Building the Future of Biodefense

Recommendation: Argentina reported a resurgence of locally acquired chikungunya in recent years, following multiple years of low to no activity. Organizations in Argentina should reduce mosquito populations at their facilities by eliminating standing water. Employees can prevent mosquito bites by wearing protective clothing, using insect repellent, and eliminating standing water near their homes. Organizations should inform employees with planned work travel to Argentina and support pregnant employees who opt not to travel. Employees should consult a doctor about vaccination against chikungunya before traveling to affected areas. Vaccine eligibility and availability may vary by country.

Situation: Argentina reported 3,202 suspected chikungunya cases, of which 199 were confirmed and probable cases, from August 2025 to mid-March 2026. Of the confirmed and probable cases, 54 were in individuals who recently traveled internationally, mostly in Bolivia, Brazil, Paraguay, and Cuba. 145 cases were locally acquired, clustered in the northern part of Argentina, near the border with Bolivia, though locally acquired cases were recorded in more southern regions as well. Regionally, most cases were reported from Salta (126), followed by Jujuy (6), Tucuman (4), Catamarca (4), Santiago del Estero (3), Buenos Aires (1), and Chaco (1). The outbreak in Salta may have emerged following importation of the disease from Bolivia, where transmission is ongoing (see PHC alert on 3/10). Health officials noted that the rise of locally acquired cases in Argentina follows a sustained regional increase in chikungunya activity across the Americas. [Confidence: Very High]

Recommendation: Over 8 million people worldwide are infected with the Chagas disease parasite. It is most common in rural areas of Mexico and Central and South America. It usually spreads through bites from triatomine bugs, known as kissing bugs, but can also be transmitted through oral ingestion of food or beverages, like açaí, contaminated with the feces of infected triatomine bugs or crushed insects. Oral infection is associated with local outbreaks and often results in more severe acute disease, including fever, acute myocarditis, and severe heart issues, with mortality rates reaching up to 33% in some cases. Employees should avoid consuming açaí products in the South Zone of Macapá, Brazil, during the ongoing outbreak and exercise caution regarding the source of any açaí purchased.

Situation: Health officials are responding to an acute Chagas disease outbreak in southern Macapá, Brazil, with 6 confirmed cases. Affected neighborhoods include Jardim Marco Zero, Zerão, Buritizal, and Universidade. Officials activated a contingency plan focused on containment, case investigation, and patient care. While the source of the outbreak remains under investigation, officials are inspecting açaí processing sites and temporarily closing establishments that cannot verify proper sanitization, as contaminated açaí juice is a known oral transmission source. Businesses are allowed to reopen once compliance is confirmed. The public was also provided guidance on Chagas symptoms. Earlier this year, consumption of improperly prepared açaí was the suspected source of infection of a Chagas disease outbreak in Ananindeua, Brazil (see PHC alert on 1/27). [Confidence: Very High]

Recommendation: Respiratory diphtheria can be a severe disease requiring both antibiotics and antitoxin, but there is an effective vaccine. Organizations in the Northern Territory, Australia, should provide flexible work schedules to support employees who need to make vaccine appointments for themselves or their family members.

Situation: Health officials are investigating a diphtheria outbreak in the Northern Territory, Australia, after 4 cases of respiratory diphtheria were reported in the last week (3 in Darwin and 1 in Alice Springs). Additionally, 33 cases of cutaneous diphtheria have been recorded since 2025. Health clinicians were urged to watch for suspicious skin sores, infected wounds, or upper respiratory illness in Darwin and Alice Springs, especially among under- or unvaccinated individuals or those with known contact with a case. [Confidence: Very High]

Recommendation: Avian influenza H9N2 human cases have been sporadically reported in Asia, mostly in China. Historically, the risk of an outbreak has been extremely low since human-to-human transmission does not usually occur. Organizations can lower barriers to seasonal flu vaccines for their employees. Employees in countries where H9N2 is commonly detected in animals should avoid live-animal markets and not have contact with or consume diseased poultry.

Situation: Italy reported Europe’s 1st ever human case of the low-pathogenicity avian influenza A(H9N2) in Lombardy. The infected individual, who is currently hospitalized but stable, is described as a frail person with concomitant illnesses who recently arrived in Italy from a non-European country. The source of infection was not provided, but H9N2 infection usually occurs through contact with infected poultry or contaminated environments. Officials activated routine surveillance and prevention measures, identified contacts, and are monitoring the situation. [Confidence: Very High]