Analysis of sulphadoxine-pyrimethamine resistance-associated mutations in Plasmodium falciparum isolates obtained from asymptomatic pregnant women in Ogun State, Southwest Nigeria

Intermittent preventive treatment in pregnancy with sulphadoxine-pyrimethamine (IPTp-SP) is one of the main strategies for protecting pregnant women, fetus, and their new-born against adverse effects of P. falciparum infection. The development of the drug resistance linked to mutations in P. falciparum dihydrofolate reductase gene (pfdhfr) and P. falciparum dihydropteroate synthase gene (pfdhps), is currently threatening the IPTp-SP approach. This study determined the prevalence of pfdhfr and pfdhps mutations in isolates obtained from pregnant women with asymptomatic P. falciparum infection in Nigerian. Additionally, P. falciparum genetic diversity and multiplicity of infection (MOI) was assessed by genotyping the P. falciparum merozoite surface Protein 1 and 2 (pfmsp-1 and pfmsp-2) genes. The pfdhfr and pfdhps were genotyped by direct sequencing, and the pfmsp-1 and pfmsp-2 fragment analysis by polymerase chain reaction was used to determine P. falciparum genetic diversity. Of the 406 pregnant women recruited, 123 had P. falciparum infection by PCR, and of these, 52 were successfully genotyped for pfdhfr and 42 for pfdhps genes. The pfdhfr triple-mutant parasites (N51I, C59R, and S108N) or the IRN haplotype were predominant (98%), whereas pfdhfr mutations C50R and I164L did not occur. For pfdhps gene, the prevalence of A437G, A581G, A436A, and A613S mutations were 98, 71, 55, and 36%, respectively. Nineteen (44%) isolates with quintuple mutations (CIRNI- SGKGA) had the highest combined pfdhfr-pfdhps haplotype. Isolates with sextuple mutants; CIRNI- AGKAS and CIRNI- AGKGA had a prevalence of 29 and 14%, respectively. High genetic diversity (7 pfmsp-1 alleles and 10 pfmsp-2 alleles) and monoclonal infection rate (76%) was observed. This study demonstrated a continuous high prevalence of pfdhfr mutation and an increase in pfdhps mutations associated with SP-resistance in southwest Nigeria. Continuous surveillance of IPTp-SP effectiveness and consideration of alternative IPTp strategies is recommended.

Use and effects of malaria control measures in pregnancy in Lagos, Nigeria

In Nigeria, malaria causes up to 11% of maternal mortality. Our main aim was to find out the most common mosquito control measures employed by the pregnant women in Lagos and their effects on malaria infection. The study was carried out over a period of 6 months during which trained interviewers administered questionnaires to 400 pregnant women. The prevalence of malaria was 8.4%. There was no significant association between the prevalence of malaria and age, level of education, or occupation of the participants. Pregnant women in the age range 26-30 had the mean parasite density (409.9 ± 196.80). Insecticide spray (32.8%), mosquito coil (27.5%), and insecticide-treated nets (ITN) (15.5%) were the major mosquito control measures employed by the participants while the prevalence of infection among them were 2.3%, 6.2%, and 3.2%, respectively (P<0.05). Only 18.3% of the women had taken more than one dose of intermittent preventive treatment (IPT), while another 11.8% had taken a single dose. The infection rate among them was 4.1% and 6.4%, respectively. Malaria prevalence was highest among those who had not received any dose of IPT (10%). This study showed that the use of ITN and IPT among the pregnant women were still unacceptably low. It also showed that the use of insecticide spray which was the most common malaria control measure adopted by the participants was effective despite the fact that it is not a National Malaria Control Policy. We recommend that a sustained integrated mosquito management and public education should be strengthened in Nigeria.

High-level parasitic contamination of soil sampled in Ibadan metropolis

Soil transmitted helminthes infections are common chronic human infections worldwide, this has been recognized as an important health problem, particularly in developing countries. The study was conducted within Ibadan metropolis in Oyo State, south western Nigeria between September 2008 and March 2009 to determine the prevalence of intestinal parasite in soil samples within the city. A total of 102 soil samples were collected from different sources from five local government areas ranging from refuse dumps, vegetable farms, school play grounds, abattoir, hospital, vicinity of house, gutter and road side. Two different methods of concentrating ova/cysts of parasites were used to analyze the samples--the zinc sulphate floatation technique and concentrated glucose solution method. Fifty-seven (55.9%) soil samples were positive for one or more parasites. These included; hookworm (37.3%), Strongyloides stercoralis (20%), Entamoeba histolytica (18.7%), Ascaris lumbricoides (17.3%), Trichuris trichiura (6.7%) respectively. The total number of parasites recovered was 75 (73.5%) and 74 (98.7) of these were recovered by the zinc sulphate floatation technique while only 44% was recovered by the concentrated normal saline-glucose solution technique. This study thus established the high prevalence rate of intestinal parasites in the soil sampled in Ibadan city and this obviously is one major means by which residents are at risk of parasitic diseases and also one of the means of vegetable contamination.

Residual efficacy of field-applied permethrin, d-phenothrin, and resmethrin on plant foliage against adult mosquitoes

Backpack sprayer applications of permethrin, d-phenothrin, and resmethrin to vegetation and plants at Anastasia Island, St. Augustine, FL, were evaluated for duration of residual efficacy against adult mosquitoes. All treatments produced 100% mortality (24 h) of mosquitoes in test cages placed within the vegetation. At 48 h and 1 wk posttreatment, insecticide treatments resulted in 70-100% reduction of adult mosquitoes caught by Centers for Disease Control and Prevention traps baited with 1-octen-3-ol. Insecticide residues in excised leaves from both treated and control areas of the study sites were evaluated against adult female Culex quinquefasciatus by laboratory bioassay. Permethrin produced 90% mortality up to 1 wk postapplication. Both d-phenothrin and resmethrin produced nearly this level of mortality for a much shorter duration of <48 h postapplication, with residual effects dropping significantly thereafter. Average insecticide concentrations in leaves were quantified by gas chromatography/mass spectroscopy, and some correlation was observed between chemical and biological results.

The effects of artemether-lumefantrine vs amodiaquine-sulfalene-pyrimethamine on the hepatomegaly associated with Plasmodium falciparum malaria in children

An open randomized controlled study of artemether-lumefantrine (AL) and amodiaquine-sulfalene-pyrimethamine (ASP) for the treatment of uncomplicated Plasmodium falciparum malaria was carried out in 181 children. In 79 children, the hepatomegaly reduction ratios (HRR) and the speed of resolution of hepatomegaly, the hepatomegaly resolution rates (HRSR), were calculated and compared between the two treatment groups. HRR and HRSR were similar in the two treatment groups. HRSR was 71% and 62% in AL- and ASP-treated children, respectively, 14 days after commencing treatment. There was no significant correlation between HRR and parasite reduction ratio in the same patient. In children in whom parasitaemia cleared and hepatomegaly resolved within 14 days, recurrence of parasitaemia was associated with reoccurrence of hepatomegaly, suggesting that the propensity for recurrence of infection drives the malaria-attributable hepatomegaly in children from this endemic area. Combination therapy may provide additional beneficial effects on pathophysiological processes and changes associated with falciparum malaria by rapid clearing of asexual parasitaemia and reducing the propensity for recurrence of infection.

Plasmodium falciparum malaria in Nigerian children during high and low transmission seasons: gametocyte carriage and response to oral chloroquine

Plasmodium falciparum malaria during high and low transmission seasons was evaluated in 1031 children treated with different antimalarial drug in a hyperendemic area of southwestern Nigeria. Seventy-three (10.5%) of 693 and forty (11.8%) of 338 children were gametocyte carriers in the high transmission seasons (HTS) and low transmission seasons (LTS), respectively. In a multiple regression model, two factors were found to be independent risk factors for the presence of gametocytemia at enrolment in the HTS: duration of illness >3 d, and asexual parasite densities less than 10,000/microl. Similarly male gender, duration of illness >4 d and parasite density less than 5000/mul were found independent risk factors for presence of gametocytemia during LTS. The presenting parasitemia, parasite clearance times, intensity of gametocytemia and proportion carrying gametocytes post treatment differ significantly in the 333 (32.3%) of these children that were treated with chloroquine in the two seasons. These findings may be important in our understanding of P. falciparum transmission sustenance, response to chloroquine therapy and contribution of chloroquine to gametocyte carriage as seasonal changes occur.