ABSTRACT
BACKGROUND: In Mexico, combined chloroquine (CQ) and primaquine (PQ) treatment has been used since the late 1950s to treat Plasmodium vivax infections. Although malaria transmission has declined, current treatment strategies must be evaluated to advance towards malaria elimination. METHODS: The clinical and parasitological outcome of treating symptomatic P. vivax with the 14-day (T14) treatment or intermittent single dose (ISD) regimen was evaluated in southern Mexico between February 2008 and September 2010. Patients over 12 months old with P. vivax mono-infection and asexual parasitaemia ≥500 parasites/µl were treated under supervision. After diagnosis (day 0), treatment began immediately. T14 patients received CQ for 3 days (10, 10 and 5 mg/kg) and PQ daily for 14 days (0.25 mg/kg), while ISD patients received a single dose of CQ (10 mg/kg) and PQ (0.75 mg/kg) on days 0, 30, 60, 180, 210, and 240. Follow-up was done by observing clinical and laboratory (by microscopy, serology and PCR) outcome, considering two endpoints: primary blood infection clearance and clinical response at ~28 days, and the incidence of recurrent blood infection during 12 months. Parasite genotypes of primary/recurrent blood infections were analysed. RESULTS: During the first 28 days, no differences in parasite clearance or clinical outcome were observed between T14 (86 patients) and ISD (67 patients). On day 3, 95 % of patients in both groups showed no blood parasites, and no recurrences were detected on days 7-28. Contrarily, the therapeutic effectiveness (absence of recurrent parasitaemia) was distinct for T14 versus ISD at 12 months: 83.7 versus 50 %, respectively (p = 0.000). Symptomatic and asymptomatic infections were recorded on days 31-352. Some parasite recurrences were detected by PCR and/or serological testing. CONCLUSIONS: T14 was effective for opportune elimination of the primary blood infection and preventing relapse episodes. The first single dose of CQ-PQ eliminated primary blood infection as efficiently as the initial three-dose scheme of T14, but the ISD regimen should be abandoned. A single combined dose administered to symptomatic patients in remote areas while awaiting parasitological diagnosis may contribute to halting P. vivax transmission. Alternatives for meeting the challenge of T14 supervision are discussed. TRIAL REGISTRATION: NIH-USA, ClinicalTrial.gov Identifier: NCT02394197.
Subject(s)
Antimalarials/administration & dosage , Chloroquine/administration & dosage , Malaria, Vivax/drug therapy , Primaquine/administration & dosage , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Diagnostic Tests, Routine , Drug Therapy, Combination/methods , Female , Genotype , Humans , Infant , Malaria, Vivax/parasitology , Malaria, Vivax/pathology , Male , Mexico , Middle Aged , Plasmodium vivax/classification , Plasmodium vivax/genetics , Plasmodium vivax/isolation & purification , Recurrence , Treatment Outcome , Young AdultABSTRACT
The aim of this study was to assess levels of DDT and DDE in two environmental matrices (soil and dust) and to investigate the blood levels of these insecticides in exposed children living in a north Mexican state (Chihuahua) where DDT was sprayed several years ago during (1) health campaigns for the control of malaria and (2) agricultural activities. DDT and DDE were analyzed by gas chromatography/mass spectrometry. In general, lower levels were found in household outdoor samples. The levels in outdoor samples ranged from 0.001 to 0.788 mg/kg for DDT and from 0.001 to 0.642 mg/kg for DDE. The levels in indoor samples ranged from 0.001 to 15.47 mg/kg for DDT and from 0.001 to 1.063 mg/kg for DDE. Similar results to those found in indoor soil were found in dust, in which the levels ranged from 0.001 to 95.87 mg/kg for DDT and from 0.001 to 0.797 mg/kg for DDE. Moreover, blood levels showed that all of the communities studied had been exposed to DDT and/or DDE, indicating a general past or present exposure to DDT. It is important to note that the quotient DDT/DDE in all matrices was always >1. Whether the people living in our study area are at risk is an issue that deserves further analysis. However, applying precautionary principles, it is important to initiate a risk-reduction program to decrease exposure to DDT and its metabolites in people living in this area.
Subject(s)
DDT/blood , Dichlorodiphenyl Dichloroethylene/blood , Dust/analysis , Environmental Monitoring/methods , Soil/analysis , Child , Child, Preschool , Humans , Insecticides/blood , Malaria/prevention & control , Mexico , Mosquito Control/methods , Soil/chemistryABSTRACT
OBJECTIVE: To evaluate, under laboratory conditions, the sensitivity and specificity of a rapid diagnostic test (OptiMAL), based on immunoreactive strips, to detect Plasmodium vivax infection in febrile patients in Southern Chiapas, Mexico. MATERIAL AND METHODS: The presence of parasites in blood samples of 893 patients was investigated by Giemsa-stained thick blood smear microscopic examination (gold standard). A blood drop from the same sample was smeared on immunoreactive strips to investigate the presence of the parasite pLDH. Discordant results were resolved by PCR amplification of the parasite's 18S SSU rRNA, to discard infection. RESULTS: OptiMAL had an overall sensitivity of 93.3% and its specificity was 99.5%. Its positive and negative predictive values were 96.5% and 98.9%, respectively. Signal intensity in OptiMAL strips correlated well with the parasitemia density in the blood samples (r = 0.601, p = 0.0001). CONCLUSION: This rapid test had acceptable sensitivity and specificity to detect P. vivax under laboratory conditions and could be useful for malaria diagnosis in field operations in Mexico.
Subject(s)
Malaria, Vivax/diagnosis , Plasmodium vivax/isolation & purification , Adolescent , Adult , Aged , Aged, 80 and over , Animals , Child , Child, Preschool , Female , Humans , Infant , Malaria, Vivax/parasitology , Male , Mexico , Middle Aged , Parasitemia/diagnosis , Polymerase Chain Reaction , Predictive Value of Tests , RNA, Protozoan/analysis , Reagent Strips , Sensitivity and Specificity , Time FactorsABSTRACT
OBJETIVO: Evaluar en condiciones de laboratorio la sensibilidad y especificidad de una prueba rápida de diagnóstico (OptiMAL), basada en tiras inmunorreactivas para detectar Plasmodium vivax en pacientes febriles del sur de Chiapas, México. MATERIAL Y MÉTODOS: Entre diciembre de 2000 a abril de 2002 se investigó la presencia de parásitos en muestras sanguíneas de 893 pacientes por examen microscópico de gotas gruesas teñidas con Giemsa (prueba de referencia). Otra gota de sangre de la misma punción fue empleada en las tiras inmunorreactivas para investigar la presencia de pLDH del parásito. Los resultados discordantes se resolvieron por PCR del gen de la subunidad ribosomal 18S del parásito para descartar infección. RESULTADOS: OptiMAL mostró una sensibilidad de 93.3 por ciento y especificidad de 99.5 por ciento, con valores predictivo positivo y negativo de 96.5 y 98.9 por ciento, respectivamente. La intensidad de las reacciones en las tiras OptiMAL correlacionaron con la densidad parasitaria (r=0.601, p=0.0001). CONCLUSIONES: La prueba rápida presentó sensibilidad y especificidad aceptables para detectar P. vivax en condiciones de laboratorio y podría ser útil para el diagnóstico de paludismo en operaciones de campo en México.
