Spleen rates and infant parasite rates as surveillance tool for malaria control in remote hard to reach areas of central India

Towards malaria control in Nigeria: implications of the malaria parasite rate and spleen rate among children living in a rural community in southwest Nigeria

BACKGROUND

The World Health Organization prioritizes malaria surveillance for accurate tracking of progress of intervention programmes. The malaria parasite rate (PR) and spleen rate (SR) are economical surveillance tools. There has been a global decline in the burden of malaria over the last decade, but most African countries, like Nigeria, have a slow rate of decline. There is a need for adequate malaria surveillance to guide malaria control strategies and policymaking.

METHODS

A community-based cross-sectional study was conducted among 363 children ages 1-15 y in rural southwest Nigeria. The participants' PR was determined by microscopy and the SR was determined by palpation and ultrasonography. The associations between PR and SR and other covariates were assessed.

RESULTS

The PR was 26.7% and the SR was 12.9%. There was no significant association between PR or SR across age groups, but low social class was significantly associated with PR (55 [33.5%], p=0.004) and SR (29 [17.3%], p=0.013). The odds of having splenomegaly doubled with malaria parasitaemia (odds ratio 2.03 [95% confidence interval 1.06 to 3.88).

CONCLUSIONS

The PR and SR suggest that the study area is meso-endemic. The PR in the study area was almost equal across age groups; our findings suggest there may be a need for policy review to plan malaria intervention programmes and include older children, not just children <5 y of age. Routine malaria surveillance using simple tools such as the PR and SR are necessary for reviewing malaria control programmes in the community.

Asymptomatic low-density Plasmodium infection during non-transmission season: a community-based cross-sectional study in two districts of North Eastern Region, India

BACKGROUND

Malaria elimination requires targeting asymptomatic and low-density Plasmodium infections that largely remain undetected. Therefore we conducted a cross-sectional study to estimate the burden of asymptomatic and low-density Plasmodium infection using conventional and molecular diagnostics.

METHODS

A total of 9118 participants, irrespective of age and sex, were screened for malaria using rapid diagnostic tests (RDTs), microscopy and polymerase chain reaction.

RESULTS

Among the participants, 707 presented with symptoms and 8411 without symptoms, of which Plasmodium was present in 15.6% (110/707) and 8.1% (681/8411), respectively. Low-density infection was found in 5.1% (145/2818) of participants and 8327 of 9118 were Plasmodium negative. Endemicity was propotional to asymptomatic infections (high endemicity 11.1% [404/3633] vs low endemicity 5.8% [277/4778]; odds ratio [OR] 2.0 [95% confidence interval {CI} 1.7 to 2.4]) but inversely related to low-density infection (high endemicity 3.7% [57/1545] vs low endemicity 6.9% [88/1273]; OR 1.9 [95% CI 1.4 to 2.7]). The spleen rate in children 2-9 y of age was 17.9% (602/3368) and the enlarged spleen index was 1.6. Children between 8 and 14 y showed higher odds for asymptomatic (adjusted OR [aOR] 1.75 [95% CI 1.4 to 2.2]) and low-density infections (aOR 0.63 [95% CI 0.4 to 1.0)] than adults.

CONCLUSIONS

The prevalence of asymptomatic and low-density Plasmodium infection undermines the usefulness of standard diagnostic tools used by health agencies. This necessitates deploying molecular tools in areas where malaria microscopy/RDTs indicate a dearth of infection.

Prevalence of afebrile parasitaemia due to Plasmodium falciparum & P. vivax in district Balaghat (Madhya Pradesh): Implication for malaria control

Background & objectives:

Balaghat district in Central India is a highly malarious district where both Plasmodium falciparum and P. vivax are prevalent. In this district, the persistence of malaria was on an increase and not responsive to intervention measures even though there was no drug resistance. This study was undertaken by conducting mass screening to determine the prevalence of malaria among particularly vulnerable tribe of Balaghat, for developing evidence-based intervention measures for malaria control in hard to reach areas.

Methods:

This prospective study was carried out during 2013-2014 by conducting mass survey of the population in 10 villages of Birsa community health centre (CHC) and 12 villages of Baihar CHC. Finger-pricked blood smears were collected from all consenting individuals with or without fever for microscopic examination.

Results:

In the febrile group, the slide positivity rate (SPR) and slide falciparum rate (SFR) were 32.4 and 28.9 per cent, respectively, with 89.4 per cent P. falciparum, while in the afebrile individuals also, the SPR and SFR were high (29 and 26%, respectively), but these were significantly lower than that of febrile group. The gametocyte carriers were significantly higher (odds ratio 1.67, 95% confidence interval 1.25-2.25, P =0.0004) in afebrile patients when compared with febrile group. Vector incrimination showed the presence of four sporozoite-positive Anopheles culicifacies out of 1953 assayed.

Interpretation & conclusions:

Plasmodium falciparum malaria was high in young children (up to 8 years) as compared to the adult in both afebrile and febrile group in Balaghat district. High prevalence of gametocyte was observed in all age groups among the afebrile cases. The identification of afebrile malaria parasitaemia is an important challenge for the malaria elimination initiatives. A strong malaria surveillance system is fundamental to both programme design and implementation.

Turf wars: exploring splenomegaly in sickle cell disease in malaria-endemic regions

Sickle cell disease (SCD) is a group of recessively inherited disorders of erythrocyte function that presents an ongoing threat to reducing childhood and adult morbidity and mortality around the world. While decades of research have led to improved survival for SCD patients in wealthy countries, survival remains dismal in low- and middle-income countries. Much of the early mortality associated with SCD is attributed to increased risk of infections due to early loss of splenic function. In the West, bacterial infections with encapsulated organisms are a primary concern. In sub-Saharan Africa, where the majority of infants with SCD are born, the same is true. However malaria presents an additional threat to survival. The search for factors that define variability in sickle cell phenotypes should include environmental modifiers, such as malaria. Further exploration of this relationship could lead to novel strategies to reduce morbidity and mortality attributable to infections. In this review, we explore the interactions between SCD, malaria and the spleen to better understand how splenomegaly and splenic (dys)function may co-exist in patients with SCD living in malaria-endemic areas.

Malaria elimination in India and regional implications

The malaria situation in India is complex as a result of diverse socio-environmental conditions. India contributes a substantial burden of malaria outside sub-Saharan Africa, with the third highest Plasmodium vivax prevalence in the world. Successful malaria control in India is likely to enhance malaria elimination efforts in the region. Despite modest gains, there are many challenges for malaria elimination in India, including: varied patterns of malaria transmission in different parts of the country demanding area-specific control measures; intense malaria transmission fuelled by favourable climatic and environment factors; varying degrees of insecticide resistance of vectors; antimalarial drug resistance; a weak surveillance system; and poor national coordination of state programmes. Prevention and protection against malaria are low as a result of a weak health-care system, as well as financial and socioeconomic constraints. Additionally, the open borders of India provide a potential route of entry for artesunate-resistant parasites from southeast Asia. This situation calls for urgent dialogue around tackling malaria across borders-between India's states and neighbouring countries-through sharing of information and coordinated control and preventive measures, if we are to achieve the aim of malaria elimination in the region.

Ultrasonographic assessment of splenic volume at presentation and after anti-malarial therapy in children with malarial anaemia

Background

Splenic enlargement is a component of the host response to malaria and may also influence the genesis and progression of malarial anaemia. Few cross-sectional and no longitudinal studies have assessed the relationship between splenic volume measured ultrasonographically and haemoglobin concentrations in children with malaria.

Methods

Fifteen Papua New Guinean children with severe malarial anaemia (SMA; haemoglobin <50 g/L) and ten with moderate malarial anaemia (MMA; 51–99 g/L) were recruited. The SMA patients were given intramuscular artemether followed by oral artemisinin combination therapy (ACT), and were transfused one unit of packed cells 0.3-4.0 days post-admission. The MMA patients were treated with ACT. Splenic enlargement (Hackett’s grade, subcostal distance and ultrasonographically determined volume) and haemoglobin concentrations were measured on days 0, 1, 2, 3, 7, 14, 28, and 42.

Results

Associations between Hackett’s grade, subcostal distance and splenic volume were modest (r_s ≤ 0.62, P <0.001). Baseline splenic volume was not associated with age or haemoglobin (P ≥0.90). Mean splenic volume had fallen by approximately 50 % at day 14 in children with MMA (P ≤0.011 vs days 0, 1 and 2), but there was no change in the SMA group (P ≥0.30). There was no change in haemoglobin in the MMA group during follow-up but a rise in the SMA group to day 7 (P ≤0.05 vs days 0, 1, 2, and 3) which paralleled the packed cell volume transfused.

Conclusions

Clinical assessment of splenomegaly is imprecise compared with ultrasonography. Serial splenic volumes and haemoglobin concentrations suggest that the spleen does not influence post-treatment haemoglobin, including after transfusion.

Dynamics of forest malaria transmission in Balaghat district, Madhya Pradesh, India

Background

An epidemiological and entomological study was carried out in Balaghat district, Madhya Pradesh, India to understand the dynamics of forest malaria transmission in a difficult and hard to reach area where indoor residual spray and insecticide treated nets were used for vector control.

Methods

This community based cross-sectional study was undertaken from January 2010 to December 2012 in Baihar and Birsa Community Health Centres of district Balaghat for screening malaria cases. Entomological surveillance included indoor resting collections, pyrethrum spray catches and light trap catches. Anophelines were assayed by ELISA for detection of Plasmodium circumsporozoite protein.

Findings

Plasmodium falciparum infection accounted for >80% of all infections. P. vivax 16.5%, P. malariae 0.75% and remaining were mixed infections of P. falciparum, P. vivax and P. malariae. More than, 30% infections were found in infants under 6 months of age. Overall, an increasing trend in malaria positivity was observed from 2010 to 2012 (chi-square for trend  =  663.55; P<0.0001). Twenty five Anopheles culicifacies (sibling species C, D and E) were positive for circumsporozoite protein of P. falciparum (44%) and P. vivax (56%). Additionally, 2 An. fluviatilis, were found positive for P. falciparum and 1 for P. vivax (sibling species S and T). An. fluviatilis sibling species T was found as vector in forest villages for the first time in India.

Conclusion

These results showed that the study villages are experiencing almost perennial malaria transmission inspite of indoor residual spray and insecticide treated nets. Therefore, there is a need for new indoor residual insecticides which has longer residual life or complete coverage of population with long lasting insecticide treated nets or both indoor residual spray and long lasting bed nets for effective vector control. There is a need to undertake a well designed case control study to evaluate the efficacy of these interventions.

Malaria in a tertiary health care facility of Central India with special reference to severe vivax: implications for malaria control

Plasmodium vivax is now recognized as a cause of severe and fatal infection in many parts of the world. This prospective observational study was undertaken in a tertiary health setting to understand the spectrum of the disease burden and associated complications due to P. vivax malaria in central India. A malaria clinic under Regional Medical Research Centre for Tribals is operational at Netaji Subhash Chandra Bose Medical College and Hospital, Jabalpur in central India, where all fever cases and cases with history of fever were referred for screening of malaria parasite by microscopy and rapid diagnostic test kits. Confirmation of all the cases was done by PCR targeting 18s ribosomal RNA gene of the parasite to exclude mixed infection with P. falciparum. Severe vivax malaria was found in 22 (11·1%) out of 198 vivax patients. Cerebral malaria, seizures, severe malaria anaemia, and respiratory distress each were observed in 32% subjects. Multi-organ dysfunction syndrome was common (36%). Mortality was recorded in two patients and neurological sequelae were also observed in two patients at the time of discharge. This is the first report from Central India where P. vivax has been shown to be associated with severe signs of malaria. Severe vivax malaria is a relatively new clinical entity and further studies from different parts of the world are needed to understand clinical spectrum and burden of P. vivax not only for successful treatment, but also for designing and developing effective malaria control measures.

Emergence of a new focus of Plasmodium malariae in forest villages of district Balaghat, Central India: implications for the diagnosis of malaria and its control

OBJECTIVE

During an epidemiological study (January-July 2012) on malaria in forest villages of Central India, Plasmodium malariae-like malaria parasites were observed in blood smears of fever cases. We aimed to confirm the presence of P. malariae using molecular tools i.e. species-specific nested polymerase chain reaction (PCR) and DNA sequencing.

METHODS

All fever cases or cases with history of fever in 25 villages of Balaghat district were screened for malaria parasite using bivalent rapid diagnostic test and microscopy after obtaining written informed consent. Nested PCR was employed on microscopically suspected P. malariae cases. DNA sequences in the target region for PCR diagnosis were analysed for all the suspected cases of P. malariae.

RESULTS

Among the 22 microscopy suspected P. malariae cases, nested PCR confirmed the identity of P. malariae in 19 cases. Among these 14 were mono P. malariae infections, three were mixed infection of P. malariae with Plasmodium falciparum and two were mixed infection of P. malariae with Plasmodium vivax. Clinically P. malariae subjects generally presented with fever and headache. However, the typical 3-day pattern of quantum malaria was not observed. The parasite density of P. malariae was significantly lower than that of P. vivax and P. falciparum.

DISCUSSIONS

Plasmodium malariae may have been in existence in forest villages of central India but escaped identification due to its close resemblance to P. vivax. The results re-affirm the importance of molecular methods of testing on routine basis for efficacious control strategies against malaria.

Mass blood survey for malaria: pooling and real-time PCR combined with expert microscopy in north-west Thailand

BACKGROUND

Asymptomatic carriage of Plasmodium falciparum and Plasmodium vivax is common in both low-and high-transmission settings and represents an important reservoir of infection that needs to be targeted if malaria elimination is to succeed.

METHODS

Mass blood examinations (475 individuals) were conducted in two villages in Mae Hong Son, an area of endemic but low-transmission malaria in the north-west of Thailand. The microscopist at the local malaria clinic did not detect any infections. Pools of four samples were screened by real-time PCR; individual members of all of the positive pools were then re-examined by expert microscopy and by a second species-specific PCR reaction.

RESULTS

Eight subjects were found to be positive by both PCR and expert microscopy and one was found to be positive by PCR alone. The slides contained asexual stage parasites of P. vivax, P. falciparum and Plasmodium malariae, but no gametocytes. The local clinic was notified within two to eight days of the survey.

CONCLUSION

A combination of pooling, real-time PCR and expert microscopy provides a feasible approach to identifying and treating asymptomatic malaria infections in a timely manner.