This year, the worst ever outbreak of West Nile virus happened in the United States where 1,993 persons were infected and 87 were killed, the number tripling in just two weeks. This is the largest mosquito-carried infection since 1999, when this infection was detected for the first time in the country, now involving 48 states, out of 50. Fifty-three percent (1069 cases) were neuro-invasive. This was reported by the US-CDC’s division of vector-borne diseases. The worst outbreak in history was in 2003 with 9,862 cases and 264 deaths.
The state hardest hit is Texas, which has more than half of the cases and half of the deaths from West Nile virus infection, and the number of cases around the country is expected to increase with more deaths predicted in this mosquito season, “usually throughout September.” So far, only Vermont, Hawaii, and Alaska have not reported any cases of this virus infection.
The virus has been found circulating not only in mosquitoes but birds and people. Why it has dramatically increased this year is not clear, but the transmissibility of the virus from mosquitoes has been noted to be enhanced by hot weather, as shown in laboratory experiments. Even the large outbreaks in Europe and Africa appear to be affected by hot weather. Could global warming or virus mutation to a more dangerous form have anything to do with the dramatic escalation? No one knows for sure.
What are the chances of getting infected after the bite?
Following the bite of a mosquito carrying the West Nile virus (WNV), about 20 percent, or one in five, comes down with the West Nile Fever. A lot of cases go unreported, especially in outlying areas, and from those who were lucky enough to have milder form of the infection. The symptoms usually appear between 3 to 14 days after the bite.
What are the symptoms?
Director Petersen himself was infected with the WNV in 2003 and said “the illness appears suddenly. I was out for a jog, and in one mile I went from perfectly normal to the point where I could hardly walk.” Obviously, he was infected days before this. Signs and symptoms could vary in gravity and could include fever, headache, nausea, vomiting, rash on the chest, stomach, back, and swollen neck glands, severe tiredness, weakness, or fatigue, which could last for weeks or even months.
What are the complications?
The more alarming scenario includes what is termed “neuroinvasive disease” that complicates the illness. About one out of 150 of WNV infected individuals develop encephalitis (inflammation of the brain), or meningitis (spinal cord and connecting nerves). There were 629 cases reported, with 58 cases of paralysis, affecting one or more extremities. With meningitis, there are fever, eye pain, headaches, stiff neck. With encephalitis, victims acquire cognitive problem, unable to think properly, and the condition could lead to coma and death.
Who are at risk?
Anyone and any age group is vulnerable when bitten by a WNV-carrying mosquito. However, those who are 50 and older were found to have the more serious form of the disease. Past statistics show 61% were over 50 and 39%, over 60. The older age group is at a higher risk. But in most any disease or infection, exceptions can happen, so everyone, including young people, must be careful.
What conditions increase the risk?
Those who live in homes with potential mosquito-breeding grounds (old tires and areas where water collect, etc) are obviously attracting mosquitoes to thrive and bite them. Persons who spend a great a period outdoors are at a higher risk, worse during dawn and dusk, when mosquitoes are abound and hungry. Individuals with lowered immune system might also have an increased risk.
Can pregnant mothers infect their unborn?
Yes, but it appears to be very rare. And as far as infants are concerned, they appear not to be at a high risk. Again, this observation should not allow us to be careless and let our guard down. As we stated earlier, exceptions can occur, and no one wants her child to be that exception.
Can the virus be transmitted by transfusion?
Yes, the virus could be transmitted by blood transfusion. While 242 samples of donated blood have been found to have WNV, these were discarded, and there has been no known WNV infection via blood transfusion in the United States.
Can the virus remain in the body?
In some individuals, somehow the virus remains in their body, “hiding” in their kidneys, and after some years, leads to renal disease which destroys the kidneys. Those with “neuroinvasive” WNV infection are the ones who most likely will have chronic infection and renal disease. Studies on this issue are still ongoing.
Do insecticides help?
Yes, insecticides help keep the mosquitoes away, but this should be done together with getting rid of all mosquito-breeding grounds, the same recommended for the prevention of dengue, malaria and other mosquito-borne illnesses. Texas for one has started the use of mosquito traps with insecticide and bombarding the grounds with insecticides with aerial planes. The areal “fumigation” appears to be effective so far.
Is there a cure for West Nile fever?
No, there is no known cure for West Nile fever at this time. Treatment for patients with this virus infection includes symptomatic and supportive care, to prevent complications. As with any disease or infection, the best “cure” is prevention, safer, less painful, and less expensive.
What are the preventive measures?
Instituting preventive measures can reduce the risk by more than 90 per cent. For a potentially deadly disease, this is a most significant “bargain.” The strategy can be summarized using one letter – “D,” for Discipline, the discipline to keep our home and the surrounding environment clean and safe. The other four “Ds” include, the use insect repellant that contains DEET, DRAIN any mosquito-breeding water pools, DUSK-to-DAWN stay-indoor practice, and DRESSing properly for protection against mosquito bites. And if in DOUBT, consult your DOCTOR.
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Philip S. Chua, MD, FACS, FPCS, Cardiac Surgeon Emeritus in Northwest Indiana and chairman of cardiac surgery from 1997 to 2010 at Cebu Doctors University Hospital, where he holds the title of Physician Emeritus in Surgery, is based in Las Vegas, Nevada. He is a Fellow of the American College of Surgeons, the Philippine College of Surgeons, and the Denton A. Cooley Cardiovascular Surgical Society. He is the chairman of the Filipino United Network – USA, a 501(c)(3) humanitarian foundation in the United States. Email:[email protected]
