Arizona reports concurrent West Nile, St Louis encephalitis outbreak
Arizona residents are experiencing the first known outbreak of concurrent West Nile virus (WNV) and St. Louis encephalitis virus (SLEV) infections in the United States, and most cases involve neurologic disease, the Centers for Disease Control and Prevention (CDC) reported today in Morbidity and Mortality Weekly Report (MMWR).
The viruses, both flaviviruses, are carried by Culex mosquitoes.
As of Nov 24, 117 cases of flavivirus disease had been reported to the Arizona Department of Health Services, including 75 WNV, 19 SLEV, and 23 unspecified flavivirus disease cases. In addition, during the summer the Maricopa County Vector Control Division identified 60 pools of C tarsalis or C quinquefasciatus mosquitoes that tested positive for SLEV RNA by polymerase chain reaction, and 97 pools that tested positive for WNV RNA.
Among all cases, 103 (88%) occurred from July through September. Seventy-nine patients (68%) had neuroinvasive disease, such as meningitis, encephalitis, or acute flaccid paralysis, including 47 (63%) with WNV infection, 17 (89%) with SLEV infection, and 15 (65%) with unspecified flavivirus infection. Of the patients, 86 (74%) were hospitalized and 5 (4%) died.
Eight (53%) of the state's 15 counties reported cases, and 45 WNV cases (60%) and 18 SLEV cases (95%) were in Maricopa County, the CDC said.
The authors warn, "Because of the similarity in clinical presentation for WNV and SLEV disease cases, cross reactivity between WNV and SLEV antibodies, and the lack of availability of a commercial SLEV test, SLEV disease cases could be incorrectly diagnosed as WNV disease cases or remain undetected if clinicians only request WNV testing and no confirmatory testing is conducted."
Dec 11 MMWR report
Dengue vaccine approved for use in Mexico to make it world's first
Mexican authorities have approved Sanofi Pasteur's Dengvaxia, making it the first vaccine to be licensed in the world for preventing dengue, the company said yesterday in a news release.
Mexico's Federal Commission for the Protection against Sanitary Risks (COFEPRIS) approved the tetravalent vaccine against all four dengue virus serotypes in those 9 to 45 years of age who live in dengue-endemic areas.
Sanofi CEO Olivier Brandicourt, MD, said, "This is a historic milestone for our company, for the global public health community and, most importantly, for half the world's population who lives at risk of dengue."
The COFEPRIS approval is based on results from clinical trials involving more than 40,000 people in 15 countries, Sanofi said. Dengue-endemic areas of Mexico participated in all three trial phases.
In January phase 3 trial results showed 60% overall efficacy for the vaccine, and in July phase 2 and 3 results indicated that it might drop hospital risks in older children.
Dec 9 Sanofi news release
Jan 9 and Jul 27 CIDRAP News items on clinical trials