PLOS NTDs: Aedes aegypti in five comunas of Medellín still carry Wolbachia after the releases

A paper of 10 August 2026 in PLOS Neglected Tropical Diseases surveyed Wolbachia in Aedes aegypti in five comunas of Medellín, Colombia, after wMel releases from 2017 to 2022. Estimated infection frequencies ran from about 60% to near fixation, depending on the sampling and the test.

Insects

Main points

• The World Mosquito Program released Ae. aegypti carrying the wMel strain across Medellín from 2017 to 2022. A team at the Instituto Colombiano de Medicina Tropical and Universidad de Antioquia surveyed Santa Cruz, Castilla, Robledo, Belén and Buenos Aires, about 32.66 km², nearly 29% of the urban area (116 km²), with an estimated population of about 850,000.
• They set 216 ovitraps from 4 August to 11 September 2025. Eggs were found in 45.4% of households (98/216). Adult Ae. aegypti were collected in 74.3% (81/109) of aspirated households. Pooled PCR of adults emerging from ovitraps gave posterior infection probabilities near fixation in Santa Cruz (0.994) and Castilla (0.996), lower in Robledo (0.287) and Belén (0.372), and intermediate in Buenos Aires (0.768).
• Of 209 adults caught indoors (138 females, 71 males), conventional PCR found 104 positive and 105 negative; qPCR found 169 positive and 40 negative. The summary says frequencies generally ranged from about 60% to nearly 100%.
• The study was funded by the World Mosquito Program under contract WOLBACHIA-2025-1981. The paper says the funder had no role in design, collection, analysis, the decision to publish, or writing. The paper does not measure dengue case counts.

VPMA’s note

After a release, infection needs to be checked again because the rate is not even across districts. Do not use the Medellín figures to describe a programme in Vietnam.

Source: PLOS Neglected Tropical Diseases (summarised in English by VPMA). Read the Vietnamese page.

← Back to news