Emerging viruses Social history of viruses

1 emerging viruses

1.1 sars
1.2 west nile virus
1.3 nipah virus
1.4 viral haemorrhagic fevers

emerging viruses

emerging viruses have relatively infected host species. in humans, many emerging viruses have come other animals. when viruses jump other species diseases caused in humans called zoonoses or zoonotic infections.

sars

severe acute respiratory syndrome (sars) caused new type of coronavirus. other coronaviruses known cause mild infections in humans, virulence , rapid spread of novel virus strain caused alarm among health professionals public fear. fears of major pandemic not realised, , july 2003, after causing around 8,000 cases , 800 deaths, outbreak had ended. exact origin of sars virus not known, evidence suggests came bats.

west nile virus

west nile virus, flavivirus, first identified in 1937 when found in blood of feverish woman. virus, carried mosquitoes , birds, caused outbreaks of infection in north africa , middle east in 1950s , 1960s horses in europe fell victim. largest outbreak in humans occurred in 1974 in cape province, south africa , 10,000 people became ill. increasing frequency of epidemics , epizootics (in horses) began in 1996, around mediterranean basin, , 1999 virus had reached new york city. since virus has spread throughout us. in us, mosquitoes carry highest amounts of virus in late summer, , number of cases of disease increases in mid july september. when weather becomes colder, mosquitoes die , risk of disease decreases. in europe, many outbreaks have occurred; in 2000 surveillance programme began in uk monitor incidence of virus in humans, dead birds, mosquitoes , horses. mosquito (culex modestus) can carry virus breeds on marshes of north kent. mosquito species not thought present in uk, widespread in southern europe carries west nile virus.

nipah virus

in 1997 outbreak of respiratory disease occurred in malaysian farmers , pigs. more 265 cases of encephalitis, of 105 fatal, recorded. new paramyxovirus discovered in victim s brain; named nipah virus, after village had lived. infection caused virus fruit bats, after colony had been disrupted deforestation. bats had moved trees nearer pig farm , pigs caught virus droppings.

viral haemorrhagic fevers


marburg virus

several highly lethal viral pathogens members of filoviridae. filoviruses filament-like viruses cause viral haemorrhagic fever, , include ebola , marburg viruses. marburg virus attracted widespread press attention in april 2005 after outbreak in angola. beginning in october 2004 , continuing 2005, there 252 cases including 227 deaths.

the ebola virus epidemic in west africa, began in 2013, devastating since emergence of hiv. initial outbreak occurred in december 2013 in meliandou, village in southern guinea. among first victims two-year-old boy, three-year-old sister, mother , grandmother. after grandmother s funeral, attended family , caregivers, disease spread neighbouring villages. march 2014 outbreak severe enough raise concern of local health officials reported guinean ministry of health. middle of year epidemic had spread liberia , sierra leone. of june 2015, world health organisation reported on 27,000 cases of disease, had resulted in more 11,000 deaths.

the natural source of ebola virus bats. marburg viruses transmitted humans monkeys, , lassa fever rats (mastomys natalensis). zoonotic infections can severe because humans have no natural resistance infection , when viruses become well-adapted new host virulence decreases. zoonotic infections dead ends , in after initial outbreak rate of subsequent infections subsides because viruses not efficient @ spreading person person.

the beginning of 21st century saw increase in global awareness of devastating epidemics in developing countries, which, in previous decades had passed relatively unnoticed international health community.