The epidemiology of malaria in a Karen population on the western border of Thailand.
From November 1991 to November 1992 a prospective, descriptive study of malaria epidemiology was conducted in a Karen population on the western border of Thailand. Two study groups were selected at random and more than 80% of the subjects were followed for one year. In Group 1, comprising 249 school...
| Main Authors: | , , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
1996
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| _version_ | 1826296136132984832 |
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| author | Luxemburger, C Thwai, K White, N Webster, H Kyle, D Maelankirri, L Chongsuphajaisiddhi, T Nosten, F |
| author_facet | Luxemburger, C Thwai, K White, N Webster, H Kyle, D Maelankirri, L Chongsuphajaisiddhi, T Nosten, F |
| author_sort | Luxemburger, C |
| collection | OXFORD |
| description | From November 1991 to November 1992 a prospective, descriptive study of malaria epidemiology was conducted in a Karen population on the western border of Thailand. Two study groups were selected at random and more than 80% of the subjects were followed for one year. In Group 1, comprising 249 schoolchildren (aged 4-15 years), daily surveillance for illness was combined with fortnightly malaria surveys. These children experienced 1.5 parasitaemic infections per child-year (95% confidence interval [CI] 1.3-1.7), of which 68% (193/285) were symptomatic (Plasmodium falciparum 84%, P. vivax 57%). The estimated pyrogenic densities were 1460/microL for P. falciparum and 181/microL for P. vivax. In Group 2, comprising subjects of all age from 428 households, malaria was diagnosed during two-monthly surveys, at weekly home visits, and otherwise by passive case detection. Malaria and splenomegaly prevalence rates were low in all age groups (spleen index 2-9%; P. falciparum prevalence rate 1-4%; P. vivax 1-6%). Group 2 subjects had 1.0 infections per person-year (95% CI 0.9-1.1), most of which were symptomatic (312/357; 87%). Malaria infections clustered in households. Overall, P. vivax caused 53% and P. falciparum 37% of the infections (10% were mixed), but whereas P. vivax was most common in young children, with a decline in incidence with increasing age, P. falciparum incidence rates rose with age to a peak incidence between 20 and 29 years, although the risk of developing a severe malaria decreased with increasing age. There was no death from malaria during the study. P. falciparum infections were more common in males, subjects with a history of malaria before the study, and in those who had travelled outside their village. These findings suggest a higher transmission rate for P. vivax than P. falciparum, although adults still suffered symptomatic malaria due to both species. The 2 malaria parasites found in this area contribute approximately 50% of infections each, but their clinical epidemiology is very different. |
| first_indexed | 2024-03-07T04:11:41Z |
| format | Journal article |
| id | oxford-uuid:c808ec39-098a-4731-ad55-d6957cc6700e |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T04:11:41Z |
| publishDate | 1996 |
| record_format | dspace |
| spelling | oxford-uuid:c808ec39-098a-4731-ad55-d6957cc6700e2022-03-27T06:49:26ZThe epidemiology of malaria in a Karen population on the western border of Thailand.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:c808ec39-098a-4731-ad55-d6957cc6700eEnglishSymplectic Elements at Oxford1996Luxemburger, CThwai, KWhite, NWebster, HKyle, DMaelankirri, LChongsuphajaisiddhi, TNosten, FFrom November 1991 to November 1992 a prospective, descriptive study of malaria epidemiology was conducted in a Karen population on the western border of Thailand. Two study groups were selected at random and more than 80% of the subjects were followed for one year. In Group 1, comprising 249 schoolchildren (aged 4-15 years), daily surveillance for illness was combined with fortnightly malaria surveys. These children experienced 1.5 parasitaemic infections per child-year (95% confidence interval [CI] 1.3-1.7), of which 68% (193/285) were symptomatic (Plasmodium falciparum 84%, P. vivax 57%). The estimated pyrogenic densities were 1460/microL for P. falciparum and 181/microL for P. vivax. In Group 2, comprising subjects of all age from 428 households, malaria was diagnosed during two-monthly surveys, at weekly home visits, and otherwise by passive case detection. Malaria and splenomegaly prevalence rates were low in all age groups (spleen index 2-9%; P. falciparum prevalence rate 1-4%; P. vivax 1-6%). Group 2 subjects had 1.0 infections per person-year (95% CI 0.9-1.1), most of which were symptomatic (312/357; 87%). Malaria infections clustered in households. Overall, P. vivax caused 53% and P. falciparum 37% of the infections (10% were mixed), but whereas P. vivax was most common in young children, with a decline in incidence with increasing age, P. falciparum incidence rates rose with age to a peak incidence between 20 and 29 years, although the risk of developing a severe malaria decreased with increasing age. There was no death from malaria during the study. P. falciparum infections were more common in males, subjects with a history of malaria before the study, and in those who had travelled outside their village. These findings suggest a higher transmission rate for P. vivax than P. falciparum, although adults still suffered symptomatic malaria due to both species. The 2 malaria parasites found in this area contribute approximately 50% of infections each, but their clinical epidemiology is very different. |
| spellingShingle | Luxemburger, C Thwai, K White, N Webster, H Kyle, D Maelankirri, L Chongsuphajaisiddhi, T Nosten, F The epidemiology of malaria in a Karen population on the western border of Thailand. |
| title | The epidemiology of malaria in a Karen population on the western border of Thailand. |
| title_full | The epidemiology of malaria in a Karen population on the western border of Thailand. |
| title_fullStr | The epidemiology of malaria in a Karen population on the western border of Thailand. |
| title_full_unstemmed | The epidemiology of malaria in a Karen population on the western border of Thailand. |
| title_short | The epidemiology of malaria in a Karen population on the western border of Thailand. |
| title_sort | epidemiology of malaria in a karen population on the western border of thailand |
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