Report describes locally acquired dengue cases in Arizona

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Aedes albopictus mosquito
CDC / Pablo Cabrera

Local scientists and their colleagues from the US Centers for Disease Control and Prevention (CDC) detail two cases of locally acquired dengue virus (DENV) infection in November 2022 in Maricopa County, Arizona, according to a report today in Morbidity and Mortality Weekly Report (MMWR).

A county resident tested positive for DENV on November 7, 2022, by reverse transcription–polymerase chain reaction (RT-PCR) testing after being hospitalized on October 19 for a dengue-like illness, 7 days after traveling to Mexicali, Mexico. The person stayed in Mexicali for less than 4 hours. The patient stayed in the hospital for 3 days and has recovered.

Maricopa County Environmental Services Department officials then conducted retrospective testing for DENV in samples collected from 21 mosquito pools located within 5 miles of the patient's home from October 1 to November 3. A sample from one mosquito pool tested positive, and whole-genome sequencing by the CDC revealed that it was closely related to the DENV-3 strain that infected the patient. Since neither strain is known to be circulating in places the patient had traveled in Mexico, the findings suggest locally acquired dengue.

The scientists then interviewed 73 people on November 17 through 19 and found that 12 had dengue-like symptoms in the previous 2 weeks and were tested. All tested negative on RT-PCR.

The investigators, however, conducted serum enzyme immunoassay for DENV immunoglobulin M testing on blood specimens from 53 interviewees, and 1 result was positive. The CDC confirmed DENV-3 by plaque reduction neutralization testing. This second person had not traveled in the 2 weeks before symptom onset.

The earliest recent locally acquired dengue cases in the United States occurred in Laredo, Texas, in 1999, followed by cases in Hawaii in 2001-2002; Brownsville, Texas, in 2005; and southern Florida in 2009-2010.

US maternal death rates jumped for second year in a row amid pandemic

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Pregnant woman in hospital gownThe US pregnancy-related death rate shot up faster in 2021 than in 2020, nearly doubling from prepandemic rates in 2019 and disproportionately affecting women of minority races, concludes a study published yesterday in Obstetrics & Gynecology.

Researchers from the University of Maryland and Boston University analyzed data from the Centers for Disease Control and Prevention to estimate death rates during pregnancy and 1 year postpartum from pregnancy-related causes from January 2019 to March 2020 and April to December 2020 and 2021. The highly transmissible Delta and Omicron SARS-CoV-2 variants emerged in 2021. 

'Rates not seen since 1964'

Maternal death rates were significantly higher in 2021 (45.5 per 100,000 live births, spiking to 56.9/100,000 in the third quarter) than in 2020 (36.7/100,000) and before the pandemic (29.0/100,000).

While pregnancy-related mortality rates rose among all races and rural-urban residence categories in 2021, the biggest hike occurred among American Indian/Alaska Native (AIAN) women (160.8 vs 79.0/100,000 live births; relative increase, 104%) in 2021 relative to April to December 2020. Black women saw the largest absolute increase in 2021 (16.5/100,000), and Hispanic women had the greatest relative increase (34%).

Medium to small metropolitan (52.4 vs 37.7/100,000 live births; relative change, 39.0%) and rural (56.2 vs 46.5/100,000; relative change, 21.0%) areas saw a larger increase in 2021 than in April to December 2020 compared with large urban areas (39.1 vs 33.7/100,000; relative change, 15.9%).

The pandemic exacerbated what were already poor maternal outcomes in the US.

"Pregnancy-related mortality ratios increased more rapidly in 2021 than in 2020, consistent with rising rates of COVID-19–associated mortality among women of reproductive age," amid COVID-19 and the pandemic-related shuttering of many obstetric facilities and services, the authors wrote.

In a Boston University press release, senior author Eugene Declercq, PhD, said the dramatic rise in AIAN maternal deaths deserves more attention. "The pandemic exacerbated what were already poor maternal outcomes in the US by deepening disparities by race/ethnicity and place of residence resulting in maternal death rates not seen since 1964," he said.

Polio cases in DRC, Burundi linked to new oral vaccine

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The Global Polio Eradication Initiative (GPEI) said yesterday that newly detected cases of vaccine-derived polio in the Democratic Republic of the Congo (DRC) and Burundi appear to be linked to the novel oral polio vaccine type 2 (nOPV2).

GPEI said isolates of vaccine-derived poliovirus type 2 (cVDPV2) were detected in stool samples of six children with acute flaccid paralysis in DRC and one in Burundi. The virus was also isolated from five environmental samples in Burundi. All the reported isolates stem from two separate and new emergences of cVDPV2 linked with nOPV2 that originated in Tanganyika and South Kivu provinces in DRC.

Close to 600 million doses of nOPV2 have been administered in 28 countries since rollout of the vaccine began in March 2021. GPEI said these are the first two instances of cVDPV2 linked to the vaccine.

Young boy receiving oral polio vaccine
CDC / Michael Washington, PhD

"While detection of these outbreaks is a tragedy for the families and communities affected, it is not unexpected with wider use of the vaccine," the organization said in a statement. "All available clinical and field evidence continues to demonstrate that nOPV2 is safe and effective and has a significantly lower risk of reverting to a form that cause paralysis in low immunity settings when compared to monovalent oral polio vaccine type 2."

In a news release today, the World Health Organization (WHO) said cVDPV2 has been confirmed in two additional children in Burundi, leading the government to declare an outbreak.

While detection of these outbreaks is a tragedy for the families and communities affected, it is not unexpected with wider use of the vaccine.

Authorities in both countries, with assistance from the WHO and GPEI, are investigating the cases, have stepped up polio surveillance in the areas of detection, and will launch initial vaccination campaigns in April. Subsequent campaigns may be expanded to include parts of neighboring countries.

The polio cases in DRC and Burundi were among those reported by GPEI in its most recent polio update. Detection of cVDPV2 was also reported in Chad (two cases), Niger (one), and Benin (one). Wild poliovirus type 1 was detected in an environmental sample in Pakistan.

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