---
title: "Emergence of Plasmodium malariae and Co-endemicity of Three Plasmodium Species in Khanh Hoa Provin"
id: "cdc-emerging-infectious-diseases-journal-1-emergence-of-plasmodium-malariae-and-co-endemicity-of-3-plasmodium-species"
canonical_url: "https://medichelpline.com/clinical-feed/cdc-emerging-infectious-diseases-journal-1-emergence-of-plasmodium-malariae-and-co-endemicity-of-3-plasmodium-species"
content_type: "clinical_feed_article"
specialty: "Infectious Disease"
source_name: "CDC Emerging Infectious Diseases Journal"
source_url: "https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article"
published_at: "2026-09-18T04:00:00.000Z"
evidence_level: "Agency Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Emergence of Plasmodium malariae and Co-endemicity of Three Plasmodium Species in Khanh Hoa Provin
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/cdc-emerging-infectious-diseases-journal-1-emergence-of-plasmodium-malariae-and-co-endemicity-of-3-plasmodium-species
- **Specialty:** [Infectious Disease](https://medichelpline.com/clinical-feed/infectious-disease.md)
- **Primary Source:** CDC Emerging Infectious Diseases Journal
- **Source URL:** [Original Journal Publication](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article)
- **Published At:** 2026-09-18T04:00:00.000Z
- **Evidence Rating:** Agency Feed
## Executive GIST (TL;DR)
- A large outbreak of **Plasmodium malariae** began in Khanh Hoa Province, Vietnam, in 2023 and persisted through 2025, altering local malaria epidemiology. - Surveillance data from January 2023–December 2025 identified 493 symptomatic, laboratory-confirmed malaria cases using microscopy and molecular assays targeting 18S rRNA. - Annual case totals were 209 (2023), 199 (2024), and 85 (2025). Overall species breakdown: **P. malariae** 44.8% (n = 221), **P. falciparum** 36.9% (n = 182), **P. vivax** 17.9% (n = 88), mixed 0.4% (n = 2). - Three-species co-endemicity (_P. malariae_, **P. falciparum**, **P. vivax**) occurred in 2023–2024; in 2025 only **P. malariae** and **P. falciparum** remained prevalent. - Khanh Vinh district accounted for 93.1% (n = 459) of provincial cases; other districts reported 15 years: n = 344; 75.0%). The Raglai ethnic group comprised 66.2% (n = 304) of cases. - Most case-patients were forest-goers (n = 314; 68.4%), with additional cases among rangers and workers; no meaningful association between demographics and specific species was found. - All **P. malariae** infections detected were monoinfections by molecular testing, despite reports elsewhere that **P. malariae** often occurs in mixed infections. - The proximate cause of the outbreak is not established in the source. The authors note the possibility that successful control of **P. falciparum** and **P. vivax** could have changed ecological niches, and that **P. malariae** may have been increasing since 2022; further details were not reported in the source.
## Clinical Analysis & Structured Key Points
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[EID Journal](https://wwwnc.cdc.gov/eid/) 2. [Volume 32](https://wwwnc.cdc.gov/eid/early-release) 3. [Early Release](https://wwwnc.cdc.gov/eid/early-release#issue-1346) 4. [Main Article](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article) * [Facebook](https://www.facebook.com/sharer/sharer.php?u=%2Feid%2Farticle%2F32%2F10%2F26-0751_article "Share to Facebook") * [Twitter](http://twitter.com/share?url=%2Feid%2Farticle%2F32%2F10%2F26-0751_article&text= "Share to Twitter") * [LinkedIn](https://www.linkedin.com/shareArticle?url=%2Feid%2Farticle%2F32%2F10%2F26-0751_article&title= "Share to LinkedIn") * [Syndicate](https://tools.cdc.gov/medialibrary/index.aspx#/sharecontent//eid/article/32/10/26-0751_article "Embed this Page") [ Emerging Infectious Disease journal ISSN: 1080-6059 ](https://wwwnc.cdc.gov/eid/) _Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released._ #### Volume 32, Number 10—October 2026 ##### _Dispatch_ ### Emergence of _Plasmodium malariae_ and Co-endemicity of 3 _Plasmodium_ Species Parasites, Khanh Hoa Province, Vietnam, 2023–2025 On This Page [The Study](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article) * * * [Conclusions](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article) * * * [Suggested Citation](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article) Figures [Figure 1](https://wwwnc.cdc.gov/eid/article/32/10/26-0751-f1) * * * [Figure 2](https://wwwnc.cdc.gov/eid/article/32/10/26-0751-f2) * * * [Figure 3](https://wwwnc.cdc.gov/eid/article/32/10/26-0751-f3) * * * [Figure 4](https://wwwnc.cdc.gov/eid/article/32/10/26-0751-f4) Downloads [RIS [TXT - 2 KB] ](https://wwwnc.cdc.gov/eid/article/32/10/26-0751.ris) Article Metrics [Metric Details](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article) Related Articles [Dengue Virus in _Aedes aegypti_ Mosquitoes, Dubai](https://wwwnc.cdc.gov/eid/article/32/8/26-0324_article) * * * [Discovery of Cinchona as Antimalarial, Peru](https://wwwnc.cdc.gov/eid/article/32/7/26-0042_article) * * * [Zoonotic and Anthroponotic _Plasmodium_ spp.](https://wwwnc.cdc.gov/eid/article/32/5/25-1695_article) * * * [More articles on Malaria](https://wwwnc.cdc.gov/eid/spotlight/malaria) Tuấn Cường Võ[1](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#fn1), Chau Van Khanh[1](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#fn1), Hương Giang Lê[1](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#fn1), Nguyen Cong Trung Dung, Đăng Thùy Dương Nguyễn, Thu Hằng Nguyễn, Byoung-Kuk Na[2](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#fn2)[![Comments to Author](https://wwwnc.cdc.gov/eid/content/images/icon/email.gif)](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#comment) , and Huynh Hong Quang[2](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#fn2) Author affiliation: Gyeongsang National University College of Medicine and Institute of Health Science, Jinju, South Korea (T.C. Võ, H.G. Lê, D.T.D. Nguyễn, T.H. Nguyễn, B.K. Na); Institute of Malariology, Parasitology, and Entomology, Quy Nhon, Vietnam (C.V. Khanh, N.C.T. Dung, H.H. Quang) [Suggested citation for this article](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#suggestedcitation) ### Abstract A large malaria outbreak caused by _Plasmodium malariae_ parasites occurred in Khanh Hoa Province, Vietnam, in 2023. Since then, _P. malariae_ parasites have persisted in the region alongside _P. falciparum_ and _P. vivax_ species, changing malaria patterns. Those findings reinforce the need for strengthened surveillance in the region. Malaria, a mosquitoborne disease caused by _Plasmodium_ species parasites, poses a global health burden. Malaria incidence and mortality rates have markedly decreased in Vietnam over the past few decades ([_1_](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#r1 "1")); however, the Central Highlands region is a malaria hotspot, accounting for >90% of malaria cases in the country. _P. falciparum_ and _P. vivax_ are the major parasite species responsible for malaria in the region ([_2_](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#r2 "2"),[_3_](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#r3 "3")), whereas _P. malariae_ cases historically have been rare. However, a large _P. malariae_ outbreak occurred in Khanh Hoa Province, Vietnam, in 2023 ([_4_](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#r4 "4")), and the epidemic has persisted, further complicating malaria patterns and control efforts in the province. We investigated the epidemiologic characteristics of malaria cases and _Plasmodium_ species in Khanh Hoa Province, Vietnam, during January 2023–December 2025, to characterize the epidemic in the province. ### The Study We retrieved epidemiologic data on malaria cases from the Electronic Case-based Disease Surveillance—Malaria and Mosquito-borne Diseases Reporting System, a national electronic reporting system in Vietnam. We performed statistical analyses by using negative binomial regression followed by Tukey-adjusted pairwise comparisons. We calculated incidence rate ratios (IRRs) and 95% CIs and considered p 15 years of age ([Figure 3](https://wwwnc.cdc.gov/eid/article/32/10/26-0751-f3), panel B). Ethnic analysis revealed that the Raglai community was the most affected (304 cases; 66.2%), followed by the Kinh (53 cases; 11.6%) and Co Ho (50 cases; 10.9%) populations ([Figure 4](https://wwwnc.cdc.gov/eid/article/32/10/26-0751-f4), panel A). Affected persons largely were forest-goers (n = 314; 68.4%) but also included rangers (n = 29; 6.3%) and government or factory workers (n = 15; 3.3%) ([Figure 4](https://wwwnc.cdc.gov/eid/article/32/10/26-0751-f4), panel B). Heavy dependence on the forest or forest farming for subsistence places the Raglai population at greater risk for malaria infection, and that community accounts for most malaria cases in Central Vietnam ([_7_](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#r7 "7"),[_8_](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#r8 "8")). We observed no meaningful association between patient demographic characteristics and specific _Plasmodium_ species infections. The cause of the _P. malariae_ outbreak in Khanh Hoa Province, particularly in Khanh Vinh district, remains unclear. Successful interventions targeting _P. falciparum_ and _P. vivax_ parasites might have inadvertently expanded the ecologic niche of _P. malariae_ ([_9_](https://wwwnc.cdc.gov/eid/article/32/10/26-0751_article#r9 "9")). Given the increase in _P. malariae_ infections (10 of 12 total malaria cases) in Khanh Hoa Province in 2022, _P. malariae_ might have begun to emerge at
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