A second death case from West Nile virus (WNV) has been reported in the Midwest State of Iowa, thus bringing the total number of WNV fatalities to 67 across the U.S. this year.
Patricia Quinlisk, medical director with Iowa Public Health Department, confirmed the death case to local radio on Wednesday.
“The mosquitoes that carry West Nile actually are more prevalent now than they were at the beginning of the summer and we are still having cases of West Nile reported to us,” she added. WNV cases have been reported in all of the continental United States.
West Nile fever is a mosquito-borne infection by the West Nile virus. Approximately 80% of West Nile virus infections in humans have few or no symptoms. In the cases where symptoms do occur—termed West Nile fever in cases without neurological disease—the time from infection to the appearance of symptoms is typically between 2 and 15 days.
Symptoms may include fever, headaches, feeling tired, muscle pain or aches, nausea, loss of appetite, vomiting, and rash. Less than 1% of the cases are severe and result in neurological disease when the central nervous system is affected. People of advanced age, the very young, or those with immunosuppression, either medically induced, such as those taking immunosuppressive drugs, or due to a pre-existing medical condition such as HIV infection, are most susceptible.
The specific neurological diseases that may occur are West Nile encephalitis, which causes inflammation of the brain, West Nile meningitis, which causes inflammation of the meninges, which are the protective membranes that cover the brain and spinal cord, West Nile meningoencephalitis, which causes inflammation of the brain and also the meninges surrounding it, and West Nile poliomyelitis—spinal cord inflammation, which results in a syndrome similar to polio, which may cause acute flaccid paralysis.
West Nile virus is an arbovirus of the Flavivirus kind in the family Flaviviridae. It is mainly spread by various species of mosquitoes, with birds being the most commonly infected animal and serving as the prime reservoir host. WNV has been found in various species of ticks, but current research suggests they are not important vectors of the virus.
WNV also infects various mammal species, including humans, and has been identified in reptilian species, including alligators and crocodiles, and also in amphibians. Not all animal species that are susceptible to WNV infection, including humans, and not all bird species develop sufficient viral levels to transmit the disease to uninfected mosquitoes, and are thus not considered major factors in WNV transmission.
Currently, there is no vaccine for WNV. The best method to reduce the rates of WNV infection is mosquito control on the part of municipalities, businesses and individual citizens to reduce breeding populations of mosquitoes in public, commercial and private areas via various means including eliminating standing pools of water where mosquitoes breed, such as in old tires, buckets, sagging gutters, and unused swimming pools.
On an individual basis, the use of personal protective measures to avoid being bitten by an infected mosquito, via the use of mosquito repellent, window screens, avoiding areas where mosquitoes are more prone to congregate, such as near marshes, and areas with heavy vegetation, and being more vigilant from dusk to dawn when mosquitoes are most active offers the best defense.
In the event of being bitten by an infected mosquito, familiarity of the symptoms of WNV on the part of laypersons, physicians and allied health professions affords the best chance of receiving timely medical treatment, which may aid in reducing associated possible complications and also appropriate palliative care.
WNV is found in temperate and tropical regions of the world. It was first identified in the West Nile subregion in Uganda in 1937. Prior to the mid-1990s, WNV disease occurred only sporadically and was considered a minor risk for humans, until an outbreak in Algeria in 1994, with cases of WNV-caused encephalitis, and the first large outbreak in Romania in 1996, with a high number of cases with neuroinvasive disease.
WNV has now spread globally, with the first case in the Western Hemisphere being identified in New York City in 1999; over the next five years, the virus spread across the continental United States, north into Canada, and southward into the Caribbean islands and Latin America. WNV also spread to Europe, beyond the Mediterranean Basin, and a new strain of the virus was identified in Italy in 2012.
WNV spreads on an ongoing basis in Africa, Asia, Australia, the Middle East, Europe, Canada and in the United States. In 2012, the US experienced one of its worst epidemics in which 286 people died, with the state of Texas being hard hit by this virus.