Successfully controlling malaria in South Africa

PKFollowing major successes in malaria control over the past 75 years, South Africa is now embarking on a malaria elimination campaign with the goal of zero local transmission by the year 2018. The key control elements have been intensive vector control, primarily through indoor residual spraying, case management based on parasitological diagnosis using evidence-based drug policies with artemisinin-based combination therapy since 2001, active health promotion in partnership with communities living in the malaria transmission areas, and cross-border collaborations. Political commitment and long-term funding for the malaria control programme have been a critical component of the programme’s success. Breaking the cycle of transmission through strengthening of active surveillance using sensitive molecular tests and field treatment of asymptomatic persons, monitoring for antimalarial drug resistance and insecticide resistance, strengthening cross-border initiatives, and ongoing programme advocacy in the face of a significant decrease in disease burden are key priorities for achieving the elimination goal

Tick bite fever in South Africa

Tick bite fever has been a constant feature of the South African medical landscape. While it was recognised many years ago that there was a wide spectrum of clinical severity of infection, only recently has it been established that there are two aetiological agents, with different epidemiologies and clinical presentations. Rickettsia conorii infections resemble the classical Mediterranean spotted fever (fièvre boutonneuse), and patients are sometimes at risk of severe or even fatal complications. On the other hand, African tick bite fever is a separate entity caused by Rickettsia africae and tends to be a milder illness, with less prominent rash and little tendency to progress to complicated disease. Irrespective of the agent, the treatment of choice for tick bite fever in South Africa remains doxycycline or tetracycline, and the role of macrolide and quinolone antibiotics is still unclear, or at least restricted. South African Family Practice Vol. 50 (2) 2008: pp. 33-3

Collective narratives catalyse cooperation

Humans invest in fantastic stories—mythologies. Recent evolutionary theories suggest that cultural selection may favour moralising stories that motivate prosocial behaviours. A key challenge is to explain the emergence of mythologies that lack explicit moral exemplars or directives. Here, we resolve this puzzle with an evolutionary model in which arbitrary mythologies transform a collection of egoistic individuals into a cooperative. We show how these otherwise puzzling amoral, nonsensical, and fictional narratives act as exquisitely functional coordination devices and facilitate the emergence of trust and cooperativeness in both large and small populations. Especially, in small populations, reflecting earlier hunter- gatherers communities, relative to our contemporary community sizes, the model is robust to the cognitive costs in adopting fictions

Odyssean malaria outbreaks in Gauteng Province, South Africa, 2007- 2013

KMBackground: Odyssean malaria refers to malaria transmitted by translocated mosquitoes and is a diagnosis of exclusion, as the probability of finding the responsible vector is miniscule. We believe that road traffic from endemic areas in and around South Africa is the source of most of the infected mosquitoes. Because of the unexpected nature of the disease, diagnosis is often delayed and severe and complicated malaria is common Objectives: To describe outbreaks of odyssean malaria during the period 2007 through 2013 in Gauteng Province, South Africa, and to educate healthcare workers about this form of malaria. Methods: Site visits, environmental hygiene inspections, patient interviews, and entomological investigations for adult mosquitoes and larvae in potential breeding sites were done in each identified outbreak. Results: Over the period, 14 laboratory-proven and 7 probable cases of odyssean malaria were investigated. There were 2 deaths (9.5% case fatality rate, approximately 10 times higher than the national fatality rate for malaria). We describe two recent clusters of cases in detail, and emphasise the importance of clinician awareness of this rare but frequently severe form of malaria. Conclusion. Odyssean malaria cases are inevitable in South Africa, given the volume of road, rail and air traffic from malaria risk areas into Gauteng and other non-endemic provinces. It is likely that many cases are missed, owing to the rare and sporadic nature of the condition. Malaria should always be kept in mind as a cause of unexplained fever and thrombocytopenia, even in the absence of a travel histor

Rabies: an evidence-based approach to management

Human rabies in South Africa is largely due to infection with the classical rabies virus (genotype 1), with the yellow mongoose the commonest vector except in KwaZulu-Natal, Eastern Cape, Mpumalanga and now Limpopo provinces where the dog is predominantly responsible for most bites. Rabies is always fatal in humans but can be prevented by timeous administration of post exposure prophylaxis( PEP). This article discusses an evidence-based approach to rabies management in South Africa. South African Family Practice Vol. 49 (7) 2007: pp. 35-4

Population-based continuous optimization, probabilistic modelling and mean shift

Evolutionary algorithms perform optimization using a population of sample solution points. An interesting development has been to view population-based optimization as the process of evolving an explicit, probabilistic model of the search space. This paper investigates a formal basis for continuous, population-based optimization in terms of a stochastic gradient descent on the Kullback-Leibler divergence between the model probability density and the objective function, represented as an unknown density of assumed form. This leads to an update rule that is related and compared with previous theoretical work, a continuous version of the population-based incremental learning algorithm, and the generalized mean shift clustering framework. Experimental results are presented that demonstrate the dynamics of the new algorithm on a set of simple test problems

Crowdsourcing malaria parasite quantification: an online game for analyzing images of infected thick blood smears

Background: There are 600,000 new malaria cases daily worldwide. The gold standard for estimating the parasite burden and the corresponding severity of the disease consists in manually counting the number of parasites in blood smears through a microscope, a process that can take more than 20 minutes of an expert microscopist’s time. Objective: This research tests the feasibility of a crowdsourced approach to malaria image analysis. In particular, we investigated whether anonymous volunteers with no prior experience would be able to count malaria parasites in digitized images of thick blood smears by playing a Web-based game. Methods: The experimental system consisted of a Web-based game where online volunteers were tasked with detecting parasites in digitized blood sample images coupled with a decision algorithm that combined the analyses from several players to produce an improved collective detection outcome. Data were collected through the MalariaSpot website. Random images of thick blood films containing Plasmodium falciparum at medium to low parasitemias, acquired by conventional optical microscopy, were presented to players. In the game, players had to find and tag as many parasites as possible in 1 minute. In the event that players found all the parasites present in the image, they were presented with a new image. In order to combine the choices of different players into a single crowd decision, we implemented an image processing pipeline and a quorum algorithm that judged a parasite tagged when a group of players agreed on its position. Results: Over 1 month, anonymous players from 95 countries played more than 12,000 games and generated a database of more than 270,000 clicks on the test images. Results revealed that combining 22 games from nonexpert players achieved a parasite counting accuracy higher than 99%. This performance could be obtained also by combining 13 games from players trained for 1 minute. Exhaustive computations measured the parasite counting accuracy for all players as a function of the number of games considered and the experience of the players. In addition, we propose a mathematical equation that accurately models the collective parasite counting performance. Conclusions: This research validates the online gaming approach for crowdsourced counting of malaria parasites in images of thick blood films. The findings support the conclusion that nonexperts are able to rapidly learn how to identify the typical features of malaria parasites in digitized thick blood samples and that combining the analyses of several users provides similar parasite counting accuracy rates as those of expert microscopists. This experiment illustrates the potential of the crowdsourced gaming approach for performing routine malaria parasite quantification, and more generally for solving biomedical image analysis problems, with future potential for telediagnosis related to global health challenges