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 $5 years (cumulative incidence 54/100,000). Cumulative incidence decreased with increasing age to 2/100,000 in persons$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

Interim report on pandemic H1N1 influenza virus infections in South Africa, April to October 2009 : epidemiology and factors associated with fatal cases

We provide an interim report on pandemic H1N1 influenza activity in South Africa, with a focus on the epidemiology and factors associated with deaths. Following the importation of the virus on 14 July 2009, and the epidemic peak during the week starting 3 August, the incidence in South Africa has declined. A total of 12,331 cases and 91 deaths have been laboratory-confirmed as of 12 October 2009. Age distribution and risk groups were similar to those observed elsewhere. The median age of patients who died (33.5 years) was significantly higher than that of the non-fatal cases (15.0 years p<0.01). The most common underlying conditions among fatal cases were infection with human immunodeficiency virus (17/32 tested) and pregnancy (25/45 women of reproductive age). Active tuberculosis coinfection was present in seven of 72 fatal cases. These findings should be taken into consideration when planning vaccination strategies for 2010

Epidemiologic Investigations into Outbreaks of Rift Valley Fever in Humans, South Africa, 2008–2011

Rift Valley fever (RVF) is an emerging zoonosis posing a public health threat to humans in Africa. During sporadic RVF outbreaks in 2008–2009 and widespread epidemics in 2010–2011, 302 laboratory-confirmed human infections, including 25 deaths (case-fatality rate, 8%) were identified. Incidence peaked in late summer to early autumn each year, which coincided with incidence rate patterns in livestock. Most case-patients were adults (median age 43 years), men (262; 87%), who worked in farming, animal health or meat-related industries (83%). Most case-patients reported direct contact with animal tissues, blood, or other body fluids before onset of illness (89%); mosquitoes likely played a limited role in transmission of disease to humans. Close partnership with animal health and agriculture sectors allowed early recognition of human cases and appropriate preventive health messaging

Human Immunodeficiency Virus-Specific CD8+ T-Cell Activity Is Detectable from Birth in the Majority of In Utero-Infected Infants▿

Human immunodeficiency virus (HIV)-infected infants in sub-Saharan Africa typically progress to AIDS or death by 2 years of life in the absence of antiretroviral therapy. This rapid progression to HIV disease has been related to immaturity of the adaptive immune response in infants. We screened 740 infants born to HIV-infected mothers and tracked development and specificity of HIV-specific CD8+ T-cell responses in 63 HIV-infected infants identified using gamma interferon enzyme-linked immunospot assays and intracellular cytokine staining. Forty-four in utero-infected and 19 intrapartum-infected infants were compared to 45 chronically infected children >2 years of age. Seventy percent (14 of 20) in utero-infected infants tested within the first week of life demonstrated HIV-specific CD8+ T-cell responses. Gag, Pol, and Nef were the principally targeted regions in chronic pediatric infection. However, Env dominated the overall response in one-third (12/36) of the acutely infected infants, compared to only 2/45 (4%) of chronically infected children (P = 0.00083). Gag-specific CD4+ T-cell responses were minimal to undetectable in the first 6 months of pediatric infection. These data indicate that failure to control HIV replication in in utero-infected infants is not due to an inability to induce responses but instead suggest secondary failure of adaptive immunity in containing this infection. Moreover, the detection of virus-specific CD8+ T-cell responses in the first days of life in most in utero-infected infants is encouraging for HIV vaccine interventions in infants

Characteristics of laboratory-confirmed measles cases before and after the vaccination campaign in seven South African provinces, 2009–2010.

*<p>Age and sex known in 6,729 and 6,866 cases respectively; <b>#</b> Age and sex known in 1,291 and 1,319 cases respectively; mo = months; yr = years.</p><p>Please note: population for the <1 year unavailable per month; as a result, the population was estimated by dividing the population of <1 year by 12.</p

Weekly* number of measles IgM positive cases: South Africa, 2009–2011.

<p>* Week calculated from date of specimen collection (n = 17 351), date received (n = 1 067) or date tested (n = 13).</p

Map showing nine South African provinces and overall cumulative incidence per 100 000 population by province, 2009–2011.

<p>Map showing nine South African provinces and overall cumulative incidence per 100 000 population by province, 2009–2011.</p

Reported administrative vaccination coverage^* by province during the nationwide mass vaccination campaign, South Africa, May/April 2010.

*<p>Administrative method: number of doses delivered divided by the target population which is determined from the census projections.</p><p>mo = months; yr = years.</p>**<p>8 of 9 provinces of South Africa included, Gauteng Province excluded as widespread vaccination was conducted in this province in 2009.</p><p>Source: Personal Communication: National Department of Health, South Africa.</p