Incidence and Prevalence of Malaria in Thrissur District, Kerala: a Time
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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 Thrissur District, Kerala: 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, India - 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 Thrissur district, 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 Pazhanji, 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.