The 2011 outbreak of African horse sickness in the African horse sickness controlled area in South Africa

African horse sickness (AHS) is a controlled animal disease in South Africa, and as a result of the high mortality rates experienced, outbreaks in the AHS controlled area in the Western Cape Province have a significant impact on affected properties as well as on the exportation of live horses from the AHS free zone in metropolitan Cape Town. An outbreak of AHS serotype 1 occurred in the surveillance zone of the AHS controlled area of the Western Cape during the summer of 2011. The epicentre of the outbreak was the town of Mamre in the magisterial district of Malmesbury and the outbreak was confined to a defined containment zone within this area by movement control of all equids and a blanket vaccination campaign. A total of 73 cases of AHS were confirmed during this outbreak, which included four confirmed subclinical cases. The morbidity rate for the outbreak was 16%with a mortality rate of 14%and a case fatality rate of 88%. Outbreak disease surveillance relied on agent identification using polymerase chain reaction (PCR)-based assays, which is novel for an AHS outbreak in South Africa. The source of this outbreak was never confirmed although it is believed to be associated with the illegal movement of an infected animal into the Mamre area. This detailed description of the outbreak provides a sound scientific basis to assist decision making in future AHS outbreaks in the AHS controlled area of South Africa and in countries where AHS is an exotic or emerging disease.

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An entry risk assessment of African horse sickness virus into the controlled area of South Africa through the legal movement of equids

PLoS ONE ◽

10.1371/journal.pone.0252117 ◽

2021 ◽

Vol 16 (5) ◽

pp. e0252117

Author(s):

John D. Grewar ◽

Johann L. Kotze ◽

Beverly J. Parker ◽

Lesley S. van Helden ◽

Camilla T. Weyer

Keyword(s):

South Africa ◽

Census Data ◽

Movement Control ◽

Control Measures ◽

Western Cape ◽

African Horse Sickness ◽

Annual Probability ◽

Local Municipality ◽

Important Health ◽

The Impact

South Africa is endemic for African horse sickness (AHS), an important health and trade-sensitive disease of equids. The country is zoned with movement control measures facilitating an AHS-free controlled area in the south-west. Our objective was to quantitatively establish the risk of entry of AHS virus into the AHS controlled area through the legal movement of horses. Outcomes were subcategorised to evaluate movement pathway, temporal, and spatial differences in risk. A ‘no-control’ scenario allowed for evaluation of the impact of control measures. Using 2019 movement and AHS case data, and country-wide census data, a stochastic model was developed establishing local municipality level entry risk of AHSV at monthly intervals. These were aggregated to annual probability of entry. Sensitivity analysis evaluated model variables on their impact on the conditional means of the probability of entry. The median monthly probability of entry of AHSV into the controlled area of South Africa ranged from 0.75% (June) to 5.73% (February), with the annual median probability of entry estimated at 20.21% (95% CI: 15.89%-28.89%). The annual risk of AHSV entry compared well with the annual probability of introduction of AHS into the controlled area, which is ~10% based on the last 20 years of outbreak data. Direct non-quarantine movements made up most movements and accounted for most of the risk of entry. Spatial analysis showed that, even though reported case totals were zero throughout 2019 in the Western Cape, horses originating from this province still pose a risk that should not be ignored. Control measures decrease risk by a factor of 2.8 on an annual basis. Not only do the outcomes of this study inform domestic control, they can also be used for scientifically justified trade decision making, since in-country movement control forms a key component of export protocols.

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Assessing the potential of plains zebra to maintain African horse sickness in the Western Cape Province, South Africa

10.1101/751453 ◽

2019 ◽

Author(s):

Thibaud Porphyre ◽

John D. Grewar

Keyword(s):

South Africa ◽

Western Cape ◽

African Horse Sickness ◽

Western Cape Province ◽

Tariff Barrier ◽

Source Of Infection ◽

Stochastic Vector ◽

Reservoir Hosts ◽

Plains Zebra

AbstractAfrican horse sickness (AHS) is a disease of equids that results in a non-tariff barrier to the trade of live equids from affected countries. AHS is endemic in South Africa except for a controlled area in the Western Cape Province (WCP) where sporadic outbreaks have occurred in the past 2 decades. There is potential that the presence of zebra populations, thought to be the natural reservoir hosts for AHS, in the WCP could maintain AHS virus circulation in the area and act as a year-round source of infection for horses. However, it remains unclear whether the epidemiology or the ecological conditions present in the WCP would enable persistent circulation of AHS in the local zebra populations.Here we developed a hybrid deterministic-stochastic vector-host compartmental model of AHS transmission in plains zebra (Equus quagga), where host populations are age- and sex-structured and for which population and AHS transmission dynamics are modulated by rainfall and temperature conditions. Using this model, we showed that populations of plains zebra present in the WCP are not sufficiently large for AHS introduction events to become endemic and that coastal populations of zebra need to be >2500 individuals for AHS to persist >2 years, even if zebras are infectious for more than 50 days. AHS cannot become endemic in the coastal population of the WCP unless the zebra population involves at least 50,000 individuals. Finally, inland populations of plains zebra in the WCP may represent a risk for AHS to persist but would require populations of at least 500 zebras or show unrealistic duration of infectiousness for AHS introduction events to become endemic.Our results provide evidence that the risk of AHS persistence from a single introduction event in a given plains zebra population in the WCP is extremely low and it is unlikely to represent a long-term source of infection for local horses.

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Assessing the potential of plains zebra to maintain African horse sickness in the Western Cape Province, South Africa

PLoS ONE ◽

10.1371/journal.pone.0222366 ◽

2019 ◽

Vol 14 (10) ◽

pp. e0222366 ◽

Cited By ~ 1

Author(s):

Thibaud Porphyre ◽

John D. Grewar

Keyword(s):

South Africa ◽

Western Cape ◽

African Horse Sickness ◽

Western Cape Province ◽

Plains Zebra

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An isolated outbreak of diphtheria in South Africa, 2015

Epidemiology and Infection ◽

10.1017/s0950268817000851 ◽

2017 ◽

Vol 145 (10) ◽

pp. 2100-2108 ◽

Cited By ~ 7

Author(s):

S. MAHOMED ◽

M. ARCHARY ◽

P. MUTEVEDZI ◽

Y. MAHABEER ◽

P. GOVENDER ◽

...

Keyword(s):

South Africa ◽

Healthcare Worker ◽

Healthcare Workers ◽

Vaccination Campaign ◽

Case Fatality ◽

Outbreak Response ◽

Household Contacts ◽

Kwazulu Natal ◽

Response Team ◽

Health Districts

SUMMARYAn outbreak of respiratory diphtheria occurred in two health districts in the province of KwaZulu-Natal in South Africa in 2015. A multidisciplinary outbreak response team was involved in the investigation and management of the outbreak. Fifteen cases of diphtheria were identified, with ages ranging from 4 to 41 years. Of the 12 cases that were under the age of 18 years, 9 (75%) were not fully immunized for diphtheria. The case fatality was 27%. Ninety-three household contacts, 981 school or work contacts and 595 healthcare worker contacts were identified and given prophylaxis against Corynebacterium diphtheriae infection. A targeted vaccination campaign for children aged 6–15 years was carried out at schools in the two districts. The outbreak highlighted the need to improve diphtheria vaccination coverage in the province and to investigate the feasibility of offering diphtheria vaccines to healthcare workers.

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Transmission patterns of African horse sickness and equine encephalosis viruses in South African donkeys

Epidemiology and Infection ◽

10.1017/s0950268801006471 ◽

2002 ◽

Vol 128 (2) ◽

pp. 265-275 ◽

Cited By ~ 8

Author(s):

C. C. LORD ◽

G. J. VENTER ◽

P. S. MELLOR ◽

J. T. PAWESKA ◽

M. E. J. WOOLHOUSE

Keyword(s):

South Africa ◽

South African ◽

Southern Africa ◽

Geographical Variation ◽

Transmission Rate ◽

Transmission Dynamics ◽

African Horse Sickness ◽

Prevalence Data ◽

Free Zone ◽

Force Of Infection

African horse sickness (AHS) and equine encephalosis (EE) viruses are endemic to southern Africa. AHS virus causes severe epidemics when introduced to naive equine populations, resulting in severe restrictions on the movement of equines between AHS-positive and negative countries. Recent zoning of South Africa has created an AHS-free zone to facilitate equine movement, but the transmission dynamics of these viruses are not fully understood. Here, we present further analyses of serosurveys of donkeys in South Africa conducted in 1983–5 and in 1993–5. Age-prevalence data are used to derive estimates of the force of infection, λ. For both viruses, λ was highest in the northeastern part of the country and declined towards the southwest. In most of the country, EE virus had a higher transmission rate than AHS. The force of infection increased for EE virus between 1985 and 1993, but decreased for AHS virus. Both viruses showed high levels of variation in transmission between districts within the same province, particularly in areas of intermediate transmission. These data emphasize the focal nature of these viruses, and indicate areas where further data will assist in understanding the geographical variation in transmission.

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Listeriosis outbreak in South Africa: Are we winning the battle?

South African Family Practice ◽

10.4102/safp.v60i1.4832 ◽

2018 ◽

Vol 60 (1) ◽

pp. 3

Author(s):

Gboyega A Ogunbanjo

Keyword(s):

South Africa ◽

South African ◽

Core Genome ◽

Case Fatality ◽

Western Cape ◽

Gauteng Province ◽

Single Nucleotide ◽

The United Kingdom ◽

Kwazulu Natal ◽

Current Outbreak

South Africa’s listeriosis outbreak has topped the charts as the largest outbreak in history. The first reported case of the current outbreak of listeriosis was in January 2017. On 27 Feb 2018, the South African National Institute of Communicable Diseases (NICD) reported 945 confirmed cases, of which 176 had died (case fatality rate of 19%). Most reported cases were from Gauteng Province (59%, 555/945), followed by the Western Cape (12%, 116/945) and KwaZulu-Natal (7%, 66/945) provinces.1 South Africa is not the only country experiencing outbreaks of listeriosis. Europe has been experiencing a multi-country outbreak since 2015, with a combined number of only 26 cases from Austria, Denmark, Finland, Sweden and the United Kingdom classified as a confirmed microbiological cluster on the basis of whole genome sequencing (WGS) analysis, including core genome multilocus sequence typing (cgMLST) and single nucleotide polymorphism (SNP) based analysis, depending on the country. Four cases have died (case fatality 15.4%).2

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An evaluation of an influenza vaccination campaign targeting pregnant women in 27 clinics in two provinces of South Africa, 2015 – 2018

BMC Health Services Research ◽

10.1186/s12913-021-06962-8 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Kate Bishop ◽

Meredith McMorrow ◽

Susan Meiring ◽

Sibongile Walaza ◽

Liza Rossi ◽

...

Keyword(s):

South Africa ◽

Influenza Vaccine ◽

Influenza Vaccination ◽

Pregnant Women ◽

Vaccine Coverage ◽

Vaccination Campaign ◽

Hiv Positive ◽

Western Cape ◽

Department Of Health ◽

Routine Antenatal Care

Abstract Introduction Despite prioritization, routine antenatal influenza vaccine coverage is < 16% in South Africa. We aimed to describe maternal influenza vaccine coverage in 27 antenatal clinics (ANCs) in Gauteng and Western Cape (WC) Provinces, where in collaboration with the Department of Health (DoH), we augmented the annual influenza vaccination programme among pregnant women. Methods From 2015 through 2018, 40,230 additional doses of influenza vaccine were added to the available stock and administered as part of routine antenatal care. Educational talks were given daily and data were collected on women attending ANCs. We compared characteristics of vaccinated and unvaccinated women using multivariable logistic regression. Results We screened 62,979 pregnant women during the period when Southern Hemisphere influenza vaccines were available (27,068 in Gauteng and 35,911 in WC). Vaccine coverage at the targeted clinics was 78.7% (49,355/62682), although pregnant women in WC were more likely to be vaccinated compared to those in the Gauteng (Odds ratio (OR) =3.7 p < 0.001). Women aged 25—29 and > 35 years were less likely to be vaccinated than women aged 18—24 years (OR = 0.9 p = 0.053; OR = 0.9 p < 0.001). HIV positive status was not associated with vaccination (OR = 1.0 p = 0.266). Reasons for not vaccinating included: vaccine stock-outs where ANCs depleted available stock of vaccines and/or were awaiting delivery of vaccines (54.6%, 6949/12723), refusal/indecision (25.8%, 3285), and current illness that contraindicated vaccination (19.6%, 2489). Conclusion Antenatal vaccination uptake was likely improved by the increased vaccine supply and vaccine education offered during our campaign.

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