacteriological quality of water drawn from River Kandutura and water taps in Nakuru North subcounty. In addition, the study was aimed at carrying out sensitivity test of the isolates to antibiotics and determining effectiveness of solar disinfection in water treatment. A total of 510 water samples; river (255) and taps (255) were collected and analyzed between January and December 2013. Antimicrobial sensitivity test was carried out using Kirby Bauer disk diffusion test. Out of five hundred and ten (510) samples examined for microorganisms, 36.86 % (188/510) were positive for E. coli, Shigella and Salmonella. Water used by Nakuru North sub-county residents is highly contaminated thus posing public health risk. Solar disinfection experiment indicated a possibility of effective decontamination of water up on exposure to sun light for 3-5 h. E. coli showed the highest resistance (26.3 %) followed by Salmonella (17.4 %) while Shigella showed the least (17.1 %). However, there was no significant deference (p=0.98) in resistance among total coliforms, Total heterotrophic and Salmonella at 0.05 level of significant. There is a need to enforce laws and policies on proper waste disposal as part of water pollution control
Chemistry & HIV and AIDS Integrated course module (Kenya)
(United Nations Educational Scientific and Cultural Organization, 2015) Ng'ang'a, Z. W; Imbuga, M; Thoruwa, L. C.; Ochanda, A.; Andam, A. B.; Kwofie, T. B.; Meyer, D
Hepatitis B Virus Sero-profiles and Genotypes in HIV-1 Infected and Uninfected Injection and Non-injection Drug Users from Coastal Kenya
(BioMed Central, 2015) Kilongosi, Mark W.; Budambula, Valentine; Lihana, Raphael; Musumba, Francis O.; Nyamache, Anthony K.; Budambula, Nancy L. M.; Ahmed, Aabid A.; Ouma, Collins; Were, Tom
Background: Information about HBV sero-markers, infection stages and genotypes in HIV-1 infected and uninfected injection and non-injection drug users (IDUs) in Kenya remains elusive. Methods: A cross-sectional study examining HBV sero-marker, infection stages and genotypes was conducted among HIV-1 infected and uninfected, respectively, IDUs (n = 157 and n = 214) and non-IDUs (n = 139 and n = 48), and HIV-1 uninfected non-drug using controls (n = 194) from coastal, Kenya. HBV sero-marker and infection stages were based on HBV 5-panel rapid test plasma sero-reactivity. DNA was extracted from acute and chronic plasma samples and genotypes established by nested-PCR and direct sequencing. Results: HBsAg positivity was higher in HIV-1 infected IDUs (9.6 %) relative to HIV-1 uninfected IDUs (2.3 %), HIV-1 infected non-IDUs (3.6 %), HIV-1 uninfected non-IDUs (0.0 %) and non-drug users (2.6 %; P = 0.002). Contrastingly, HBsAb positivity was higher in HIV-1 uninfected IDUs (14.6 %) and non-IDUs (16.8) in comparison to HIV-1 infected IDUs (8.3 %), and non-IDUs (8.6 %), and non-drug users (8.2 %; P = 0.023). HBcAb positivity was higher in HIV-1 infected IDUs (10.2 %) compared to HIV-1 uninfected IDUs (3.3 %), HIV-1 infected non-IDUs (6.5 %), HIV-1 uninfected non-IDUs (2.1 %) and non-drug users (4.6 %; P = 0.038). Acute (5.7 %, 1.4 %, 0.0 %, 0.0 % and 1.5 %) and chronic (5.1 %, 0.9 %, 3.6 %, 0.0 % and 1.5 %) stages were higher in HIV-1 infected IDUs, compared to HIV-1 uninfected IDUs, HIV-1 infected and uninfected non-IDUs and non-drug users, respectively. However, vaccine type response stage was higher in HIV-1 uninfected IDUs (15.4 %) relative to HIV-1 infected IDUs (6.4 %), and HIV-1 infected (6.5 %), and uninfected (10.4 %) non-IDUs, and non-drug users (5.7 %; P = 0.003). Higher resolved infection rates were also recorded in HIV-1 uninfected IDUs (11.2 %) compared to HIV-1 infected IDUs (8.3 %), and HIV-1 infected (7.2 %), uninfected (6.3 %) non-IDUs, and non-drug users (6.7 %; P = 0.479), respectively. Only A1 genotype showing minimal diversity was detected among the study participants. Conclusion: HBV sero-markers and infection staging are valuable in diagnosis and genotyping of HBV infections. Among IDUs, higher HBsAg and HBcAb positivity in HIV-1 infected and higher HBsAb positivity in HIV-1 negative IDUs suggests frequent exposure. Additionally, HBV genotype A is the dominant circulating genotype in both high and low risk populations of Kenya.

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