Correlation between Plasmodium vivax variants in Belém, Pará State, Brazil and symptoms and clearance of parasitaemia

Abstract

The aim of this study was to determine how different types of P. vivax affect clinical symptoms and parasitaemia clearance. Blood was collected from individuals from Pará State, Brazil. The patients were treated as chloroquine plus primaquine. P. vivax were typed daily till D7 and again on D30. Now we can confirm a previously reported correlation between P. vivax genotype and response to chloroquine. Clinical symptoms do not allow for objective identification of different P. vivax types in the Brazilian Amazon, since the VK247 and P. vivax-like have only been detected in mixed infections. Key Words: Plasmodium vivax variants, symptoms, chloroquine and primaquine treatment, clearence of parasitaemia. Plasmodium vivax has been the most common cause of human malaria in the Brazilian Amazon region during the last seven years. Its variants (VK210, are found in mixed infections; VK210 has also been found as a single infection [9]. Reduction in susceptibility to chloroquine has been reported from Papua New Guinea, India, Asia and South America [1,13,19], though no relationship between P. vivax genotypes and parasite clearance following treatment with chloroquine has been found. Kain et al. (1993) suggested that response to chloroquine varies depending on the type of P. vivax, since the VK210 genotype and mixed infection with VK247 took longer to clear, while VK247 tended to have a shorter duration in Thailand. A study conducted in Brazil showed no significant difference in the time of parasite clearance after treatment with chloroquine and primaquine, alone or combined [9]. Variants of P. vivax can produce different clinical signs and responses to treatment [5], as there is a correlation between P. vivax genotypes and the intensity of symptoms and vector preference, which can affect drug resistance and consequent failure of control measures [4]. We examined how different types of P. vivax affect clinical symptoms and parasitaemia clearance.Blood was collected from 30 individuals from Belém city (Pará State) who had signed the informed consent form. The blood samples were obtained before therapy was initiated (D0), and continued daily till day 5 (D5). Vacutainer tubes containing EDTA (Becton Dickinson, UK) were used to collected 5 mL of whole blood/ individual that was subsequently applied to glass-fibermembrane discs (Titertek, ICN Biomedicals Limited, UK) following the protocol described by Warhurst et al. [21]. The patients were treated as follows: 25 mg chloroquine/kg body weight during 3 days (10 mg/kg on day 1 and 7.5 mg/kg on days 2 and 3), plus 0.25 mg primaquine /kg for 14 days, starting on the fourth day. Plasmodium vivax types were identified by 176 BJID 2003; 7 (June) GFM/PCR/ELISA [9] for all samples. The patients were evaluated daily by a physician till D7, and again on D30.The typing of P. vivax genotype in D0 detected 16 samples with a single infection, all by VK210 (53%) and 14 samples with mixed infections (47%): four VK210 plus VK247 (13%), two VK210 plus P. vivax-like (7%), five VK247 plus P. v...

Therapeutic responses ofPlasmodium vivaxandP. falciparumto chloroquine, in an area of western India whereP. vivaxpredominates

“…The baseline levels of P. vivax parasitaemia seen at Pansora were generally higher than those seen at Deva (Table 1) but the mean parasite-clearance times (for the CQsensitive cases) observed at the two PHC did not differ much. This may indicate the existence of a single variant infection at both sites (Machado et al, 2003). Although the results of the genotyping in the present study are taken as evidence of true treatment failure in at least two of the cases of P. vivax malaria, it is possible (but unlikely) that the apparent recrudescences in these two cases may have originated from the posttreatment activation of hypnozoites, following the successful 'cure' of the baseline parasitaemia (Baird, 2004).…”

Genetic Diversity of Plasmodium Vivax PVCSP and PVMSP 1 in Guyana, South America

“…29,30,32,54 Researchers in Brazil have also noted increasing levels of infection caused by P. vivax, chloroquine and primaquine drug resistance, and evidence of severe malaria in a subset of those infected with P. vivax. 1 Thus, results from both Brazil and Guyana suggest that increasing health/treatment problems associated with P. vivax infections may be prevalent yet unrecorded throughout the South American Amazon region.…”

Plasmodium vivax Chloroquine Resistance and Anemia in the Western Brazilian Amazon

“…After the first evidence of failure of combined CQ and primaquine (PQ) therapy for P. vivax malaria acquired by Canadian travelers in Guyana (8), some studies carried out in different regions did not detected recurrent parasitemia within 28 days (9-11) or 30 days (12). In Brazil, the first clinical evidence was reported in 2000 in Manaus (13).…”