Original Article

Malarial Trend of Ranibandh Block of Bankura District, West Bengal in a decade (2005-2014)

Sasmita Rani Jena*, Sudarsan Mandal**, Satyajit Sen***

* Filaria Consultant, Regional Office for Health & Family Welfare, Salt Lake, Kolkata
** Additional Director, All India Institute of Hygiene and public health, Kolkata
*** Senior Regional Director, Regional Office for Health & Family Welfare, Salt Lake, Kolkata

Corresponding Author:
Sasmita Rani Jena,
E-mail - sjena4@gmail.com


Abstract:

Background & objective: Malaria is a major public health problem in the world as well as in India. In India, West Bengal is one of the malaria endemic states contributing to huge number cases and deaths. Malaria Control Programme has given priority to Plasmodium falciparum malaria due to its life-threatening complications. But in some endemic areas , Plasmodium vivax also is playing a major role contributing to more than 90% of total malaria cases and also in maintaining perennial transmission. The objectives of the study were to study the rising trend of P. vivax in a block (Ranibandh) of Bankura district of West Bengal and the role of P. vivax in perennial transmission of the disease in the study area.

Method: Data of malaria cases of last 10 years (2005-2014) were collected from District Health Office of Bankura District. Retrospective statistical analysis was conducted with the help of Microsoft Excel sheet and for graph plotting Origin (ver. 8) was used.

Result: Ranibandh block of Bankura is contributing to 59% of total malarial cases of the district. In 2005, Ranibandh block reported 49.5% P. falciparum and 50.1% P. vivax cases, while in 2008 P. falciparum and P. vivax cases were 88.5% and 11.5% respectively among the total malaria cases. Proportion of P. falciparum cases were decreased from 28.5 % to 7.4 % during the year 2009 to 2014, while P. vivax cases were showing increasing trend from 71.5% to 92.6 % in the same duration.

Interpretation & conclusion: In Ranibandh block, increasing trend of P. vivax malaria during 2009-2014 is a matter of concern. The decrease in P. falciparum cases may due to the impact of Artemisinin Based Combination Therapy (ACT). But P. vivax malaria situation is alarming and indicating a need of field based research giving emphasis on vector dynamics, insecticide susceptibility and relapse pattern of P. vivax.

Key words: Malaria Elimination, Plasmodium falciparum, Plasmodium vivax, Endemicity, West Bengal

Introduction:

Malaria is one of the major public health problems globally with an estimated 214 million of malaria cases and 438000 deaths.1 In India, malaria is also an important cause of mortality and morbidity and is a public health concern. In 2015 (till November), India has reported 1036629 malaria cases with 687932 (66.4%) Plasmodium falciparum positive cases and 273 deaths. West Bengal alone has reported 22633 malaria cases with 5237 P. falciparum positive cases(23.1%) and 32 deaths.2 It is documented that one third of the world’s population are at risk for malaria in India, where 50% of the total cases is P. falciparum and other 50% is P. vivax.3

Government of India, Researchers and Funding Bodies in India as well as globally4 have given priority to control P. falciparum malaria in the country because of the life threatening complications of P. falciparum. In contrast, Plasmodium vivax species is considered as a "benign" infection and supposed to have an uncomplicated course of illness.3,4,5 Recently, some complicated cases from vivax malaria have been reported3, 6, 7 ,8,9,10,11,12. Ten countries including India are at the risk of vivax infection. In some regions, P. vivax malaria is very important in maintaining the perennial indigenous transmission. 3, 4, 13 Thus, high emphasis on P. falciparum though appropriate, P. vivax malaria should not be ignored.

These two plasmodium species are distinct in biologically and clinically, and different strategies are needed to combat P. falciparum and P. vivax challenges.10,11 Several new initiatives have been launched from time to time for combating the disease, specially the falciparum malaria, but the situation remained static and even worsens in year of good rainfall11. However, the disease scenario has changed due to the emergence of Chloroquine resistance mainly in P. falciparum and occurrence of severe and complicated cases due to P. vivax infection reported from India and many other malaria endemic countries10, 14,15.

Climate plays an important role in dynamic and transmission of malaria. Role of rainfall is crucial in providing suitable habitat for mosquito breed; moreover temperature is key driver for mosquito and parasite life cycle. The climatic of West Bengal provides suitable condition for adaptation of these species. The summer temperatures in the state ranges between 24°C and 40°C while the winter temperatures range from 7°C to 26°C14. Bankura district is one of the endemic regions for malaria in West Bengal. It is contributing distinct number of cases for total malaria cases of the state16. Ranibandh block of the district is constantly contributing the highest number of malaria case in the district. This study was undertaken to find out the current status of Plasmodium falciparum and P. vivax malaria in Ranibandh block of Bankura district and also to assess the trend of malaria in the block in last 10 years (2005 to 2014).

Material and Methods:

Type of study: Record based descriptive epidemiological study showing the time and person distribution of P. falciparum and P. vivax cases malaria cases in a malaria endemic block of Bankura district of West Bengal

Study Area: Present study was conducted in Ranibandh block, a malaria endemic block of Bankura district. Bankura district has 22 blocks and out of total malaria cases, Ranibandh block is contributing around 59% of the total malaria cases of the whole district16. Bankura is located on the geographical coordinates of 23° 15' 0" N, 87° 4' 0" E. Ranibandh is the western part of that district and part of Chota Nagpur plateau region. It has an elevation of 83 m of sea level. The area is mostly covered with seditious forest. Humidity varies from 71 to 90 %, temperature ranges from 29° C to 45° C and annual average rain fall rate is about 1,400 millimeters14. Ranibandh block is known for its endemic malarial situation of the district for the past few decades16. Table 1 depicts the variation of malaria cases detected at Bankura district during year 2005 to 2014. It was observed that Ranibandh is a highly malaria-affected block as compared to 21 other blocks of the same district.

Presently in Ranibandh block, malaria control is based on (i) DDT Indoor Residual Spraying (IRS) and Long Lasting Insecticidal Net (LLIN) distribution (ii) early case detection by microscopic examination of blood smear or the Rapid Diagnostic Test (RDT) and (iii) treatment of malaria with proper drug as per guidelines of NVBDCP, India.

In 2012 at the study block, 90% of the population was covered by LLIN at the rate of 1 bed net for 2.5 people2. Along with LLIN, DDT spray is being conducted based on the epidemiological data as the vector control tool. The particular block is situated in an interior part of Bankura district, the whole population depends mainly upon the health services provided by the government. Majority of the people belong to lower socio-economic status and are from tribal community14.

Data collection: Data were collected from District Health Office of Bankura for the period 2005 to 2014. This data recorded by the health department based on the laboratory test report of malaria cases of that particular block of Bankura District.

Data Analysis: The secondary data were analyzed for distribution of (i) Plasmodium falciparum and P. vivax malaria cases in Ranibandh block of Bankura district, (ii) seasonal transmission of Plasmodium falciparum and P. vivax, (iii) Person distribution of malaria cases according to age and gender. For data analysis Microsoft Excel and for graph plotting Origin (ver. 8) was used.

Results:

A total of 13324 cases of malaria were detected from 22 blocks of Bankura district during 2005-2014 of which 6733 cases (50.5%) were detected only from Ranibandh block. At Ranibandh block, 4690 (69.6%) were infected with P. vivax and 2045 (30.3%) with Plasmodium falciparum. Table 1 depicts the endemicity of malaria of Ranibandh block in Bankura district.

Table 1: Year-wise malaria cases in the district of Bankura and in Ranibandh block of the district (2005 to 2014)

Year

Total number of malaria cases detected in Bankura district

Total number of cases from Ranibandh block

% of total malaria cases from Ranibandh block

2005

2293

1379

60.13

2006

1294

636

49.14

2007

1058

439

41.49

2008

1552

575

37.04

2009

1163

406

34.90

2010

1028

453

44.26

2011

1104

482

43.65

2012

1507

1018

67.55

2013

988

558

56.47

2014

1337

787

58.86


Figure 1 depicts the total malaria cases of Ranibandh block of Bankura District during 2005-2014. It was observed that during year 2005-2009, number of malaria cases was decreased to a large extent (70% approx) over a duration of five years. However, number malaria cases again increased from 2009 up to 2014 with maximum number of cases in 2012

.



Comparison of the number of two types of reported malaria cases are shown in figure 1 also. It was observed that total number of malaria cases including P. vivax cases was decreased during 2005-2008 whereas, Plasmodium falciparum malaria cases were increased during the same period, but 2009 onwards the proportion of P. falciparum cases were decreased while there was an increasing trend of P. vivax cases. The decreasing trend of P. falciparum might be due to effective diagnosis of parasite, indoor residual spraying and proper drug administration. This situation also might reflect the effective implementation of National Drug Policy for Malaria. The increasing trend of P. vivax since 2008 onwards may be due to drug resistance to P. vivax, relapse and reinfection cases and another reason may be that P. vivax was not considered as a priority for National Malaria Control Programme

Table 2: Some malario-metric measures and deaths due to Malaria in Ranibandh Block of last 5 year (2010-2014)

Year

Population

ABER

SPR

API

PV%

Death

2010

110460

23.44

1.67

3.9

85

0

2011

118771

16.8

2.42

4.06

93

0

2012

121639

20.19

4.15

8.37

95

1

2013

124678

21.29

2.1

4.48

96

0

2014

126250

14.27

4.37

6.23

93

0



Table 2 showed the malariometric indicators. Average ABER for year 2010-2014 was 19.2%. Average SPR, API and P. vivax of year 2010-2014 is around 3, 5.4 and a 92.4 % respectively. However, during the period only one death due to P. falciparum was reported in the year 2012 ( Report of District Health Office, Bankura).





Figure 2 reflected the distribution of malaria cases among different age- group of the population during year (2010-2014). Maximum number of malaria cases was for population with age group of 15 years and above. The population with age of 0-4 years is less affected. But in year 2014, the prevalence of malaria in younger age group (< 5 years age) has increased. The young children have become more vulnerable to malaria attack, indicating an alarming scenario in the present study area. If this situation continues in Ranibandh Block, then P. vivax infection may lead to severe morbidity and mortality due to renal failure, jaundice, and acute respiratory distress syndrome (ARDS), cerebral malaria, seizures, anemia, thrombocytopenia, pulmonary edema etc 3,4,5,7,8,9,10,11.



It was observed that during five years (2010-2014), the male population was more affected with malaria then female population (Figure 3). During the period, 56.8% of malaria occurred in male population and 43.2 % cases in female population.

Figure 4 depicts month-wise distribution of P. falciparum and P. vivax cases during year 2010-2014 . Cases of malaria were reported throughout the year with distinct peak during the months of July- Septmeber for P. vivax malaria. In those months, Bankura district used to experience good rainfall. While Plasmodium falciparum malaria cases showed uneven distribution of malaria cases.

Year

Population

slide examined

No Of Cases

PV

PF

API

AFR

AVR

 

2005

109068

29097

1379

691

682

12.643

6.253

6.3355

PRE ACT

2006

110460

24662

636

373

263

5.7577

2.381

3.3768

2007

110460

21062

439

455

510

3.9743

4.6171

4.1191

2008

110460

23612

575

66

509

5.2055

4.608

0.5975

2009

110460

28671

406

290

116

3.6755

1.0502

2.6254

POST ACT

2010

110460

27320

453

390

63

4.101

0.5703

3.5488

2011

118771

6192

482

449

33

4.0582

0.2778

3.7804

2012

121639

24557

1018

963

55

8.369

0.4522

7.9169

2013

124678

26543

558

540

18

4.4755

0.1444

4.3312

2014

126250

18018

787

728

59

6.2337

0.4673

5.7663



In 2009 Artimisinin Combination Therapy (ACT) was introduced in Ranibandh and chloroquine resistant cases were also reported (Data of Regional Office of MOHFW, Kolkata). So, after the implementation of ACT, the scenario of P. falciparum was changed with a sharp decrease in number of P. falciparum cases as well as AFR. Table 3, represents the pre-ACT and Post-ACT impact on the prevelance of P. falciparum cases. Initially in the year 2008, RDKs were monovalent and this may be one of the reason for low P. vivax as the microscopy was also limited.



The present study revealed that P. vivax malaria cases in Ranibandh block is high and likely to propagate to nearby regions of Bankura district. This burning issue needs to be addressed for control of P. vivax malaria.11,13,17 The present data on P. vivax malaria situation at Ranibandh block would be vital in planning of malaria control intervention as strategy for elimination of malaria.

Discussion:

During 11th five year plan period (2007-2012), malaria strategy was implemented for malaria control and prevention. 12th five year plan period (2012-2017) is targeted towards the scaling up malaria control interventions with a focus on high burden areas and categorized strategic interventions for achieving pre-elimination status. During the year 2017-2022 National Malaria Strategic Plan may include the concept of elimination of malaria from the India. However, in India with diverse malaria related problems along with well-established malaria control program, strategic planning of malaria elimination should not be confined only to scaling up of standard interventions.

The epidemiological information of the present study indicates that the average ABER for last 5 year (2010-2014) was 19, which reflects that surveillance work was well implemented. However, there was no significant change in API during years (2010-2014). During year 2014, API was 6.23 with five years (2010-2014) average of 5.4, which indicates that study area is endemic for malaria and indigenous transmission occurs. It was also observed that during year 2010-2014 an average increase of 92.2 % P. vivax malaria cases. After implementation of ACT there is a decrease of P. falciparum cases but there is no more change in API. So, P. vivax is responsible in maintaining the endemicity of that area. In case of P. vivax malaria, there may be several reasons/factors responsible for increase in cases in the study area where there is good P. falciparum control. Radical treatment of P. vivax is for long duration and it is very important tool for control of P. vivax transmission. So, incomplete radical treatment may be the major fact for increase in P. vivax cases. There might be some relapse cases of P. vivax malaria, which is responsible for perennial indigenous transmission. So, more emphasis should be given on radical treatment along with field level research for control of P. vivax malaria.

Age-specific distribution of total cases reveled that prevalence in adult population is very high and increasing trend of malaria cases in children is alarming one. While, gender-specific distribution showed that the males were more prone to malaria. This might be due to the difference in dress pattern (male are less clothed) and they generally lead more outdoor life than females. The majority of the adult population belongs to bread earner group. So, malaria has an economic impact in the family as well as in the country. P. vivax and P. falciparum cases were studied month-wise basis also for the years (2010-2014). P. vivax malaria showed a perennial transmission trend and peak coincides with Monsoon season during July to September every year. While in case of P. falciparum, there was no fix period of transmission and different pattern was observed in every year. Correlating with the implementation strategy of NVBDCP and malarial prevalence of the study area, it is clear that after introduction of RDT for diagnosis and ACT combination therapy for treatment, sharp decreasing trend of P. falciparum malaria cases from year 2009 onward was observed. So, it may be concluded that there is a very good impact of artemisinin based combination therapy (ACT) for P. falciparum malaria control. Similar aspect has also been reported from urban Kolkata, India and from other countries3,18,19, 20, 21. As data regarding mixed infection is not readily available the topic has not been discussed.

Conclusion:

The present analysis revealed that P. vivax malaria in Ranibandh block was substantial and likely to perpetuate. Whereas, there is good control on P. falciparum malaria after the implementation of ACT since year 2009 as the revised drug schedule of uncomplicated P. falciparum malaria. India may be able to proceed for elimination of P. falciparum with the help of simultaneous judicious use of RDK with microscopy, artemisinin based combination therapy (ACT) and IVM but increasing trend in P. vivax malaria is a matter of concern. The scenario of present situation at Ranibandh may be due to several factors such as climatic6, vector dynamics6, resistance of the vector towards the applied insecticide, resistivity of the parasite to the drug therapy involved 15,22,23, or due to relapse pattern of the P. vivax malaria14, 18. Further clinical and field-based studies are required in above mentioned field.

Acknowledgment:

The authors thank to CMOH, Bankura District, West Bengal for providing the data and Block Medical Officer and PHN of Ranibandh block for giving information. Authors are also grateful to Director of NVBDCP and SPO, NVBDCP, West Bengal for giving their consent to publish the data.

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