Comparison of active and passive case detection systems in Jepara District, Indonesia

This study compares the role and performance of active case detection (ACD) and passive case detection (PCD) in Jepara district, Indonesia. The number of blood slides examined and positive for malaria reported from 1994-1998 was retrieved from the district surveillance registers. Age of cases, parasite species, types of drugs and dosage, and time lapse were recorded from malaria registers at the three most endemic health centres. The quality of diagnosis was examined by re-reading 153 slides at the Department of Parasitology, Faculty of Medicine, Gadjah Mada University. Almost 60% of the 10,493 confirmed cases in Jepara district were identified from ACD. ACD detected significantly higher P. falciparum gametocyte infections than PCD (14.7% vs. 5.7%; p=0.002). The duration for slides prepared for examination was longer in ACD than in PCD (2.3 vs. 1.1 days; p<0.001), but this was still within the presumptive treatment period. Based on this we conclude that in the transition period to a decentralised health system, ACD for malaria parasites should be continued in a specified endemic area and therefore, efforts to retain the village malaria workers should be considered.     

Endemic malaria in four villages of the Pakistani province of Punjab

The prevalence of malaria in 4 villages 60 km south of Lahore, Punjab, where Anopheles culicifacies is the vector was estimated from blood films made during three mass malaria surveys (MS) and at 204 clinics (CS) held over 18 consecutive months. The highest parasite rate occurred during October 1984 when 43% of the CS population had parasitaemias. Plasmodium vivax predominated early in the major transmission season (23% and 15% vivax parasitaemias in August 1983 and 1984 respectively) whereas P. falciparum was the most common species later in the transmission season (an average falciparum prevalence of 37% in October and November 1984) and following the transmission season through March. Despite the proximity and habitat similarity of the 4 villages, both total and species malaria prevalence rates showed inter-village differences. Asexual stage and gametocyte parasite rates in children were 2 to 5 times higher than in adults. No increased mortality due to malaria was detected among the 4000 study population. Malaria was stable and endemic, albeit seasonally transmitted, in these 4 villages during 1983 and 1984.     

Increasing incidence of malaria in Kurseong, Darjeeling District, West Bengal, India, 2000-2004

In Kurseong, Darjeeling District, India, malaria caused concern but insufficient information was available. We analysed surveillance data to estimate the burden of malaria and to examine trends. Confirmed malaria reports were reviewed and climatic records were collected. The annual parasite incidence (API; number of cases/population) and the annual blood examination rate (ABER; number of slides examined/population) were calculated to assess case detection activities, and the slide positivity rate (SPR; number of slides positive/total number examined) was calculated to assess transmission trends. The API increased from 2 to 7.8 per 1000 population between 2000 and 2004 (no deaths), with a high incidence among all age groups. Two foothill areas with forests and slow-moving streams accounted for 88% of the 697 cases in 2004. The average 2000-2004 ABER was 4.8%, below the 10% examination target of the National Anti-Malaria Programme. The proportion of Plasmodium falciparum increased from 62% in 2000 to 77% in 2004. More than 50% of P. falciparum in the area were chloroquine resistant. The SPR increased from 8.1% in 2000 to 11.9% in 2004 and peaked during monsoons. Annual rainfall increased from 2000 to 2003. Malaria transmission increased, with an increasing proportion of P. falciparum in a context of resistance to chloroquine. We recommend increasing case detection and using artemisinin-based combination therapy to treat P. falciparum malaria.     

Epidemiology of malaria transmission in forest and plain ecotype villages in Sundargarh District, Orissa, India

A study of the epidemiology of malaria transmission was undertaken in 13 tribal villages located in forest and plain areas of Sundargarh District of Orissa state, India, from January 2001 to December 2003. In forest areas, intense transmission of malaria is attributed to the highly anthropophagic vector Anopheles fluviatilis sibling species S and is complemented by A. culicifacies sibling species C. In plain areas, A. culicifacies sibling species C is responsible for malaria transmission. The entomological inoculation rate in the forest and plain areas was 0.311 and 0.014 infective bites/person/night, respectively, during 2003. Malaria transmission is perennial both in forest and plain areas but is markedly low in the plain area compared with the forest area. Plasmodium falciparum accounted for 85.0% of the total malaria cases during the study period. In forest and plain areas, the number of P. falciparum cases per 1000 population per year was 284.1 and 31.2, respectively, whereas the parasite rate was 14.0% and 1.7%, respectively. In forest areas, clinical malaria occurs more frequently in children aged 0-5 years and declines gradually with increasing age. The study showed that villages in forest and plain areas separated by short geographical distances have distinct epidemiology of malaria transmission.     

一次性输入7例恶性疟疾的调查及处理报告

[目的] 根据1999年7月15日收到的韩国籍“皇家”号轮在航行中转发的电报,对其实施医疗救助。[方法] 在组织医疗救护的同时,开展了流行病学调查、个案调查、医学监测、血片镜检疟原虫等工作。[结果] 至1999年7月19日,“皇家”号轮本次共发生5例疟疾现症病人;2例带虫者。全船17名船员血检,发现阳性血片7份,阳性率为41．2％;6名发热船员血检,发现阳性血片5份,阳性率为83．3％。对现症病人和带虫者,为避免抗药性采用蒿甲醚根治疗法;对其它船员作假定性抗疟治疗,全部船员投放足量预防药(备用)。对货物(圆木)用体积分数为0.3％的敌敌畏行快速有效灭蚊,切断传播途径。[结论] 本次调查、处理中,利用因特网等现代技术迅速获取有关流行病学资料,在本次疫情的顺利调查及时诊断方面,显示其重要性;快速有效灭蚊措施的落实,切断了传播途径是本次疫情扑灭的关键。     

Demonstration by the polymerase chain reaction of mixed Plasmodium falciparum and P. vivax infections undetected by conventional microscopy.

Mixed malaria infections (Plasmodium falciparum and P. vivax) are suspected to occur at a greater frequency than is detected by conventional light microscopy. To determine this frequency we carried out a prospective 'blinded' comparison of diagnosis by conventional light microscopy and enzymatic amplification of the circumsporozoite gene extracted from dried spotted blood samples. Patients were previously healthy, active duty Thai soldiers assigned to a malaria risk area presenting with malaria. Microscopy (oil immersion objective at 1000 x magnification) involved examination of Giemsa-stained thick and thin blood films by an experienced microscopist. Whole blood samples (25 microliters) dried on filter paper were used for species-specific parasite deoxyribonucleic acid (DNA) amplification by the polymerase chain reaction (PCR) and hybridization with radiolabelled P. falciparum and P. vivax probes. Of 137 consecutive cases of malaria studied, 9% (3/32) of microscopically diagnosed P. falciparum infections and 5% (5/104) of microscopically diagnosed P. vivax infections were found to be mixed by the PCR/DNA probe systems, while 1 case was diagnosed as mixed by both microscopy and PCR. The possibility that malaria patients may have undetected mixed infections should be kept in mind because of the specific therapy required both for P. falciparum and for radical cure of P. vivax.     

Congenital malaria. Parasitological and serological studies in Niamey (Niger)

Congenital malaria is defined as the presence of Plasmodium parasites in the erythrocytes of newborns less than seven days old. The aim of this study was to determine the incidence of congenital malaria and its possible clinical consequences. We carried out a prospective survey in Niamey, the capital of Niger (600,000 inhabitants) from July to September 1993. Niamey is in an area of mesoendemic malaria and this period of the year corresponds to the rainy season, when malaria transmission is maximal. Ninety mothers and their newborns were included. We assessed the clinical status of the mother and child at the time of the delivery, and took blood smears to check for parasitemia and blood samples to check for antimalaria antibodies by indirect immunofluorescence (IIF). The placenta was not examined. Clinical signs of malaria (fever, splenomegaly, anemia and jaundice) were absent in all mothers and children and 88 of the 90 children had normal birth weights. Plasmodium falciparum was the only parasite detected, with 49 of the 90 mothers and 12 of the 90 newborns having positive blood smears. Serological tests detected the presence of antimalaria antibodies in 73 of the 90 mothers (81.1%) and 68 of the 90 newborns (75.5%). Thus, we found no cases of congenital malaria with clinical signs in this study, despite the high frequency of parasites and antimalaria antibodies. The reasons for this absence of cases of congenital malaria with symptoms are discussed.     

Point-of-care testing for malaria outbreak management

A rapid antigen assay for malaria was performed on blood samples collected during a simultaneous outbreak of falciparum malaria and vivax malaria on a remote island in the Indonesian archipelago. During the outbreak, a total of 89 patients (4.3% of the population) were diagnosed with malaria within a week. Microscopic examination revealed 78 malaria slide-positive cases, of whom 49 (62.8%) were identified as P. falciparum, 7 (9.0%) as P. vivax and 22 (28.2%) as mixed P. falciparum and P. vivax infections. The rapid malaria assay showed excellent correlation with expert-confirmed routine microscopy for P. falciparum and P. vivax monoinfections and mixed infections with a parasite density >50 parasites/microl. Several slide-negative blood samples collected from febrile patients with clinical malaria tested positive in the rapid test. The estimated sensitivity calculated for the rapid test (91.0%) was slightly higher than that of microscopy (87.6%). The result indicates that rapid antigen detection for malaria could be a useful alternative to microscopy to reduce the workload during emergency outbreak situations.     

Imported malaria in Kuwait

The number of imported malaria cases in Kuwait rose from 87 in 1980 to 504 in 1983, an increase of 579%. The continued resurgence of malaria in endemic zones, improved diagnostic techniques and a heightened awareness of imported malaria have contributed to the increase in the number of microscopically proved cases. Thick blood films fixed in acetone and stained in Giemsa proved a rapid method of diagnosis; species identification on the basis of a thin film on the same slide was performed with ease. Malaria was acquired in 38 countries. Most patients were young male adults. Most of the cases were due to Plasmodium vivax originating from India, although an increasing number of P. falciparum cases are also now being diagnosed from there. P. falciparum infections were evenly distributed throughout the year and most cases presented within 14 days of their arrival in the country. The highest number of P. vivax cases were diagnosed between May and October, when heat stress might have been a factor in precipitating a clinical attack of an infection previously acquired in the endemic zone. Attention is drawn to the importance of delayed attacks of P. vivax and, in semi-immunes, of P. falciparum. The time interval involved in establishing a history of "recent" travel in clinically suspected cases of malaria needs to be more clearly defined in each geographical area. Cases of induced malaria due to transfusion, accidental and congenital infections were identified. The fatality rate due to P. falciparum infections was low. In terms of the risk of renewed transmission, Kuwait may be considered a vulnerable area.     

Population dynamics of Anopheles culicifacies and malaria in the tribal area of central India.

A longitudinal study (1993-94) on malaria was conducted in Dungaria, a typical forest fringe tribal village in Mandla district of central India (Madhya Pradesh). Our initial objective was to obtain in-depth baseline data on malaria transmission in the tribal village to elucidate the factors responsible for persistent malaria in the area and thereby to help in formulating an improved malaria control program. Anopheles culicifacies Giles was the predominant vector of malaria, although Anopheles fluviatilis James were recorded in small numbers. The transmission season was from May to November. Analysis of the malaria cases revealed hyperendemic malaria, with Plasmodium falciparum the predominant species. The prevalence of Plasmodium vivax was mainly in the summer and that of P. falciparum in autumn. The study suggested that a number of factors were responsible for the continuation of malaria transmission in the village.     

The phenomenon of the delayed initial attack of tertian malaria]

From 1986 to 1990 we have treated 215 patients with falciparum malaria. In 8 patients (4%) who had not returned to any malarial area, malaria attacks recurred after 6-20 weeks. Curiously these were now caused by different species: Plasmodium vivax (4 patients) and P. ovale (4 patients). After proper management of malignant tertian malaria caused by P. falciparum, patients are considered cured, provided the treatment has been in accordance with the resistance pattern of the parasite in the country of origin. Yet, in a small number of patients attacks of malaria recur after different time intervals. The explanation of this seemingly paradoxical phenomenon is that these were delayed primary attacks of benign tertian malaria rather than recrudescences of malignant tertian malaria. Consequently the patients must have been infected by two different species of malaria at a time. In P. vivax and P. ovale hypnozoites occur (notably absent in P. falciparum), dormant stages in the liver that are not susceptible to the antimalarials in use for the eradication or prophylaxis of the blood stages which cause the acute attacks of malaria. After a variable amount of time the blood is then (re)invaded and the patient suffers a delayed primary attack or a relapse. Physicians should be aware that definite cure of malignant tertian malaria does not prevent future attacks of benign tertian malaria. They should inform their patients accordingly.     

Differences in automated depolarization patterns of Plasmodium falciparum and P. vivax malaria infections defined by the Cell-Dyn CD4000 haematology analyser

Of 1014 samples submitted for full blood count analysis and malaria screening, 854 were designated malaria-negative by blood film microscopy, 79 were unequivocally identified as Plasmodium vivax and 81 as P. falciparum. All samples were additionally analysed with the Abbott Cell-Dyn CD4000 haematology instrument, and leucocyte differential plots of 90 degrees polarized vs. 90 degrees depolarized (NEU-EOS plot) and 90 degrees depolarized vs. 0 degree light (EOS I plot) scatter were specifically examined for abnormal depolarization patterns. Depolarization pattern types were correlated with microscopy (species) results, and these correlations were consolidated by polymerase chain reaction analysis. All 854 microscopically-designated malaria-negative samples showed a type 1 (normal) CD4000 depolarization pattern. Abnormal pattern types 2, 3a and 3b were entirely restricted to one of the two malaria categories. Plasmodium falciparum malaria showed two CD4000 pattern types only; a 'normal' type 1 pattern was seen in 36/75 (48%) cases and the remaining 39 cases were all abnormal pattern type 3a. In contrast, most (79/85) P. vivax malaria cases showed a distinctive clustered EOS I population (types 2 and 3b patterns) that was not seen with P. falciparum. Automated depolarization analysis provides an effective means of detecting malaria-associated haemozoin, and the patterns of intracellular haemozoin further appear to provide species differentiation between P. falciparum and P. vivax.     

Malaria surveillance--United States, 1998.

PROBLEM/CONDITION: Human malaria is caused by one or more of four species of intraerythrocytic protozoa of the genus Plasmodium (i.e., P. falciparum, P. vivax, P. ovale, or P. malariae). The protozoa are transmitted by the bite of an infective female Anopheles species mosquito. The majority of malaria infections in the United States occur among persons who have traveled to areas with endemic transmission. Cases occasionally occur that are acquired through exposure to infected blood products, by congenital transmission, or by local mosquitoborne transmission. Malaria surveillance is conducted to identify episodes of local transmission and to guide prevention recommendations for travelers. REPORTING PERIOD: Cases with an onset of symptoms during 1998. DESCRIPTION OF SYSTEM: Malaria cases confirmed by blood smear are reported to local and state health departments by health-care providers and laboratory staff members. Case investigations are conducted by local and state health departments, and reports are sent to CDC through the National Malaria Surveillance System (NMSS). This report uses NMSS data. RESULTS: CDC received reports of 1,227 cases of malaria with onsets of symptoms in 1998, among persons in the United States and its territories. This number represents a decrease of 20.5% from the 1,544 cases reported during 1997. P. falciparum, P. vivax, P. malariae, and P. ovale were identified in 42.8%, 37.8%, 3.5%, and 2.1% of cases, respectively. More than one species was present in seven patients (0.6% of total). The infecting species was not determined in 162 (13.2%) cases. Compared with reported cases in 1997, reported malaria cases acquired in Africa increased by 1.3% (n = 706); those acquired in Asia decreased by 52.1% (n = 239); and those acquired in the Americas decreased by 6.5% (n = 229). Of 636 U.S. civilians who acquired malaria abroad, 126 (19.8%) reportedly had followed a chemoprophylactic drug regimen recommended by CDC for the area to which they had traveled. Five persons became infected in the United States. One case was congenitally acquired; one was acquired by blood transfusion; and three were isolated cases that could not be epidemiologically linked to another case. Four deaths were attributed to malaria. INTERPRETATION: The 20.5% decrease in malaria cases during 1998 compared with 1997 resulted primarily from decreases in P. vivax cases acquired in Asia among non-U.S. civilians. This decrease could have resulted from local changes in disease transmission, decreased immigration from the region, decreased travel to the region, incomplete reporting from state and local health departments, or increased use of effective antimalarial chemoprophylaxis. In a majority of reported cases, U.S. civilians who acquired infection abroad had not taken an appropriate chemoprophylaxis regimen for the country where they acquired malaria. PUBLIC HEALTH ACTIONS TAKEN: Additional information was obtained from state and local health departments and clinics concerning the four fatal cases and the five infections acquired in the United States. Persons traveling to a malarious area should take a recommended chemoprophylaxis regimen and use personal protection measures to prevent mosquito bites. Any person who has been to a malarious area and subsequently develops fever or influenza-like symptoms should seek medical care immediately; the investigation should include a blood smear for malaria. Malaria infections can be fatal if not diagnosed and treated promptly. Current recommendations concerning prevention and treatment of malaria can be obtained from CDC.     

Effects of untreated bed nets on the transmission of Plasmodium falciparum, P. vivax and Wuchereria bancrofti in Papua New Guinea

The impact of untreated bed nets on the transmission of human malaria and filariasis in a village in a hyperendemic area of Papua New Guinea was studied. In anopheline mosquitoes, the Plasmodium falciparum sporozoite antigen positivity rate, filarial infection rates and human blood indices dropped significantly after bed nets were introduced. This reduction in human-vector contact did not affect mosquito density as no significant difference in either landing rates or indoor resting catches was found. The number of bed nets in a house and ownership of dogs were factors significantly associated with a reduction in the number of indoor resting mosquitoes. However, the reduction in the P. falciparum sporozoite antigen rate in mosquitoes was not accompanied by a reduction in either malaria parasite or antibody prevalences or titres against the P. falciparum circumsporozoite protein.     

Malaria in southern Mozambique: malariometric indicators and malaria case definition in Manhiça district

A total of 2057 children aged <10 years were selected at random from a demographic surveillance system and enrolled in 4 malariometric cross-sectional surveys in different seasons in Manhi?a district in southern Mozambique. Plasmodium falciparum accounted for 90% of all malaria infections and the prevalence of asexual P. falciparum ranged from 13.7-21.7% at the end of the dry season to 30.5-34.0% at the end of rainy season. In order to determine the malaria attributable fraction (MAF) of fever, 1021 children from a nearby hospital acted as fever cases and from this separate case-control study the crude MAF was 36%, showing a marked age dependency. Plasmodium falciparum is the most common malaria species in Manhi?a. This malaria-mesoendemic area has year-round transmission. The importance of other non-malarial fever-causing conditions among infants was highlighted. Malaria appeared to be a major contributory factor to anaemia in the area.     

Changes in the epidemiological pattern of malaria in a rural area of the middle Rio Negro, Brazilian Amazon: a retrospective analysis

A retrospective study on reported malaria cases in the municipality (county) of Barcelos, Amazonas State, Brazil, was performed from 1992 to 2004, emphasizing the high endemic area along the Padauiri, an affluent of the Rio Negro. 16,795 cases were reported, 10,318 (61.4%) from the rural area and 6,477 (38.6%) from the urban area. Mean annual parasite index for the period was 136.7 per 1,000 inhabitants in the urban area and 613.6 per 1,000 in the rural area of Barcelos and 708.9 per 1,000 in the Padauiri area. In the latter area, two periods were considered: one epidemic, from 1992 to 1998, and the other post-epidemic, from 1999 to 2004. Comparing the two periods, the male/female ratio changed from 1.8 to 1.14, mean patient age from 17.9 to 14.8, proportion of Plasmodium falciparum cases from 51.9% to 23.7%, proportion of slides with low P. falciparum parasite density from 35.3% to 44.9%, and proportion of P. vivax from 24% to 35% (all these differences were statistically significant, with p < 0.05). The changes in the epidemiological pattern of malaria in the Padauiri area will be further elucidated through prospective studies.     

Seroepidemiology of malaria in a residual focus in Algeria: Khemis El Kechua district

The residual focus of Khemis el Kechna represented in 1981 nearly the totality of the autochtonous cases detected in Algeria that year (51 cases/53 cases). Control measures were applied during 3 successive years, the number of cases dropped from 51 in 1981 to 18 in 1982 and to 0 in 1983. In order to confirm the interruption of malaria transmission a sero-epidemiological study was carried out in 1984. The analysis of serological results by age, time and place of residence led to the conclusion that malaria transmission no longer occurs. A comparison of the serological results obtained by two blood sampling techniques (serum/dried blood on filter paper) confirmed the reliability of the results when eluted dried blood is used. A statistically significant difference was observed between the proportions of positives sera according to the antigen species used (P. falciparum culture strain or P. vivax obtained from patient originating from India.     

Phylogenetic analysis of CSP and MSP-9 gene sequences demonstrates the close relationship of Plasmodium coatneyi to Plasmodium knowlesi.

Plasmodium coatneyi is a simian malaria parasite with various biological features similar to the human malaria P. falciparum and potential as a model for severe cases of malaria. We have characterized two single-copy genes from P. coatneyi, the circumsporozoite protein and merozoite surface protein-9 genes, and determined its phylogenetic relationship among Plasmodium species. This study demonstrates that while it has similarities to P. falciparum, P. coatneyi belongs to a distant clade including several simian malaria parasites and the human malaria P. vivax. P. coatneyi forms a monophyletic group with P. knowlesi, demonstrating their close relationship despite some very distinctive biological characteristics.     

Malaria persistence in Kumaon foothills of District Nainital, Uttarakhand, India

Clinic data depicted a high incidence of malaria in a forest ecotype in the Kumaon foothills of District Nainital, Uttarakhand, India. A study was therefore conducted to determine the risk factors associated with the transmission of malaria from 2002 to 2004. The man-hour densities of Anopheles culicifacies and An. fluviatilis varied from 2 to 139 and 1 to 69, respectively. The sporozoite rate of 0.24% was recorded in An. culicifacies. Sibling species investigation revealed prevalence of species B (53.8%) and C (46.2%) of An. culicifacies and of species T (100%) of An. fluviatilis complexes. The slide positivity rate and slide falciparum rate were 50.4% and 28.3%, respectively. The infant parasite rate was 42.9% and the enlarged spleen rate among the children was 25.95%. The findings revealed the persistence of malaria in the area mainly due to indigenous transmission through the malaria vector An. culicifacies and the inadequacy of intervention measures. Transmission could be curtailed by indoor residual application of malathion.     

Malaria on the Thai-Burmese border: treatment of 5192 patients with mefloquine-sulfadoxine-pyrimethamine

Multidrug-resistant falciparum malaria is a major health problem along the Thai-Burmese border. From July 1985 until December 1986 a total of 5192 patients with falciparum malaria (1734 males, 3458 females) from this area were given supervised treatment with the combination mefloquine—sulfadoxine—pyrimethamine (MSP). The radical cure rate, assessed 21 days after drug administration, was 98.4% for the first 1975 patients, and 98.8% when assessed at 28 days for the remaining 3217 patients. In 3.8% of cases, parasites were still detected in peripheral blood smears on day 7 after treatment but this had fallen to 0.27% by day 9. Adverse reactions among the first 1975 patients were: vertigo (7.5% of patients), vomiting (5.8%), epigastric pain (0.6%), and transient confusional state (one case). MSP is an effective and well-tolerated drug for the treatment of drug-resistant falciparum malaria; however, delayed parasite clearance may give a false impression of RII resistance.