“Record Outbreak of West Nile Virus in Arizona: Latest News and Travel Advice”

2023-04-29 19:57:00

To UNITED STATESin L’Arizonaa record outbreak of HIV infections virus West Nile killed 101.

West Nile virus (WNV) was discovered in the United States in 1999 and first detected in Arizona in 2003, when only 12 cases were recorded. Since then, annual state totals have often hovered around 100 cases, the Maricopa County always taking the lion’s share. A record was set in 2004, with 391 cases recorded, including 355 in Maricopa County.

During the summer of 2021, the Maricopa WNV outbreak totaled 1,487 symptomatic cases, more than four times the 2004 record. This is the largest WNV outbreak ever recorded in a county nationwide. . Still, the number of recorded cases in Maricopa County is likely far below reality. Of the 1,487 ill people, 1,014 (68%) were hospitalized and 956 (64%) developed neuroinvasive disease. The 101 deaths occurred in people with neurological impairment. The median age of all cases was 66 and the median age of those who died was 79. In addition, 78 asymptomatic infections were detected during routine screening of blood donations.

It is estimated that for every neuroinvasive case, there are between 30 and 70 symptomatic non-neuroinvasive cases. The true number of cases from the 2021 outbreak would therefore be between 28,700 and 67,000 in the county, which has a population of around 4.5 million.

It is unclear what exactly triggered this massive outbreak. But it is likely to be explained by a confluence of factors: increased rainfall and temperatures that extend the WNV season in Arizona, recent population growth and habitat development in Maricopa, and the changing health care behaviors during the Covid19 pandemic.

Reminders on the virus West Nile

The virus West Nile is considered today as the Flavivirus the most common following dengue fever. It belongs to the family of Flaviviridae of the kind Flavivirus. It is migratory birds that act as reservoir animals for the West Nile virus. The West Nile virus is transmitted through the bite of mosquitoes of the genus Culex : following biting infected birds, female mosquitoes become competent to transmit the virus to humans during a blood meal.

In the majority of cases (80%), West Nile virus infection is asymptomatic.

• The symptomatic forms of the disease are characterized by the sudden appearance of a high fever following 3 to 6 days of incubation. This fever is accompanied by headache and back pain, muscle aches, cough, swollen glands in the neck, and often a rash, nausea, abdominal pain, diarrhea, and symptoms respiratory.
• Neurological complications (meningitis, encephalitis) occur in less than 1% of cases. Even more rarely, other complications (hepatitis, pancreatitis or myocarditis) may appear.

Generally, the patient recovers spontaneously, sometimes with sequelae. But the viral infection can be fatal mainly in older adults.

Travel advice

• Although West Nile virus infection is rare among travelers, for protection it is advisable to wear light colored clothing with long sleeves, long pants and socks in areas where mosquitoes are present, especially at dusk and at night. dawn when they are most active; and protect yourself from mosquito bites by using insect repellent containing DEET.
• Consult a doctor in case of sudden onset of flu-like symptoms accompanied by a high temperature (fever) following traveling to a risk area.

Source : ProMED

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