Pandemiology Watch (October 22-28, 2025)
Cholera
Democratic Republic of the Congo
Médecins Sans Frontières (MSF) reports a severe cholera epidemic in the Democratic Republic of the Congo, with over 58,000 suspected cases and 1,700 deaths since January. Twenty of 26 provinces are affected, and urgent coordinated action is needed.
Rift Valley Fever
Senegal.
On October 27, Africa CDC (Africa Centres for Disease Control and Prevention) reported a total of 1,989 suspected Rift Valley Fever cases in Senegal (1,333 new). The number of confirmed cases has risen to 277 (106 new) since the last update of 132 confirmed cases on October 19. A total of 22 deaths (2 new) have been reported. Of the cases reported, males accounted for 64% of cases, 56% of cases were aged 15–34 years, and 87% of cases occurred in the Saint Louis region.
Mauritania.
On October 27, Africa CDC reported Rift Valley Fever cases in Mauritania. Since ACDC’s previous update on October 19, there have been 63 new suspected cases, 7 new confirmed cases, and 1 new death, bringing the totals to 133 suspected cases, 43 confirmed cases, and 14 deaths. Males accounted for 79% of cases, and 81% of cases were in individuals over 10 years old.
MPOX
Africa.
Sierra Leone: The latest update from the World Health Organization shows 5,433 confirmed mpox cases as of October 19, a surge of 5 cases since October 12. According to the most recent report from Africa CDC on October 27, the outbreak was linked to clade 2b. Among confirmed cases, 6.5% were in children under 15 years and 52% in males, with a 77% positivity rate.
Uganda: No new update has been reported since October 12, 2025, with Uganda confirming 6,896 mpox cases, an increase of 2 cases since October 5, according to the World Health Organization. Testing showed a 48.31% positivity rate.
Guinea: As of October 12, 2025, The World Health Organization has reported 1,077 cases in 2025 and one death in Guinea. This is an increase of 20 cases since October 12. According to Africa CDC testing shows a 42% positivity rate, and the outbreak is linked to clade 2b.
MEASLES
U.S.
As of October 22, 2025, Center for Disease Control reports a total of 1,618 confirmed measles cases in the U.S. in 2025. 12 % of cases have required hospitalization (198 cases of 1,618 ), and three deaths have been reported.
As of October 27, 2025, the measles outbreak in South Carolina has reached 25 confirmed cases, with 22 of them linked to the Upstate outbreak, according to CIDRAP. Both new infections were traced to close contacts of known cases who had been under quarantine following exposures at two schools with a high percentage of unvaccinated students.
On October 24, 2025, Rockland County, New?York, confirmed a second measles case this year, unrelated to the first case in August. Health officials are tracing known contacts.
Canada.
As of October 27, 2025, Canada has reported 5,109 measles cases where 71% occurred in children, according to the Public Health Agency of Canada. Ontario accounts for 47% of the cases, followed by Alberta with 38%. 88% were unvaccinated, and 7% required hospitalization. Genotype D8 remains the most frequently detected strain. 1 death has been reported.
POLIO
As of October 22, 2025, the Global Polio Eradication Initiative reported two new WPV1 cases and eleven WPV1-positive environmental samples in Afghanistan.
H5N1
U.S.
As of October 28, Centers for Disease Control and Prevention has not reported any cases of person-to-person transmission of H5N1 in the United States. The total remains at 70 confirmed human cases and one death.