It is largely preventable by sleeping under a treated bed net and taking antimalarial drugs. Malaria remains a significant threat for those who travel to malaria areas. The combination of anti-mosquito measures and treatment has reduced mortality from malaria by over half since 2000 although over 400,000 people, mainly children in Africa, die every year. In addition to attacking the vectors, the other key intervention has been early diagnosis and treatment. It remains however a major threat in several areas, and in particular its African heartlands. There are a number of ways to reduce malaria by preventing or killing the mosquito vector of which spraying DDT on walls and more recently insecticide treated bed nets have proved the most effective.Ī campaign to eradicate malaria significantly reduced its geographical footprint, including removing it from Europe, North America, parts of Asia, Australia and much of North Africa. The lecture will consider the mathematics of vectorial capacity and why killing mosquitoes after they have bitten a human is important. It can also vary over time, for example only being a significant problem over the rainy season/monsoon. It can vary over quite short distances for example, mountains or dense urban spaces make it much less likely. They are then injected into any person it bites.īecause transmission depend geographically on where mosquitoes are breeding in large numbers, the transmission of malaria is highly variable. The female Anopheles mosquito sucks up malaria parasites when it feeds, these mature in the mosquito gut over around 9 to 11 days. The discovery of the life cycle of malaria was one of the great breakthroughs in medicine. Land-use changes reduced it in parts of Europe, including England but it is still a major threat globally. It was a major problem globally including much of Europe, USA and Australia. Marsh fever or ague was well known from ancient times. Malaria is currently the most important vectorborne disease. Killing lice by hot water washing or DDT was the key intervention. Another historically very important disease was epidemic typhus which was passed on by body lice. The risk of a plague pandemic is now zero. In the great plague epidemics 30 to 60% of Europe’s population died. It is spread by two routes: vector (fleas) and respiratory. Plague is an example of the power of the vectorborne disease to shape human history. They do however remain a very major threat globally. The UK currently has relatively few vectors with epidemic potential although global warming could change that, but not for a long time. These included plague, epidemic typhus and malaria. Vectorborne epidemics are gone for now in the UK, but they were a serious threat when this College was founded. On the other hand, many vectorborne diseases have a specific geographical range because of where the vector lives, and critically if you can kill or reduce the population of the insect vector you can prevent or reduce transmission. With an insect vector you do not need to meet the person or animal that infects you, which may be over long distances or extended time. Insect vectors are often very efficient at infection. Vectorborne diseases need different control measures from other transmission methods. These include historically important diseases such as plague but also major current diseases including malaria, dengue, sleeping sickness, river blindness, Lyme disease and typhus. Most of the major vectors are insects (a few are arachnids). Many major diseases are entirely or largely vectorborne. These notes are not a transcript of the lecture but rather highlight some of the issues that are covered. Infections seldom change their route of transmission even if they jump species. Usually, one route of infection is dominant but there may be a secondary route. In this series of talks we will be considering the five common groups of infections: vectorborne (the subject of this talk) food or water sexual and blood-borne respiratory touch. The route by which an infectious disease infects a human is important both to understand how it spreads but also how to combat it.
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