JONATHAN M. METSCH, Dr.P.H. – Tracking Emerging Public Health Challenges – September 27, 2026 – CHIKUNGUYA
” Viruses can replicate only in the cells of cellular creatures (animals, plants, fungi, microbes), and because we humans are animals ourselves, animal viruses most readily adapt to infect us. This connection is worth remembering as we deal with the continuous onslaught of newly emerging and reemerging viruses. Identifying the animal source of a virus allows disease scientists to infer how and where the transfer into humans occurred, and that inference can guide measures to assure that it doesn’t happen again.” (1)
“During the week ending September 19, the Mauritius Ministry of Health reported six additional confirmed chikungunya cases and no deaths.
Since the beginning of the year (the start of the outbreak), 6,928 confirmed cases have been reported from the two islands – Mauritius (6.826) and Rodrigues (102).” (2)
“Update on mosquito-borne diseases, dengue fever and chikungunya fever
The Centre for Health Protection (CHP) of the Department of Health today (September 25) announced the latest situation regarding dengue fever (DF) and chikungunya fever (CF). The CHP also reminded members of the public to take appropriate measures to prevent mosquito bites when engaging in outdoor activities during the Mid-Autumn Festival holiday, such as visiting parks, grassy areas and beaches, in order to prevent mosquito-borne diseases.
From September 18 to yesterday (September 24), the CHP recorded one imported DF case. The patient had visited Malaysia during the incubation period.
Hong Kong has recorded 32 DF cases so far this year, comprising 30 imported cases and two local cases. A total of 59 DF cases were recorded last year (2025), all of which were imported cases. In 2024, 161 DF cases were recorded, comprising 156 imported cases and five local cases.
According to the World Health Organization (WHO), the global incidence of DF has markedly increased over the past two decades, posing a substantial public health challenge. In 2024, the WHO recorded over 14 million DF cases, which was a record number. In 2025, over five million cases and over 4 000 DF-related deaths were reported in over 90 countries/territories. From January to August 2026, around 2.2 million cases and over 1 000 DF-related deaths have been recorded globally.
DF has been prevalent in many neighbouring tourist destinations all along. So far this year, Sri Lanka and Vietnam each recorded over 90 000 cases; Cambodia, Indonesia and Malaysia each recorded over 70 000 cases; Bangladesh recorded over 60 000 cases; and Singapore recorded over 2 400 cases. Meanwhile, according to the Guangdong Provincial Disease Control and Prevention Administration, as of August 31, 2026, Guangdong Province has recorded 431 cases, of which 150 were recorded in August.” (3)
Chikungunya likely entered Réunion Island once then spread through human movement, study suggests, edited by Gaby Clark, https://medicalxpress.com/news/2026-09-chikungunya-runion-island-human-movement.html
1.The Urgent Mystery of Where Viruses Hide, by New York Times, https://www.omanobserver.om/article/1196775/scitech/science/the-urgent-mystery-of-where-viruses-hide
2.Chikungunya in Mauritius: Latest data, by Robert Herriman, https://outbreaknewstoday.substack.com/p/chikungunya-in-mauritius-latest-data
3.CHP Warns Public About Dengue and Chikungunya Risks During Mid-Autumn Festival Celebrations, https://www.bastillepost.com/global/article/6192251-chp-warns-public-about-dengue-and-chikungunya-risks-during-mid-autumn-festival-celebrations
curated by Jonathan M. Metsch, Dr.P.H.
Clinical Professor of Environmental Medicine, Icahn School of Medicine at Mount Sinai