Absence of seasonal variation in malaria parasitaemia in an area of intense seasonal transmission

Smith, T.; Charlwood, J. D.; Kihonda, Japhet; Mwankusye, S; Billingsley, Peter F.; Meuwissen, J. H. E. T.; Lyimo, E. O.; Takken, Willem; Teuscher, T.; Tanner, Marcel

doi:10.1016/0001-706x(93)90068-m

Cited by 254 publications

(221 citation statements)

References 18 publications

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“…However, the level of P. falciparum endemicity in Ifakara town proved to be much lower than had been expected on the basis of previous studies (Charlwood et al, 1998;Smith et al, 1993). It is now apparent that, owing to ongoing malaria control activities and urbanization, there has been a sustained decrease in transmission in this area in the last decade .…”

Section: Discussionmentioning

confidence: 70%

“…The Kilombero district is mostly an area of intense and perennial malaria transmission, predominantly P. falciparum (Smith et al, 1993) with Anopheles gambiae and A. funestus as the two main vectors. Prevalence of P. falciparum infections shows no marked seasonality, but mosquito densities, exposure and incidence of clinical malaria episodes in young children vary over the year.…”

Section: Study Sitementioning

confidence: 99%

“…Prevalence of P. falciparum infections shows no marked seasonality, but mosquito densities, exposure and incidence of clinical malaria episodes in young children vary over the year. A decade ago, the average entomological inoculation rate (EIR) recorded in nearby rural areas was more than 300 infectious bites per person per year (Smith et al, 1993). However, recent field surveys have found much lower levels of malaria transmission, in particular in Ifakara town where an annual EIR of 29 infective bites per person has been estimated (Drakeley et al, 2003).…”

Section: Study Sitementioning

confidence: 99%

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A prospective study of Plasmodium falciparum multiplicity of infection and morbidity in Tanzanian children

Henning

Schellenberg

Smith

et al. 2004

Transactions of the Royal Society of Tropical Medicine and Hygi

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Summary Several studies suggest that in individuals with substantial previous exposure to malaria, co-infection with multiple clones of Plasmodium falciparum can protect against subsequent clinical malaria attacks. Other studies, mainly of individuals with little previous exposure, found the converse relationship. To test whether acquisition of such cross-protection tracks the acquisition of clinical immunity in general, 610 Tanzanian children aged 0-6 years were enrolled in a nine-month prospective study of the risk of morbidity in relation to parasitological status and merozoite surface protein 2 genotypes on enrolment. Prevalence of parasitaemia and multiplicity of infection increased with age. In the first year of life, the incidence of clinical malaria was almost three times higher in children with parasites at baseline than in those without. In older children, baseline P. falciparum infections appeared to protect against both parasitaemic and non-parasitaemic fever episodes. In children aged less than three years, baseline multiple infection tended to be associated with higher prospective risk of clinical malaria than single infection while in children aged more than three years the converse was found, but these effects were not statistically significant. These results provide further evidence that relationships between asymptomatic malaria infections and clinical malaria change with cumulative exposure.

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Section: Discussionmentioning

confidence: 70%

Section: Study Sitementioning

confidence: 99%

Section: Study Sitementioning

confidence: 99%

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A prospective study of Plasmodium falciparum multiplicity of infection and morbidity in Tanzanian children

Henning

Schellenberg

Smith

et al. 2004

Transactions of the Royal Society of Tropical Medicine and Hygi

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“…Malaria is frequently reported as a major cause of anemia in studies from Africa (Garner & Gulmezoglu, 2000), and is related to acute phase markers (Hurt et al, 1994). Blood slide microscopy may, however, not be a useful marker of malaria disease in persons with acquired immunity (Smith et al, 1993), and this would reduce the association with anemia. The predictive values of blood slide results may be particularly low under strained operational conditions.…”

Section: Infections and Related Factorsmentioning

confidence: 99%

Anemia in pregnancy in rural Tanzania: associations with micronutrients status and infections

et al. 2002

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“…Whilst the intensity of malaria transmission is highly seasonal, there is transmission all year round. The average entomological inoculation rate in adults was estimated in a neighbouring village to be about I inoculation per person per night, and prevalence and density of parasites show little seasonality (Smith et al 1993).…”

Section: Study Areamentioning

confidence: 99%

Plasmodium falciparum malaria in the first year of life in an area of intense and perennial transmission

Kitua

Smith

Alonso

et al. 1996

Tropical Med Int Health

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110

113

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SummaryA longitudinal study of Plasmodium falciparum malaria in infants in Idete village, south-eastern Tanzania, was conducted over a period of 14 months in order to determine the incidence of P. falciparum infection and clinical malaria in the first year of life. Of 1356 blood slides from cross-sectional surveys, 52.1% were positive for asexual stages of P. falciparum. There were marked increases in P. falciparum prevalence, parasite densities, overall fever incidence and the incidence of malaria fevers with age for the first 6 months of life. The average attack rate, estimated from a reversible catalytic model, was 0.029 per day with a slight increase with age but there was no initial period of protection against infection in neonates. Estimated average duration of infections was 64 days, with infections in older infants lasting much longer than those contracted during the first 2 months of life.These results support the hypotheses that the main effect of passively transferred maternal immunity to malaria is in the control of asexual stage parasites, and that the level of clinical immunity depends upon the extent of recent exposure to parasites. Infants as young as 4 months of age are at high risk of clinical attacks. Intervention programmes against malaria in areas of the highest transmission should therefore be designed to include this group.

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Absence of seasonal variation in malaria parasitaemia in an area of intense seasonal transmission

Cited by 254 publications

References 18 publications

A prospective study of Plasmodium falciparum multiplicity of infection and morbidity in Tanzanian children

A prospective study of Plasmodium falciparum multiplicity of infection and morbidity in Tanzanian children

Anemia in pregnancy in rural Tanzania: associations with micronutrients status and infections

Plasmodium falciparum malaria in the first year of life in an area of intense and perennial transmission

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