23 research outputs found
Genotypic analysis of measles viruses in southern Africa: implications for regional and global elimination of measles
Measles is a vaccine-preventable disease. Implementation of global vaccination
programmes has resulted in a dramatic decrease in measles-related deaths, from 2.6 million
in 1980 to 164 000 in 2008. To support the global measles elimination goal, laboratories
provide case-based surveillance which includes both serological diagnosis and viral
characterisation using molecular platforms.
In this study, conventional hemi-nested amplification methods were developed to detect the
nucleoprotein- and haemagglutinin-genes of measles virus, in specimens collected for rashsurveillance
programmes in Africa. Viral characterisation involved amplicon sequencing and
phylogenetic analyses of 1402 PCR-positive specimens (2655 specimens tested, 52.8%
PCR-positive) with sequence submission to global databases. Only imported strains of
genotypes B2, B3, D2, D4 and D8, have been detected in South Africa since 2002,
demonstrating the successful interruption of transmission of endemic strains. Genotypic
analyses of specimens from African countries provided information relating to strain origins,
as well as temporal and spatial data relevant to the molecular epidemiology of measles in
Southern Africa
Measles Virus Strain Diversity, Nigeria and Democratic Republic of the Congo
Differences in epidemiologic patterns are only partially explained by vaccination practices
Antecedent causes of a measles resurgence in the Democratic Republic of the Congo
Introduction: Despite accelerated measles control efforts, a massive measles resurgence occurred in the Democratic Republic of the Congo (DRC) starting in mid-2010, prompting an investigation into likely causes. Methods: We conducted a descriptive epidemiological analysis using measles immunization and surveillance data to understand the causes of the measles resurgence and to develop recommendations for elimination efforts in DRC. Results: During 2004-2012, performance indicator targets for case-based surveillance and routine measles vaccination were not met. Estimated coverage with the routine first dose of measles-containing vaccine (MCV1) increased from 57% to 73%. Phased supplementaryimmunization activities (SIAs) were conducted starting in 2002, in some cases with sub-optimal coverage (≤95%). In 2010, SIAs in five of 11 provinces were not implemented as planned, resulting in a prolonged interval between SIAs, and a missed birth cohort in one province. During July 1, 2010-December 30, 2012, high measles attack rates (>100 cases per 100,000 population) occurred in provinces that had estimated MCV1 coverage lower than the national estimate and did not implement planned 2010 SIAs. The majority of confirmed case-patients were aged <10 years (87%) and unvaccinated or with unknown vaccination status (75%). Surveillance detected two genotype B3 and one genotype B2 measlesvirus strains that were previously identified in the region. Conclusion: The resurgence was likely caused by an accumulation of unvaccinated, measles-susceptible children due to low MCV1 coverage and suboptimal SIA implementation. To achieve the regional goal of measles elimination by 2020, efforts are needed in DRC to improve case-based surveillance and increase two-dose measles vaccination coverage through routine services and SIAs.Keywords: Measles, outbreak, elimination, immunization, vaccination, surveillance, DRC, RD
Measles outbreak reveals measles susceptibility among adults in Namibia, 2009 - 2011
Background. The World Health Organization, African Region, set the goal of achieving measles elimination by 2020. Namibia was one of seven African countries to implement an accelerated measles control strategy beginning in 1996. Following implementation of this strategy, measles incidence decreased; however, between 2009 and 2011 a major outbreak occurred in Namibia.Methods. Measles vaccination coverage data were analysed and a descriptive epidemiological analysis of the measles outbreak was conducted using measles case-based surveillance and laboratory data.Results. During 1989 - 2008, MCV1 (the first routine dose of measles vaccine) coverage increased from 56% to 73% and five supplementary immunisation activities were implemented. During the outbreak (August 2009 - February 2011), 4 605 suspected measles cases were reported; of these, 3 256 were confirmed by laboratory testing or epidemiological linkage. Opuwo, a largely rural district in north-western Namibia with nomadic populations, had the highest confirmed measles incidence (16 427 cases per million). Infants aged ≤11 months had the highest cumulative age-specific incidence (9 252 cases per million) and comprised 22% of all confirmed cases; however, cases occurred across a wide age range, including adults aged ≥30 years. Among confirmed cases, 85% were unvaccinated or had unknown vaccination history. The predominantly detected measles virus genotype was B3, circulating in concurrent outbreaks in southern Africa, and B2, previously detected in Angola.Conclusion. A large-scale measles outbreak with sustained transmission over 18 months occurred in Namibia, probably caused by importation. The wide age distribution of cases indicated measles-susceptible individuals accumulated over several decades prior to the start of the outbreak
Studies of Reservoir Hosts for Marburg Virus
Marburg virus nucleic acid was found in 12 bats, antibodies were found in 2 species of these bats, but no live virus was isolated
A retrospective 5-year review of rubella in South Africa prior to the introduction of a rubella-containing vaccine
South Africa has yet to introduce a rubella-containing vaccine (RCV) into its Expanded Programme on Immunisation (EPI). Here we evaluated the incidence of laboratory-confirmed
rubella and congenital rubella syndrome (CRS) cases over the years 2015 to 2019, to document the epidemiology of rubella and CRS within South Africa prior to a RCV introduction. This
retrospective study evaluated the number of laboratory-confirmed rubella cases reported
through the national febrile rash surveillance system. A positive test for rubella immunoglobulin
M (IgM) antibodies was considered a confirmed rubella case. For CRS cases, we reported laboratory-confirmed CRS cases collected from 28 sentinel-sites from all nine provinces of South
Africa. From 2015–2019, 19 773 serum samples were tested for rubella IgM antibodies, 6 643
(33.6%) were confirmed rubella cases. Rubella was seasonal, with peaks in spring (September to November). Case numbers were similar between males (n = 3 239; 50.1%) and females
(n = 3 232; 49.9%). The highest burden of cases occurred in 2017 (n = 2 526; 38%). The
median age was 5 years (IQR: 3–7 years). Importantly, of females with rubella, 5.0% (161 of 3
232) of the cases were among women of reproductive age (15–44 years). A total of 62 CRS
cases were reported, the mortality rate was 12.9% (n = 8), and the most common birth defect
was congenital heart disease. In conclusion, rubella is endemic in South Africa. Children
below the age of 10 years were the most affected, however, rubella was also reported among
women of reproductive age. The baseline data represented here provides insight into the burden of rubella and CRS in South Africa prior to the introduction of a RCV, and can enable planning of RCV introduction into the South African EPI.The National Institute for Communicable Diseases, a division of the National Health Laboratory Service, South Africa.http://www.plosone.orgdm2022School of Health Systems and Public Health (SHSPH
Measles outbreak in South Africa: epidemiology of laboratory-confirmed measles cases and assessment of intervention, 2009-2011
BACKGROUND: Since 1995, measles vaccination at nine and 18 months has been routine in South Africa; however, coverage
seldom reached .95%. We describe the epidemiology of laboratory-confirmed measles case-patients and assess the impact
of the nationwide mass vaccination campaign during the 2009 to 2011 measles outbreak in South Africa.
METHODS: Serum specimens collected from patients with suspected-measles were tested for measles-specific IgM antibodies
using an enzyme-linked immunosorbent assay and genotypes of a subset were determined. To estimate the impact of the
nationwide mass vaccination campaign, we compared incidence in the seven months pre- (1 September 2009–11 April
2010) and seven months post-vaccination campaign (24 May 2010–31 December 2010) periods in seven provinces of South
Africa.
RESULTS: A total of 18,431 laboratory-confirmed measles case-patients were reported from all nine provinces of South Africa
(cumulative incidence 37 per 100,000 population). The highest cumulative incidence per 100,000 population was in children
aged ,1 year (603), distributed as follows: ,6 months (302/100,000), 6 to 8 months (1083/100,000) and 9 to 11 months
(724/100,000). Forty eight percent of case-patients were 40 years. A single strain of measles virus (genotype B3) circulated
throughout the outbreak. Prior to the vaccination campaign, cumulative incidence in the targeted vs. non-targeted age
group was 5.9-fold higher, decreasing to 1.7 fold following the campaign (P,0.001) and an estimated 1,380 laboratoryconfirmed
measles case-patients were prevented.
CONCLUSION: We observed a reduction in measles incidence following the nationwide mass vaccination campaign even
though it was conducted approximately one year after the outbreak started. A booster dose at school entry may be of value
given the high incidence in persons .5 years.Our acknowledgements go to the Department of Health South Africa,
National, provincial and districts, the South African Field Epidemiology
and Laboratory Training Programme (SAFELTP), for ongoing support in
surveillance and outbreak activities; Division of Epidemiology (Tsakani
Nkuna, Kelebogile Lebogang Motsepe) and Virology (Londiwe Mahlaba,
Mduduzi Buthelezi, Nomfundo Radebe, Muzi Hlanzi, Wayne Howard) at
the NICD-NHLS for data management and laboratory testing support
respectively and Private Laboratories for their support and referring
specimens to the NICD.www.plosone.orgam201
Identical Genotype B3 Sequences from Measles Patients in 4 Countries, 2005
Surveillance of measles virus detected an epidemiologic link between a refugee from Kenya and a Dutch tourist in New Jersey, USA. Identical genotype B3 sequences from patients with contemporaneous cases in the United States, Canada, and Mexico in November and December 2005 indicate that Kenya was likely to have been the common source of virus
Congenital rubella syndrome surveillance in South Africa using a sentinel site approach : a cross-sectional study
BACKGROUND. Congenital rubella syndrome (CRS) includes disorders associated with intrauterine rubella infection. Incidence
of CRS is higher in countries with no rubella-containing vaccines (RCV) in their immunization schedules. In the World Health
Organization African region, RCVs are being introduced as part of the 2012–2020 global measles and rubella strategic plan. This study
aimed to describe the epidemiology of confirmed CRS in South Africa prior to introduction of RCVs in the immunization schedule.
METHODS. This was a descriptive study with 28 sentinel sites reporting laboratory-confirmed CRS cases in all 9 provinces of
South Africa. In the retrospective phase (2010 to 2014), CRS cases were retrieved from medical records, and in the prospective phase
(2015 to 2017) clinicians at study sites reported CRS cases monthly.
RESULTS. There were 42 confirmed CRS cases in the retrospective phase and 53 confirmed CRS cases in the prospective phase.
Most frequently reported birth defects were congenital heart disease and cataracts. The median age of mothers of CRS cases was
21 years in the retrospective phase (range: 11 to 38 years) and 22 years in the prospective phase (range: 15 to 38 years).
CONCLUSION. Baseline data on laboratory-confirmed CRS will enable planning and monitoring of RCV implementation in the
South African Expanded Programme on Immunization program. Ninety-eight percent of mothers of infants with CRS were young
women 14–30 years old, indicating a potential immunity gap in this age group for consideration during introduction of RCV.The NICD/NHLS, South Africahttp://cid.oxfordjournals.orgam2020Paediatrics and Child Healt
Hepatitis B sero-prevalence in children under 15 years of age in South Africa using residual samples from community-based febrile rash surveillance.
Introduction and methodsHepatitis B is a vaccine preventable disease and is notifiable in South Africa. Hepatitis B vaccination was incorporated into the Expanded Programme on Immunisation in South Africa in 1995. We used a convenience sample from community-based febrile rash surveillance in 2013 to estimate hepatitis B sero-prevalence. Of samples serologically negative for acute measles infection, 450 samples spanning nine provinces of South Africa were tested for hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs) and hepatitis B core antibody (anti-HBc).ResultsTwo children (2/450; 0.4%) tested positive for HBsAg. Three hundred and three children (67.3%) had evidence of vaccine induced immunity. Vaccine induced immunity was present in 80.2% of 1-5 year olds, but only 60.3% of 10-14 year olds. Natural immunity, indicating exposure to circulating hepatitis B, was present in 13/450 (2.9%) children.ConclusionChronic hepatitis B in South African has decreased in prevalence from highly endemic levels prior to vaccine introduction to approximately 0.4% in this sample, demonstrating impact of a successful vaccination programme 18 years after introduction. Decreased vaccine-induced immunity with increasing age may reflect waning antibody titres over time