Data on US COVID-19 activity continue to reflect low but increasing levels of illness, with activity increasing in most parts of the country, the US Centers for Disease Control and Prevention (CDC) said today in its latest update.

The agency said the epidemic trend for the disease is growing in 16 states and likely growing in 14 others, plus in Washington, DC.

Over the past week, test positivity for SARS-CoV-2, the virus that causes COVID-19, rose from 10.2% to 11.2%, with levels as high as 17.9% in the south-central part of the country (region 6), followed by levels in the 11.3% to 14.3% range in the West and 11.6% in the Southeast.

ED visits, hospitalizations up a bit

Emergency department (ED) visits for COVID, still infrequent, rose from 1.3% to 1.5%. Levels are highest in the South, Southeast, and West. The CDC said ED visits are increasing for all age-groups and are highest in young children.

Hospitalization rates have steadily increased since July, rising from 1.3 to 1.7 per 100,000 population in the past week. The percentage of deaths from COVID remains low, at 0.5% of all US deaths, with no change from the previous week. 

Nationally, the wastewater viral activity level for COVID-19 is currently moderate.

SARS-CoV-2 detections in wastewater are "very high" in Alabama, Hawaii, Louisiana, Nebraska, Nevada, South Carolina, Texas, Utah, and Washington, DC. They are high in 11 states. "Nationally, the wastewater viral activity level for COVID-19 is currently moderate," the CDC said.

In comparison, flu and respiratory syncytial virus (RSV) wastewater levels are listed as very low nationwide. ED visits for those two diseases are also listed as very low, but they are increasing for flu.

The number of cases and deaths in a Legionnaire's disease cluster in New York's Central Harlem neighborhood has grown, according to an update yesterday from the New York City Health Department (NYC Health).

As of August 28, 114 confirmed cases and 7 deaths have been reported, with 6 case-patients currently hospitalized. The outbreak was first reported in late July.

Legionnaire's disease is a type of pneumonia caused by Legionella bacteria, which grow in warm water. People who inhale mist containing the bacteria can become ill with flu-like symptoms 2 to 10 days after exposure. People over 50, and those who smoke or have chronic lung disease or a weakened immune system are at increased risk.

Testing and monitoring

Cooling towers are a common source of exposure in community clusters of Legionnaire's disease. NYC Health says it has sampled and tested water from cooling towers in the investigation zone, and that any towers with initial positive results for Legionella have completed the treatment required by the department. 

"We are continuing to monitor and let buildings know if additional treatment is needed," the department said.

The Pan American Health Organization (PAHO) today issued another alert urging countries to bolster their surveillance, medical management, and vector-control activities in ongoing battles against chikungunya and Oropouche viruses.

Fourteen countries in the Americas have reported more than 212,000 cases this year, a decline from last year. Cases have been concentrated in South America, especially Bolivia, Brazil, and Paraguay, as well as parts of the Caribbean. 

The agency said the outbreaks are linked to a shift in the circulating genotypes. Since 2014, cases in the Americas region have mainly involved the Asian genotype, but this year the most affected countries are also seeing circulation from the East/Central/South African (ECSA) genotype. 

Presence of the ECSA genotype in at least four countries is concerning, because cocirculation enhances the risk of adaptation. "Understanding chikungunya's genetic lineages is essential to predict transmission dynamics and tailor public health responses," PAHO said.

Also, it warned that cases linked to ongoing outbreaks in the Indian Ocean, Europe, and Asia also raise the risk of reintroduction and further spread into new areas with conditions conducive to transmission.

Extra vigilance for Oropouche illness

For Oropouche virus, mainly spread by biting midges, about 12,700 cases have been reported in 11 Americas countries in the first 7 months of the year, with local cases reported in Brazil, Colombia, Cuba, Panama, Peru, and Venezuela. Continuing a trend that began in 2024, the virus continues to spread to previously unaffected areas.

PAHO urged countries to focus on early case detection and to include Oropouche infection in the differential diagnosis for suspected dengue infections and be alert for possible neurologic complications. It added that community engagement is crucial for reducing populations of insects that spread the two diseases.