Journal of Communicable Diseases Volume 50, Issue 1 - 2018, Pg. No. 16-21 Peer Reviewed & Open Access Journal Research Article Incidence and Prevalence of Malaria in District, : A Time Series Analysis Nidhish G1, E Pushpalatha2, Anju Viswan K3 1,3Research Scholar, 2Assistant Professor, Biopesticides and Toxicology Laboratory, Department of Zoology, University of Calicut, Malappuram District, Kerala, - 673635. DOI: https://doi.org/10.24321/0019.5138.201804 Abstract Objectives:Malaria continues to be the major health concern in India, with its massive progress, reemergence and drug resistance. Even though Kerala is a less-incidence zone, the reintroduction of parasites makes the state oversensitive. The present retrospective study was designed to evaluate the trends in species- wise, region-wise annual malaria incidence (2012–2016) and migrant malaria incidence (2014–2016) of , Kerala.

Methods: The annual malaria surveillance data and monthly reports of migrant screening data were collected from the National Vector Borne Disease Control Program, Thrissur, and the data were analyzed using MS-excel 2008 and SPSS 20.

Results: During the five-year study period, the district annual malaria incidence showed fluctuating pattern with a decline from 2014 to 2016. A total of 686 cases were reported, of which 528 were Plasmodium vivax cases, 70 were dreadful Plasmodium falciparum cases and 88 were mixed. Regional difference was found in malaria prevalence and reemergence. Compared to the indigenous people, migrants showed a gradual rise in the prevalence of malaria from 49.17% to 71.11% during 2014–2016 and migrant P. falciparum incidence increased from 4.16% to 30%.

Conclusions: Our analysis showed annual decline in recent malaria cases. It also revealed the reemergence of P. falciparum cases in various eradicated regions, under the enormous impact of immigrants from different malaria-endemic areas. A sharp surveillance system, effective screenings and other multiple approaches are vital for the complete eradication of the parasitic condition.

Keywords: Annual incidence, Malaria, Plasmodium falciparum, Plasmodium vivax, Regional prevalence

Introduction identified cases and 429,000 deaths. Most number of cases were reported from the African Region, followed by the Malaria, the deadliest parasitic disease, has gained Southeast Asia Region.1 greater significance owing to the plasmodial resistance evolved recently against many of the antimalarial drugs Malaria continues as a major health burden with high death in developing countries. It remains as the leading health rate in India. Plasmodium falciparum and Plasmodium hazard in many of the countries and nearly half of the vivax are the two major malaria parasites in India. India’s world’s population is living under the risk of malaria. As geography and diverse climate provide ideal environmental per the WHO estimates, 91 countries and territories had an condition for sustaining malaria parasites and its vectors.2 ongoing transmission of malaria in 2015 with 212 million According to the World Malaria Report 2013, 22% of India’s

Corresponding Author: Dr. E Pushpalatha, Biopesticides and Toxicology Laboratory, Department of Zoology, University of Calicut, Malappuram District, Kerala, India - 673635. E-mail Id: [email protected] Orcid Id: https://orcid.org/0000-0002-1859-6338 How to cite this article: Nidhish G, Pushpalatha E, Anju VK. Incidence and Prevalence of Malaria in Thrissur District, Kerala: A Time Series Analysis. J Commun Dis 2018; 50(1): 16-21.

Copyright (c) 2018 Journal of Communicable Diseases (P-ISSN: 0019-5138 & E-ISSN: 2581-351X) Nidhish G et al. 17 J. Commun. Dis. 2018; 50(1) population lives under the dreadful risk of malaria with Migrant Screening Data 400–1000 deaths annually and is the major contributor to the confirmed malaria cases in Southeast Asia Region.3 Monthly reports of migrant screening data from 2014 to 2016 were obtained from the NVBDCP, Thrissur, Kerala. The Migrants have key role in the spreading and reemergence annualized state-wise and species-wise immigrant malaria of malaria over the territories. They are the major threat reports were prepared from the collected surveillance in the control and complete eradication of malaria and data. The annual migrant malaria data were compared have very limited access to receive effective treatment and with the annual surveillance data of the indigenous of the preventive measures for a prolonged period of time. Kerala, same period. The same identification and confirmatory located in the southern tip of India, is the major attraction procedures were used for the identification of malaria for migrant labors from central and Northeastern states cases among the immigrants. The same tools were used because of higher job opportunities and better life style. in the computation of data.

The present study aimed to evaluate the species-specific Ethics Statement malaria outbreaks in different regions of Thrissur district The entire data were collected from the NVBDCP, Thrissur of Kerala, from the year 2012–2016. The results provide an district in de-identified manner, during regular intervals. overview of malaria statistics and also help to understand The Individual information like patient’s name, personal the role of migrants in malaria emergence of the district, details was not used in any part as written descriptions central Kerala. or photographs. Materials and Methods Results Study Area Trends in Annual Malaria Incidences in Thrissur Thrissur district, situated in central Kerala, covers an area District, 2012–2016 of 3027 sq. km. with 10.530345° N latitude and 76.214729° Between 2012 and 2016, the annual malaria incidences E longitude.4 Thrissur has a population of 3,121,200, in Thrissur district exhibited a fluctuating pattern with a of which 1,480,763 are male and 1,640,437 constitute 5 decreasing trend from 0.0471/1000 population in 2014 to female. Thrissur is recently afflicted with increased malaria 0.033 in 2016 (Table 1). The mean differences of examined outbreaks, predominantly cerebral malaria and has a years was 0.044 per 1000 population (95% CI: 0.0297 to gradual rise in the number of immigrants from different 0.0582, P= 0.001). high malaria transmission zones. Table 1. Annual Malaria Incidence and Blood Examination Rate in Thrissur District, 2012–2016 Year Blood Samples Blood Slides Annual Blood Malaria Cases Annual Malaria Collected by the Examined by the Examination Confirmed by the Incidence per 1000 NVBDCP NVBDCP Rate (%) NVBDCP Population 2012 225799 225799 7.25 194 0.0622 2013 242093 242093 7.78 115 0.0368 2014 255574 255574 8.21 147 0.0471 2015 256140 256140 8.23 127 0.0406 2016 219879 219879 7.07 103 0.033

Malaria Surveillance Data Trends in Species-Wise Malaria Incidences in Thrissur, 2012–2016 Region-wise annual malaria surveillance data (2012–2016) were collected from the NVBDCP, Thrissur, Kerala. Five-year A total of 686 malaria cases were identified in Thrissur confirmed cases, blood slides examined, and species-wise district from the year 2012 to 2016. Among the recorded incidences were obtained from the collected data. For diagnosis, P. vivax-mediated malaria was predominant, analyzing the regional distribution, 28 study sites were which constitutes 528 cases and 70 were P. falciparum taken up from the district. The annual and monthly malaria cases. Mixed conditions include 88 confirmed cases reports from all the 28 institutions were prepared after (Table 2). There was a significant decrease in the average proper blood examination followed by the confirmatory prevalence of P. vivax cases in last three years of the study Rapid Diagnostic Test. Blood examination is the key period. The estimated mean difference of malaria mediated indicator test in the identification of pathogenic stages in by P. vivax was 0.038 per 1000 population (95% CI: 0.0179 the suspected cases. Data analysis and assessment were to 0.0497, P=0.004). The occurrence of P. falciparum cases conducted using the MS-Excel 2008 (Microsoft, Redmond, increased progressively from 3 to 27 during 2014–2016. WA, USA) and SPSS 20 (IBMCorp, Armonk, NY, USA). The mean difference of P. falciparum transmit malaria

ISSN: 0019-5138 DOI: https://doi.org/10.24321/0019.5138.201804 Nidhish G et al. J. Commun. Dis. 2018; 50(1) 18 during the study period was 0.0046 per 1000 population malaria and P. vivax malaria was predominant in regions (95% CI: 0.0001 to 0.0091, P=0.048). like , Aloor, Mattathur, Ollur and Anandapuram. Table 2. Species-Wise Annual Malaria Incidences from 2012 to 2016, Thrissur Year P. vivax P. falciparum Mixed 2012 169 8 17 2013 90 7 18 2014 117 3 27 2015 85 25 17 2016 67 27 9 Total 528 70 88

Regional Prevalence of Malaria in Thrissur, 2012–2016 The reemergence of P. falciparum malaria was observed in regions like Erumapetty and Aloor during the study period. There were evident variations in the recorded diagnosis Certain regions had the prolonged existence of both the P. and prevalence of malaria conditions between different vivax and P. falciparum malaria cases. The increased and regions of Thrissur district. Among the 28 study sites, most prevalent occurrences of both the P. vivax and P. Pazhanji, Erumapetty, Mattathur, Thiruvillwamala and falciparum malaria conditions were found in the Pazhanji Aloor were the high-incidence zones for P. falciparum region (Figs. 1, 2).

Figure 1. Region-Wise Outbreak of P. falciparum Cases In Thrissur District, 2012–2016

Figure 2. Region-Wise Recorded Diagnosis of P. vivax Cases in Thrissur District, 2012-2016

ISSN: 0019-5138 DOI: https://doi.org/10.24321/0019.5138.201804 Nidhish G et al. 19 J. Commun. Dis. 2018; 50(1)

Trends in Migrant Malaria Incidences in Thrissur, among the immigrants was observed in migrant laborers 2014–2016 from Odisha state (Fig. 4).

From 2014 to 2016, there was a consistent upward trend Both the migrant and imported people were the major in P. falciparum malaria conditions among the other state contributors to recorded malaria diagnosis in Thrissur district migrant laborers in Thrissur district. The prevalence of P. compared to the indigenous. The incidence percentage falciparum incidence was rose from 4.16% to 30% (Fig. 3). In of the migrants exhibited a gradual uphill fashion from 2015, there was substantial decrease in -mediated malaria 49.17% to 71.11%. There was a steady downward trend in from 85% to 38.7%, but in 2016 considerable elevation to the malaria incidence percentage of imported ones from 64.44% was recorded. The highest malaria prevalence rate 50.83% to 27.7% (Fig. 5).

Figure 3. Species wise Malaria Incidence Among The Migrant Labors In Thrissur District, 2014-2016

Figure 4. Trends in Malaria Incidences of Other State Migrant Laborers from 2014 to 2016, Thrissur

Figure 5. Trends in Total Malaria Incidences among the Migrants, Imported and Indigenous from 2014 to 2016, Thrissur

ISSN: 0019-5138 DOI: https://doi.org/10.24321/0019.5138.201804 Nidhish G et al. J. Commun. Dis. 2018; 50(1) 20

Discussion high incidence of malaria in these localities over the years. The present study results denote that, the migrant labors Malaria is a mosquito-transmitted major public concern from states such as Odisha, UP, Maharashtra, Karnataka and in India. Among Southeast Asian Regions, India has the West Bengal are the major contributors of malaria incidence highest malaria burden, which constitutes 61% of total in Thrissur district and they are the important source for malaria incidence and 41% of malaria deaths.6 Compared increasing P. falciparum-mediated malaria. These results to many central and northeastern states of India, Kerala pinpoint the involvement of internal migrants from these is a less-incidence zone for malaria and was declared malaria-endemic areas in carrying the malaria pathogens to as an indigenous malaria-eradicated State in 1965.7 The Thrissur and also in the reintroduction of infection to many present study examined the trends in malaria emergence in malaria-eradicated areas. The unhygienic surroundings, Thrissur district from 2012 to 2016. During the study period, overcrowding shelters, polluted labor sites and life styles 686 cases were confirmed and the maximum incidence make migrant laborers more susceptible to malaria vectors, was reported in 2012. In the study of Antony et al.,7 139 and through this way the transmission of parasites and confirmed cases were reported at the central part of Kerala, reemergence of condition takes place much easily. including Thrissur, during the time period of 5 years from 2005 to 2010. Sajna et al.8 in her study conducted from The steady blood examination rate in Thrissur district 2007 to 2012, a total of 204 cases were reported in the was a key indication of efficient malaria surveillance in study area, a tertiary care center of Thrissur district and the study sites (Table 1). The decline of malaria incidence among the study period, the highest incidence was in 2012. per 1000 population from the period 2014 to 2016 was a critical indicator of effective anti-malaria activities in P. vivax was the most common type of malaria parasite Thrissur district. A study conducted by Sandeep et al.15 found in Thrissur district during the study period. P. vivax- in Kerala reported the effectiveness of various Malaria mediated malaria declined during 2014–2016, whereas control programs like National Malaria Control Program, the P. falciparum case rates increased abruptly (Table 2). National Malaria Eradication Program, and Modified Plan In a retrospective study conducted by Singh et al.,9 in the of Operation and Malaria Action Plan in reducing the western part of Uttar Pradesh, a total of 1330 confirmed incidence rate over Kerala. According to Pradhan et al.,16 cases were reported, of which 67% were predominant P. there was a reduction of 44.32% in confirmed malaria vivax cases, 32% P. falciparum cases and there was a sharp cases of Odisha state from 2003 to 2013, because of the decline in the number of P. vivax cases from the year 2010 massive surge in anti-malaria activities, supported by the to 2014. Mishra et al.10 in her study showed 59.09% of state government. Certain externally supported projects malaria infection in Ratnagiri district, Maharashtra, due like Intensified Malaria Control Project Phase II had been to P. falciparum. According to Sinh et al11 investigation, implemented in many high-malaria-incidence states and P. vivax-mediated infections reduced over time, whereas districts for eradication of the infection. National Vector prevalence of P. falciparum infections increased. Borne Disease Control Program (NVBDCP) is the agency responsible for the eradication of various vector-borne P. falciparum -mediated malaria is more horrendous when diseases including malaria. The most important challenges P. vivax compared with infection. The majority of malaria faced in malaria control include insecticidal resistance P. falciparum research was focused on eradication because among the vectors and antimalarial drug resistance. of its dreadfulness. In Thrissur district, malaria parasite distribution was varying with regional difference (Figs. 1 When compared with other states in India, Kerala has a well- and 2). The three main climatic factors that influence the known health status. Malaria-like vector-borne diseases malaria prevalence are temperature, precipitation and negatively affect the overall health condition and economic humidity.12 According to Pemola et al.13 studies, malaria development of the state. The decline in annual malaria risk increases with temperature over 28°C and humidity incidence gives hope for the complete eradication of the at 95%. Hill streams and their tributaries are the major condition in Thrissur district, Kerala, in the near future, breeding areas of mosquitos, and rainfall, water logging, but the recent uphill in dreadful P. falciparum-mediated rise in pooling facilitate the spreading of malaria vector. cases is spreading a negative shade over the surveillance system. In order to reduce the reintroduction of parasites Migrants and imported population are the major carriers through the migrants and imported population, effective of malaria to Thrissur district. According to the present screening operations need to be implemented from the study results, out of the total incidence in 2016, 71.11% of government side. parasite infection was carried by the immigrants and 1.11% was among the indigenous, which indicates the influence Conclusion of migrants in overall malaria incidence of Thrissur (Fig. 5). Other studies conducted in different states like Odisha, The present study revealed the annual decline in total Uttar Pradesh, Maharashtra and Karnataka14 indicate very malaria incidence of Thrissur district along with the uphill

ISSN: 0019-5138 DOI: https://doi.org/10.24321/0019.5138.201804 Nidhish G et al. 21 J. Commun. Dis. 2018; 50(1) in dreadful P. falciparum cases during the study period. thrissur-kerala-india-1392.html. (Accessed on Oct 3, The prolonged existence and reemergence of malaria 2017). parasites in various study sites is a clear indication of 5. District Census Handbook Thrissur; 2011. Available malaria prevalence in Thrissur, central Kerala. The consistent from: www.censusindia.gov.in/2011census/ upward trend in migrant P. falciparum malaria cases is a dchb/3207_PART_B_THRISSUR.pdf. (Accessed on Oct direct representation of the immigrants’ influence in annual 13, 2017). malaria incidence of the district. The study also provides 6. Sharma RK, Thakor HG, Saha KB et al. Malaria situation significant knowledge on the regional difference in malaria in India with special reference to tribal areas. Indian outbreaks. Migrants from different malaria-endemic zones J Med Res. 2015; 141: 537-45. of India have massive role in the reintroduction of cerebral 7. Antony J, Celine TM, Michale C. Staging back of Malaria malaria cases in various eradicated regions of Thrissur. in Kerala, India: A retrospective study. International More governmental initiatives along with strong diagnostic Research Journal of Social Sciences 2013; 2(12): 42-46. facilities and efficient treatment modalities are required for 8. Sajna MV, Raphael L, Jose P. Epidemiological trend of washing out the dreadful malaria burden. Vector control malaria from 2007 to 2012 in a tertiary care centre programs need to be strengthened and such eradication of Kerala- a cross sectional study. IJMRD 2015; 2(2): programs have high significance in clearing out both 91-95. malaria and other mosquito-borne diseases simultaneously. 9. Singh DP, Verma RV, Singh A et al. A retrospective study More research is needed on the seasonal occurrence and of Malaria from western part of Uttar Pradesh, India. adaptation of malaria parasites and their vectors to evaluate IJPSR 2016; 7(8): 3493-96. and exterminate the dreadful condition. 10. Gauravi M et al. Hospital based study of malaria in Ratnagiri district, Maharashtra. J Vect Borne Dis 2003; Acknowledgments 40: 109-11. 11. Sinh N, Kataria O, Singh MP et al. The changing dynamics We owe our sincere gratitude to all the officials in the of plasmodium vivax and Plasmodium falciparum in National Vector Borne Disease Control Program, Thrissur, central India: Trends over a 27 year period (1975-2002). for providing the malaria screening data for the study. Vector Borne Zoonotic Diseases 2004; 4(3): 239-48. We are also thankful to the members of Biopesticides 12. Pampana EA. Textbook of Malaria Eradication, 2nd Edn. and Toxicology Laboratory for constructive criticism and London, New York, Toronto: Oxford University Press encouragement. 1969; 593. Conflict of Interest: None 13. Pemola DN et al. Meteorological variables and malaria cases based on 12 years data analysis in Dehradun References (Uttarakhand). India Euro. J. Exp. Bio. 2013; 3(1): 28-37. 14. Acharya AR, Magisetty JL, Adarsha VR et al. Trend of 1. WHO. World Malaria Report 2016. Geneva: World Health malaria incidence in the state of Karnataka, India for Organization 2016. Available from: http://apps.who. 2001 to 2011. Archives of Applied Science Research int/iris/bitstream/10665/252038/1/9789241511711- 2013; 5 (3): 104-111. eng.pdf. (Accessed on Oct 10, 2017). 15. Sandeep K. Control, eradication and resurgence of 2. Das A, Anvikar AR, et al. Malaria in India: The Center malaria in Kerala during the past 50 years. Kerala for the Study of Complex Malaria in India. Acta Trop Medical Journal 2008; 1(2): 41-44. 2012; 121(3): 267-73. 16. Pradhan A, Anasuya A, Pradhan MM et al. Trends in 3. WHO. World Malaria Report 2013. Geneva: World Malaria in Odisha, India – An Analysis of the 2003– Health Organization 2013. Available from: http:// 2013 Time-Series Data from the National Vector Borne www.who.int/malaria/publications/world_malaria_ Disease Control Program. PLOS ONE 2016; 11(2): 1-16. report_2013/report/en/. (Accessed on Oct 10, 2017). 4. Thrissur, Kerala, India Lat Long Coordinates Info. Date of Submission: 2018-01-11 Available from: https://www.latlong.net/place/ Date of Acceptance: 2018-01-12

ISSN: 0019-5138 DOI: https://doi.org/10.24321/0019.5138.201804