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My experiences of diseases in a rural district very early in my career made me develop and interest in Epidemiology and Public health. Malaria epidemiology and control have since been a focus of my research activities. Malaria is a very complex disease with a complicated life cycle involving both asexual and sexual reproduction in two different organisms, humans and mosquitoes. It is caused by 5 species of Plasmodia, P. falciparum, P. vivax, P. malariae, P. ovale and P. knowlesi. Malaria is a disease of antiquity and is mentioned in Chinese writings nearly 5000 years ago, Greek and Roman times and affected the whole planet until very recently. It has co-evolved with humans and is responsible for major inherited red cell abnormalities such as haemoglobin S, thalassemia, ovalocytosis amongst others.
With the discovery of the life cycle by Ronal Ross, a British Army surgeon in India, at the end of the 19th century, control and elimination efforts were targeted at getting rid of the vector and its known habitats in a locality. This gained impetus with the discovery of DDT in the first half of the 20th century and a Global Malaria Eradication Programme (GMEP) was launched by the WHO in 1955. The program, although achieving some successes in some parts of the world, never made any impact in the heart of the malaria world – Sub-Saharan Africa (SSA). This is because, the programme hardly touched this part of the world. Nevertheless there have been arguments that malaria elimination was not necessarily the results of the GMEP with the use of DDT but rather marked improvement in the general socio-economic conditions of the population. It is difficult to attribute the improvement to a single cause and it is more probable that vector control, improvement in socio-economic conditions and several other factors resulted in the successes achieved.
Malaria control in Ghana had its origins in the colonial administration’s efforts to reduce the morbidity and mortality of its serving officers. Initial efforts were attempts to target all aspects of the life cycle and included improvement in housing such as screening, use of nets, drainage of swamps and distribution quinine among others. These measures were intensified during the 2nd World War to minimize the loss of manpower and equipment among the allied forces stationed in Accra.
The GMEPGlobal Malaria Eradication Program launched in 1955 hardly affected SSA and in Ghana the activities were limited to preparatory field surveys carried out by the Malaria Field Unit led by Dr. Beausoleil.) By the time the program was declared a failure in the early 70’s only a couple of experimental studies had taken place in Africa and even in these the conclusions had been drawn that eradication was not possible albeit after a few years.
The incidence of malaria worsened after cessation of the GMEP at the end of the 60’s when the main control strategy depended on the presumptive treatment of fevers with chloroquine. A major contributory factor to this situation was the development of resistance to chloroquine by the parasite. The efficacy of chloroquine for the treatment of malaria declined from more than 90% in 1989 to 38% in 2003. This necessitated the replacement of chloroquine as the first line treatment. Working with the National Malaria Control Program (NMCP), we provided the evidence to support the treatment policy change to artemisinin combination therapy (ACTs) in 2005 and have since then continued to monitor their effectiveness in the field. More than 10 years after the change from chloroquine as the preferred drug of treatment, ACTs remain effective with cure rates of more than 95%. Another significant finding is our observation that the prevalence of the molecular markers associated with chloroquine resistance have seen a reduction since the change. This opens up the possibility of future drug rotation.
Despite the complexity of the parasite life cycle, involving both asexual and sexual reproduction in two different hosts, marked reductions in parasite prevalence, clinical malaria and malaria mortality have been achieved. Improvements in the malaria situation were observed following the renewed interest in reversing the deteriorating malaria situation worldwide with the formation of the Roll Back Malaria (RBM) partnership, Multilateral Initiative on Malaria (MIM) and Global Fund among others. This development has made available increased resources for the provision of intervention tools on a large scale and also supported the development of new ones.
The scaling up of known intervention strategies – Insecticide Treated Nets (ITNs), Indoor Residual Spraying (IRS) and currently chemoprevention – is contributing to a drop in the incidence and prevalence of the disease. Availability of ITNs have increased from a low of 18% in 2006 to 70% in 2014. Our data shows marked drops in the prevalence of parasitaemia among febrile children across the country and although malaria continues to lead disease reports from our health facilities, the absolute numbers have decreased.
These statistics engender hope and should spur us to develop an all-encompassing assault on the malaria problem. In driving towards elimination we need to take cognisance of the fact that the complex human, mosquito plasmodium ecology flourishes best in situations where the opportunities for mosquitoes to co-habit with and bite humans exist and exploit to the maximum our knowledge of the life cycle of the parasite, vector behavior, human behavior among other known determinants of malaria. The increasing availability of ITNs is welcome but to have a lasting impact on the problem, we will have to engage other actors, such as architects, town planners, policy makers, to ensure a lasting improvement in the general socio-economic conditions that will underpin a lasting improvement in the malaria situation.
The task of malaria elimination is not going to be an easy one. However, it has to be undertaken in order that we are fully prepared to face the looming epidemic of non-communicable diseases such as diabetes, cancers, cardiovascular diseases in addition to controlling re-emerging infections such as Ebola. It will require patience, dedication and a continuous attention to all facets of the program. We will have to be innovative both in development of new tools and use available tools intelligently. To be able to better compete against changing and adapting parasites /vectors, we have to strengthen our surveillance activities as well as develop and test new tools. This should enable us to respond and adjust our strategies to potential challenges that we are likely to face on the challenging but promising road to malaria elimination. The resultant benefits that will accrue from malaria elimination will far outweigh the costs and therefore we should strive to make malaria elimination a reality and not a pipe dream. |
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