22OCT

Peru overtakes Guatemala on new measles

3 min read

16:36UTC

PAHO counted 53,957 measles cases in the Americas by 19 September; in the latest fortnight Guatemala added fewer than Peru or the United States.

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Key takeaway

measles growth in the Americas is moving from Guatemala towards Peru and the United States.

The Pan American Health Organization (PAHO), WHO's regional office for the Americas, counted 53,957 confirmed measles cases and 68 deaths in 17 countries and territories by 19 September, 3.8 times the same period of 2025⁠¹. Guatemala holds 33,866 of them, up 11.5% in nine weeks after a near-fivefold jump in the month to mid-July. In the fortnight to 12 September it added 176 cases, fewer than Peru (190) or the United States (290).

Guatemala's deaths rose from 26 to 45 over the same nine weeks. Deaths usually lag cases by weeks, so the rise suggests the summer jump in cases was at least partly real infection, and more than a backlog of old tests being cleared. Mexico stands at 12,943 cases and 22 deaths and is declining, and the US count of 3,471 extends the record it passed in July.

PAHO is supporting Peru's outbreak response in Puno and Arequipa, and says October's Señor de los Milagros festivities and Pope Leo XIV's visit in November could increase the risk of measles transmission. Large crowds put unvaccinated people in close contact for hours, which is the condition an airborne virus needs.

Deep Analysis

In plain English

measles had been wiped out as a local disease across the Americas. This year it is back, with almost 54,000 confirmed cases, nearly four times last year's count by this point. Guatemala has had the most cases, 33,866, but its numbers now grow more slowly. In the fortnight to 12 September, Peru and the United States each added more new cases than Guatemala. PAHO, the World Health Organization's office for the Americas, warns that big religious events in Peru, the Señor de los Milagros processions in October and Pope Leo XIV's visit in November, could help the virus spread.

Deep Analysis

Root Causes

The 2026 Americas surge rests on coverage gaps that opened during the COVID-19 pandemic, when routine immunisation and campaigns were paused across the region. Several countries, Guatemala and Mexico among them, have not fully closed those gaps.

Peru's outbreak sits in the highland regions of Puno and Arequipa, where remote communities are harder to reach with second doses. October's Señor de los Milagros processions in Lima draw very large crowds from across the country.

Migration links the outbreaks. Mexico's epidemic began in 2025 and has since recorded 19,553 cases, which keeps importations flowing north and south along travel routes.

What could happen next?

Risk
Peru could see a post-festival rise in cases in late October and November.
Short term · Suggested
Consequence
Countries with continuous transmission for 12 months risk losing measles elimination status at the next commission review.
Medium term · Assessed
Meaning
Guatemala's case-fatality ratio rose from 0.09% to 0.13% as deaths caught up with earlier infections.
Immediate · Assessed

Source Landscape

This story draws on neutral-leaning sources

Primary parallel: Brazil lost its measles elimination certificate in 2019 after a chain seeded by imports from Venezuela in 2018 ran for more than 12 months. Losing it required no single huge outbreak, only one unbroken year of spread.

Counter-parallel: A December 2014 outbreak linked to Disneyland in California spread to several states and was contained within months. California then passed a 2015 law ending personal-belief exemptions for school vaccination, so a mass-gathering outbreak produced lasting policy change rather than endemic spread.

Losing elimination status carries a cost beyond health spending. Countries that lose it face more travel advisories and must fund intensive surveillance for at least a year before recertification.

The Pope's November visit to Peru adds an expense: health authorities typically run pre-event vaccination drives and set up surveillance at venues, paid from emergency budgets.

Consensus view: PAHO's situation report 12 shows regional new cases falling 43% in a fortnight, from 1,244 to 709, though 333 of the earlier figure were late reports. The organisation reads this as a slowing epidemic with new fronts, and its Regional Verification Commission has already visited Mexico, Bolivia and Peru to review their elimination status.

Counter-view: PAHO itself flags reporting delays and under-reporting, and Guatemala's slowdown came straight after a near-fivefold jump in a single month. If part of that jump was a cleared laboratory backlog, today's low fortnightly count could also be a backlog in the other direction rather than a real fall.

Key tension: Whether Guatemala, now preparing its annual elimination report, has truly bent its curve or simply stopped clearing tests.

Sources:PAHO

Mentions:PAHO →Peru →Guatemala →Mexico →United States →Puno →Arequipa →Pope Leo XIV →measles →California →Bolivia →Venezuela →World Health Organization →Brazil →Señor de los Milagros →Regional Verification Commission →Lima →Americas →

First Reported In

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PAHO· 3 Oct 2026

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Causes and effects

Caused by

Guatemala passes Mexico on measles cases

Guatemala's count rose 11.5% in nine weeks from the 30,371 PAHO published in August.

Occurred 7 Aug 2026

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US measles passes 2025's full-year total

The US count reached 3,471, extending the record it passed in July.

Occurred 24 Jul 2026

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This Event

Peru overtakes Guatemala on new measles

New measles cases in the Americas are now growing faster outside Guatemala, with Peru facing two mass gatherings.

Led to

Peru records first measles death of 2026

Peru's measles outbreak produced its first death of 2026 after its new cases overtook Guatemala's in September.

Occurred 20 Oct 2026

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Different Perspectives

Pan American Health Organization

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UK Health Security Agency

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ECDC

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Ghana Ministry of Health

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Government of Côte d'Ivoire

Spokesperson Amadou Coulibaly reported 23 yellow fever cases and 11 deaths in Bounkani on 14 October and said the country holds more than 400,000 vaccine doses. He did not say how many cases were laboratory-confirmed, which leaves the outbreak's true size unclear.

World Health Organization

WHO says no cause has been found for the Irkutsk technician's death and a laboratory-associated exposure cannot be fully excluded. Tedros Adhanom Ghebreyesus urged states to finish the pathogen-sharing annex that holds the Pandemic Agreement back from signature.

Written with AI from Lowdown's published reporting. Not individually reviewed by an editor. Editorial standards.