ANSTEY NM, TJITRA E, SUPRIANTO S, DYER M, CURRIE BJ, MCBROOM J; Interscience Conference on Antimicrobial Agents and Chemotherapy.

Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 1999 Sep 26-29; 39: 728 (abstract no. 1849).

Menzies Sch. of Health Res. and Royal Darwin Hosp., Darwin, AUSTRALIA

BACKGROUND: A problem with rapid dipstick HRP-2 antigen (Ag) detection tests for asexual falciparum parasitemia is the persistence of antigen in blood after the disappearance of both asexual parasitemia & clinical symptoms. This may result in false positive (FP) test results. To date there are no data on Ag persistence with the new ICT Pf/Pv Ag detection test (which detects both the P. falciparum-specific Ag HRP-2 & a pan-malarial Ag [PMA] found in both P. falciparum & P. vivax) and whether persistent sexual forms (gametocytes) are a cause of FP tests after treatment.METHODS: To examine whether presence of gametocytes was associated with FP antigenemia (microscopy negative for asexual parasites, but Ag positive) after treatment for malaria, we compared results of microscopy and the ICT Pf/Pv Ag detection test in 76 Sumbanese patients with symptomatic P. falciparum malaria treated with chloroquine (CQ) & 36 treated with sulphadoxine/ pyrimethamine (S/P), followed for 28 days. Frequency of gametocytemia in those with FP Ag testing was compared with frequency in those with true neg (TN) tests on days 7 & 14 after each treatment, for both HRP-2 & PMA.RESULTS: Persistent FP antigenemia post S/P occurred in 29% (HRP2) & 42% (PMA) on d7, and 10% (HRP2) & 23% (PMA) on d14. Proportion with gametocytes on d7 post-treatment was significantly greater in those with FP Ag tests: 11/14 FP vs 3/10 TN (p=0.035) & 9/9 FP vs 8/ 21 TN (p=0.001) for HRP2 after CQ & S/P respectively, & 11/12 FP vs 3/12 TN (p=0.0009) & 13/13 FP vs 4/17 TN (p=0.0001) for PMA following CQ & S/P respectively. Gametocyte frequency on d14 also greater in those with FP Ag tests- for PMA testing post S/ P: 6/7 FP vs 9/24 TN (p=0.02). PMA persists longer than HRP2 giving a FP diagnosis of P. vivax in up to 16% on day 14.CONCLUSION: High rates of persistent HRP2 & PMA antigenemia occur after treatment for falciparum malaria which are strongly associated with presence of gametocytemia.

Publication Types:

• Meeting Abstracts

Keywords:

• Chloroquine
• Humans
• Malaria
• Malaria Vaccines
• Malaria, Falciparum
• Microscopy
• Parasitemia
• Plasmodium
• Plasmodium falciparum
• Plasmodium vivax
• Protozoa
• Sulfadoxine
• parasitology

Other ID:

• GWAIDS0008996

UI: 102246493

From Meeting Abstracts