Methods for Measuring the Immunological Response to Plasmodia

Voller, A.; Meuwissen, J. H. E. T.; Verhave, J.P.

doi:10.1016/b978-0-12-426103-7.50008-2

Cited by 7 publications

(8 citation statements)

References 27 publications

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“…This is likely to reflect a true P. falciparum infection since the serum tested negative with schizonts of P. fieldii that show stronger cross-reactivity with the remaining human plasmodia. 17 In one subject, the pretravel IFAT result was positive, and 77% of the subjects had traveled to tropical destinations previously. The study population may therefore not have been entirely nonimmune to P. falciparum.…”

Section: Discussionmentioning

confidence: 92%

“…However, all subjects with positive blood slides had detectable anti-blood-stage antibodies, most of them at two weeks after onset of symptoms, when maximum titers can be expected. 17,18 In other studies, the IFAT has shown high sensitivity for retrospective identification of P. falciparum malaria in nonimmune individuals, especially when homologous plasmodia are used as antigen, and in most cases of P. falciparum malaria in nonimmune individuals titers remain detectable for 1-6 months. 8,18 Infection with non-P. falciparum plasmodia is unlikely in these subjects since they tested negative with P. fieldii antigen.…”

Section: Discussionmentioning

confidence: 99%

“…However, sporozoites have been shown to be highly immunogenic, and anti-CS titers decrease rapidly after the onset of symptoms. 17,19 Therefore, antibody responses may have been initially present in all infected subjects, but remained undetected as they had decreased below the detection threshold by the time they were measured. This hypothesis is supported by our finding that positive ELISA results were only found in samples collected shortly after the malaria attack, and by the increase in incidence of seroconversion when the analysis was restricted to subjects whose samples were taken within eight weeks after the first possible exposure.…”

Section: Discussionmentioning

confidence: 99%

“…17 In addition, pretravel sera of subjects with IFAT-positive post-travel sera were tested in both IFATs. Schizonts of the simian plasmodium P. fieldii show higher cross-reactivity with antibodies to P. vivax than schizonts of P. falciparum.…”

Section: Methodsmentioning

confidence: 99%

“…Schizonts of the simian plasmodium P. fieldii show higher cross-reactivity with antibodies to P. vivax than schizonts of P. falciparum. 17 The IFATs using P. fieldii were therefore performed to distinguish between infections with P. falciparum and other human plasmodia (particularly P. vivax). In both IFATs, late trophozoites and schizonts were applied to antigen slides, air-dried, and stored at Ϫ70ЊC.…”

Section: Methodsmentioning

confidence: 99%

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Testing for anti-circumsporozoite and anti-blood-stage antibodies for epidemiologic assessment of Plasmodium falciparum infection in travelers.

Cobelens

Verhave²,

Leentvaar-Kuijpers³

et al. 1998

The American Journal of Tropical Medicine and Hygiene

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Abstract. The purpose of this investigation was to assess the role of serology for establishing incidences of Plasmodium falciparum malaria and of exposure to P. falciparum in epidemiologic studies of travelers using chemoprophylaxis. The design was a prospective cohort study involving 548 short-term Dutch travelers to areas endemic for P. falciparum malaria. Sera were collected before departure and, together with the medical history, 2-6 weeks after return. All sera were tested for anti-circumsporozoite (CS) antibodies by an R32tet 32 -ELISA; sera of subjects reporting febrile illness during travel or after return or with anti-CS responses were tested for anti-blood-stage antibodies by an indirect fluorescence antibody test (IFAT). Five subjects (0.9%) reported P. falciparum malaria confirmed by thick blood smear examination (documented cases) and six (1.0%) reported treatment for malaria without a documented diagnosis (presumptive cases). Conversions in the IFAT were detected in six subjects, including all five documented cases and one presumptive case. Anti-CS antibodies were detected in seven subjects (1.3%), including three documented cases and four of 442 subjects with no history of fever or malaria treatment (0.9%). Incidence rates per 1,000 person-months of travel (95% confidence interval) of infection with P. falciparum, whether or not suppressed by chemoprophylaxis, were 16.9 (8-31) for all destinations and 91.6 (33-200) for West Africa. In epidemiologic studies of P. falciparum malaria in travelers, testing for antibodies to blood stages can increase the sensitivity and specificity of case detection; testing for antibodies to sporozoites may be useful for the assessment of exposure to P. falciparum in travelers using chemoprophylaxis, but the sensitivity is limited.In most epidemiologic studies that assess risks of Plasmodium falciparum malaria or efficacies of prophylactic measures in nonimmune travelers, incidences are based retrospectively on cases of malaria that are confirmed by blood slide evaluation.

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Section: Discussionmentioning

confidence: 92%