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In 1976, the world\'s attention was caught by two almost simultaneous outbreaks of a new and then a mysterious virus named Ebola () in the Sudan and what was then Zaire, now known as the Democratic Republic of Congo. Since then, sporadic outbreaks caused by Ebola virus have resulted in approximately 2387 cases and 1590 deaths (). This year, Ebola virus returned to the center stage as the Western African countries of Guinea, Liberia, and Sierra Leone are facing an unprecedented and uncontrolled outbreak caused by a new strain that has been linked by epidemiological evidence to a potential “patient zero” who succumbed to infection in December, 2013 (). The number of cases in this outbreak has surpassed that for all previously reported Ebola virus outbreaks combined. As of September 18, 2014, there have been more than 5347 cases with 2630 deaths; these numbers include 318 infected healthcare workers, half of whom have died (). In past outbreaks, the case fatality rates have varied from 25% to 90% (); the case fatality rate of the current outbreak is 53% (). However, due to limited access to Ebola treatment units and the mu opioid receptor antagonist associated with this disease, many infections may have gone unreported, so the true number of infected people is most likely much higher, and the true case fatality rate will not be known until the outbreak is over. The early symptoms of Ebola virus hemorrhagic fever disease are non-specific: fever, malaise, muscle pain, diarrhea, and vomiting. Eventually, recognizable hemorrhagic symptoms are evident including vomiting of blood, nosebleeds, and a characteristic rash, late in the course of the disease, in roughly half of those infected (). Transmission occurs through direct contact with virus-contaminated body fluids (blood, secretions, or other bodily fluids), materials such as bedding contaminated with these fluids, through the handling and preparation of contaminated food such as bush meat, or through direct or indirect contact with infected bats, a potential animal reservoir for Ebola virus ().
There remains no doubt that the development of antiretroviral therapy (ART) for the prevention and treatment of HIV infection has been one of the greatest medical advancements in the past few decades. When those without HIV use ART appropriately as either pre-exposure prophylaxis (PrEP) or post-exposure prophylaxis (PEP), HIV acquisition is almost universally prevented (). Similarly, when those with HIV use therapy appropriately, transmission to others rarely if ever occurs (), and the risk of developing AIDS is completely eliminated.
Malaria remains the most prevalent parasitic infection in the world. Up to 40% of the world population is estimated to be at risk of contracting malaria. This figure may increase in the future with increasing temperature brought about by global warming. 207million cases (uncertainty interval, 135–287million) and 627,000 malaria deaths (uncertainty interval, 473,000–789,000) were estimated in 2013 (). The majority of the deaths that result from infection (the most lethal of the species) occur among infants, children and prima–gravida women living in sub-Saharan Africa (). , the second malaria species in terms of epidemiological importance but less deadly than , causes ~70–80million clinical malaria cases annually with 2.85billion people living at risk of infection () and generates a substantial economic burden worldwide. This parasite species is prevalent mainly in Asia, Oceania, the Americas, and several countries of Africa, and accounts for half of the malaria cases outside Africa. The current malaria-control tools in malaria-endemic countries rely on effective mosquito control and artemisinin-based case management. Challenges to controlling the burden of disease include the development of resistance of mosquitoes to certain insecticides; the development of resistance of malaria parasites to chemotherapeutic agents (); the absence of a gametocidal drug suitable for mass administration (), and the risk of re-importation of malaria into geographic regions despite environmental elimination measures.