Browsing by Author "Chirwa, Masuzyo"

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A pilot study on use of live attenuated rotavirus vaccine (Rotarix™) as an infection challenge model.
(2020-Oct-27) Chilengi, Roma; Simuyandi, Michelo; Chibuye, Mwelwa; Chirwa, Masuzyo; Sukwa, Nsofwa; Laban, Natasha; Chisenga, Caroline; Silwamba, Suwilanji; Grassly, Nicholas; Bosomprah, Samuel
BACKGROUND: Rotavirus remains the commonest cause of dehydrating diarrhoea, particularly in developing countries. Human infection challenge studies in children in these countries offers an opportunity to rapidly evaluate new vaccine candidates that may have improved efficacy. We evaluated use of Rotarix™ as a live-attenuated challenge agent. METHODS: We undertook an open label, exploratory study in infants receiving two standard doses of Rotarix™ at 6 and 10 weeks of age in a cohort of 22 Zambian infants. The first vaccine dose was considered as primary vaccination, and the second at day 28 as a live-attenuated virus challenge. Saliva, stool and serum samples were collected on days 0, 3, 5, 7, 14, and 28 following each dose. The primary outcome was stool shedding of rotavirus, determined by NSP2 qPCR. We calculated mean shedding index as average of natural logarithm of viral copies per gram of stool. FINDINGS: After the first dose, viral shedding was high at day 3, peaked by day 5. After the second dose, viral shedding at day 3 was low and reduced gradually in most infants until day 14. Mean shedding index was significantly lower post dose 2 across all infants and timepoints (5.0 virus copies/g of stool [95%CI: 0.3-9.7] vs 10.4 virus copies/g of stool [95%CI: 6.2-14.6]; p-value < 0.0001; rho = 0.20, SD = 4.97. Seroconversion at day 28 was associated with a mean reduction of -1.03 (95%CI = -8.07, 6.01) in viral shedding after challenge dose but this was not statistically significant (p = 0.774). A borderline positive correlation between fold-change in IgA titre at day 28 from day 0 in saliva and serum was observed; Spearman's correlation coefficient, r = 0.69; p = 0.086. INTERPRETATION: Shedding after the 'challenge' dose was reduced compared with the first dose, consistent with the induction of mucosal immunity by the first dose. This supports the use of Rotarix vaccine as a live-attenuated infection challenge. FUNDING: Medical Research Council (UK) through the HIC-Vac Network.
Clinical presentation of congenital syphilis in a rotavirus vaccine cohort study in Lusaka: a case series.
(2021-Apr-01) Sukwa, Nsofwa; Simuyandi, Michelo; Chirwa, Masuzyo; Kumwimba, Yvonne M.; Chilyabanyama, Obvious N.; Laban, Natasha ; Koyuncu, Aybüke; Chilengi, Roma
BACKGROUND: Despite an otherwise robust national antenatal clinic program, maternal and congenital syphilis remains an important public health issue in Zambia. This case series reports the clinical presentation of seven infants diagnosed with congenital syphilis in Lusaka, Zambia. CASE PRESENTATIONS: The cases in this series were incidental findings from a cohort of infants enrolled in a rotavirus vaccine immunogenicity study recruiting infants at 6 weeks of age. As part of clinical care for enrolled participants, we screened mothers of children who presented with adverse events of (i) repeated upper respiratory tract infections/coryza, (ii) skin lesions, and (iii) poor weight gain, for syphilis using rapid plasma reagin test. From a cohort of 214 mother-infant pairs enrolled between September and December 2018, a total of 115 (44.4%) of the mothers reported to have not been screened during antenatal care. Of these, four (3.5%) reported to have tested positive; and only two received treatment. Seven out of 57 (26.6%) children meeting the screening criteria had a positive rapid plasma reagin test result. The mean age at diagnosis was 4.5 months (1.3 months standard deviation), and the common presenting features included coryza (6/7), skin lesions (4/7), conjunctivitis (3/7), pallor/anemia (5/7), wasting (2/7), and underweight (5/7). Three of the seven infants were exposed to human immunodeficiency virus. Following diagnosis, all seven cases received standard treatment according to national treatment guidelines. That is, 6/7 cases received inpatient care with benzylpenicillin for 10 days, while 1/7 was treated as an outpatient and received daily procaine penicillin for 10 days. CONCLUSION: These findings suggest that, though screening for syphilis is part of the standard antenatal care in Zambia, it is not offered optimally. There is urgent need to address programmatic shortcomings in syphilis screening and treatment to avoid long-term sequelae. Additionally, clinicians need to raise their index of suspicion and rule out syphilis when confronted with these clinical symptoms, regardless of the mother's human immunodeficiency virus status.
Comparing growth velocity of HIV exposed and non-exposed infants: An observational study of infants enrolled in a randomized control trial in Zambia.
(2021) Chilyabanyama, Obvious N.; Chilengi, Roma; Laban, Natasha M.; Chirwa, Masuzyo ; Simunyandi, Michelo; Hatyoka, Luiza M.; Ngaruye, Innocent; Iqbal, Najeeha T.; Bosomprah, Samuel
BACKGROUND: Impaired growth among infants remains one of the leading nutrition problems globally. In this study, we aimed to compare the growth trajectory rate and evaluate growth trajectory characteristics among children, who are HIV exposed uninfected (HEU) and HIV unexposed uninfected (HUU), under two years in Zambia. METHOD: Our study used data from the ROVAS II study (PACTR201804003096919), an open-label randomized control trial of two verses three doses of live, attenuated, oral RotarixTM administered 6 &10 weeks or at 6 &10 weeks plus an additional dose at 9 months of age, conducted at George clinic in Lusaka, Zambia. Anthropometric measurements (height and weight) were collected on all scheduled and unscheduled visits. We defined linear growth velocity as the rate of change in height and estimated linear growth velocity as the first derivative of the mixed effect model with fractional polynomial transformations and, thereafter, used the second derivative test to determine the peak height and age at peak heigh. RESULTS: We included 212 infants in this study with median age 6 (IQR: 6-6) weeks of age. Of these 97 (45.3%) were female, 35 (16.4%) were stunted, and 59 (27.6%) were exposed to HIV at baseline. Growth velocity was consistently below the 3rd percentile of the WHO linear growth standard for HEU and HUU children. The peak height and age at peak height among HEU children were 74.7 cm (95% CI = 73.9-75.5) and 15.5 months (95% CI = 14.7-16.3) respectively and those for HUU were 73 cm (95% CI = 72.1-74.0) and 15.6 months (95% CI = 14.5-16.6) respectively. CONCLUSION: We found no difference in growth trajectories between infants who are HEU and HUU. However, the data suggests that poor linear growth is universal and profound in this cohort and may have already occurred in utero.