Slide Positivity Rate Research Articles

Epidemiology of malaria in Nikshahr, Sistan and Baluchestan province, Southeast Iran, during 2004-2010

Objective: Malaria is a major health problem in Nikshahr. In 2010, about 11.9% of the total malaria cases in Iran occurred in Nikshahr. The main purpose of this study was to survey the epidemiological features of malaria in Nikshahr, Southeast Iran, during a 7-year period, 2004-2010. Materials and Methods: The present survey is a descriptive study that involves positive cases of Malaria reported from the center of communicable diseases in Nikshahr. The data were entranced to a computer according to demographic and epidemiological characteristics of patients as well as plasmodium species; then they were analyzed by SPSS 16 software. Results: A total of 12233 cases were reported during 2004-2010 and three types of species of malaria parasite were detected. The highest positive number (2937) was reported in 2006 and the lowest number (221) in 2010. Malaria-positive cases of Nikshahr were mainly (60.2%) found among male individuals. The annual parasite incidence (API), which is the index of malaria incidence in the community, has decreased from 9.5 in 2004 to 1.09 in 2010. The slide positive rate among indigenous residents was significantly higher than that of the migrant population. Most (96.5%) of the malaria-positive cases were found among the Iranian population. About 0.3% of cases were identified to be mixed (falciparum and vivax), 98% Plasmodium vivax, and 1.7% Plasmodium falciparum. The largest number of malaria-positive cases occurred in October when the average percentage of humidity was 29.4 and the mean ambient temperature was 30.8°C. Conclusions: Several measures should ideally be implemented in an integrated pattern to contain the dissemination of malaria parasites and mosquito vectors; these include improvement of policies, regulations, and practices regarding malariological screening.

How protected are populations if transmission relapses? Insights from mathematical modeling and simulation

Background Malaria control measures have been successful in reducing malaria mortality and morbidity in sub-Saharan Africa in the last decade. In particular, in Principe Island, Sao Tome e Principe, after 5 years of control measures, Plasmodium falciparum incidence has decreased 99% and prevalence measured by slide-positivity rate was below 1% in 2009 [1]. However, this method lacks sensitivity for detection of asymptomatic and sub-patent parasite carriage that has implications on transmission [2]. Furthermore, control measures have the adverse effect of promoting decrease of immunity against the parasite, and a relapse in transmission might therefore have more severe consequences on infected individuals [3].

The baseline distribution of malaria in the initial phase of elimination in Sabang Municipality, Aceh Province, Indonesia

BackgroundSabang Municipality, in Aceh Province, Indonesia, plans to initiate a malaria elimination programme in 2013. A baseline survey of the distribution of malaria in the municipality was conducted to lay the foundations for an evidence-based programme and to assess the island’s readiness to begin the elimination process.MethodsThe entire population of the municipality was screened for malaria infection and G6PD deficiency. Specimens collected included blood slides, blots and tubes for selected households.Results and DiscussionSamples were collected from 16,229 residents. Microscopic examination of the blood smears revealed 12 malaria infections; 10 with Plasmodium falciparum and 2 with Plasmodium vivax. To confirm the parasite prevalence, polymerase chain reaction (PCR) diagnosis was performed on the entire positive cases by microscopy and randomized 10% of the microscopically negative blood samples. PCR revealed an additional 11 subjects with malaria; one P. falciparum infection from the village of Paya Keunekai, and nine P. vivax infections and one mixed P. falciparum/P. vivax infection from the village of Batee Shok. The overall slide positivity rate was 0.074% (CI 95%: 0.070 – 0.078) and PCR corrected prevalence 0,590% (CI 95%: 0.582 – 0.597). Analysis of 937 blood samples for G6PD deficiency revealed two subjects (0.2%) of deficient G6PD. Analysis of several genes of the parasite, such as Pfdhfr, Pfdhps, Pfmdr1, Pfcrt, Pfmsp1, Pfmsp2, Pvdhfr, Pvdhps, Pvmdr1 and host gene, such as G6PD gene revealed that both P. falciparum and P. vivax carried the mutation associated with chloroquine resistance.ConclusionMalariometric and host genetic analysis indicated that there is a low prevalence of both malaria and G6PD deficiency in the population of Sabang Municipality. Nevertheless, malaria cases were clustered in three rural villages and efforts for malaria elimination in Sabang should be particularly focused on those three villages.

Malaria prevalence among pregnant women in two districts with differing endemicity in Chhattisgarh, India

BackgroundIn India, malaria is not uniformly distributed. Chhattisgarh is a highly malarious state where both Plasmodium falciparum and Plasmodium vivax are prevalent with a preponderance of P. falciparum. Malaria in pregnancy (MIP), especially when caused by P. falciparum, poses substantial risk to the mother and foetus by increasing the risk of foetal death, prematurity, low birth weight (LBW), and maternal anaemia. These risks vary between areas with stable and unstable transmission. The specific objectives of this study were to determine the prevalence of malaria, its association with maternal and birth outcomes, and use of anti-malarial preventive measures for development of evidence based interventions to reduce the burden of MIP.MethodsA cross-sectional study of pregnant women presenting to antenatal clinics (ANC) or delivery units (DU), or hospitalized for non-obstetric illness was conducted over 12 months in high (Bastar) and low (Rajnandgaon) transmission districts in Chhattisgarh state. Intensity of transmission was defined on the basis of slide positivity rates with a high proportion due to P. falciparum. In each district, a rural and an urban health facility was selected.ResultsPrevalence of peripheral parasitaemia was low: 1.3% (35/2696) among women at ANCs and 1.9% at DUs (19/1025). Peripheral parasitaemia was significantly more common in Bastar (2.8%) than in Rajnandgaon (0.1%) (p < 0.0001). On multivariate analysis of ANC participants, residence in Bastar district (stable malaria transmission) was strongly associated with peripheral parasitaemia (adjusted OR [aOR] 43.4; 95% CI, 5.6-335.2). Additional covariates associated with parasitaemia were moderate anaemia (aOR 3.7; 95% CI 1.8-7.7), fever within the past week (aOR 3.2; 95% CI 1.2-8.6), and lack of formal education (aOR 4.6; 95% CI 2.0-10.7). Similarly, analysis of DU participants revealed that moderate anaemia (aOR 2.5; 95% CI 1.1-5.4) and fever within the past week (aOR 5.8; 95% CI 2.4-13.9) were strongly associated with peripheral and/or placental parasitaemia. Malaria-related admissions were more frequent among pregnant women in Bastar, the district with greater malaria prevalence (51% vs. 11%, p < 0.0001).ConclusionsGiven the overall low prevalence of malaria, a strategy of enhanced anti-vector measures coupled with intermittent screening and targeted treatment during pregnancy should be considered for preventing malaria-associated morbidity in central India.

Trends in malaria cases, hospital admissions and deaths following scale-up of anti-malarial interventions, 2000–2010, Rwanda

BackgroundTo control malaria, the Rwandan government and its partners distributed insecticide-treated nets (ITN) and made artemisinin-based combination therapy (ACT) widely available from 2005 onwards. The impact of these interventions on malaria cases, admissions and deaths was assessed using data from district hospitals and household surveys.MethodsDistrict records of ITN and ACT distribution were reviewed. Malaria and non-malaria indictors in 30 district hospitals were ascertained from surveillance records. Trends in cases, admissions and deaths for 2000 to 2010 were assessed by segmented log-linear regression, adjusting the effect size for time trends during the pre-intervention period, 2000–2005. Changes were estimated by comparing trends in post-intervention (2006–2010) with that of pre-intervention (2000–2005) period. All-cause deaths in children under-five in household surveys of 2005 and 2010 were also reviewed to corroborate with the trends of deaths observed in hospitals.ResultsThe proportion of the population potentially protected by ITN increased from nearly zero in 2005 to 38% in 2006, and 76% in 2010; no major health facility stock-outs of ACT were recorded following their introduction in 2006. In district hospitals, after falling during 2006–2008, confirmed malaria cases increased in 2009 coinciding with decreased potential ITN coverage and declined again in 2010 following an ITN distribution campaign. For all age groups, from the pre-intervention period, microscopically confirmed cases declined by 72%, (95% Confidence Interval [CI], 12-91%) in 2010, slide positivity rate declined 58%, (CI, 47%–68%), malaria inpatient cases declined 76% (CI, 49%–88%); and malaria deaths declined 47% (CI, 47%–81%). In children below five years of age, malaria inpatients decreased 82% (CI, 61%-92%) and malaria hospital deaths decreased 77% (CI, 40%–91%). Concurrently, outpatient cases, admissions and deaths due to non-malaria diseases in all age groups either increased or remained unchanged. Rainfall and temperature remained favourable for malaria transmission. The annual all-cause mortality in children under-five in household surveys declined from 152 per 1,000 live births during 2001–2005, to 76 per 1,000 live births in 2006–2010 (55% decline). The five-year cumulative number of all-cause deaths in hospital declined 28% (8,051 to 5,801) during the same period.ConclusionsA greater than 50% decline in confirmed malaria cases, admissions and deaths at district hospitals in Rwanda since 2005 followed a marked increase in ITN coverage and use of ACT. The decline occurred among both children under-five and in those five years and above, while hospital utilization increased and suitable conditions for malaria transmission persisted. Declines in malaria indicators in children under 5 years were more striking than in the older age groups. The resurgence in cases associated with decreased ITN coverage in 2009 highlights the need for sustained high levels of anti-malarial interventions in Rwanda and other malaria endemic countries.

Clinical and Epidemiological Profiles of Severe Malaria in Children from Delhi, India

Plasmodium vivax is traditionally known to cause benign tertian malaria, although recent reports suggest that P. vivax can also cause severe life-threatening disease analogous to severe infection due to P. falciparum. There are limited published data on the clinical and epidemiological profiles of children suffering from 'severe malaria' in an urban setting of India. To assess the clinical and epidemiological profiles of children with severe malaria, a prospective study was carried out during June 2008-December 2008 in the Department of Pediatrics, Guru Teg Bahadur Hospital, a tertiary hospital located in East Delhi, India. Data on children aged < or = 12 years, diagnosed with severe malaria, were analyzed for their demographic, clinical and laboratory parameters. All patients were categorized and treated as per the guidelines of the World Health Organization. In total, 1,680 children were screened for malaria at the paediatric outpatient and casualty facilities of the hospital. Thirty-eight children tested positive for malaria on peripheral smear examination (2.26% slide positivity rate). Of these, 27 (71%) were admitted and categorized as severe malaria as per the definition of the WHO while another 11 (29%) received treatment on outpatient basis. Most (24/27; 88.8%) cases of severe malaria (n=27) were infected with P. vivax. Among the cases of severe malaria caused by Plasmodium vivax (n=24), 12 (50%) presented with altered sensorium (cerebral malaria), seven (29.1%) had severe anaemia (haemoglobin <5 g/dL), and 17 (70.8%) had thrombocytopaenia, of which two had spontaneous bleeding (epistaxis). Cases of severe vivax malaria are clinically indistinguishable from severe falciparum malaria. Our study demonstrated that majority (88.8%) of severe malaria cases in children from Delhi and adjoining districts of Uttar Pradesh were due to P. vivax-associated infection. P. vivax should, thus, be regarded as an important causative agent for severe malaria in children.

Effectiveness and durability of Interceptor® long-lasting insecticidal nets in a malaria endemic area of central India.

BackgroundIn the present study, Interceptor®, long-lasting polyester net, 75 denier and bursting strength of minimum 250 kPa coated with alpha-cypermethrin @ 200 mg/m2 was evaluated for its efficacy in reducing the mosquito density, blood feeding inhibition and malaria incidence in a tribal dominated malaria endemic area in Chhattisgarh state, central India. Its durability, washing practices and usage pattern by the community was also assessed up to a period of three years.MethodsThe study was carried out in two phases. In the first phase (September 2006 to August 2007), 16 malaria endemic villages in district Kanker were randomized into three groups, viz. Interceptor net (LN), untreated polyester net (100 denier) and without net. Malaria cases were detected by undertaking fortnightly surveillance by home visits and treated as per the national drug policy. Mosquito collections were made by hand catch and pyrethrum space spray methods from human dwellings once every month. Slide positivity rate (SPR) and malaria incidence per 1000 population (PI) were compared between the three study arms to assess the impact of use of Interceptor nets. Simultaneously, wash resistance studies were carried out in the laboratory by doing cone bioassays on Interceptor LNs washed up to 20 times. Activities undertaken in second Phase (April 2008 to October 2009) after an interval of about 18 months post-net distribution included questionnaire based surveys at every six months, i.e. 18, 24, 30 and 36 months to observe durability, usage pattern of LNs and washing practices by the community. After 36 months of field use, 30 nets were retrieved and sampled destructively for chemical analysis.ResultsInterceptor nets were found effective in reducing the density, parity rate and blood feeding success rate of main malaria vector Anopheles culicifacies as compared to that in untreated net and no net villages. SPR in LN villages was 3.7% as compared to 6.5% in untreated and 11% in no net villages. PI in LN villages was 16.4 in comparison to 24.8 and 44.2 in untreated polyester net and no net villages respectively. In surveys carried out after three years of initial distribution, 78.7% (737/936) nets were still in possession with the households, of which 68% were used every night. An. culicifacies mortality was >80% in cone bioassays done on LNs washed up to 20 times in laboratory. Mean alpha-cypermethrin content was 43.5 ± 31.7 mg/m2 on Interceptor LNs withdrawn after three years of household use against the baseline specification of 200 mg/m2. A gradual increase in the proportion of holed nets was observed with the increased period of usage.ConclusionInterceptor nets were highly effective in reducing vector densities as well as malaria incidence in the study villages. Availability of 78% nets with the households in usable condition clearly indicated durability of Interceptor LNs up to three years in the rural setting of India. The nets were found to contain an effective concentration of alpha-cypermethrin against malaria vector after three years of household use.

The changing serological profile of hepatitis A in Victoria, Australia: a comparison of three time points

Background: Pakistan had country’s history worst floods in August 2010 and water surrounding populated areas added mosquito breeding sites hence, increased malariogenic potential. Pakistan in control phaseofMalaria eradicationefforts, in year2009 reported 167579 confirmedMalaria cases.MuzafarGarhwas one of theworst flood hit districtwhere 1420Malaria caseswere reported by September in year 2010. We analysed Malaria surveillance data from a tehsil of District Muzafar Garh. Methods: All the public sector hospitals of tehsil Ali Pur, having Malaria investigation facilities from Aug-Nov, 2010 have contributed data in this data review study. To know flood’s effects on potential increase in malaria incidence, previous year’s data for similar months is taken as baseline figures. Database was prepared in Microsoft Excel and data analysis was performed using Epiinfo software version 3.5.1®. Results: Though after even after floods, Malaria endemicity is of low transmission level (<1 per 1000 persons), yet there is four times increased confirmed cases in year 2010 as compared to year 2009. From Aug to Nov Slide positive rate (SPR) increased from 18 to 26% compared to 18 to 16% a year prior and Falciparum positive cases rate climbed from 18% in 2009 to 34% in 2010. Majority of the patients (71%) are from rural areas, while most of them are male (61%) and are of 15-49 year age group. Conclusion: Though overall endemicity is at low transmission level, yet there is rise in other indicators like SPR and Falciparum positive cases from previous baseline of 20% and 30% respectively. Disease burden may be even higher as private sector and people taking over the counter treatment are not part of abovementioned figures. Use of Rapid diagnostic tests, preventive strategies like mass drug administration as prophylaxis, and insecticide treated nets may help lessen the disease burden.

Malaria, dynamic epidemiology in flood affected area od District Muzafar Garh, Punjab, Pakistan in 2010

Background: Pakistan had country's history worst floods in August 2010 and water surrounding populated areas added mosquito breeding sites hence, increased malariogenic potential. Pakistan in control phase of Malaria eradication efforts, in year 2009 reported 167579 confirmed Malaria cases. Muzafar Garh was one of the worst flood hit district where 1420 Malaria cases were reported by September in year 2010. We analysed Malaria surveillance data from a tehsil of District Muzafar Garh. Methods: All the public sector hospitals of tehsil Ali Pur, having Malaria investigation facilities from Aug-Nov, 2010 have contributed data in this data review study. To know flood's effects on potential increase in malaria incidence, previous year's data for similar months is taken as baseline figures. Database was prepared in Microsoft Excel and data analysis was performed using Epiinfo software version 3.5.1®. Results: Though after even after floods, Malaria endemicity is of low transmission level (<1 per 1000 persons), yet there is four times increased confirmed cases in year 2010 as compared to year 2009. From Aug to Nov Slide positive rate (SPR) increased from 18 to 26% compared to 18 to 16% a year prior and Falciparum positive cases rate climbed from 18% in 2009 to 34% in 2010. Majority of the patients (71%) are from rural areas, while most of them are male (61%) and are of 15-49 year age group. Conclusion: Though overall endemicity is at low transmission level, yet there is rise in other indicators like SPR and Falciparum positive cases from previous baseline of 20% and 30% respectively. Disease burden may be even higher as private sector and people taking over the counter treatment are not part of above mentioned figures. Use of Rapid diagnostic tests, preventive strategies like mass drug administration as prophylaxis, and insecticide treated nets may help lessen the disease burden.

Using community-owned resource persons to provide early diagnosis and treatment and estimate malaria burden at community level in north-eastern Tanzania

BackgroundAlthough early diagnosis and prompt treatment is an important strategy for control of malaria, using fever to initiate presumptive treatment with expensive artemisinin combination therapy is a major challenge; particularly in areas with declining burden of malaria. This study was conducted using community-owned resource persons (CORPs) to provide early diagnosis and treatment of malaria, and collect data for estimation of malaria burden in four villages of Korogwe district, north-eastern Tanzania.MethodsIn 2006, individuals with history of fever within 24 hours or fever (axillary temperature ≥37.5°C) at presentation were presumptively treated using sulphadoxine/pyrimethamine. Between 2007 and 2010, individuals aged five years and above, with positive rapid diagnostic tests (RDTs) were treated with artemether/lumefantrine (AL) while under-fives were treated irrespective of RDT results. Reduction in anti-malarial consumption was determined by comparing the number of cases that would have been presumptively treated and those that were actually treated based on RDTs results. Trends of malaria incidence and slide positivity rates were compared between lowlands and highlands.ResultsOf 15,729 cases attended, slide positivity rate was 20.4% and declined by >72.0% from 2008, reaching <10.0% from 2009 onwards; and the slide positivity rates were similar in lowlands and highlands from 2009 onwards. Cases with fever at presentation declined slightly, but remained at >40.0% in under-fives and >20.0% among individuals aged five years and above. With use of RDTs, cases treated with AL decreased from <58.0% in 2007 to <11.0% in 2010 and the numbers of adult courses saved were 3,284 and 1,591 in lowlands and highlands respectively. Malaria incidence declined consistently from 2008 onwards; and the highest incidence of malaria shifted from children aged <10 years to individuals aged 10–19 years from 2009.ConclusionsWith basic training, supervision and RDTs, CORPs successfully provided early diagnosis and treatment and reduced consumption of anti-malarials. Progressively declining malaria incidence and slide positivity rates suggest that all fever cases should be tested with RDTs before treatment. Data collected by CORPs was used to plan phase 1b MSP3 malaria vaccine trial and will be used for monitoring and evaluation of different health interventions. The current situation indicates that there is a remarkable changing pattern of malaria and these areas might be moving from control to pre-elimination levels.

Age-dependent sex bias in clinical malarial disease in hypoendemic regions.

Background and ObjectivesExperimental models show a male bias in murine malaria; however, extant literature on biases in human clinical malaria is inconclusive. Studies in hyperendemic areas document an absence of sexual dimorphism in clinical malaria. Data on sex bias in clinical malaria in hypoendemic areas is ambiguous—some reports note a male bias but do not investigate the role of differential mosquito exposure in that bias. Moreover, these studies do not examine whether the bias is age related. This study investigates whether clinical malaria in hypoendemic regions exhibits a sex bias and whether this bias is age-dependent. We also consider the role of vector exposure in this bias.MethodsRetrospective passive clinical malaria datasets (2002–2007) and active surveillance datasets (2000–2009) were captured for the hypoendemic Mumbai region in Western India. To validate findings, passive retrospective data was captured from a primary malaria clinic (2006–2007) in hypoendemic Rourkela (Eastern India). Data was normalized by determining percent slide-positivity rates (SPRs) for males and females, and parasite-positivity distributions were established across age groups. The Mann–Whitney test, Wilcoxon Signed Rank test, and Chi-square analysis were used to determine statistical significances.ResultsIn both the Mumbai and Rourkela regions, clinical malaria exhibited an adult male bias (p<0.01). A sex bias was not observed in children aged ≤10. Post-puberty, male SPRs were significantly greater than females SPRs (p<0.01). This adult male bias was observed for both vivax and falciparum clinical disease. Analysis of active surveillance data did not reveal an age or sex bias in the frequency of parasite positivity.ConclusionThis study demonstrates an age-dependent sex bias in clinical malaria in hypoendemic regions and enhanced incidence of clinical malaria in males following puberty. Possible roles of sex hormones, vector exposure, co-infections, and other factors in this enhanced susceptibility are discussed.

Cross-sectional survey of malaria prevalence in tsunami-affected districts of Aceh Province, Indonesia

BackgroundMalaria is endemic to Indonesia. However, there are few prevalence data available from Aceh Province because of the long-standing separatist conflict and decentralization of the public health system. The Mentor Initiative, which specializes in malaria control in humanitarian emergencies, was one of the non-governmental organizations to respond to the 2004 Indian Ocean tsunami in Aceh. Data on malaria prevalence were gathered to guide and evaluate programmatic efforts.FindingsThe Mentor Initiative conducted community-based malaria prevalence surveys in 2005 and 2006 in five districts along the tsunami-affected western coastline. A total of 11,763 individuals in 3,771 households were tested. The overall slide positivity rate in 2005 and 2006 for all Plasmodium species was 2.1% (n = 252, 95% CI 1.9%-2.4%). Slide positivity rates ranged from 0 to 55% among villages. Overall, 57% of the 252 cases were infected with P. falciparum (n = 144, 95% CI 51.0%-63.3%), and 40.1% were infected with P. vivax (n = 101, 95% CI 34.0%-46.1%), with 0.03% (n = 7, 95% CI 0.8%-4.8%) being mixed infections. Males were significantly more likely to be affected than females (2.8% vs 1.5%, p < 0.01). Infection was more common in those over the age of 5 (2.3% vs. 0.6%, p < 0.01).ConclusionsLocal prevalence data are needed to design effective community-based malaria control programs, as endemicity varies greatly within districts. Certain villages were found to be hyperendemic, with slide positivity rates far higher than average in Indonesia. There is a need for ongoing malaria surveillance in Aceh Province to monitor prevention and treatment efforts.

A longitudinal study of malaria associated with deforestation in Sonitpur district of Assam, India

Assam–Arunachal forest fringed foothill area is endemic for malaria incidence. The present study deals with the temporal analysis of malaria incidence and determines its association with deforestation in 24 villages along the Assam–Arunachal forest fringed foothill area of Sonitpur district of Assam. Malaria epidemiological survey has been carried out in the study area from the year 1994 to 2005. Remote sensing (RS) technique has been used to map the areas of forest changes from the year 2000 to 2005. Geographical information system (GIS) was used to map the malaria incidence and forest cover. The study villages are endemic to malaria infections and there was increasing trend of malaria incidence over the years. The slide positivity rate (SPR) ranged from 5.1% in 1997 to 44.4% in 2005. The percentage forest cover decreased significantly from 23.6% during 2000 to 15.4% during 2005, whereas SPR was increased during 2000–2005. The present study is the first attempt to understand the role of deforestation in malaria incidence using RS and GIS in the north-eastern region of India at a micro-geographic level. The study suggests that the area is endemic to malaria transmission. The decrease in forest cover is a serious ecological concern besides its role in elevating the malaria incidence in the study area.

A cross sectional investigation of malaria epidemiology among seven tea estates in Assam, India

In the present investigation, the epidemiology of malaria among seven tea estates of Nagaon and Udalguri districts of Assam, India has been described. A cross-sectional open study was carried out to understand the malaria epidemiology and associated risk factors among the tea tribes during March to September 2009. Out of 1,182 peripheral blood smears examined, 506 found positive for malaria (slide positivity rate, SPR=42.8) with Plasmodium falciparum as predominant species. Dimakuchi tea estate was having highest SPR (P=0.0275) and contributed more number of P. falciparum cases (P<0.00001). Tea estates studied in both Udalguri and Nagaon districts were equally affected and the SPR recorded were 41.75 and 43.32% respectively. 154 malaria cases detected were having 'O' blood group but each blood group was found to have similar susceptibility of acquiring malaria infection (χ(2)=3.603; P=0.3076) and P. falciparum infection (χ(2)=1.818; P=0.6110). The SPR was highest among children more than 2years of age group and variation in SPR among the age groups was statistically significant (χ(2)=17.186; P=0.0018). No gender biasing was observed in malaria distribution. Anemia was found associated with the infection among both the sexes. The findings suggest that tea estates are endemic for stable malaria transmission primarily due to P. falciparum and the prevalence rate decline with age, suggesting the development of protective immunity. Promising intervention measures could be able to reduce the malaria prevalence effectively in the study areas.

Disease dynamics, distribution and surveillance of malaria in arid ecology of Jodhpur, Rajasthan, India during 2002 to 2006

Malaria is under regular and ongoing surveillance, to detect changes in its trends or distribution in order to initiate investigative or control measures in the country. Owing to limited availability of resources and rational use under the program, prevention and control activities against malaria varies in areas with different intensity of malaria transmission. Transmission dynamics, surveillance, mapping of disease burden for malaria in arid ecological setting of Jodhpur, Rajasthan has described in this study. Monthly epidemiological reports of Jodhpur City, district Jodhpur and all its community health centres were obtained from the office, Chief Medical and Health Officer district Jodhpur for the period 2002 to 2006. Secular trend of malaria incidence, transmission dynamics, mapping of disease burden areas and surveillance of malaria was described. The range of annual parasite incidence (API) was from 0.52 to 2.85 in district Jodhpur, with API <2 in the last consecutive 3 years (2004 to 2006). The slide positivity rate (SPR) ranged from 0.59 to 2.29 in district Jodhpur with continuous decline from 1.51 in 2004 to 0.56 in 2006. Transmission dynamics of total malaria varies from one year to another. Total malaria cases during each year reached at peak in the different months in the duration of 2002 to 2006. Malaria is a persistent health problem in district Jodhpur with variation in its transmission dynamics within and between the years. District Jodhpur with its rural and urban areas is a low risk area for malaria. Malaria prophylaxis and management strategies as applicable in low risk area would be appropriate for district Jodhpur.

Diversity and seasonal densities of vector anophelines in relation to forest fringe malaria in district Sonitpur, Assam (India)

The prevalence and bionomics of known Indian malaria vector anophelines was studied in three forest fringe villages in Sonitpur district of Assam, India. Anopheles philippinensis/nivipes (36.8%) and An. annularis (25.6%) were the most abundant of the seven vector anopheline species recorded. Densities of vector anophelines in general were high during monsoon season and low during winter months. An. dirus s.l. was the most anthropophagic (91.6%) of all the species collected whereas, An. annularis, An. fluviatilis s.l. and An. varuna were predominantly zoophagic. The highest and the lowest slide positivity rates (SPR) was recorded during monsoon (36%) and winter (12.5%) seasons, respectively. SPR was positively correlated with vector anopheline densities (r=0.902), which itself was found to be correlated with mean minimum temperature and relative humidity (RH).

The clinical burden of malaria in Nairobi: a historical review and contemporary audit

BackgroundWidespread urbanization over the next 20 years has the potential to drastically change the risk of malaria within Africa. The burden of the disease, its management, risk factors and appropriateness of targeted intervention across varied urban environments in Africa remain largely undefined. This paper presents a combined historical and contemporary review of the clinical burden of malaria within one of Africa's largest urban settlements, Nairobi, Kenya.MethodsA review of historical reported malaria case burdens since 1911 within Nairobi was undertaken using archived government and city council reports. Contemporary information on out-patient case burdens due to malaria were assembled from the National Health Management and Information System (HMIS). Finally, an audit of 22 randomly selected health facilities within Nairobi was undertaken covering 12 months 2009-2010. The audit included interviews with health workers, and a checklist of commodities and guidelines necessary to diagnose, treat and record malaria.ResultsFrom the 1930's through to the mid-1960's malaria incidence declined coincidental with rapid population growth. During this period malaria notification and prevention were a priority for the city council. From 2001-2008 reporting systems for malaria were inadequate to define the extent or distribution of malaria risk within Nairobi. A more detailed facility review suggests, however that malaria remains a common diagnosis (11% of all paediatric diagnoses made) and where laboratories (n = 15) exist slide positivity rates are on average 15%. Information on the quality of diagnosis, slide reading and whether those reported as positive were imported infections was not established. The facilities and health workers included in this study were not universally prepared to treat malaria according to national guidelines or identify foci of risks due to shortages of national first-line drugs, inadequate record keeping and a view among some health workers (17%) that slide negative patients could still have malaria.ConclusionCombined with historical evidence there is a strong suggestion that very low risks of locally acquired malaria exist today within Nairobi's city limits and this requires further investigation. To be prepared for effective prevention and case-management of malaria among a diverse, mobile population in Nairobi requires a major paradigm shift and investment in improved quality of malaria diagnosis and case management, health system strengthening and case reporting.

Slide positivity rate of malaria among patients attending two hospitals in Kano metropolis

Slide positivity rate of malaria among patients attending two hospitals in Kano metropolis was investigated during the wet season using four hundred blood films. A slide positvity rate of 250 (62.5%) was recorded with 117 (64.63) from slides of male patients and 133(60.70%) from slides of female patients, however the difference was not significant (p>0.05). blood films from age range of 0-10 recorded highest slide positivitiy rates 114 (81.0%). The disease burden was found to be high despite the different ongoing malaria campaigns in the state, therefore intensifying the campaign was highly recommended. Key words: malaria, slide positivity rate, Kano metropolis

Distribution of sibling species of Anopheles culicifacies s.l. and Anopheles fluviatilis s.l. and their vectorial capacity in eight different malaria endemic districts of Orissa, India

The study was undertaken in eight endemic districts of Orissa, India, to find the members of the species complexes of Anopheles culicifacies and Anopheles fluviatilis and their distribution patterns. The study area included six forested districts (Keonjhar, Angul, Dhenkanal, Ganjam, Nayagarh and Khurda) and two non-forested coastal districts (Puri and Jagatsingpur) studied over a period of two years (June 2007-May 2009). An. culicifacies A, B, C and D and An. fluviatilis S and T sibling species were reported. The prevalence of An. culicifacies A ranged from 4.2-8.41%, B from 54.96-76.92%, C from 23.08-33.62% and D from 1.85-5.94% (D was reported for the first time in Orissa, except for occurrences in the Khurda and Nayagarh districts). The anthropophilic indices (AI) were 3.2-4.8%, 0.5-1.7%, 0.7-1.37% and 0.91-1.35% for A, B, C and D, respectively, whereas the sporozoite rates (SR) were 0.49-0.54%, 0%, 0.28-0.37% and 0.41-0.46% for A, B, C and D, respectively. An. fluviatilis showed a similarly varied distribution pattern in which S was predominant (84.3% overall); its AI and SR values ranged from 60.7-90.4% and 1.2-2.32%, respectively. The study observed that the co-existence of potential vector sibling species of An. culicifacies (A, C and D) and An. fluviatilis S (> 50%) was responsible for the high endemicity of malaria in forested districts such as Dhenkanal, Keonjhar, Angul, Ganjam, Nayagarh and Khurda (> 5% slide positivity rate). Thus, the epidemiological scenario for malaria is dependent on the distribution of the vector sibling species and their vectorial capacity.

Potential threat of malaria epidemics in a low transmission area, as exemplified by São Tomé and Príncipe

BackgroundPlasmodium falciparum is the major cause of malaria infection in the island of São Tomé, in the Republic of São Tomé and Príncipe (STP), with an incidence of 40 - 50% before 2004. Since 2004, through the coordination of the Ministry of Health of STP and their Centro Nacional de Endemias (CNE), an integrated malaria control programme has been intensively deployed on the island of São Tomé. Malaria morbidity and mortality decreased by 95% after three years of effective intervention. In the low transmission settings, however, malaria seasonal fluctuation can be a potential problem directly related to epidemics if ongoing control measures are interrupted. Studies on a number of associated factors with malaria epidemics and the measures taken to respond to outbreaks are presented.MethodsThe integrated malaria control programme included indoor residual spraying (IRS), long-lasting insecticidal nets (LLINs), intermittent preventive therapy for pregnant women, as well as early diagnosis and prompt treatment with artemisinin-based combination therapy (ACT). Regular implementation of an island-wide IRS programme was carried out yearly in 2004-2007, and enhanced throughout the island in 2009. Malaria incidence and prevalence were estimated based on passive case detection and mass screening, respectively. Slide positivity rates were used for monitoring the beginning of a malaria epidemic or a seasonal peak.ResultsA steep decline of ca. 95% of malaria morbidity and mortality was observed between 2004 and 2008 with use of the combined control methods. Malaria incidence was 2.0%, 1.5%, and 3.0% for 2007, 2008, and 2009, respectively. In April 2008, a cross-sectional country-wide surveillance showed malaria prevalence of 3.5%, of which 95% cases were asymptomatic carriers. Only 50% of asymptomatic carriers were cured with ACT treatment, while 90% of the symptomatic patients were cured by ACT treatment as confirmed with a follow up study. Malaria morbidity increased by three-fold during the first half of 2009 as compared to the same period in 2008. Over this period of six months, severe malaria was also noted in all age groups and malaria mortality increased by two-fold in children less than five years old. After an emergency IRS was deployed, with increased use of LLINs, and an active search of asymptomatic carriers was followed and given complete ACT treatment, malaria incidence decreased to less than 1% in the second half of 2009.ConclusionAt the initial stage of the integrated malaria control programme, IRS contributed to the visible effect on the rapid reduction of malaria morbidity and mortality, while this programme highlights an urgent demand for the improvement of other measures, particularly promotion of LLINs usage, with close monitoring of asymptomatic carriers and with ACT treatment in malaria transmission hotspots. In addition, both daily reports and a regular active surveillance to prevent malaria outbreaks should be established permanently, so that a fast response to epidemics can be effectively made when necessary.