Occurrence and Distribution of Nonfalciparum Malaria Parasite Species Among Adolescents and Adults in Malawi

BACKGROUND

Plasmodium falciparum malaria dominates throughout sub-Saharan Africa, but the prevalence of Plasmodium malariae, Plasmodium ovale spp., and Plasmodium vivax increasingly contribute to infection in countries that control malaria using P. falciparum-specific diagnostic and treatment strategies.

METHODS

We performed quantitative polymerase chain reaction (qPCR) on 2987 dried blood spots from the 2015-2016 Malawi Demographic and Health Survey to identify presence and distribution of nonfalciparum infection. Bivariate models were used to determine species-specific associations with demographic and environmental risk factors.

RESULTS

Nonfalciparum infections had broad spatial distributions. Weighted prevalence was 0.025 (SE, 0.004) for P. malariae, 0.097 (SE, 0.008) for P. ovale spp., and 0.001 (SE, 0.0005) for P. vivax. Most infections (85.6%) had low-density parasitemias ≤ 10 parasites/µL, and 66.7% of P. malariae, 34.6% of P. ovale spp., and 40.0% of P. vivax infections were coinfected with P. falciparum. Risk factors for P. malariae were like those known for P. falciparum; however, there were few risk factors recognized for P. ovale spp. and P. vivax, perhaps due to the potential for relapsing episodes.

CONCLUSIONS

The prevalence of any nonfalciparum infection was 11.7%, with infections distributed across Malawi. Continued monitoring of Plasmodium spp. becomes critical as nonfalciparum infections become important sources of ongoing transmission.

Prevalence, characteristics and risk factors of imported and local malaria cases in North-Western Province, Zambia: a cross-sectional study

BACKGROUND

Imported malaria is a major challenge for countries that are in malaria elimination stage such as Zambia. Legitimate cross-border activities add to the risk of transmission, necessitating determination of prevalence, characteristics and risk factors of imported and local malaria.

METHODS

This cross-sectional study was conducted in 103 consented child and adult patients with clinical malaria symptoms, from selected health facilities in north-western Zambia. Patient demographic data and blood samples for malaria microscopy and full blood count were obtained. Chi-square and penalized logistic regression were performed to describe the characteristics and assess the risk factors of imported and local malaria in North-Western Province.

RESULTS

Overall, malaria prevalence was 78.6% with 93.8% Plasmodium falciparum and 6.2% other species. The local cases were 72 (88.9%) while the imported were 9 (11.1%) out of the 81 positive participants. About 98.6% of the local cases were P. falciparum compared to 55.6% (χ2 = 52.4; p < 0.01) P. falciparum among the imported cases. Among the imported cases, 44% were species other than P. falciparum (χ2 = 48; p < 0.01) while among the local cases only 1.4% were. Gametocytes were present in 44% of the imported malaria cases and only in 2.8% of the local cases (χ2 = 48; p < 0.01). About 48.6% of local participants had severe anaemia compared to 33.3% of participants from the two neighbouring countries who had (χ2 = 4.9; p = 0.03). In the final model, only country of residence related positively to presence of species other than P. falciparum (OR = 39.0, CI [5.9, 445.9]; p < 0.01) and presence of gametocytes (OR = 23.1, CI [4.2, 161.6]; p < 0.01).

CONCLUSION

Malaria prevalence in North-Western Province is high, with P. falciparum as the predominant species although importation of Plasmodium ovale and Plasmodium malariae is happening as well. Country of residence of patients is a major risk factor for malaria species and gametocyte presence. The need for enhanced malaria control with specific focus on border controls to detect and treat, for specific diagnosis and treatment according to species obtaining, for further research in the role of species and gametocytaemia in imported malaria, cannot be overemphasized.

Role of Anopheles gambiae s.s. and Anopheles coluzzii (Diptera: Culicidae) in Human Malaria Transmission in Rural Areas of Bouaké, in Côte d'Ivoire

Studies done in Bouaké (Côte d'Ivoire) about 20-yr ago reported that Anopheles gambiae s.l. Giles was the major malaria vector. The present study aimed to update these data and to identify the main vectors. Mosquitoes were collected in Allokokro and Petessou villages between June 2014 and December 2015 using the human landing catching method. Potential breeding sites of An. gambiae s.l. were identified in August and October 2014 and mapped using GPS. Anopheles species were morphologically and molecularly [polymerase chain reaction (PCR)] identified. Ovaries of female were dissected to determine the parity and infection with Plasmodium was detected in head and thorax by quantitative PCR. In Allokokro, the biting rate of An. gambiae s.s was significantly greater than Anopheles coluzzii, whereas, in Petessou, biting rates of both species were comparable. Plasmodium falciparum (Haemosporida: Plasmodiidae), Plasmodium malariae (Haemosporida: Plasmodiidae), and Plasmodium ovale (Haemosporida: Plasmodiidae) identified in both villages. The infection rates of An. gambiae s.s. and An. coluzzii were not significantly different. The entomological inoculation rate (EIR) of An. gambiae s.s. for P. falciparum was 9-fold greater than that of An. coluzzii in Allokokro; however, in Petessou, the EIRs of both species were comparable. In both village, An. gambiae s.s was responsible for P. falciparum and P. ovale transmission whereas An. coluzzii transmitted all three Plasmodium species.

A case of Plasmodium malariae recurrence: recrudescence or reinfection?

BACKGROUND

Plasmodium malariae is the most neglected of the six human malaria species and it is still unknown which is the mechanism underlying the long latency of this Plasmodium.

CASE PRESENTATION

A case of PCR-confirmed P. malariae recurrence in a 52-year old Italian man was observed 5 months after a primary attack. In the interval between the two observed episodes of malaria the patient denied any further stay in endemic areas except for a visit to Libya, a country considered malaria-free. Genomic DNA of the P. malariae strain using five microsatellites (PM2, PM9, PM11, PM25, PM34) and the antigen marker of circumsporozoite (csp) was amplified and sequenced. Analysis of polymorphisms of the P. malariae csp central repeat region showed differences between the strains responsible of the first and second episode of malaria. A difference in the allele size was also observed for the sequence analysis of PM2 microsatellites.

CONCLUSIONS

Plasmodium malariae is a challenging human malaria parasite and even with the use of molecular techniques the pathogenesis of recurrent episodes cannot be precisely explained.

Behavior and abundance of Anopheles darlingi in communities living in the Colombian Amazon riverside

In the past few years, relative frequencies of malaria parasite species in communities living in the Colombian Amazon riverside have changed, being Plasmodium vivax (61.4%) and Plasmodium malariae (43.8%) the most frequent. Given this epidemiological scenario, it is important to determine the species of anophelines involved in these parasites’ transmission. This study was carried out in June 2016 in two indigenous communities living close to the tributaries of the Amazon River using protected human bait. The results of this study showed a total abundance of 1,085 mosquitos, of which 99.2% corresponded to Anopheles darlingi. Additionally, only two anopheline species were found, showing low diversity in the study areas. Molecular confirmation of some individuals was then followed by evolutionary analysis by using the COI gene. Nested PCR was used for identifying the three Plasmodium species circulating in the study areas. Of the two species collected in this study, 21.0% of the An. darlingi mosquitoes were infected with P. malariae, 21.9% with P. vivax and 10.3% with Plasmodium falciparum. It exhibited exophilic and exophagic behavior in both study areas, having marked differences regarding its abundance in each community (Tipisca first sampling 49.4%, Tipisca second sampling 39.6% and Doce de Octubre 10.9%). Interestingly, An. mattogrossensis infected by P. vivax was found for the first time in Colombia (in 50% of the four females collected). Analysis of An. darlingi COI gene diversity indicated a single population maintaining a high gene flow between the study areas. The An. darlingi behavior pattern found in both communities represents a risk factor for the region’s inhabitants living/working near these sites. This highlights the need for vector control efforts such as the use of personal repellents and insecticides for use on cattle, which must be made available in order to reduce this Anopheline’s abundance.

A new high-resolution melting analysis for the detection and identification of Plasmodium in human and Anopheles vectors of malaria

Among vector-borne diseases malaria is the leading cause of morbidity in the world, with more than 200 million cases per year and a large number of deaths. The techniques traditionally used for the detection of Plasmodium in humans and Anopheles mosquitoes include microscopy, IRMA, ELISA, antibody or molecular assays, and anopheline dissection. However, these techniques are limited by their requirement of skilled personnel, low sensitivity or long processing times. A PCR-based high-resolution melting (PCR-HRM) analysis was developed for the detection and identification of P. falciparum, P. vivax and P. malariae that infect humans and Anopheles. In 41 human samples PCR-HRM detected 14 samples positive for P. vivax, 17 for P. falciparum, three for P. malariae, three mixed infections for P. vivax/P. malariae and four negative samples. Whereas benchmarking assays of microscopy and nested PCR had false positive detections. Additionally, PCR-HRM was able to detect natural infection with Plasmodium spp. in An. darlingi and An. mattogrossensis. The PCR-HRM presented is the first single assay developed for the detection and identification of P. vivax, P. falciparum and/or P. malariae in human and Anopheles. This method improves on currently available assays as it is easy-to-use, rapid, sensitive and specific with a low risk of contamination.

Plasmodium malariae Prevalence and csp Gene Diversity, Kenya, 2014 and 2015

In Africa, control programs that target primarily Plasmodium falciparum are inadequate for eliminating malaria. To learn more about prevalence and genetic variability of P. malariae in Africa, we examined blood samples from 663 asymptomatic and 245 symptomatic persons from western Kenya during June–August of 2014 and 2015. P. malariae accounted for 5.3% (35/663) of asymptomatic infections and 3.3% (8/245) of clinical cases. Among asymptomatic persons, 71% (32/45) of P. malariae infections detected by PCR were undetected by microscopy. The low sensitivity of microscopy probably results from the significantly lower parasitemia of P. malariae. Analyses of P. malariae circumsporozoite protein gene sequences revealed high genetic diversity among P. malariae in Africa, but no clear differentiation among geographic populations was observed. Our findings suggest that P. malariae should be included in the malaria elimination strategy in Africa and highlight the need for sensitive and field-applicable methods to identify P. malariae in malaria-endemic areas.

A novel PCR-based system for the detection of four species of human malaria parasites and Plasmodium knowlesi

A microscopy-based diagnosis is the gold standard for the detection and identification of malaria parasites in a patient’s blood. However, the detection of cases involving a low number of parasites and the differentiation of species sometimes requires a skilled microscopist. Although PCR-based diagnostic methods are already known to be very powerful tools, the time required to apply such methods is still much longer in comparison to traditional microscopic observation. Thus, improvements to PCR systems are sought to facilitate the more rapid and accurate detection of human malaria parasites Plasmodium falciparum, P. vivax, P. ovale, and P. malariae, as well as P. knowlesi, which is a simian malaria parasite that is currently widely distributed in Southeast Asia. A nested PCR that targets the small subunit ribosomal RNA genes of malaria parasites was performed using a “fast PCR enzyme”. In the first PCR, universal primers for all parasite species were used. In the second PCR, inner-specific primers, which targeted sequences from P. falciparum, P. vivax, P. ovale, P. malariae, and P. knowlesi, were used. The PCR reaction time was reduced with the use of the “fast PCR enzyme”, with only 65 minutes required to perform the first and second PCRs. The specific primers only reacted with the sequences of their targeted parasite species and never cross-reacted with sequences from other species under the defined PCR conditions. The diagnoses of 36 clinical samples that were obtained using this new PCR system were highly consistent with the microscopic diagnoses.

Epidemiology of Malaria in the city of Kaedi (Mauritania, 2014)

BACKGROUND

In the face of ongoing and projected environmental and climate change, the epidemiology of malaria in the city of Kaédi (Mauritania), bordering the Senegal River Valley, requires special attention.

OBJECTIVE

To describe the epidemiological situation of malaria in the city of Kaédi, Mauritania, during the wet season of 2014.

METHODS

We conducted a descriptive cross-sectional survey in the city of Kaédi in september 2014 (wet season), to assess the prevalence of malaria parasites and vectors. For the choice of households, a cluster sampling was carried out and the city was subdivided into 10 sub-spatial units using a map of the city and the contribution of local populations. All household members were subjected to microscopic examination. In addition, larval surveys, morning wildlife sprays and night trap breaks were conducted.

RESULTS

Of the 4671 thick drops made, three were positive, ie an average plasmid index of 0.06%. Prevalence was 0.04% (2/4671) and 0.02% (1/4671) for Plasmodium malariae and Plasmodium falciparum, respectively. In addition, the larval fauna consisted essentially of Culex larvae (100%). Two (2) female Anopheles mosquitoes were collected during the study.

CONCLUSION

Even if transmission is low, in a context of absence of rainfall, the health authorities must foresee a strategy of malaria pre-elimination in riparian wilayas of the Senegal River.

Age-specific Plasmodium parasite profile in pre and post ITN intervention period at a highland site in western Kenya

BACKGROUND

Monitoring and evaluation of entomological, parasitological and clinical data is an important component of malaria control as it is a measure of the success of the interventions. In many studies, clinical data has been used to monitor trends in malaria morbidity and mortality. This study was conducted to demonstrate age dependent prevalence of malaria in the pre- and post-interventions period.

METHODS

A series of cross-sectional malaria parasitological surveys were conducted in Iguhu, western Kenya. Participants were randomly selected school-aged children between 6 and 13 years. The study was conducted between June 2002-December 2003 and January 2012-February 2015. Sexual and asexual parasite prevalence and densities were determined using microscopy. Age-dependence in parasite infections was compared between 2002-2003 and 2012-2015.

RESULTS

Plasmodium falciparum had the highest prevalence of 43.5 and 11.5% in the pre- and post-intervention periods. Plasmodium malariae had a prevalence of 2.3 and 0.2%, while Plasmodium ovale had a prevalence of 0.3 and 0.1% during the pre- and post-intervention period, respectively. There was a 73.7% reduction in prevalence of P. falciparum in the post-intervention compared to the pre-intervention period. Plasmodium falciparum parasite density increased by 71.2% between pre- and post-intervention period from (geometric mean of) 554.4-949.2 parasites/µl. Geometric mean gametocytaemia in Iguhu was higher in the post-intervention period (106.4 parasites/µl), when compared to the pre-intervention period (54.1 parasites/µl). Prevalence and density of P. falciparum showed a lower age-dependency during post-intervention period when compared to pre-intervention period.

CONCLUSION

The study provides evidence for reduction of malaria prevalence following the introduction of LLINs and ACT in western Kenya. Fewer people become infected but the few infected may be more infectious as suggested by higher gametocyte densities. The high parasite densities, which were not dependent on age, observed in the post intervention period imply that a more comprehensive integrated malaria management may be required to sustain the current interventions and hence reduce malaria transmission.

Molecular Detection of Plasmodium malariae/Plasmodium brasilianum in Non-Human Primates in Captivity in Costa Rica

One hundred and fifty-two blood samples of non-human primates of thirteen rescue centers in Costa Rica were analyzed to determine the presence of species of Plasmodium using thick blood smears, semi-nested multiplex polymerase chain reaction (SnM-PCR) for species differentiation, cloning and sequencing for confirmation. Using thick blood smears, two samples were determined to contain the Plasmodium malariae parasite, with SnM-PCR, a total of five (3.3%) samples were positive to P. malariae, cloning and sequencing confirmed both smear samples as P. malariae. One sample amplified a larger and conserved region of 18S rDNA for the genus Plasmodium and sequencing confirmed the results obtained microscopically and through SnM-PCR tests. Sequencing and construction of a phylogenetic tree of this sample revealed that the P. malariae/P. brasilianum parasite (GenBank KU999995) found in a howler monkey (Alouatta palliata) is identical to that recently reported in humans in Costa Rica. The SnM-PCR detected P. malariae/P. brasilianum parasite in different non-human primate species in captivity and in various regions of the southern Atlantic and Pacific coast of Costa Rica. The similarity of the sequences of parasites found in humans and a monkey suggests that monkeys may be acting as reservoirs of P.malariae/P. brasilianum, for which reason it is important, to include them in control and eradication programs.

The etiology of Ebola virus disease-like illnesses in Ebola virusnegative patients from Sierra Leone

During the 2014 Ebola virus disease (EVD) outbreak, less than half of EVD-suspected cases were laboratory tested as Ebola virus (EBOV)-negative, but disease identity remained unknown. In this study we investigated the etiology of EVD-like illnesses in EBOV-negative cases. From November 13, 2014 to March 16, 2015, EVD-suspected patients were admitted to Jui Government Hospital and assessed for EBOV infection by real-time PCR. Of 278 EBOV negative patients, 223 (80.21%), 142 (51.08%), 123 (44.24%), 114 (41.01%), 59 (21.22%), 35 (12.59%), and 12 (4.32%) reported fever, headache, joint pain, fatigue, nausea/vomiting, diarrhea, hemorrhage, respectively. Furthermore, 121 (43.52%), 44 (15.83%), 36 (12.95%), 33 (11.87%), 23 (8.27%), 10 (3.60%) patients were diagnosed as infection with malaria, HIV, Lassa fever, tuberculosis, yellow fever, and pneumonia, respectively. No significant differences in clinical features and symptoms were found between non-EVD and EVD patients. To the best of our knowledge, the present study is the first to explore the etiology of EVD-like illnesses in uninfected patients in Sierra Leone, highlighting the importance of accurate diagnosis to EVD confirmation.

[MALARIA IMPORTATION BY RUSSIA'S CITIZENS AND FOREIGNERS, INTO THE CITIES AND TOWNS OF THE RUSSIAN FEDERATION]

A total of 436 malaria cases, including 12 from the CIS countries and 424 from far foreign countries (of Africa and Central and South-East Asia), were imported into the Russian Federation in 2010-2014. Most (96.6%) cases were notified in the urban areas of 52 administrative subjects of Russia. The largest number of the imported cases were seasonal workers (39.2%), tourists (31.3%), students and foreign postgraduate students (19.5%), and ship or aircraft crews (10%). During a short malaria transmission season (June to August), there were 150 cases of different types, out of them there were only 63 cases of tertian malaria (its pathogen is Plasmodium vivax, to which malaria mosquitoes of Russia's fauna are susceptible). The relatively small number of infection sources in the short transmission (June to August) season of malaria, its importation into low-susceptibility large towns, and a small proportion of imported vivax malaria cases substantially reduce the risk of malaria in the highrisk areas of the country.

Plasmodium malariae Infection Associated with a High Burden of Anemia: A Hospital-Based Surveillance Study

Background

Plasmodium malariae is a slow-growing parasite with a wide geographic distribution. Although generally regarded as a benign cause of malaria, it has been associated with nephrotic syndrome, particularly in young children, and can persist in the host for years. Morbidity associated with P. malariae infection has received relatively little attention, and the risk of P. malariae-associated nephrotic syndrome is unknown.

Methodology/Principal Findings

We used data from a very large hospital-based surveillance system incorporating information on clinical diagnoses, blood cell parameters and treatment to describe the demographic distribution, morbidity and mortality associated with P. malariae infection in southern Papua, Indonesia. Between April 2004 and December 2013 there were 1,054,674 patient presentations to Mitra Masyarakat Hospital of which 196,380 (18.6%) were associated with malaria and 5,097 were with P. malariae infection (constituting 2.6% of all malaria cases). The proportion of malaria cases attributable to P. malariae increased with age from 0.9% for patients under one year old to 3.1% for patients older than 15 years. Overall, 8.5% of patients with P. malariae infection required admission to hospital and the median length of stay for these patients was 2.5 days (Interquartile Range: 2.0–4.0 days). Patients with P. malariae infection had a lower mean hemoglobin concentration (9.0g/dL) than patients with P. falciparum (9.5g/dL), P. vivax (9.6g/dL) and mixed species infections (9.3g/dL). There were four cases of nephrotic syndrome recorded in patients with P. malariae infection, three of which were in children younger than 5 years old, giving a risk in this age group of 0.47% (95% Confidence Interval; 0.10% to 1.4%). Overall, 2.4% (n = 16) of patients hospitalized with P. malariae infection subsequently died in hospital, similar to the proportions for the other endemic Plasmodium species (range: 0% for P. ovale to 1.6% for P. falciparum).

Conclusions/Significance

Plasmodium malariae infection is relatively uncommon in Papua, Indonesia but is associated with significant morbidity from anemia and a similar risk of mortality to patients hospitalized with P. falciparum and P. vivax infection. In our large hospital database, one in 200 children under the age of 5 years with P. malariae infection were recorded as having nephrotic syndrome.

Plasmodium malariae is a relatively rare, but widely distributed, cause of malaria. It can persist in the human host for years, often without causing significant symptoms. As a result, P. malariae will be a very difficult species to eradicate. Our study used data from a routine hospital-based surveillance system in southern Papua, Indonesia to describe the clinical epidemiology of P. malariae infections. Over a 10-year period there were 5,097 patient presentations to Mitra Masyarakat Hospital associated with P. malariae infection constituting 2.6% of all malaria cases. Patients with P. malariae malaria had a significantly older age distribution than those with P. vivax infections. They also had lower mean hemoglobin concentrations than patients infected with P. falciparum, P. vivax or mixed Plasmodium species. We speculate that this may be due to chronic hemolysis of parasitized and non-parasitized red cells as a result of persistent infection. One in 200 children under the age of 5 years with P. malariae infection were recorded as having nephrotic syndrome, a well-known but to date unquantified complication. Overall, 0.3% of patients with P. malariae malaria died. These findings emphasize the need to consider this parasite when designing comprehensive malaria elimination strategies.

Novel Cross-Border Approaches to Optimise Identification of Asymptomatic and Artemisinin-Resistant Plasmodium Infection in Mobile Populations Crossing Cambodian Borders

Background

Human population movement across country borders presents a real challenge for malaria control and elimination efforts in Cambodia and its neighbouring countries. To quantify Plasmodium infection among the border-crossing population, including asymptomatic and artemisinin resistant (AR) parasites, three official border crossing points, one from each of Cambodia's borders with Thailand, Laos and Vietnam, were selected for sampling.

Methods and Findings

A total of 3206 participants (of 4110 approached) were recruited as they crossed the border, tested for malaria and interviewed. By real-time polymerase chain reaction (RT-PCR), 5.4% of all screened individuals were found to harbour Plasmodium parasites. The proportion was highest at the Laos border (11.5%). Overall there were 97 P. vivax (55.7%), 55 P. falciparum (31.6%), two P. malariae (1.1%) and 20 mixed infections (11.5%). Of identified infections, only 20% were febrile at the time of screening. Of the 24 P. falciparum samples where a further PCR was possible to assess AR, 15 (62.5%) had mutations in the K13 propeller domain gene, all from participants at the Laos border point. Malaria rapid diagnostic test (RDT) pLDH/HRP-2 identified a positivity rate of 3.2% overall and sensitivity compared to RT-PCR was very low (43.1%). Main individual risk factors for infection included sex, fever, being a forest-goer, poor knowledge of malaria prevention methods and previous malaria infection. Occupation, day of the week and time of crossing (morning vs. afternoon) also appeared to play an important role in predicting positive cases.

Conclusions

This study offers a novel approach to identify asymptomatic infections and monitor AR parasite flow among mobile and migrant populations crossing the borders. Similar screening activities are recommended to identify other hot borders and characterise potential hot spots of AR. Targeted “customised” interventions and surveillance activities should be implemented in these sites to accelerate elimination efforts in the region.

Malaria in a tertiary hospital in Singapore--clinical presentation, treatment and outcome: an eleven year retrospective review

BACKGROUND

Malaria remains a global health threat and poses significant health risks even in non-endemic regions like Singapore.

METHODS

A retrospective analysis of 214 patients with smear-positive malaria treated at Singapore General Hospital (SGH) between year 2000 and 2010.

RESULTS

One hundred and sixty-seven (78%) patients were male; median age was 35 y (range, 25–52 y). Sixty-four (41%) patients had past history of treated malaria. Seven (4.9%) patients did not travel out of Singapore. One hundred and twenty-seven (76.5%) cases of malaria were acquired in Southeast Asia (SEA) and the Indian subcontinent. There were 127 (59.3%) Plasmodium vivax, 83 (38.8%) Plasmodium falciparum, 1 (0.3%) Plasmodium malariae and 3 (1.4%) mixed infections. Fever was the most common symptom and thrombocytopaenia was the most common laboratory finding. There were 43 severe and 171 uncomplicated cases of malaria, including 8 severe P. vivax cases. Those with severe malaria were older, stayed longer in hospital, had a higher percentage parasitaemia and took longer to clear the parasite. The diagnosis of malaria was suspected at the first contact with healthcare provider in 194 (91.9%) cases. Sixty-one (85.9%) patients with P. falciparum infection received combination anti-malarial therapy and 109 (98.2%) of patients with P. vivax received primaquine for hypnozoite clearance in combination with schizontocidal agent. All the patients survived.

CONCLUSION

In this study, P. vivax was the most common cause of malaria. Severe P. vivax was not uncommon. Cryptic transmission of malaria exists, highlighting the importance of continued vigilance, malaria surveillance and vector control. Early recognition of malaria improved the overall outcome.

Prevalence of malaria and HIV coinfection and influence of HIV infection on malaria disease severity in population residing in malaria endemic area along the Thai-Myanmar border

The objective of the study is to investigate the prevalence of malaria and HIV coinfection and assess the effect of HIV coinfection on malaria disease severity in malaria patients from the endemic area of Thailand along the Thai-Myanmar border. Blood samples were collected from a total of 867 patients with malaria (all species and severity) who attended Mae Tao clinic for migrant workers, Tak Province during 2005-2007 (439 samples), 2008-2010 (273 samples), and 2011-2013 (155 samples). The average prevalence rate of malaria and HIV coinfected cases in this malaria endemic area of the country during the three periods was 1.85%. HIV coinfection was observed only in samples with mono-infection of Plasmodium falciparum or Plasmodium vivax, with similar proportions (0.81 vs. 1.04%). Patients' admission parasite density, an indicator of disease severity, was significantly higher in cases with HIV coinfection observed during 2008-2010. Anemia was found at a significantly higher frequency in patients coinfected with malaria and HIV observed during 2005-2007 compared with those infected with malaria alone. No association was observed between malaria and HIV coinfection and gender, and infected malaria species during the three observation periods. Patients with malaria and HIV coinfection had a significantly lower hemoglobin level than those with malaria infection alone. In conclusion, the prevalence of malaria and HIV coinfection in population of the malaria endemic area along the Thai-Myanmar border is low. HIV coinfection tended to increase parasite density, an indicator of malaria disease severity.

[Two cases of African imported Plasmodium malariae malaria]

The process of diagnosis, epidemiological survey and treatment of two cases of African imported quartan malaria is reported in this paper.

Epidemiological pattern of imported malaria in Jordan from 2007 to 2011

Imported malaria is of major health concern to countries considered as free from this infection and Jordan is no exception. The aim of this study was to highlight various epidemiological aspects of imported malaria into Jordan over a period of five years. Information pertinent to all malaria cases registered in the Ministry of Health (Jordan) from January 2007 to November 2011 was retrieved from the database of the Department of Parasitic and Zoonotic Diseases. Data was grouped according to age, gender, country of acquisition and etiologic agents. During the study period, a total of 304 malaria cases were registered, 192 cases among Jordanians returning home and the remaining were detected among foreign nationals who arrived in the country for work or tourism. The majority of infections were due to Plasmodium falciparum (199 cases) followed by Plasmodium vivax (93) and then Plasmodium malariae (8). Mixed infection was detected in just 4 cases. The origin of these imported cases was in a descending order; Eritrea, Côte d'Ivoire, India, Sudan, Liberia and Pakistan. These countries contributed to 86.5% of cases while the remaining were acquired from other areas. It is believed that most Jordanians with imported malaria were military personnel who participated in Peace Keeping Forces with the United Nations. It is concluded that with the exception of imported cases reported herein, Jordan remains a malaria free country. Continuous vigilance by health authorities is needed to avoid reintroduction of the disease into the kingdom.

Malaria and HIV co-infection and their effect on haemoglobin levels from three health-care institutions in Lagos, southwest Nigeria

BACKGROUND

Malaria and human immunodeficiency virus (HIV) are two major infections with enormous public health consequence. Together, they are endemic in many developing countries with anaemia being the most frequent haematological consequence of the infections.

OBJECTIVES

To determine the prevalence of malaria and HIV co-infection as well as anaemia among selected patients from three health-care institutions in Lagos, Nigeria.

METHODS

A cross-sectional study of 1080 patients was carried out to determine the prevalence of malaria and HIV co-infection as well as anaemia. Blood sera from each of the patients were screened for malaria parasites, HIV-1 and HIV-2 using Giemsa stain, Cambridge Biotech Recombigen HIV-1/HIV-2 rapid device, respectively while haemoglobin estimation was performed using cyanmethemoglobin method.

RESULTS

Our data showed that the total number of malaria infected patients were significantly higher in HIV sero-positive patients 47.7% (31/65) when compared with their HIV sero-negative counterparts 25.8% (262/1015) P = 0.047. The result also revealed that 25.8% (8/31) of the patients co-infected with malaria and HIV had anaemia as compared to 11.1% (29/262) infected with malaria alone. Multivariable logistic regression analysis showed that patients with dual infection of malaria and HIV were twice likely to be anaemic than those infected with malaria alone [adjusted OR 2.4, 95% CI, 1.3 to 2.7, P = 0.014].

CONCLUSIONS

Our data indicated a higher prevalence of malaria in HIV infected patients and also revealed that patients co-infected with malaria and HIV were more likely to be anaemic.

Persistent foci of falciparum malaria among tribes over two decades in Koraput district of Odisha State, India

BACKGROUND

Koraput, a predominantly tribe-inhabited and one of the highly endemic districts of Odisha State that contributes a substantial number of malaria cases to the India's total. Control of malaria in such districts would contribute to change the national scenario on malaria situation. Hence, a study was carried out to measure the magnitude of malaria prevalence in the district to strengthen the malaria control activities.

METHODS

Prevalence of malaria was assessed through a sample blood survey (SBS) in seven randomly selected community health centres (CHCs). Individuals of all age groups in the villages selected (one in each subcentre) were screened for malaria infection. Both thick and thin smears were prepared from blood samples collected by finger prick, stained and examined for malaria parasites searching 100 fields in each smear. The results of a blood survey (n = 10,733) carried out, as a part of another study, during 1986-87 covering a population of 17,722 spread in 37 villages of Koraput district were compared with the current survey results. Software SPSS version 16.0 was used for data analysis.

RESULT

During the current study, blood survey was done in 135 villages screening 12,045 individuals (16.1% of the total population) and among them, 1,983 (16.5%) were found positive for malaria parasites. Plasmodium falciparum was the major malaria parasite species accounted for 89.1% (1,767) of the total positives; Plasmodium vivax and Plasmodium malariae accounted for 9.3% (184) and 0.2% (5), respectively. Gametocytes were found in 7.7% (n = 152) of the positive cases. The majority of parasite carriers (78.9%) were afebrile. The 1986-87 blood survey showed that of 10,733 people screened, 833 (7.8%) were positive for malaria parasites, 714 (85.7%) with P. falciparum, 86 (10.3%) with P. vivax, 12 (1.4%) with P. malariae and 21 (2.5%) with mixed infections.

CONCLUSION

The results of the current study indicated a rising trend in transmission of malaria in Koraput district compared to the situation during 1986-87 and indicated the necessity for a focused and reinforced approach for the control of the disease by improving people's access to diagnosis and treatment and ensuring implementation of the intervention measures with adequate coverage and compliance.

Hyperparasitaemia during bouts of malaria in French Guiana

BACKGROUND

High circulating parasite load is one of the WHO criteria for severe falciparum malaria. During a period of 11 years (2000-2010), the frequency of hyperparasitaemia (HP) (≥4% infected erythrocytes) during bouts of malaria due to Plasmodium falciparum, Plasmodium vivax and Plasmodium malariae in patients referred to Cayenne General Hospital (CGH) in French Guiana and the frequency of their admission to the Intensive Care Unit (ICU) were evaluated.

METHODS

A mean of 1,150 malaria cases were referred to the Parasitology Laboratory of CGH each year over the last decade. During this period, malaria diagnostic (microscopy) and parasitaemia evaluation have remained unchanged: determination of the parasitized erythrocytes percentage with asexual forms on thin blood smears for all cases of parasitaemia exceeding 0.1%. Patients admitted to the ICU can be counted by origin of the request for malaria testing. All the data collected retrospectively were anonymized in a standardized case report form and in database.

RESULTS

Between 2000 and 2010, 12,254 bouts of malaria were confirmed at the Parasitology Laboratory of CHG: P. vivax: 56.2%, P. falciparum: 39.5%, co-infection with both species: 3.4%, P. malariae: 0.9%. HP was observed in 262 cases, at a frequency of 4.9% for P. falciparum and only 0.041% for P. vivax, with no recorded cases for P. malariae. The need for intensive care was correlated with P. falciparum parasite load: 12.3% of cases for parasitaemia of 4-9%, 21.2% for parasitaemia 10-19%, 50% for parasitaemia 20-29% and 77.8% for parasitaemia ≥30% (n=9). The patient with the highest parasitaemia (75% infected erythrocytes with asexual form) presented a major concomitant lupus flare-up treated with corticoids. He survived without obvious sequelae.

CONCLUSIONS

In French Guiana during bouts of malaria, HP was observed at a frequency of ~ 5% for P. falciparum and two orders of magnitude less frequent for P. vivax. HP is a severity criterion for falciparum malaria in this endemic area. However, two of the patients with HP ≥30% were not admitted to the ICU and sequel-free cure in malaria patients with 75% parasitaemia is, therefore, possible.

[A history of malaria in modern Korea 1876-1945]

Although it is not certain when malaria began to appear in Korea, malaria is believed to have been an endemic disease from ancient times. It was Dr. H. N. Allen (1858-1932) who made the first description and diagnosis of malaria in terms of Western medicine. In his first year report (1885) of Korean Government Hospital he mentioned malaria as the most prevalent disease. Very effective anti-malarial drug quinine was imported and it made great contribution in treating malaria. After Japan had annexed Korea in 1910, policies for public health system were fundamentally revised. Japan assumed control of Korean medical institutions and built high-quality Western hospitals for the health care of Japanese residents. The infectious diseases which were under special surveillance were cholera, typhoid fever, dysentery, typhus, scarlet fever, smallpox, and paratyphoid fever. Among chronic infectious diseases tuberculosis and leprosy were those under special control. Malaria, however, was not one of these specially controlled infectious diseases although it was widely spread throughout the peninsula. But serious studies on malaria were carried out by Japanese medical scientists. In particular, a Japanese parasitologist Kobayasi Harujiro(1884-1969) carried out extensive studies on human parasites, including malaria, in Korea. According to his study, most of the malaria in Korea turned out to be tertian fever. In spite of its high prevalence, malaria did not draw much attention from the colonial authorities and no serious measure was taken since tertian fever is a mild form of malaria caused by Plasmodium vivax and is not so much fatal as tropical malaria caused by P. falciparum. And tertian malaria was easily controlled by taking quinine. Although the majority of malaria in Korea was tertian fever, other types were not absent. Quartan fever was not rarely reported in 1930s. The attitude of colonial authorities toward malaria in Korea was contrasted with that in Taiwan. After Japan had set out to colonize Taiwan as a result of Sino-Japanese war, malaria in Taiwan was a big obstacle to the colonization process. Therefore, a lot of medical scientists were asked to engage the malaria research in order to handle health problems in colonized countries caused by malaria. Unlike the situation in Taiwan, malaria in Korea did not cause a serious health problem as in Taiwan. However, its risk was not negligible. In 1933 there were almost 130,000 malaria patients in Korea and 1,800 patients among them died of malaria. The Japanese Government General took measures to control malaria especially during the 1930s and the number of patients decreased. However, as Japan engaged in the World War II, the general hygienic state of the society worsened and the number of malarial patients increased. The worsened situation remains the same after Liberation (1945) and during the Korean war (1950-53).

Plasmodium infection and its risk factors in eastern Uganda

BACKGROUND

Malaria is a leading cause of disease burden in Uganda, although surprisingly few contemporary, age-stratified data exist on malaria epidemiology in the country. This report presents results from a total population survey of malaria infection and intervention coverage in a rural area of eastern Uganda, with a specific focus on how risk factors differ between demographic groups in this population.

METHODS

In 2008, a cross-sectional survey was conducted in four contiguous villages in Mulanda, sub-county in Tororo district, eastern Uganda, to investigate the epidemiology and risk factors of Plasmodium species infection. All permanent residents were invited to participate, with blood smears collected from 1,844 individuals aged between six months and 88 years (representing 78% of the population). Demographic, household and socio-economic characteristics were combined with environmental data using a Geographical Information System. Hierarchical models were used to explore patterns of malaria infection and identify individual, household and environmental risk factors.

RESULTS

Overall, 709 individuals were infected with Plasmodium, with prevalence highest among 5-9 year olds (63.5%). Thin films from a random sample of 20% of parasite positive participants showed that 94.0% of infections were Plasmodium falciparum and 6.0% were P. malariae; no other species or mixed infections were seen. In total, 68% of households owned at least one mosquito although only 27% of school-aged children reported sleeping under a net the previous night. In multivariate analysis, infection risk was highest amongst children aged 5-9 years and remained high in older children. Risk of infection was lower for those that reported sleeping under a bed net the previous night and living more than 750 m from a rice-growing area. After accounting for clustering within compounds, there was no evidence for an association between infection prevalence and socio-economic status, and no evidence for spatial clustering.

CONCLUSION

These findings demonstrate that mosquito net usage remains inadequate and is strongly associated with risk of malaria among school-aged children. Infection risk amongst adults is influenced by proximity to potential mosquito breeding grounds. Taken together, these findings emphasize the importance of increasing net coverage, especially among school-aged children.

High prevalence and gender bias in distribution of Plasmodium malariae infection in central east-coast India

Light microscopy, the mainstay of malaria diagnosis in epidemiologic studies, exhibits limited sensitivity for detecting low level infections and often under-estimates the frequency of mixed Plasmodium species infections. To overcome these shortcomings we performed the PCR method for detection and identification of Plasmodium species in blood specimens from 242 individuals collected during the peak season of malaria incidence (July-October). Malaria prevalence was 81.4% and 43.4% by PCR and microscopy respectively. Moreover, while PCR detected Plasmodium malariae DNA in 108 (44.6%), microscopic examination detected only 20 (8.3%) individuals parasitized with this species. Further data analysis revealed an independent random distribution pattern of parasites irrespective of age groups (0-5 yrs, chi-square7df=2.77, P>0.95; 6-15 yrs, chi-square7df=4.82, P>0.50; >15 yrs, chi-square7df=4.4, P>0.70) and sexes (for male chi-square7df=2.48, P>0.95; for female, chi-square7df=1.85, P>0.95). However, although the parasite distribution is random irrespective of sex, females had more P. malariae infections (P=0.004, OR=2.312, 95% CI=1.3-4.1). Our study demonstrates that the parasite distribution in Orissa is random with substantially higher prevalence of P.malariae than previously suspected and this may be seasonal. A study of the bionomics of vector(s) responsible for P. malariae transmission in Orissa is needed to provide information for the control of malaria in the state.

[Results of epidemiological supervision of malaria vectors in the open water reservoirs of Moscow]

In the past 2 years, the malaria epidemiological situation has drastically improved in Moscow: only sporadic cases of local transmission of tertian (Plasmodium vivax) malaria have been notified, which sets a task to eradicate malaria in the megalopolis in 2010. In this connection, the surveillance of the malaria vectors Anopheles mosquitoes is assuming prime importance. The results of entomological monitoring have shown its efficiency on the territory of the megalopolis. Main efforts have been directed to the application of safe controlling methods against the mosquitoes and to hydraulic engineering actions to reduce "area susceptibility". Entomological observations have demonstrated benefits from the correctly chosen and constantly performed hydraulic engineering measures that guarantee a long-term and positive impact on the malaria situation.

Detection & molecular confirmation of a focus of Plasmodium malariae in Arunachal Pradesh, India

BACKGROUND & OBJECTIVE

During a malaria epidemiological study in Arunachal Pradesh, Plasmodium malariae like human malaria parasites were seen in blood smears from fever cases. The study was undertaken to detect the presence of P. malariae and to confirm its identity through DNA based polymerase chain reaction approach.

METHODS

Fever survey was carried out in 22 villages in Indo-Myanmar bordering district of Lohit, Arunachal Pradesh in 2005. Morphologically suspected P. malariae cases were confirmed using nested PCR based on 18S small subunit ribosomal DNA gene sequence.

RESULTS

Screening of 1,995 fever cases resulted in 9 probable cases of P. malariae based on morphological identification in Chakma tribe people residing in 2 villages. Nested PCR confirmed the identity of all probable cases of P. malariae by producing diagnostic band of 144 bp. PCR method was able to detect mixed infection of P. malariae with P. vivax and with P. falciparum.

INTERPRETATION & CONCLUSION

P. malariae may have been present in Arunachal Pradesh but most probably is being misdiagnosed due to its close resemblance with P. vivax, especially in ring forms. Estimation of actual case load of P. malariae in north-east India is, therefore, important with accurate species identification using molecular methods.

Acute renal failure in Plasmodium malariae infection

We report an unusual case of transfusion-transmitted malaria which remained undiagnosed for several months in an Italian woman splenectomised and polytransfused for thalassaemia major. The infecting species was Plasmodium malariae, and the patient developed acute renal failure, severe thrombocytopenia, and hepatic failure. Treatment with chlorochine was followed by a slow, but complete recovery of renal function.

Comparison of Quantitative Buffy Coat technique (QBC) with Giemsa-stained thick film (GTF) for diagnosis of malaria

The renewed interest in the use of fluorescent microscopy for malaria diagnosis prompted the comparison of Quantitative Buffy Coat technique (QBC) with the old standard Giemsa-stained Thick blood Film (GTF) in Ikeja General Hospital, now Lagos State University Teaching Hospital, in Lagos. Blood samples were collected from 353 patients, each examined with the QBC and GTF techniques. Of these, 68 were positive with GTF, 70 with QBC giving a positive rate of 19.3% and 19.8% respectively. The malaria positive rate was calculated as 19.3% using GTF as the standard. In general, females recorded higher percentages (58.6% and 54.4%) than males (41.4% and 45.6%) among those positive with QBC and GTF respectively. The overall sensitivity rate for QBC was 55.9% and the specificity was 88.8%. The positive and negative predictive values of QBC compared to GTF were 54.3%, 89.4% respectively while the concordance of the two techniques was 82.4%. These values were lower than those reported for QBC in previous studies. The sensitivity of QBC reduced further (33.3%) with samples having low parasite density (<1000 parasites/ul). QBC test was not able to accurately differentiate between different Plasmodium species but with the GTF, 86.7% of the infected individuals had Plasmodium falciparum, 7.5% had P. malariae and only 5.9% had mixed infections. In spite of the speed and simplicity of QBC technique, it cannot be considered an acceptable alternative to GTF under routine clinical laboratory situation. However, its speed and ease of use make it an important new tool for the diagnosis of malaria.

The epidemiology of malaria in the Papua New Guinea highlands: 6. Simbai and Bundi, Madang Province

Although predominantly a lowland province, Madang also includes highland areas such as Simbai and Bundi along the northern highland fringe. While the malaria situation in the coastal lowlands has been studied in great detail, the current malaria situation in the highland fringe communities has not been studied in depth since the 1960s. A series of recent malariological surveys found that the malaria situation has changed little over the last 40 years in both Simbai and Bundi. In the Simbai area there is little malaria transmission in villages above 1400 m, with a prevalence rate (PR) of 2.5-4.2%. Below 1400 m, however, there is moderate to high transmission (PR 8.6-24.7%) with surprisingly little difference in prevalence rates between survey villages, despite large differences in altitude. Prevalence rates of malaria infection were low in all Bundi villages (2.5-8.5%) with most infections occurring in adolescents and adults, which indicates limited acquisition of effective immunity to malaria and the possibility that many infections are acquired when travelling to the highly malarious lowlands area. Based on spleen rates the lower Simbai area would be regarded as mesoendemic, and the upper Simbai and Bundi areas as hypoendemic. Only in the lower Simbai area is malaria a major cause of febrile illness. However, in all areas village mean haemoglobin (Hb) levels were highly correlated with the prevalence of malaria infections, while concurrent parasitaemia reduced individual Hb levels by 1.3 g/dl (CI95 [1.0-1.5], p < 0.001) and significantly increased the risk for moderate-to-severe anaemia (Hb < 8 g/dl) (adjusted odds ratio 5.6, CI95 [3.6-8.6], p < 0.001). Based on the survey results, areas of different malaria epidemiology are delineated and options for control in each area are discussed.

The epidemiology of malaria in the Papua New Guinea highlands: 5. Aseki, Menyamya and Wau-Bulolo, Morobe Province

Although not strictly a highlands province, Morobe encompasses large highlands areas, the most important being Aseki, Menyamya and Wau-Bulolo. A series of rapid malaria surveys conducted in both the wet and dry seasons found malaria to be clearly endemic in areas below 1400 m in Menyamya and Wau-Bulolo, with overall prevalence rates in the wet season (25.5%, range: 9.1%-39.2%) greatly exceeding those in the dry season (8.3%, range: 2.4%-22.8%; p < 0.001). In the wet season surveys Plasmodium falciparum was the clearly predominant species, accounting for 63% of all infections. P. vivax increased in frequency in the dry season (from 27% to 46%, p < 0.001), while P. falciparum and P. malariae decreased. In line with past surveys a low prevalence of malaria was found in the Aseki area. Malaria was found to be the main source of febrile illness in the wet season with at least 60% of measured or reported fever associated with parasitaemia. Other causes of febrile illness dominated in the dry. In villages with parasite prevalence rates < 20% mean haemoglobin levels and prevalence of severe anaemia were strongly correlated with overall parasite prevalence. In addition concurrent malarial infections were associated with a strong reduction of individual haemoglobin levels (-1.2 g/dl) and there was increased risk of moderate-to-severe anaemia with concurrent malaria. Malarial infections are thus the most significant cause of febrile illness and anaemia in the highlands fringe populations in Morobe. As a consequence all villages below 1500-1600 m in Morobe Province should be included in malaria control activities.

Plasmodium malariae and Plasmodium ovale--the "bashful" malaria parasites

Although Plasmodium malariae was first described as an infectious disease of humans by Golgi in 1886 and Plasmodium ovale identified by Stevens in 1922, there are still large gaps in our knowledge of the importance of these infections as causes of malaria in different parts of the world. They have traditionally been thought of as mild illnesses that are caused by rare and, in case of P. ovale, short-lived parasites. However, recent advances in sensitive PCR diagnosis are causing a re-evaluation of this assumption. Low-level infection seems to be common across malaria-endemic areas, often as complex mixed infections. The potential interactions of P. malariae and P. ovale with Plasmodium falciparum and Plasmodium vivax might explain some basic questions of malaria epidemiology, and understanding these interactions could have an important influence on the deployment of interventions such as malaria vaccines.

Epidemiologic aspects of the malaria transmission cycle in an area of very low incidence in Brazil

BACKGROUND

Extra-Amazonian autochthonous Plasmodium vivax infections have been reported in mountainous regions surrounded by the Atlantic Forest in Espírito Santo state, Brazil.

METHODS

Sixty-five patients and 1,777 residents were surveyed between April 2001 and March 2004. Laboratory methods included thin and thick smears, multiplex-PCR, immunofluorescent assay (IFA) against P. vivax and Plasmodium malariae crude blood-stage antigens and enzyme-linked immunosorbent assay (ELISA) for antibodies against the P. vivax-complex (P. vivax and variants) and P. malariae/Plasmodium brasilianum circumsporozoite-protein (CSP) antigens.

RESULTS

Average patient age was 35.1 years. Most (78.5%) were males; 64.6% lived in rural areas; 35.4% were farmers; and 12.3% students. There was no relevant history of travel. Ninety-five per cent of the patients were experiencing their first episode of malaria. Laboratory data from 51 patients were consistent with P. vivax infection, which was determined by thin smear. Of these samples, 48 were assayed by multiplex-PCR. Forty-five were positive for P. vivax, confirming the parasitological results, while P. malariae was detected in one sample and two gave negative results. Fifty percent of the 50 patients tested had IgG antibodies against the P. vivax-complex or P. malariae CSP as determined by ELISA. The percentages of residents with IgM and IgG antibodies detected by IFA for P. malariae, P. vivax and Plasmodium falciparum who did not complain of malaria symptoms at the time blood was collected were 30.1% and 56.5%, 6.2% and 37.7%, and 13.5% and 13%, respectively. The same sera that reacted to P. vivax also reacted to P. malariae. The following numbers of samples were positive in multiplex-PCR: 23 for P. vivax; 15 for P. malariae; 9 for P. falciparum and only one for P. falciparum and P. malariae. All thin and thick smears were negative. ELISA against CSP antigens was positive in 25.4%, 6.3%, 10.7% and 15.1% of the samples tested for "classical" P. vivax (VK210), VK247, P. vivax-like and P. malariae, respectively. Anopheline captures in the transmission area revealed only zoophilic and exophilic species.

CONCLUSION

The low incidence of malaria cases, the finding of asymptomatic inhabitants and the geographic separation of patients allied to serological and molecular results raise the possibility of the existence of a simian reservoir in these areas.

Outpatient treatment of malaria in recently arrived African migrants

OBJECTIVE

To describe the clinical features and management of African migrants recently arrived in Western Australia and subsequently diagnosed with malaria.

DESIGN, PARTICIPANTS AND SETTING

Retrospective case record analysis of African migrants aged > or = 16 years with malaria referred to Royal Perth Hospital (RPH) from the WA Migrant Health Unit (MHU) between 1 March 2003 and 30 September 2005.

MAIN OUTCOME MEASURES

Demographic variables; clinical and laboratory variables; Plasmodium species; antimalarial medications used and their efficacy.

RESULTS

57 (3.5%) of 1609 adult African migrants screened at the MHU were diagnosed with malaria and referred for treatment. 52 were infected with P. falciparum, two with P. ovale, one with P. malariae, and one with both P. falciparum and P. malariae; the malaria parasite could not be identified in one individual. No patients had severe malaria by World Health Organization criteria. Most patients (53/57) were treated as outpatients with oral antimalarial therapy; four patients without severe malaria were admitted to hospital for treatment and observation. Atovaquone-proguanil was the antimalarial medication most commonly used (in 52/57), and treatment was well tolerated in most patients. Post-treatment follow-up was possible in 50 patients; all 27 of those who were followed for 4 weeks or longer were cured. Cure could not be concluded in patients with shorter follow-up periods. All follow-up blood films were negative for malarial parasites.

CONCLUSIONS

Outpatient treatment of malaria in recently arrived adult African migrants appeared to be safe and efficacious in our cohort.

Characterization and application of multiple genetic markers for Plasmodium malariae

Plasmodium malariae, a protozoan parasite that causes malaria in humans, has a global distribution in tropical and subtropical regions and is commonly found in sympatry with other Plasmodium species of humans. Little is known about the genetics or population structure of P. malariae. In the present study, we describe polymorphic genetic markers for P. malariae and present the first molecular epidemiological data for this parasite. Six microsatellite or minisatellite markers were validated using 76 P. malariae samples from a diverse geographical range. The repeat unit length varied from 2 to 17 bp, and up to 10 different alleles per locus were detected. Multiple genotypes of P. malariae were detected in 33 of 70 samples from humans with naturally acquired infection. Heterozygosity was calculated to be between 0.236 and 0.811. Allelic diversity was reduced for samples from South America and, at some loci, in samples from Thailand compared with those from Malawi. The number of unique multilocus genotypes defined using the 6 markers was significantly greater in Malawi than in Thailand, even when data from single genotype infections were used. There was a significant reduction in the multiplicity of infection in symptomatic infections compared with asymptomatic ones, suggesting that clinical episodes are usually caused by the expansion of a single genotype.

Space-time clustering of childhood malaria at the household level: a dynamic cohort in a Mali village

BACKGROUND

Spatial and temporal heterogeneities in the risk of malaria have led the WHO to recommend fine-scale stratification of the epidemiological situation, making it possible to set up actions and clinical or basic researches targeting high-risk zones. Before initiating such studies it is necessary to define local patterns of malaria transmission and infection (in time and in space) in order to facilitate selection of the appropriate study population and the intervention allocation. The aim of this study was to identify, spatially and temporally, high-risk zones of malaria, at the household level (resolution of 1 to 3 m).

METHODS

This study took place in a Malian village with hyperendemic seasonal transmission as part of Mali-Tulane Tropical Medicine Research Center (NIAID/NIH). The study design was a dynamic cohort (22 surveys, from June 1996 to June 2001) on about 1300 children (<12 years) distributed between 173 households localized by GPS. We used the computed parasitological data to analyzed levels of Plasmodium falciparum, P. malariae and P. ovale infection and P. falciparum gametocyte carriage by means of time series and Kulldorff's scan statistic for space-time cluster detection.

RESULTS

The time series analysis determined that malaria parasitemia (primarily P. falciparum) was persistently present throughout the population with the expected seasonal variability pattern and a downward temporal trend. We identified six high-risk clusters of P. falciparum infection, some of which persisted despite an overall tendency towards a decrease in risk. The first high-risk cluster of P. falciparum infection (rate ratio = 14.161) was detected from September 1996 to October 1996, in the north of the village.

CONCLUSION

This study showed that, although infection proportions tended to decrease, high-risk zones persisted in the village particularly near temporal backwaters. Analysis of this heterogeneity at the household scale by GIS methods lead to target preventive actions more accurately on the high-risk zones identified. This mapping of malaria risk makes it possible to orient control programs, treating the high-risk zones identified as a matter of priority, and to improve the planning of intervention trials or research studies on malaria.

Detection and identification of human Plasmodium species with real-time quantitative nucleic acid sequence-based amplification

Background

Decisions concerning malaria treatment depend on species identification causing disease. Microscopy is most frequently used, but at low parasitaemia (<20 parasites/μl) the technique becomes less sensitive and time consuming. Rapid diagnostic tests based on Plasmodium antigen detection do often not allow for species discrimination as microscopy does, but also become insensitive at <100 parasites/μl.

Methods

This paper reports the development of a sensitive and specific real-time Quantitative Nucleic Acid Sequence Based Amplification (real-time QT-NASBA) assays, based on the small-subunit 18S rRNA gene, to identify the four human Plasmodium species.

Results

The lower detection limit of the assay is 100 – 1000 molecules in vitro RNA for all species, which corresponds to 0.01 – 0.1 parasite per diagnostic sample (i.e. 50 μl of processed blood). The real-time QT-NASBA was further evaluated using 79 clinical samples from malaria patients: i.e. 11 Plasmodium. falciparum, 37 Plasmodium vivax, seven Plasmodium malariae, four Plasmodium ovale and 20 mixed infections. The initial diagnosis of 69 out of the 79 samples was confirmed with the developed real-time QT-NASBA. Re-analysis of seven available original slides resolved five mismatches. Three of those were initially identified as P. malariae mono-infection, but after re-reading the slides P. falciparum was found, confirming the real-time QT-NASBA result. The other two slides were of poor quality not allowing true species identification. The remaining five discordant results could not be explained by microscopy, but may be due to extreme low numbers of parasites present in the samples. In addition, 12 Plasmodium berghei isolates from mice and 20 blood samples from healthy donors did not show any reaction in the assay.

Conclusion

Real-time QT-NASBA is a very sensitive and specific technique with a detection limit of 0.1 Plasmodium parasite per diagnostic sample (50 μl of blood) and can be used for the detection, identification and quantitative measurement of low parasitaemia of Plasmodium species, thus making it an effective tool for diagnostic purposes and useful for epidemiological and drug studies.

[Malaria in mangrove areas of the Saloum delta (Senegal)]

This study of malaria biodiversity in Senegal used an entomological approach that combined parasite surveys and clinical investigations in the mangrove area of the Saloum delta from 1996 to 1998. The parasitologic studies took place in two of the six villages in the coastal area of Palmarin (Djifère and Diakhanor) during three distinct periods: at the end of the dry season, in the middle of the rainy season, and at the end of the rainy season. The clinical investigations at the Palmarin health station took place from July 1996 through February 1998. A malaria attack was defined as the presence of malaria symptoms (including fever, headaches, sweating, and shivering) associated with plasmodic parasitemia > 3,000 trophozoites/microL of blood. All the positive thick smears were infected with Plasmodium falciparum, one also with P. falciparum, and none with P. ovale. The average plasmodic index (5.6%) classifies the delta of Saloum as a hypoendemic area. The average parasite load was estimated at 2,239 trophozoites (95% CI: 1,660-3,020) of P. falciparum per microliter of blood, and 86.9% of patients with symptoms of a malaria attack were febrile. Malaria attacks accounted for 1.9% of the total consultations, 12.2% of the presumed malaria cases, and 14.0% of the febrile subjects. The finding that malaria attacks affected all age groups confirms the weakness of anti-malaria immunity among the population of the Saloum delta. Malaria cases were more frequent at the end of the rainy season and the beginning of the dry season, periods when parasite loads were highest. In this area, which is increasingly attractive to tourists and has a quite superficial fresh water table, man-made environmental changes favor mosquito breeding sites that promote the development of An. arabiensis and An. gambiae spp, both known to be major malaria vectors. In view of the population's weak anti-malaria immunity, this situation may increase malaria transmission and could be followed by epidemics. It is therefore important to set up a functional system of epidemiological monitoring to detect any malaria outbreaks.

Identification and typing of Cameroonian isolates of P. malariae using monoclonal antibodies against P. brasilianum

In the present study, monoclonal antibodies raised against Plasmodium brasilianum were used to demonstrate, for the first time, antigenic diversity in natural populations of Plasmodium malariae isolates and as diagnostic tool to detect low parasitaemia P. malariae infection. Seventeen McAbs reacting by indirect immunoflorescence antibody (IFA) assay with no other Plasmodium species than P. brasilianum, were shown to react with P. malariae and were used for typing 29 P. malariae isolates from hyperendemic areas in Yaounde and in three villages of South Cameroon with parasitaemia ranging from 0.01% to 1.8%. All 29 isolates were distinguished by their ability to react with certain antibodies and considered as representing different isolates of P. malariae. One of these McAbs (No. 14) recognized P. malariae isolates to both in Yaounde and from Mengang but not in Edou or in Nkol Mvae, which may recognize a specific epitope that is less common in strains found in these villages and provide evidence of regional variation within the P. malariae parasites. The McAbs Nos. 16 and 17 were used to determine their usefulness as diagnostic tools for 30 suspected blood samples that were collected from patients with fever and it became clear that they could detect sub-microscopical infections of P. malariae. This study supports the concept of using of P. brasilianum as a substitute for P. malariae during immuno-diagnosis of malaria in endemic areas where PCR assay cannot be used for identification of the P. malariae parasites. In addition our results for the first time provide evidence of considerable antigenic diversity of clinical P. malariae isolates in Cameroon.

Diagnosis of mixed Plasmodium malariae and P. vivax infection in a development aid volunteer by examination of bone-marrow specimens by real-time PCR

Mixed Plasmodium malariae and P. vivax infections in humans are reported very infrequently. The case of a 27-year-old male who sustained malaria quartana/tertiana caused by an unbalanced mixed P. malariae-P. vivax infection is reported here. Conventional tests and serology for malarial parasites were uniformly negative. Identification and quantification of the parasites were accomplished by examining bone-marrow specimens using specific real-time TaqMan PCR.

Malaria in Wanokaka and Loli sub-districts, West Sumba District, East Nusa Tenggara Province, Indonesia

Malaria has long been known as one of the major public health problems in West Sumba District, East Nusa Tenggara Province, Indonesia. To obtain baseline data for establishment of a suitable malaria control program in the area, malariometric surveys were conducted in two sub-districts, Wanokaka and Loli, during the periods of January, May, and August 2005. The survey included three selected villages in each sub-district, and blood smear analyses of 701, 921, and 894 randomly selected subjects in January, May, and August revealed 30.5%, 25.3%, and 28.2% malaria positives, respectively, consisting mainly of Plasmodium falciparum and P. vivax, and in a few cases, P. malariae. Analysis of malaria prevalence at different age groups clearly reflected the common phenomenon that younger individuals are more vulnerable by infection of either P. falciparum or P. vivax. In falciparum malaria, the frequency of cases carrying gametocytes was also relatively high involving all age groups. The findings indicate that the malaria incidence and transmission in the area are relatively high and that further exploration is warranted to establish a precise malaria control program.

Mixed Plasmodium falciparum-Plasmodium malariae infection and hemoglobin SC disease: a case report

In today's society, immigration and travel has resulted in large-scale population movements. This poses an additional challenge to the clinician when he or she takes the patient's history. The differential diagnosis of any presentation would need to include any diseases endemic to the area where the patient had been in. Ghana is considered a holoendemic high-risk area for the transmission of malaria. Moreover, compound heterozygous inheritance of hemoglobin (Hb) S and HbC often occurs in this area. We present a case of mixed Plasmodium falciparum-Plasmodium malariae infection complicating HbSC disease in a 34-year-old Ghanaian immigrant. We postulate that the malaria infection has transformed the patient's silent combined hemoglobinopathies (HbS/HbC) into a syndrome resembling a sickle cell crisis.

Association of haptoglobin levels with age, parasite density, and haptoglobin genotype in a malaria-endemic area of Gabon

Haptoglobin (Hp) levels were investigated in relation to host genotype in a malaria-endemic area in Gabon. A cross-sectional study of 1-12-year-old children was conducted in the rainy season, a period of high malaria transmission, to examine this relationship. Variables that influenced Hp levels were Hp genotype, location, and age interacting with parasite density. At low parasite densities, there was a negative correlation between Hp levels and age. At higher densities, there was a positive correlation with age. This suggests that in the presence of greater parasite-induced hemolysis, older children are capable of increased production of Hp. Sickle cell trait and ABO blood group was not associated with Hp levels in this population.

Epidemiology of highland malaria in western Kenya

OBJECTIVES

To investigate the epidemiology of falciparum malaria in workers from a highland tea plantation in western Kenya with very seasonally limited malaria transmission to determine what factors are associated with increased risk of malaria transmission in the Kenyan highlands.

DESIGN

A cross-sectional study with rolling, random subject enrollment from April 1998 through October 1999.

SETTING

Highland tea plantation located at 0 degrees 22' south and 35' 17' east in the Rift Valley highlands of western Kenya, an area with seasonally limited malaria transmission.

SUBJECTS

The data for the study were obtained from enrollment of outpatients from the healthcare system of a major tea company, which has 18 estates with 22,000 workers and approximately 50,000 persons eligible for health care. Of the 2796 patients evaluated during the study period, 798 cases of malaria were confirmed by positive peripheral blood smear; 1998 smear-negative patients were pressured to be non-infected and served as controls (Ratio: 2.52: 1).

INTERVENTIONS

Tea estate workers do not receive malaria chemoprophylaxis, but were given easily available free treatment for any symptomatic infections.

MAIN OUTCOME MEASURES

Smear-positive cases were compared with smear-negative patients for multiple demographic and disease variables, including sex, age, travel history, ethnic origin, home district transmission risk index and length of residence. Disease characteristics, including parasite types, counts and clinical symptoms, and treatments administered were described.

RESULTS

Malaria was predominantly P. falciparum (>99%); asexual parasite counts ranged from 1-10,440 per mm3, with a mean of 803.6 (95% confidence interval: 695.2, 912.0). Gametocytemia was present in 7.5% of smear-positive malaria cases, but was rare in the absence of blood asexual forms (0.5%). Prior use of a variety of antimalarial drugs was extremely common and negatively predictive of parasitemia in patients presenting for clinical treatment (Pearson Chi-square 50.81, p < 0.001), as was a subjective history of previous malaria infection in the past year (F = 26.65, 14 df, p < 0.001; univariate ANOVA). Amodiaquine was the most commonly used drug to treat cases of either smear-proven or clinically suspected malaria, accounting for 56% of therapy; pyrimethamine/sulfadoxine was used to treat 27%, artemesinin 8% and chloroquine was administered to only 3%, while combination therapy was used in 5% of cases, and only a single treatment (0.1 %) was recorded using quinine. Subjects with a prior history of treatment for malaria were statistically less likely to be infected again (Pearson Chi-square 50.81, p < 0.001). Presenting with symptoms suggestive of malaria was statistically associated with parasitemia, particularly fever, headache and dizziness, (p <0.001 for all, univariate ANOVA), but in general, clinical symptoms were not an effective discriminator of malarial disease. Ethnic group predicted malaria infection with groups traditionally from the Lake Victoria lowland regions having a greater prevalence of parasitemia (F = 2.04, 4. df, p = 0.002, univariate ANOVA). Parasitemia was significantly associated with age less than ten years (Pearson Chi-Square 145.99, p < 0.001), with a history of travel more than twenty kilometers from site within six weeks (Pearson Chi-square 58.28, p < 0.001) and with time since arrival on the plantation of one year or less (Pearson Chi-square 185.12, p <0.001)

CONCLUSION

Lower infection rates in persons with a history of prior infection implies a protective effect; the predilection of malaria for young and immunologically naive victims was confirmed. The proclivity in some ethnic groups for travel to holoendemic areas also accounts for the strong associations between recent travel, lowland ethnic group and infection. These findings taken together suggest that importation of malaria to the highlands, as well as travel away from the highlands, are important sources of new infections among persons living and working there.

Plasmodium malariae malaria--a case report

The tropical zone is the endemic home for all malarial parasites. Plasmodium vivax and Plasmodium falciparum are the species that are prevalent commonly in India. Plasmodium malariae is a parasite of both the tropical and subtropical zones, especially West and East Africa, Guiana and parts of India, but its presence in various zones tends to be patchy. In Karnataka state, its prevalence is rare. A case of Plasmodium malariae malaria from St John's Medical College, Bangalore in the background of the rarity of occurrence in this part of the country is presented.

[Relapse of Plasmodium malariae malaria 20 years after living in an endemic area]

INTRODUCTION

Malaria has been eradicated in Tunisia since 1979. Although it continues to be evoked in the case of fever after travel to an endemic zone, its diagnosis is however difficult during relapses, notably when they are delayed.

OBSERVATION

A 50 year-old man having lived in Mauritania from 1978 to 1982 was hospitalized for interstitial pneumopathy and urarthritis. In spite of treatment with broad spectrum antibiotics, the fever accompanied by abundant sweating persisted. A thick blood drop and blood smear was requested and led to the diagnosis of Plasmodium malariae malaria.

DISCUSSION

This observation recalls the possibility of parasitic upsurge of some plasmodial species. It should prompt physicians to be careful and evoke malaria in the case of fever in subjects having stayed, even several years before, in an endemic zone. This would permit early diagnosis and treatment.

Detection of four Plasmodium species in blood from humans by 18S rRNA gene subunit-based and species-specific real-time PCR assays

There have been reports of increasing numbers of cases of malaria among migrants and travelers. Although microscopic examination of blood smears remains the "gold standard" in diagnosis, this method suffers from insufficient sensitivity and requires considerable expertise. To improve diagnosis, a multiplex real-time PCR was developed. One set of generic primers targeting a highly conserved region of the 18S rRNA gene of the genus Plasmodium was designed; the primer set was polymorphic enough internally to design four species-specific probes for P. falciparum, P. vivax, P. malarie, and P. ovale. Real-time PCR with species-specific probes detected one plasmid copy of P. falciparum, P. vivax, P. malariae, and P. ovale specifically. The same sensitivity was achieved for all species with real-time PCR with the 18S screening probe. Ninety-seven blood samples were investigated. For 66 of them (60 patients), microscopy and real-time PCR results were compared and had a crude agreement of 86% for the detection of plasmodia. Discordant results were reevaluated with clinical, molecular, and sequencing data to resolve them. All nine discordances between 18S screening PCR and microscopy were resolved in favor of the molecular method, as were eight of nine discordances at the species level for the species-specific PCR among the 31 samples positive by both methods. The other 31 blood samples were tested to monitor the antimalaria treatment in seven patients. The number of parasites measured by real-time PCR fell rapidly for six out of seven patients in parallel to parasitemia determined microscopically. This suggests a role of quantitative PCR for the monitoring of patients receiving antimalaria therapy.