Foot and mouth disease in Zambia: Spatial and temporal distributions of outbreaks, assessment of clusters and implications for control

Zambia has been experiencing low livestock productivity as well as trade restrictions owing to the occurrence of foot and mouth disease (FMD), but little is known about the epidemiology of the disease in these endemic settings. The fundamental questions relate to the spatio-temporal distribution of FMD cases and what determines their occurrence. A retrospective review of FMD cases in Zambia from 1981 to 2012 was conducted using geographical information systems and the SaTScan software package. Information was collected from peer-reviewed journal articles, conference proceedings, laboratory reports, unpublished scientific reports and grey literature. A space–time permutation probability model using a varying time window of one year was used to scan for areas with high infection rates. The spatial scan statistic detected a significant purely spatial cluster around the Mbala–Isoka area between 2009 and 2012, with secondary clusters in Sesheke–Kazungula in 2007 and 2008, the Kafue flats in 2004 and 2005 and Livingstone in 2012. This study provides evidence of the existence of statistically significant FMD clusters and an increase in occurrence in Zambia between 2004 and 2012. The identified clusters agree with areas known to be at high risk of FMD. The FMD virus transmission dynamics and the heterogeneous variability in risk within these locations may need further investigation

Identification of the plague reservoir in an endemic area of Zambia

Yersinia pestis, the bacterial agent of plague, is primarily a parasite of wild rodents that persists in permanent, discrete enzootic foci throughout the world. The disease is transmitted in humans by bites from fleas of wildlife rodent species. Therefore surveillance is the ultimate public health solution through plague detection in domestic dogs, other carnivores and wild rodents. The investigations of die-offs amongst plague-susceptible colonial rodents are also significant to determine the presence of Y. pestis in a susceptible population.This study details the identification of the plague reservoir in a suspected endemic area of Zambia. The study was undertaken through rodent investigation for the presence of Y. pestis. A total of 105 rodents were sampled routinely and during a suspected plague period. On dissection 4 (3.81%, 95% CI: 1.23−10.0) rodents sampled during an outbreak showed signs of spleen enlargement. The blood, liver, lymph nodes and spleen of each rodent were subjected to culture on 6% sheep blood agar and MaCconkey agar. Colonies obtained were identified as Y. pestis by colony morphologic features, biochemical profiles, mouse inoculation assay and polymerase chain reaction (PCR). The PCR primers used targeted the Y. pestis plasminogen activator gene, chromosomal ferric iron uptake regulation gene and the outer membrane protein B gene.The isolates were also subjected to antibiotic sensitivity tests using the disk diffusion method on Mueller-Hinton agar with sensitivity being observed with ampicillin, amoxicillin, chloramphenicol, gentamycin, streptomycin, tetracycline and trimethoprim-sulfamethoxazole. The findings, identifies a natural reservoir of Y. pestis in Zambia providing the public health officials with a definite host for the control strategy.</jats:p

Variations on the Planar Landau Problem: Canonical Transformations, A Purely Linear Potential and the Half-Plane

The ordinary Landau problem of a charged particle in a plane subjected to a perpendicular homogeneous and static magnetic field is reconsidered from different points of view. The role of phase space canonical transformations and their relation to a choice of gauge in the solution of the problem is addressed. The Landau problem is then extended to different contexts, in particular the singular situation of a purely linear potential term being added as an interaction, for which a complete purely algebraic solution is presented. This solution is then exploited to solve this same singular Landau problem in the half-plane, with as motivation the potential relevance of such a geometry for quantum Hall measurements in the presence of an electric field or a gravitational quantum well

Risk factors and outcomes of sepsis-associated acute kidney injury in intensive care units in Johannesburg, South Africa

Background. Sepsis-associated acute kidney injury (SA-AKI) has been shown to be a significant contributor to morbidity and mortality in both children and adults with critical illness. In sub-Saharan Africa, there is a lack of information on factors associated with development of SA-AKI and outcomes after intensive care unit (ICU) admission. Objectives. To assess the rate of SA-AKI, factors associated with its development, and predictors of mortality at 90 days in critically ill patients admitted to the ICU with sepsis. Methods. This was a prospective observational study conducted at two of the biggest teaching hospitals in Johannesburg, South Africa, from 15 February 2016 to 15 February 2020. The study included consecutive patients with confirmed sepsis who were admitted to the ICU within 24 hours of admission to hospital. The primary outcome of the study was development of SA-AKI (defined according to Kidney Disease Improving Global Outcome (KDIGO) criteria), and secondary outcomes were risk factors for SA-AKI and predictors of mortality at 90 days. Multivariate logistic regression analysis was employed to determine the factors associated with SA-AKI and 90-day mortality. Results. In total, 327 critically ill patients with sepsis admitted to the ICUs were included in the study. The median (interquartile range) age was 39 (30 - 52) years, and 185 patients (56.6%) developed SA-AKI. Of these patients, blacks and whites comprised 91.0% and 6.1%, respectively, and the prevalent comorbidities were HIV/AIDS (19.3%), hypertension (14.2%) and diabetes mellitus (10.1%). Patients with SA-AKI were likely to be older and of male gender, and to have cardiovascular disease, malignancies, hypotension and a low serum albumin level. In multivariate analysis, the predictors of SA-AKI were age ≥55 years (odds ratio (OR) 2.43; 95% confidence interval (CI) 1.27 - 4.65), inotropic support (OR 3.61; 95% CI 2.18 - 5.96) and a low serum albumin level (OR 2.93; 95% CI 1.40 - 6.13). SA-AKI and need for inotropic support were respectively associated with 1.9-fold and 1.7-fold increased mortality at 90 days after ICU admission. Conclusion. SA-AKI was found to be frequent in this study in two tertiary hospital ICUs in Johannesburg, and the need for inotropic support predicted mortality after ICU admission

Foot-and-mouth disease control in Zambia: A review of the current situation

Zambia has been experiencing low livestock productivity as well as trade restrictions owing to the occurrence of foot-and-mouth disease (FMD) and contagious bovine pleura pneumonia (CBPP). Foot-and-mouth disease was first recorded in Zambia in 1933 in the Western Province and since then the country has experienced repeated outbreaks. Bearing in mind the pressure that may be existing on the many risk factors for FMD including climate change, there is need to review our knowledge on FMD control. We present the spatial distribution of the FMD outbreaks that have been recorded in Zambia in the last twenty years, and the effect of the vaccinations and movement control that have been applied. We propose further strain characterisation of previous FMD outbreaks, including full sequence of VP1 gene and the 5’UTR site. The data will be geo-coded and populated with risk factor attributes. We also present preliminary findings of the buffalo and cattle probang sampling that was conducted in Lochnivar and Kafue National Park. We further probang sampled 25 buffalo at each interface area in Sioma Ngwezi, Lukusuzi and Lower Zambezi national parks. Villages in close proximity to the buffalo populations as well as those not in close proximity will be multistage cluster sampled for comparison. The data will be geo-coded and populated with risk factor and foot-and-mouth disease virus (FMDV) characterisation attributes. Data collected using a pre-tested structured questionnaire will be geo-coded and populated with identified risk factors and stored in a database and will be spatially modelled to determine their effect on FMD occurrence and control measures. New outbreaks of FMD that may occur will be investigated to find out if there are new strains involved, species affected and predisposing risk factors. The authors conclude that impacts of FMD on livelihoods if appropriate control measures are not put in place are far more devastating especially at community level. Presented with the current poverty levels failure to institute result oriented control measures will exacerbate the already life-threatening situation

Discovery and genetic characterization of diverse smacoviruses in Zambian non-human primates.

The Smacoviridae has recently been classified as a family of small circular single-stranded DNA viruses. An increasing number of smacovirus genomes have been identified exclusively in faecal matter of various vertebrate species and from insect body parts. However, the genetic diversity and host range of smacoviruses remains to be fully elucidated. Herein, we report the genetic characterization of eleven circular replication-associated protein (Rep) encoding single-stranded (CRESS) DNA viruses detected in the faeces of Zambian non-human primates. Based on pairwise genome-wide and amino acid identities with reference smacovirus species, ten of the identified CRESS DNA viruses are assigned to the genera Porprismacovirus and Huchismacovirus of the family Smacoviridae, which bidirectionally encode two major open reading frames (ORFs): Rep and capsid protein (CP) characteristic of a type IV genome organization. The remaining unclassified CRESS DNA virus was related to smacoviruses but possessed a genome harbouring a unidirectionally oriented CP and Rep, assigned as a type V genome organization. Moreover, phylogenetic and recombination analyses provided evidence for recombination events encompassing the 3'-end of the Rep ORF in the unclassified CRESS DNA virus. Our findings increase the knowledge of the known genetic diversity of smacoviruses and highlight African non-human primates as carrier animals

Challenges and Economic Implications in the Control of Foot and Mouth Disease in Sub-Saharan Africa: Lessons from the Zambian Experience

Foot and mouth disease is one of the world’s most important livestock diseases for trade. FMD infections are complex in nature and there are many epidemiological factors needing clarification. Key questions relate to the control challenges and economic impact of the disease for resource-poor FMD endemic countries like Zambia. A review of the control challenges and economic impact of FMD outbreaks in Zambia was made. Information was collected from peer-reviewed journals articles, conference proceedings, unpublished scientific reports, and personal communication with scientists and personal field experiences. The challenges of controlling FMD using mainly vaccination and movement control are discussed. Impacts include losses in income of over US$1.6 billion from exports of beef and sable antelopes and an annual cost of over US$ 2.7 million on preventive measures. Further impacts included unquantified losses in production and low investment in agriculture resulting in slow economic growth. FMD persistence may be a result of inadequate epidemiological understanding of the disease and ineffectiveness of the control measures that are being applied. The identified gaps may be considered in the annual appraisal of the FMD national control strategy in order to advance on the progressive control pathway