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Since May 2022, a global outbreak of human mpox has proven to differ from the 2017–18 outbreak in Nigeria. The mpox strain responsible, Clade IIb, has mutated substantially, according to a study published in the peer-reviewed journal The Lancet Infectious Disease.

On September 4, 2023, this research study confirmed recent mpox cluster cases were described in individuals with presumed immunity through recent infection or vaccination. 

These researchers found that of 37 men who have sex with men, seven individuals had mpox reinfections, and 29 individuals had mpox infections that occurred after two appropriately spaced JYNNEOS-Bavarian Nordic vaccine courses.

And one individual had an infection that met the criteria for both reinfection and infection after vaccination.

Those men, with an average of 36, with natural immunity after initial infection had a shorter disease course with less mucosal disease upon reinfection than with their initial infection.

Few lesions, minor mucosal disease, and minimal analgesia requirements characterized Mpox infections post-vaccination.

Overall, there were no deaths or bacterial superinfections, and all individuals were managed in the ambulatory clinic, with one hospital admission for a necrotizing neck lesion reported in the study.

As of May 2023, about 87,500 mpox cases and 141 related deaths were reported from 111 World Health Organization member countries.

Previous studies from the Netherlands, Spain, England, and the United States have described infections among children and adolescents during the recent mpox outbreak. 

Globally, 1.3% of reported cases have been in children and adolescents.

This finding differed from 1970–2021 when mpox cases in Central Africa were predominately (54%–90%) reported in young children (ages 4–6).

For patients without known exposure to a person with mpox, various activities and interactions with others were reported in a separate study.

However, it was impossible to determine the likely source of infection for most of them, wrote these researchers. These highlight concerns about a potential mpox resurgence and have underscored the need to address critical knowledge gaps concerning immunity.

Previous mpox studies have been posted since 2022.

While most people have heard of norovirus outbreaks on cruise ships, this diarrhea-causing virus also impacts people on land.

The U.S. CDC's Morbidity and Mortality Weekly Report on September 8, 2023, highlighted about 27 cases of acute gastroenteritis among hikers on the Pacific Crest Trail in 2022, suggesting a possible norovirus outbreak.

The CDC wrote preventing future outbreaks will require fostering increased awareness of handwashing and the lack of effectiveness of alcohol-based hand sanitizers against norovirus and more frequent cleaning of public facilities.

These hikers and others are eagerly awaiting news of a norovirus vaccine.

On September 6, 2023, Vaxart, Inc. announced top-line data from the Phase 2b challenge study of its oral tablet monovalent norovirus vaccine candidate, VXA-G1.1-NN.

Vaccination with VXA-G1.1-NN led to a statistically significant reduction in infection rate, a non-statistically significant reduction in norovirus acute gastroenteritis, and a substantial reduction in viral shedding.

The oral vaccine candidate was also safe and well tolerated with no vaccine-related serious adverse events.

Dr. James F. Cummings, Vaxart's Chief Medical Officer, commented in a press release, "The magnitude of the reduction in shedding could have an impact on transmission and may have important public health benefits, as norovirus spreads rapidly among people gathering in large numbers, including settings such as daycare centers, nursing homes, and workplaces, and may reduce the potential spread of the infection to families at home."

"The results of this study highlight the potentially distinctive profile of mucosal vaccination and the potential that our oral pill vaccines may have in protecting against infection and blocking transmission – potential benefits that have also been seen with our influenza vaccine," added Dr. Cummings.

Norovirus is the leading cause of acute viral gastroenteritis in all age groups in the U.S. On average, norovirus causes 19 to 21 million cases, infects 15% of all children under age 5, and leads to 465,000 emergency department visits, 109,000 hospitalizations, and 900 deaths, says the U.S. CDC.

As of September 9, 2023, norovirus vaccine candidate news is posted by Precision Vaccinations.

Malaria was eliminated as a public health threat in the United States in the mid-1950s, recent locally-acquired cases refreshed the awareness of this mosquito-transmitted disease.

The species of Anopheles mosquitoes biologically capable of transmitting malaria have been found throughout the U.S.

The U.S. CDC published a Morbidity and Mortality Weekly Report on September 8, 2023, confirming eight malaria cases were reported in Florida (seven) and Texas (one) from May 18–July 17, 2023.

As of August 2023, no additional autochthonous P. vivax cases have been detected in Florida or Texas, and there has been no evidence of infected Anopheles mosquitoes since early June. 

Although the risk for autochthonous malaria in the U.S. remains very low, U.S. clinicians need to consider a malaria diagnosis in patients with an unexplained fever, especially in areas where autochthonous malaria has been recently reported, wrote the CDC.

The recent cases underscore the potential for imported malaria cases from outbreak areas with competent vectors to produce local mosquito transmission of malaria parasites.

Before traveling internationally to areas where malaria is endemic, travelers should consult their healthcare provider regarding recommended malaria prevention measures, including potentially taking malaria prophylaxis.

Furthermore, malaria is preventable with vaccines available in Africa but not in the U.S.

Separately, the Pan American Health Organization (PAHO) called on Member States to maintain surveillance, early detection, and timely treatment of malaria cases in the Americas.

On September 7, 2023, the PAHO reported between 2022 and 2023, Argentina, Bahamas, and Jamaica reported sporadic cases of imported malaria and local transmission, including in areas where this disease had not previously been reported.