Smallpox is an infectious disease of humans caused by the Variola major and V. minor viruses. V. major causes a more serious disease with a mortality rate of 30–35%; V. minor is associated with milder symptoms and below 1% mortality. The virus is mainly transmitted by the respiratory route. Smallpox localises in small blood vessels of the skin and in the mouth and throat. In the skin, this results in a characteristic maculopapular rash, and later, raised fluid-filled blisters. Long-term complications of V. major infection include characteristic scars, commonly on the face, which occur in 65–85% of survivors. Blindness resulting from corneal ulceration and scarring, and limb deformities due to arthritis and osteomyelitis are less common complications, seen in about 2–5% of cases.
Smallpox probably emerged in human populations in about 10,000 BC; the mummified body of Egyptian pharaoh Ramses V shows evidence of smallpox rash. The disease was responsible for an estimated 300–500 million deaths during the 20th century. Smallpox vaccine, the earliest vaccine, was developed in the 18th century, and intensive vaccination campaigns led to smallpox being declared the first infectious disease to be eradicated globally in 1979.
The 1918 flu pandemic was an unusually deadly influenza pandemic, the first of the two involving H1N1 influenza virus. The pandemic's geographic origin is unknown. Lasting from January 1918 until December 1920, it infected 500 million people across the entire globe, with a death toll of 50–100 million (3–5% of the world's population), making it one of the deadliest natural disasters of human history. It was also implicated in the outbreak of encephalitis lethargica in the 1920s.
Most influenza outbreaks disproportionately kill young, elderly or already weakened patients; in contrast the 1918 pandemic predominantly killed healthy young adults. Modern research suggests that the virus kills through a cytokine storm, an overreaction of the body's immune system. The strong immune reactions of young adults resulted in a more severe disease with a higher mortality rate, whereas the weaker immune systems of children and older adults resulted in fewer deaths.
25 February: WHO calls for increased measles vaccination coverage in the light of outbreaks across Europe; the ongoing outbreak in North America continues. WHO,CDC
24 February: A clinical trial in England shows that pre-exposure prophylaxis with tenofovir/emtricitabine (Truvada) reduces the risk of HIV infection by 86% in gay men engaging in high-risk sex. CROI
20 February: WHO approves the ReEBOV Antigen Rapid Test Kit, a protein-based diagnostic test for Ebola virus (pictured) that can give results in 15 minutes and does not require electricity. WHO
19 February: In the ongoing outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV; pictured), an increase in weekly cases is reported in Saudi Arabia; since the outbreak started in September 2012, there have been over 1000 cases with at least 376 deaths. WHO
18 February: In a preliminary study, gene therapy with eCD4-Ig – an engineered protein that mimics two receptors for HIV, CD4 (pictured) and CCR5 – protects rhesus macaques against SHIV, a model for HIV. Nature
17 February: Four polio vaccine workers are found shot dead after being abducted in Pakistan. BBC
16 February: A novel strain of HIV-1, CRF19_cpx, is associated with rapid progression to AIDS among some patients in Cuba. EBioMedicine
15 February: In the ongoing West African outbreak of Ebola virus disease, 128 new cases were confirmed, with transmission particularly high in Freetown, Sierra Leone; since the outbreak began, there have been over 23,000 suspected cases and 9380 deaths. WHO
14 February: An international collaboration to create a synthetic vaccine for poliovirus is announced. BBC
10 February: A novel RNA virus, Dinocampus coccinellae paralysis virus, is implicated in the parasitic wasp Dinocampus coccinellae paralysing its host, the spotted lady beetle, to form a bodyguard for its pupa. Proc. R. Soc. B
10 February: An antisense molecule targeting Ebolavirus VP24 mRNA protected 6 of 8 Rhesus monkeys from death from Ebola virus disease, suggesting that VP24 might be a target for anti-Ebola drugs. mBio
4 February: H7N9 avian influenza infection continues in China, with 83 cases reported. WHO
2 February: A Phase 2/3 clinical trial of two Ebolavirus vaccine candidates, cAd3-EBOZ and VSV-ZEBOV, commences in Liberia. NIH
30 January: A meta-analysis of all randomised clinical trials of oseltamivir (Tamiflu) in adults, including all published and unpublished data, shows that the antiviral reduces the duration of influenza symptoms by around one day in adults, and also reduces the risk of lower respiratory tract complications and the need for hospitalisation. Lancet
10 December: Gardasil 9, a nine-valent human papillomavirus (HPV) vaccine based on Gardasil that protects against an additional five high-risk HPV types, is approved by the FDA. FDA