Browsing by Author "Siwingwa M"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Norovirus infections in young children in Lusaka Province, Zambia: clinical characteristics and molecular epidemiology.
    (2017-Jan-23) Howard LM; Mwape I; Siwingwa M; Simuyandi M; Guffey MB; Stringer JS; Chi BH; Edwards KM; Chilengi R; Department of Pediatrics, Division of Pediatric Infectious Diseases, Vanderbilt University Medical Center, D-7228 MCN; 1161 21st Ave S, Nashville, TN, 37232, USA. leigh.howard@vanderbilt.edu.; Centre for Infectious Disease Research in Zambia (CIDRZ), P.O. Box 34681, Lusaka, 10101, Zambia.; Division of Global Women's Health, University of North Carolina (UNC) - Chapel Hill, 130 Mason Farm Rd., 2nd Floor, Campus Box #7030, 27599-7030, Chapel Hill, NC, USA. Roma.Chilengi@cidrz.org.; Division of Global Women's Health, University of North Carolina (UNC) - Chapel Hill, 130 Mason Farm Rd., 2nd Floor, Campus Box #7030, 27599-7030, Chapel Hill, NC, USA.; Centre for Infectious Disease Research in Zambia (CIDRZ), P.O. Box 34681, Lusaka, 10101, Zambia. Roma.Chilengi@cidrz.org.; Department of Pediatrics, Division of Pediatric Infectious Diseases, Vanderbilt University Medical Center, D-7228 MCN; 1161 21st Ave S, Nashville, TN, 37232, USA.
    BACKGROUND: The burden, clinical features, and molecular epidemiology of norovirus infection in young children in southern Africa are not well defined. METHODS: Using data from a health facility-based surveillance study of children <5 years in Lusaka Province, Zambia presenting with diarrhea, we assessed the burden of norovirus infection. A convenience sample of 454 stool specimens was tested for norovirus using reverse-transcriptase polymerase chain reaction (RT-PCR). RT-PCR positive samples underwent additional nucleotide sequencing for genogroup and genotype identification. Clinical features and severity of diarrheal illnesses were compared between norovirus-positive and -negative subjects using Chi-squared and t-tests. RESULTS: Norovirus was detected in 52/454 (11.5%) specimens tested. Abdominal pain, fever, and vomiting were the most common presenting features in norovirus-associated illnesses. However, there were no significant differences in the clinical features of norovirus-positive compared to norovirus-negative illnesses. Of 43 isolates that were available for sequencing, 31 (72.1%) were genogroup II (GII) and 12 (27.9%) were genogroup I (GI). The distribution of genotypes was diverse. CONCLUSIONS: Noroviruses were detected in approximately 10% of young children with diarrhea in the Lusaka Province of Zambia, with GII representing the majority of infections. These findings support the role of norovirus in symptomatic diarrhea disease in Africa. Further studies are needed to confirm these observations and to evaluate prevention strategies.
  • Thumbnail Image
    Item
    Trends in SARS-CoV-2 seroprevalence among pregnant women attending first antenatal care visits in Zambia: A repeated cross-sectional survey, 2021-2022.
    (2024) Heilmann E; Tembo T; Fwoloshi S; Kabamba B; Chilambe F; Kalenga K; Siwingwa M; Mulube C; Seffren V; Bolton-Moore C; Simwanza J; Yingst S; Yadav R; Rogier E; Auld AF; Agolory S; Kapina M; Gutman JR; Savory T; Kangale C; Mulenga LB; Sikazwe I; Hines JZ; Division of Parasitic Diseases and Malaria, U.S. Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.; Public Health Institute, Oakland, California, United States of America.; Division of Global HIV and Tuberculosis, U.S. Centers for Disease Control and Prevention, Lusaka, Zambia.; PATH, Lusaka, Zambia.; Adult Centre of Excellence, University Teaching Hospital, Lusaka, Zambia.; Surveillance and Disease Intelligence, Zambia National Public Health Institute, Lusaka, Zambia.; Division of Infectious Diseases, Ministry of Health, Lusaka, Zambia.; Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.; CIDRZ; Centre for Infectious Disease Research in Zambia (CIDRZ)
    SARS-CoV-2 serosurveys help estimate the extent of transmission and guide the allocation of COVID-19 vaccines. We measured SARS-CoV-2 seroprevalence among women attending ANC clinics to assess exposure trends over time in Zambia. We conducted repeated cross-sectional SARS-CoV-2 seroprevalence surveys among pregnant women aged 15-49 years attending their first ANC visits in four districts of Zambia (two urban and two rural) during September 2021-September 2022. Serologic testing was done using a multiplex bead assay which detects IgG antibodies to the nucleocapsid protein and the spike protein receptor-binding domain (RBD). We calculated monthly SARS-CoV-2 seroprevalence by district. We also categorized seropositive results as infection alone, infection and vaccination, or vaccination alone based on anti-RBD and anti-nucleocapsid test results and self-reported COVID-19 vaccination status (vaccinated was having received ≥1 dose). Among 8,304 participants, 5,296 (63.8%) were cumulatively seropositive for SARS-CoV-2 antibodies from September 2021 through September 2022. SARS-CoV-2 seroprevalence primarily increased from September 2021 to September 2022 in three districts (Lusaka: 61.8-100.0%, Chongwe: 39.6-94.7%, Chipata: 56.5-95.0%), but in Chadiza, seroprevalence increased from 27.8% in September 2021 to 77.2% in April 2022 before gradually dropping to 56.6% in July 2022. Among 5,906 participants with a valid COVID-19 vaccination status, infection alone accounted for antibody responses in 77.7% (4,590) of participants. Most women attending ANC had evidence of prior SARS-CoV-2 infection and most SARS-CoV-2 seropositivity was infection-induced. Capturing COVID-19 vaccination status and using a multiplex bead assay with anti-nucleocapsid and anti-RBD targets facilitated distinguishing infection-induced versus vaccine-induced antibody responses during a period of increasing COVID-19 vaccine coverage in Zambia. Declining seroprevalence in Chadiza may indicate waning antibodies and a need for booster vaccines. ANC clinics have a potential role in ongoing SARS-CoV-2 serosurveillance and can continue to provide insights into SARS-CoV-2 antibody dynamics to inform near real-time public health responses.