Sub-microscopic Plasmodium falciparum parasitaemia, dihydropteroate synthase (dhps) resistance mutations to sulfadoxine-pyrimethamine, transmission intensity and risk of malaria infection in pregnancy in Mount Cameroon Region

BACKGROUND

Plasmodium falciparum resistance to intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) continues to spread throughout sub-Saharan Africa. This study assessed the occurrence of microscopic and sub-microscopic P. falciparum parasitaemia, dihydropteroate synthase mutations associated with resistance to SP and maternal anaemia in the Mount Cameroon area.

METHODS

Consenting pregnant women living in semi-rural and semi-urban/urbanized settings were enrolled in this cross-sectional study. Socio-demographic, antenatal and clinical data were documented. Microscopic and sub-microscopic parasitaemia were diagnosed using peripheral blood microscopy and nested polymerase chain reaction (PCR) respectively. The dhps mutations were genotyped by restriction fragment length polymorphism analysis. The presence of A437G, K540E, and A581G was considered a marker for high-level resistance. Haemoglobin levels and anaemia status were determined.

RESULTS

Among the women, the prevalence of microscopic and sub-microscopic P. falciparum infection were 7.7% (67/874) and 18.6% (93/500) respectively. Predictors of microscopic infection were younger age (< 21 years) (AOR = 2.89; 95% CI 1.29-6.46) and semi-rural settings (AOR = 2.27; 95% CI 1.31-3.96). Determinants of sub-microscopic infection were the rainy season (AOR, 3.01; 95% CI 1.77-5.13), primigravidity (AOR = 0.45; 95% CI 0.21-0.94) and regular ITN usage (AOR = 0.49; 95% CI 0.27-0.90). Of the145 P. falciparum isolates genotyped, 66.9% (97) carried mutations associated with resistance to SP; 33.8% (49), 0%, 52.4% (76) and 19.3% (28) for A437G, K540E, A581G and A437G + A581G respectively. The A581G mutation was associated with ≥ 3 SP doses evident only among sub-microscopic parasitaemia (P = 0.027) and multigravidae (P = 0.009). Women with microscopic infection were more likely from semi-rural settings (AOR = 7.09; 95% CI 2.59-19.42), to report history of fever (AOR = 2.6; 95% CI 1.07-6.31), to harbour parasites with double resistant mutations (AOR = 6.65; 95% CI 1.85-23.96) and were less likely to have received 2 SP doses (AOR = 0.29; 95% CI 1.07-6.31). Microscopic infection decreased Hb levels more than sub-microscopic infection.

CONCLUSION

The occurrence of sub-microscopic P. falciparum parasites resistant to SP and intense malaria transmission poses persistent risk of malaria infection during pregnancy in the area. ITN usage and monitoring spread of resistance are critical.

Coverage and effectiveness of intermittent preventive treatment in pregnancy with sulfadoxine-pyrimethamine (IPTp-SP) on adverse pregnancy outcomes in the Mount Cameroon area, South West Cameroon

Background

Growing concerns about the waning efficacy of IPTp-SP warrants continuous monitoring and evaluation. This study determined coverage of IPTp-SP and compared the effectiveness of the 3-dose to 2-dose regimen on placental malaria (PM) infection and low birth weight (LBW) in the Mount Cameroon area.

Methods

Consenting pregnant women were enrolled consecutively through a cross-sectional survey at delivery at four antenatal clinics, two each from semi-rural and semi-urban settings from November 2016 to December 2017. Reported IPTp-SP use, demographic and antenatal clinic (ANC) data of the mothers and neonate birth weights were documented. Maternal haemoglobin concentration was measured using a haemoglobinometer and PM infection diagnosed by placental blood microscopy. Logistic regression analysis was used to model study outcomes.

Results

Among the 465 parturient women enrolled, 47.0% (203), 34.7% (150), 18.3% (79) and 7.1% (33) reported uptake of ≥ 3, 2.1 dose(s) and no SP, respectively. Uptake of ≥ 3 doses varied significantly (p < 0.001) according to type of medical facility, timing of ANC initiation and number of ANC visits. The prevalence of PM was 18.5% where uptake of ≥ 3 SP doses (AOR = 2.36: 95% CI  1.41–4.87), primiparity (AOR = 2.13: 95% CI  1.19–3.81), semi-rural setting (AOR = 1.85: 95% CI  1.12–3.04) increased odds of infection. Also, three or more dosing was associated (p < 0.001) with increased PM density notably among women from semi-urban areas. Compared with third trimester, ANC initiation in the second trimester (AOR: 0.39: 95% CI  0.20–0.74) lower odds of infection. The prevalence of LBW infants was 7.3% and were generally those of anaemic (AOR: 4.6: 95% CI  1.03–20.57) and semi-rural (AOR: 5.29: 95% CI  1.73–16.15) women. Although ≥ 3 (AOR: 0.31: 95% CI  0.11–0.87) and 2 (AOR: 0.32: 95% CI  0.11–0.93) doses of SP was associated with lower odds of LBW, ≥ 3 doses were not associated with additional increase in birth weight nor maternal haemoglobin levels when compared with 2 doses.

Conclusion

In the Mount Cameroon area, reported uptake of IPTp with ≥ 3 SP doses did not provide observable prophylactic benefits. SP resistance efficacy studies are necessary.

Coverage and usage of insecticide treated nets (ITNs) within households: associated factors and effect on the prevalance of malaria parasitemia in the Mount Cameroon area

Background

Insecticide-treated nets (ITNs) are a widely used tool that has been proven to be effective in the prevention and control of malaria in malaria endemic countries. However, usage varies among households and can greatly affect the benefits of ITNs as a control tool for malaria transmission. This study determined the coverage and usage of ITNS as well as associated factors and the effect of coverage and usage on the prevalence of malaria parasitemia within households in the Mount Cameroon area.

Methods

A cross-sectional survey was conducted between August and September 2014 in six communities within the Mount Cameroon area. Households within the communities were enrolled through multistage sampling and household survey was done using a structured questionnaire. Capillary blood was collected for malaria parasite determination. Data was analysed using SPSS version 20 for windows. Differences in proportions were assessed using the Chi-square test while factors affecting ITNs usage were assessed in multivariate logistic regression at a statistical significance of P ≤ 0.05.

Results

A total of 504 households were surveyed, 1564 bed spaces reported while 915(58.5, 95% CI: 56.1–60.9) of the bed spaces had nets and 391(77.6, 95% CI, 74.0–80.2) of the households had at least one bed net. The odds of using ITNs was 2 folds higher (OR = 2.41; 95% CI 1.58–3.69 p = 0.001) and 3 folds higher (OR = 3.149, 95% CI 1.53–6.47 p = 0.002) among houses with 5 to 9 occupants and above 10 occupants respectively when compared to houses with less than 5 occupants. In addition, Individuals living in cement block houses were less likely to use ITNs.

Compared to those living in wooden houses (OR = 0.488, 95% CI: 0.269–0.885; p = 0 .018). Rural communities had lower ITN coverage compared to semi-urban communities (p = 0.0001). Increase in ITNs coverage significantly reduces malaria prevalence (correlation − 0.899, p = 0.015).

Conclusion

Despite the efforts made to scale up ITN distribution so that universal coverage can be attained, coverage remains low. Increasing coverage and putting in place a mechanism to replace torn nets will go a long way reduce the prevalence of malaria parasitemia.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7555-x) contains supplementary material, which is available to authorized users.

Assessment of the current state of knowledge and risk factors of cervical cancer among women in the Buea Health District, Cameroon

Introduction

Cervical cancer is a malignant proliferation of the cells of the uterine cervix and can be treated if diagnosed earlier. It is the second most common gynecological malignancy worldwide and the leading cause of cancer associated mortality among women in Africa and Cameroon. This study sort to determine the current state of knowledge of cervical cancer and its risk factors in the Buea Health District of the South West Region of Cameroon.

Methods

This was a cross-sectional community based survey. We recruited 433 eligible women, in four (4) Health Areas (Molyko, Bolifamba, Muea and Buea Town) of the Buea Health District and used validated and pre-tested questionnaires to collect data. Collected data were keyed into Epi info version 7.2 statistical software and exported to SPSS Version 25 for analysis. Level of significance was set at P-value < 0.05.

Results

Fifty eight percent (58%) of the participants had good knowledge of cervical cancer. 58.99% (95%CI = 54.30-63.52) had good knowledge on the risk factors of cervical cancer. 40% knew at least one of the following risk factors; cigarette smoking, many sexual partners, family history of cervical cancer, being HIV/AIDS positive and giving birth 5 or more times. There was a significant association, OR = 7.5; 95%CI = 2.14-26.33; P = 0.001; X² = 11.4 between having heard of cervical cancer and having “good” knowledge of cervical cancer among women in Buea.

Conclusion

Most of the women had heard of cervical cancer but the knowledge of the risk factors of cervical cancer among women aged 18-68 years in the Buea Health District is low. We found no association between awareness and knowledge of risk factors among the women.

Cervical cancer in the Bamenda Regional Hospital, North West Region of Cameroon: a retrospective study

Introduction

Cervical cancer is ranked the 7^th most common cancer in the world. Cancer of the cervix is the second most commonly diagnosed cancer after breast cancer and the third leading cause of cancer deaths among females in less developed countries. Incidence rates are highest in countries with low income. Nearly 90% of cervical cancer deaths occur in developing parts of the world. The study researchers therefore, carried out a retrospective study to determine the proportion of cervical cancer among other types of cancer in the cancer registry of the Bamenda Regional Hospital.

Methods

The objective of this study was to determine the proportion of cervical cancer among other types of cancers in the cancer registry of the Bamenda Regional Hospital, North West Region of Cameroon from past records. We reviewed all records from the registry of patients who attended the Bamenda Regional Hospital to screen and/or be operated upon for cervical cancer and other types of cancer. Socio-demographic and clinical characteristics of cases were captured using a data collection sheet: age, type of cancer, stage of cancer, type of surgery carried out and date of surgery. Data were entered and analysed in Statistical Package for Social Sciences (SPSS) version 25 software.

Results

59 cancer cases were received in the center between 2012 and 2017. Of these, 31 (52%) had cervical cancer. Most patients who screened positive for cancer of the cervix were of the 50-54 age groups. Most of these patients (47.5%), were received at late stages (stages 3 and 4).

Conclusion

Over half (52%) of the patients receiving cancer care in this center have cervical cancer and generally turn up late for management.

Profile of red blood cell morphologies and causes of anaemia among pregnant women at first clinic visit in the mount Cameroon area: a prospective cross sectional study

Objective

Anaemia is a serious problem in pregnancy in malaria-endemic countries. This study investigated red cell morphologies and possible causes of anaemia among pregnant women at first clinic visit. Venous blood samples from consented women were used to determine haemoglobin (Hb) levels, mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) using an automated haematology analyzer. Malaria parasitaemia was diagnosed by microscopy. Definitions were as follows: anaemia (Hb < 11.0 g/dl), microcytosis (MCV < 78 fl), macrocytosis (MCV > 101 fl), hypochromasia (MCH < 27 pg), microcytic hypochromia or normocytic hypochromia with anaemia [iron deficiency anaemia (IDA)], normocytic normochromia with anaemia in the absence of malaria parasitaemia (physiological anaemia of pregnancy).

Results

Of the 279 pregnant women enrolled, 57% had anaemia. Malaria parasitaemia was associated with 23.3% of anaemic cases while 76.7% were non-malaria related. The distribution of red cell alterations was as follows: hypochromasia (32.6%), microcytosis (14.7%) and macrocytosis (1.1%). The co-occurrence of malaria parasitaemia, iron deficiency and anaemia was seen in 23.3% of the women, iron deficiency anaemia only occurred in 35.9% while physiological anaemia of pregnancy was 40.9%. Iron deficiency and physiological anaemia of pregnancy contribute to a greater proportion of anaemia in the study area.

Electronic supplementary material

The online version of this article (10.1186/s13104-017-2961-6) contains supplementary material, which is available to authorized users.

Molecular markers for artemisinin and partner drug resistance in natural Plasmodium falciparum populations following increased insecticide treated net coverage along the slope of mount Cameroon: cross-sectional study

BACKGROUND

Drug resistance is one of the greatest challenges of malaria control programmes, with the monitoring of parasite resistance to artemisinins or to Artemisinin Combination Therapy (ACT) partner drugs critical to elimination efforts. Markers of resistance to a wide panel of antimalarials were assessed in natural parasite populations from southwestern Cameroon.

METHODS

Individuals with asymptomatic parasitaemia or uncomplicated malaria were enrolled through cross-sectional surveys from May 2013 to March 2014 along the slope of mount Cameroon. Plasmodium falciparum malaria parasitaemic blood, screened by light microscopy, was depleted of leucocytes using CF11 cellulose columns and the parasite genotype ascertained by sequencing on the Illumina HiSeq platform.

RESULTS

A total of 259 participants were enrolled in this study from three different altitudes. While some alleles associated with drug resistance in pfdhfr, pfmdr1 and pfcrt were highly prevalent, less than 3% of all samples carried mutations in the pfkelch13 gene, none of which were amongst those associated with slow artemisinin parasite clearance rates in Southeast Asia. The most prevalent haplotypes were triple mutants Pfdhfr I 51 R 59 N 108 I 164(99%), pfcrt- C72V73 I 74 E 75 T 76 (47.3%), and single mutants PfdhpsS436 G 437K540A581A613(69%) and Pfmdr1 N86 F 184D1246 (53.2%).

CONCLUSIONS

The predominance of the Pf pfcrt CVIET and Pf dhfr IRN triple mutant parasites and absence of pfkelch13 resistance alleles suggest that the amodiaquine and pyrimethamine components of AS-AQ and SP may no longer be effective in their role while chloroquine resistance still persists in southwestern Cameroon.

IgG isotypic antibodies to crude Plasmodium falciparum blood-stage antigen associated with placental malaria infection in parturient Cameroonian women

BACKGROUND

Few studies have reported an association between placental malaria (PM) infection and levels of isotypic antibodies against non-pregnancy associated antigens.

OBJECTIVE

To determine and evaluate IgG isotypic antibody levels to crude P. falciparum blood stage in women with and without PM infection.

METHODS

Levels of IgG (IgG1-IgG4) and IgM to crude P. falciparum blood stage antigen were measured by ELISA in 271 parturient women. Placental malaria infection was determined by placental blood microscopy and placental histology. Age, parity and intermittent preventive treatment during pregnancy with sulphadoxine-pyrimethamine (IPTp-SP) usage were considered during analysis.

RESULTS

P. falciparum-specific IgG1 (96.5%) and IgG3 (96.7%) antibodies were predominant compared with IgG2 (64.6%) and IgG4 (49.1%). Active PM infection was associated with significant increased levels of IgG1, IgG4 and IgM while lower levels of these antibodies were associated with uptake of two or more IPTp-SP doses. PM infection was the only independent factor associated with IgG4 levels. Mean IgG1 + IgG3/IgG2 + IgG4 and IgG1 + IgG2 +IgG3/ IgG4 ratios were higher among the PM-uninfected group while IgG4/IgG2 ratio prevailed in the infected group.

CONCLUSION

PM infection and IPTp-SP dosage influenced P. falciparum-specific isotypic antibody responses to blood stage antigens. An increase in IgG4 levels in response to PM infection is of particular interest.

Assessment of the usage and effectiveness of intermittent preventive treatment and insecticide-treated nets on the indicators of malaria among pregnant women attending antenatal care in the Buea Health District, Cameroon

BACKGROUND

Malaria in pregnancy is an immense public health problem with at least 50 million pregnant women living in malaria endemic areas. To prevent malaria and its complications in pregnancy the World Health Organization recommends the use of intermittent preventive treatment sulfadoxine-pyrimethamine (IPTp-SP), the use of insecticide-treated nets (ITNs), and effective case management. In most malaria endemic countries in Africa, 40% of pregnant women sleep under ITNs. In Cameroon, about 90% of pregnant women receive the first dose of SP, while 64% take the complete dose. Following the 2011 mass-campaign of free distribution of ITNs coupled with routine ANC distribution of ITN and adoption of IPTp in Cameroon, little has been done to assess the effectiveness of both interventions outside of Yaoundé, the capital city. This study sought to assess the usage and effectiveness of IPTp-SP and ITNs on malaria in pregnancy.

METHODS

The research was a cross-sectional hospital-based study that included 410 pregnant women attending antenatal clinics in the Buea Health District. Capillary blood samples were collected to check malaria parasite by microscopy and haemoglobin levels by microhaematocrit technique.

RESULTS

A prevalence of 13.4 and 41.7% was detected for malaria and anaemia, respectively. The Overall coverage of ITN was 32.4% while that of ITPp was 63.2%. Malaria prevalence was least (7.2%) amongst women using both IPTp-SP and ITN while those with no intervention had the highest malaria prevalence of 18.6% (χ2 = 6.188; P = 0.103). Of the women with malaria, 12.73% were using ITN and had taken at least one dose of SP, 38.18% had taken at least one dose IPTp only, 10.91% were using only ITN and 38.18% were not using any preventive measure. There was a difference in anaemia status within the different intervention groups (χ2 = 8.673; P = 0.034). Pregnant women using both interventions were less associated to malaria (OR = 0.341, 95% CI = 0.138-0.841) compared to those using only one control method.

CONCLUSION

Repeated doses of SP in combination with ITN use are effective in reducing malaria parasitaemia and improving haemoglobin level of pregnant women.

Malaria, helminths, co-infection and anaemia in a cohort of children from Mutengene, south western Cameroon

Background

Malaria and helminthiases frequently co-infect the same individuals in endemic zones. Plasmodium falciparum and helminth infections have long been recognized as major contributors to anaemia in endemic countries. Several studies have explored the influence of helminth infections on the course of malaria in humans but how these parasites interact within co-infected individuals remains controversial.

Methods

In a community-based longitudinal study from March 2011 to February 2012, the clinical and malaria parasitaemia status of a cohort of 357 children aged 6 months to 10 years living in Mutengene, south-western region of Cameroon, was monitored. Following the determination of baseline malaria/helminths status and haemoglobin levels, the incidence of malaria and anaemia status was determined in a 12 months longitudinal study by both active and passive case detection.

Results

Among all the children who completed the study, 32.5 % (116/357) of them had at least one malaria episode. The mean (±SEM) number of malaria attacks per year was 1.44 ± 0.062 (range: 1–4 episodes) with the highest incidence of episodes occuring during the rainy season months of March–October. Children <5 years old were exposed to more malaria attacks [OR = 2.34, 95 % CI (1.15–4.75), p = 0.019] and were also more susceptible to anaemia [OR = 2.24, 95 % CI (1.85–4.23), p = 0.013] compared to older children (5–10 years old). Likewise children with malaria episodes [OR = 4.45, 95 % CI (1.66–11.94), p = 0.003] as well as those with asymptomatic parasitaemia [OR = 2.41, 95 % CI (1.58–3.69) p < 0.001] were susceptible to anaemia compared to their malaria parasitaemia negative counterparts. Considering children infected with Plasmodium alone as the reference, children infected with helminths alone were associated with protection from anaemia [OR = 0.357, 95 % CI (0.141–0.901), p = 0.029]. The mean haemoglobin level (g/dl) of participants co-infected with Plasmodium and helminths was higher (p = 0.006) compared to participants infected with Plasmodium or helminths alone.

Conclusion

Children below 5 years of age were more susceptible to malaria and anaemia. The high prevalence of anaemia in this community was largely due to malaria parasitaemia. Malaria and helminths co-infection was protective against anaemia.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-016-1111-2) contains supplementary material, which is available to authorized users.

Plasmodium falciparum parasitaemia and malaria among pregnant women at first clinic visit in the mount Cameroon Area

Background

Pregnant women in malaria endemic areas are at high risk of P. falciparum infection and its complications. This study investigated the prevalence and risk factors for P. falciparum infection and malaria among pregnant women reporting for first antenatal care (ANC) clinic visit in the mount Cameroon area.

Methods

Venous blood samples from consented pregnant women were screened for malaria parasitaemia by light microscopy. Haemoglobin levels, white blood cell (WBC) counts, lymphocyte counts and percentage were determined using an automated haematology analyser. Socio-demographic/economic data, environmental factors and use of malaria control measures were documented. Univariate and multivariate statistical analyses were used.

Results

Sixty-eight (22.4 %; N = 303) of the women enrolled were positive for P. falciparum parasitaemia. Malaria parasitaemia was significantly (P < 0.001) associated with febrile illness. The overall prevalence of malaria and asymptomatic infection was 16.0 % (95 % CI = 11-20 %) and 10.5 % (95 % CI = 7.3-15 %) respectively. A greater proportion of the malaria cases (61 %) reported at the clinic during unscheduled days meanwhile women with asymptomatic parasitaemia mostly (92.8 %) seek for ANC during scheduled clinic days. Lower lymphocyte percentage was significantly associated with increase parasite density (r = − 0.34; P = 0.011) and febrile status (MU = 2.46; P = 0.014). While age and gravidity were significant factors associated with P. falciparum infection and/or malaria, the presence of bush and/or standing water around human residence was an independent risk factor of P. falciparum parasitaemia (OR = 3.3: 95 % CI = 1.6 – 7.0; P = 0.002) and malaria ( OR = 5.2: 95 % CI = 2.0 – 14; P = 0.001). Being unmarried was significantly associated with increase risk (OR = 2.6:95 % CI = 1.1 – 6.0; P = 0.032) of P. falciparum parasitaemia. Similarly, single women (938) had a significantly higher (t = 2.70; P = 0.009) geometric mean parasite density (GMPD) compared with married women (338).

Conclusion

Marital status and human residence in areas with bushes and/or standing water modify risk of P. falciparum infection and malaria. Education on early ANC attendance and environmental sanitation are important public health targets for malaria control in pregnancy in this setting.

Plasmodium falciparum merozoite surface protein 1 block 2 gene polymorphism in field isolates along the slope of mount Cameroon: a cross - sectional study

BACKGROUND

Malaria remains a major global health burden despite the intensification of control efforts, due partly to the lack of an effective vaccine. Information on genetic diversity in natural parasite populations constitutes a major impediment to vaccine development efforts and is limited in some endemic settings. The present study characterized diversity by investigating msp1 block 2 polymorphisms and the relationship between the allele families with ethnodemographic indices and clinical phenotype.

METHOD

Individuals with asymptomatic parasitaemia (AP) or uncomplicated malaria (UM) were enrolled from rural, semi-rural and semi-urban localities at varying altitudes along the slope of mount Cameroon. P. falciparum malaria parasitaemic blood screened by light microscopy was depleted of leucocytes using CF11 cellulose columns and the parasite DNA genotyped by nested PCR.

RESULTS

Length polymorphism was assessed in 151 field isolates revealing 64 (5) and 274 (22) distinct recombinant and major msp1 allelic fragments (genotypes) respectively. All family specific allelic types (K1, MAD20 and RO33) as well as MR were observed in the different locations, with K1 being most abundant. Eighty seven (60 %) of individuals harbored more than one parasite clone, with a significant proportion (p = 0.009) in rural compared to other settings. AP individuals had higher (p = 0.007) K1 allele frequencies but lower (p = 0.003) mean multiplicity of genotypes per infection (2.00 ± 0.98 vs. 2.56 ± 1.17) compared to UM patients.

CONCLUSIONS

These results indicate enormous diversity of P. falciparum in the area and suggests that allele specificity and complexity may be relevant for the progression to symptomatic disease.

Determinants of infant susceptibility to malaria during the first year of life in South Western cameroon

Background.  Falciparum malaria is an important pediatric infectious disease that frequently affects pregnant women and alters infant morbidity. However, the impact of some prenatal and perinatal risk factors such as season and intermittent preventive treatment during pregnancy (IPTp) on neonatal susceptibility has not been fully elucidated. Methods.  A cohort of 415 infants born to women who were positive and negative for malaria was monitored in a longitudinal study in Southwestern Cameroon. The clinical and malaria statuses were assessed throughout, whereas paired maternal-cord and 1-year-old antimalarial antibodies were assayed by enzyme-linked immunosorbent assay. Infant susceptibility to malaria was ascertained after accounting for IPTp and season in the statistical analysis. Results.  Malaria prevalence was higher in women (P = .039) who delivered during the rainy season and their infants (P = .030) compared with their dry season counterparts. Infants born to women who were positive for malaria (6.40 ± 2.83 months) were older (P = .028) than their counterparts who were negative for malaria (5.52 ± 2.85 months) when they experienced their first malaria episode. Infants born in September-November (adjusted odds ratio [OR] = 0.31, 95% confidence interval [CI] = 0.13-0.72) and to mothers on 1 or no IPTp-sulfadoxine/pyrimethamine (SP) dose (adjusted OR = 0.51, 95% CI = 0.28-0.91) were protected, whereas those born in the rainy season (adjusted OR = 2.82, 95% CI = 1.21-6.55) were susceptible to malaria. Conclusions.  Intermittent preventive treatment during pregnancy and month of birth have important implications for infant susceptibility to malaria, with 2 or more IPTp-SP dosage possibly reducing immunoglobulin M production.

Association of candidate gene polymorphisms and TGF-beta/IL-10 levels with malaria in three regions of Cameroon: a case-control study

Background

Plasmodium falciparum malaria is one of the most widespread and deadliest infectious diseases in children under five years in endemic areas. The disease has been a strong force for evolutionary selection in the human genome, and uncovering the critical host genetic factors that confer resistance to the disease would provide clues to the molecular basis of protective immunity and improve vaccine development initiatives.

Methods

The effect of single nucleotide polymorphisms (SNPs) and plasma transforming growth factor beta (TGF-β) and interleukin 10 (IL-10) levels on malaria pathology was investigated in a case–control study of 1862 individuals from two major ethnic groups in three regions with intense perennial P. falciparum transmission in Cameroon. Thirty-four malaria candidate polymorphisms, including the sickle cell trait (HbS), were assayed on the Sequenom iPLEX platform while plasma TGF-β and IL-10 levels were measured by sandwich ELISA.

Results

The study confirms the known protective effect of HbS against severe malaria and also reveals a protective effect of SNPs in the nitrogen oxide synthase 2 (NOS2) gene against malaria infection, anaemia and uncomplicated malaria. Furthermore, ADCY9 rs10775349 (additive G) and ABO rs8176746 AC individuals were associated with protection from hyperpyrexia and hyperparasitaemia, respectively. Meanwhile, individuals with the EMR1 rs373533 GT, EMR1 rs461645 CT and RTN3 rs542998 (additive C) genotypes were more susceptible to hyperpyrexia while both females and males with the rs1050828 and rs1050829 SNPs of G6PD, respectively, were more vulnerable to anaemia. Plasma TGF-β levels were strongly correlated with heterozygosity for the ADCY9 rs2230739 and HBB rs334 SNPs while individuals with the ABO rs8176746 AC genotype had lower IL-10 levels.

Conclusion

Taken together, this study suggests that some rare polymorphisms in candidate genes may have important implications for the susceptibility of Cameroonians to severe malaria. Moreover using the uncomplicated malaria phenotype may permit the identification of novel pathways in the early development of the disease.

Antenatal care visit attendance, intermittent preventive treatment during pregnancy (IPTp) and malaria parasitaemia at delivery

Background

The determinants and barriers for delivery and uptake of IPTp vary with different regions in sub-Saharan Africa. This study evaluated the determinants of ANC clinic attendance and IPTp-SP uptake among parturient women from Mount Cameroon Area and hypothesized that time of first ANC clinic attendance could influence uptake of IPTp-SP/dosage and consequently malaria parasite infection status at delivery.

Methods

Two cross sectional surveys were carried out at the Government Medical Centre in the Mutengene Health Area, Mt Cameroon Area from March to October 2007 and June 2008 to April 2009. Consented parturient women were consecutively enrolled in both surveys. In 2007, socio-demographic data, ANC clinic attendance, gestational age, fever history and reported use/dosage of IPTp-SP were documented using a structured questionnaire. In the second survey only IPT-SP usage/dosage was recorded. Malaria parasitaemia at delivery was determined by blood smear microscopy and placental histology.

Results and discussion

In 2007, among the 287 women interviewed, 2.2%, 59.7%, and 38.1% enrolled in the first, second and third trimester respectively. About 90% of women received at least one dose SP but only 53% received the two doses in 2007 and by 2009 IPTp-two doses coverage increased to 64%. Early clinic attendance was associated (P = 0.016) with fever history while being unmarried (OR = 2.2; 95% CI: 1.3-3.8) was significantly associated with fewer clinic visits (<4visits). Women who received one SP dose (OR = 3.7; 95% CI: 2.0-6.8) were more likely not to have attended ≥ 4visits. A higher proportion (P < 0.001) of women with first visit during the third trimester received only one dose, meanwhile, those who had an early first ANC attendance were more likely (OR = 0.4; 95% CI = 0.2 - 0.7) to receive two or more doses. Microscopic parasitaemia at delivery was frequent (P = 0.007) among women who enrolled in the third trimester and had received only one SP dose than in those with two doses.

Conclusion

In the study area, late first ANC clinic enrolment and fewer clinic visits may prevent the uptake of two SP doses and education on early and regular ANC clinic visits can increase IPTp coverage.

Association of cytokine and Toll-like receptor gene polymorphisms with severe malaria in three regions of Cameroon

P. falciparum malaria is one of the most widespread and deadliest infectious diseases in children under five years in endemic areas. The disease has been a strong force for evolutionary selection in the human genome, and uncovering the critical human genetic factors that confer resistance to the disease would provide clues to the molecular basis of protective immunity that would be invaluable for vaccine development. We investigated the effect of single nucleotide polymorphisms (SNPs) on malaria pathology in a case- control study of 1862 individuals from two major ethnic groups in three regions with intense perennial P. falciparum transmission in Cameroon. Twenty nine polymorphisms in cytokine and toll-like receptor (TLR) genes as well as the sickle cell trait (HbS) were assayed on the Sequenom iPLEX platform. Our results confirm the known protective effect of HbS against severe malaria and also reveal a protective effect of SNPs in interleukin-10 (IL10) cerebral malaria and hyperpyrexia. Furthermore, IL17RE rs708567 GA and hHbS rs334 AT individuals were associated with protection from uncomplicated malaria and anaemia respectively in this study. Meanwhile, individuals with the hHbS rs334 TT, IL10 rs3024500 AA, and IL17RD rs6780995 GA genotypes were more susceptible to severe malarial anaemia, cerebral malaria, and hyperpyrexia respectively. Taken together, our results suggest that polymorphisms in some immune response genes may have important implications for the susceptibility to severe malaria in Cameroonians. Moreover using uncomplicated malaria may allow us to identify novel pathways in the early development of the disease.

Diagnostic comparison of malaria infection in peripheral blood, placental blood and placental biopsies in Cameroonian parturient women

BACKGROUND

In sub-Saharan Africa, Plasmodium falciparum malaria in pregnancy presents an enormous diagnostic challenge. The epidemiological and clinical relevance of the different types of malaria diagnosis as well as risk factors associated with malaria infection at delivery were investigated.

METHOD

In a cross-sectional survey, 306 women reporting for delivery in the Mutenegene maternity clinic, Fako division, South West province, Cameroon were screened for P. falciparum in peripheral blood, placental blood and placental tissue sections by microscopy. Information relating to the use of intermittent preventive treatment in pregnancy with sulphadoxine/pyrimethamine, history of fever attack, infant birth weights and maternal anaemia were recorded.

RESULTS

Among these women, P. falciparum infection was detected in 5.6%, 25.5% and 60.5% of the cases in peripheral blood, placental blood and placental histological sections respectively. Placental histology was more sensitive (97.4%) than placental blood film (41.5%) and peripheral blood (8.0%) microscopy. In multivariate analysis, age (< or = 20 years old) (OR = 4.61, 95% CI = 1.47 - 14.70), history of fever attack (OR = 2.98, 95% CI = 1.58 - 5.73) were significant risk factors associated with microscopically detected parasitaemia. The use of > or = 2 SP doses (OR = 0.18, 95% CI = 0.06 - 0.52) was associated with a significant reduction in the prevalence of microscopic parasitaemia at delivery. Age (>20 years) (OR = 0.34, 95% CI = 0.15 - 0.75) was the only significant risk factor associated with parasitaemia diagnosed by histology only in univariate analysis. Microscopic parasitaemia (OR = 2.74, 95% CI = 1.33-5.62) was a significant risk factor for maternal anaemia at delivery, but neither infection detected by histology only, nor past infection were associated with increased risk of anaemia.

CONCLUSION

Placenta histological examination was the most sensitive indicator of malaria infection at delivery. Microscopically detected parasitaemia was associated with increased risk of maternal anaemia at delivery, but not low-grade parasitaemia detected by placental histology only.