OBJECTIVES: Malaria cross-sectional surveys are rarely conducted in very low transmission settings. This study aimed to determine the prevalence and risk factors of Plasmodium infection in a near-elimination setting in southern Thailand. METHODS: Two cross-sectional surveys were conducted in areas of active transmission in the Surat Thani province of Thailand in January and May 2019. PCR was used to detect Plasmodium infection. RESULTS: The prevalence of Plasmodium blood infection was 0.45% and 0.61% in January and May 2019, respectively. The major parasite species was Plasmodium falciparum in January and Plasmodium vivax in May. Unexpectedly, Plasmodium knowlesi infections were also detected. Most infections, including those of Plasmodium knowlesi, were asymptomatic. Being male and staying outdoors at night-time were the only significant identified risk factors. Of people infected in January 28.0% were positive in May for the same parasite species, suggesting persistent asymptomatic infections. CONCLUSIONS: Despite the very low incidence rate in Surat Thani, most malaria infections were asymptomatic. Outdoor mosquito biting at night-time is likely an important mode of malaria transmission. Unexpectedly, asymptomatic Plasmodium knowlesi infection was found, confirming previous reports of such infection in mainland Southeast Asia.
OBJECTIVES:Malaria cross-sectional surveys are rarely conducted in very low transmission settings. This study aimed to determine the prevalence and risk factors of Plasmodiuminfection in a near-elimination setting in southern Thailand. METHODS: Two cross-sectional surveys were conducted in areas of active transmission in the Surat Thani province of Thailand in January and May 2019. PCR was used to detect Plasmodiuminfection. RESULTS: The prevalence of Plasmodiumblood infection was 0.45% and 0.61% in January and May 2019, respectively. The major parasite species was Plasmodium falciparum in January and Plasmodium vivax in May. Unexpectedly, Plasmodium knowlesiinfections were also detected. Most infections, including those of Plasmodium knowlesi, were asymptomatic. Being male and staying outdoors at night-time were the only significant identified risk factors. Of peopleinfected in January 28.0% were positive in May for the same parasite species, suggesting persistent asymptomatic infections. CONCLUSIONS: Despite the very low incidence rate in Surat Thani, most malaria infections were asymptomatic. Outdoor mosquito biting at night-time is likely an important mode of malaria transmission. Unexpectedly, asymptomatic Plasmodium knowlesiinfection was found, confirming previous reports of such infection in mainland Southeast Asia.
Authors: Wanida Mala; Polrat Wilairatana; Chutharat Samerjai; Frederick Ramirez Masangkay; Kwuntida Uthaisar Kotepui; Manas Kotepui Journal: Int J Environ Res Public Health Date: 2022-01-21 Impact factor: 3.390
Authors: Nurul Athirah Naserrudin; Rozita Hod; Mohammad Saffree Jeffree; Kamruddin Ahmed; Mohd Rohaizat Hassan Journal: Int J Environ Res Public Health Date: 2022-04-06 Impact factor: 3.390
Authors: Nurul Athirah Naserrudin; Rozita Hod; Mohammad Saffree Jeffree; Kamruddin Ahmed; Richard Culleton; Mohd Rohaizat Hassan Journal: Int J Environ Res Public Health Date: 2022-03-19 Impact factor: 3.390