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Volume 22 |
October - December 2006 |
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A survey on malaria and some related
factors in South East of Caspian SeaA Ali Karimi-Zarchi1, A Mahmoodzadeh2, H Vatani3
Abstract
Objective: Malaria is a major cause of ill health in many tropics and subtropics. The aim of this study was to determine prevalence rate (PR) and age, sex, geographic distribution of disease and anopheline vectors in south east of Caspian Sea.
Patients and Methods: This is a cross-sectional study in three regions. Data collected included clinical signs and symptoms and laboratory blood film findings for one year. Total catch were made for identification of anopheles vector.
Results: Prevalence rate of malaria was 96 in 1000 persons in slope and mountain areas. Mean age of patients was 22.5 years (SD= 18). Most patients were seen and recorded in summer. Infection with Plasmodium Vivax (PV) was 61 percent, Plasmodium Falciparum (PF) was 20.7 percent and mixed (PV+PF) was 18.3 percent respectively. The proportion of disease in male was 53 percent and in female 47 percent. Total 348 Anophelines were detected. The highest and lowest proportion of anophelines were (70.6%) Anophele marteri and (7.4%) Anophele algeriensis respectively.
Conclusion: This study shows that Anophele superpictus was as Anopheline vector. Malaria patients were seen only in slope and mountain areas. Most patients (61%) were infected by PV. Sex differences were not statistically significant (p> 0.05). During the transmission season, all non-immune travellers should use malaria chemoprophylaxis before visiting these areas.
KEY WORDS: Prevalence Rate, Cross-sectional, Malaria, Anopheline Vector.
Pak J Med Sci October - December 2006 Vol. 22 No. 4 489-492
1. Dr. A. Ali Karimi-Zarchi PhD
Department of Epidemiology & Biostatistics,
Faculty of Health2. Dr. A. Mahmoodzadeh PhD
3. Mr. H. Vatani M.Sc.
Faculty of Medicine1-3: Medical Science University of Baghyatollah,
Tehran, Iran.Correspondence:
Dr. A. Ali Karimi-Zarchi
E-Mail: alikarimi_in@yahoo.com* Received for Publication: June 20, 2005
* Revision Accepted: March 2, 2006
Introduction
Malaria is a major cause of ill health in many tropics and subtropics where socioeconomic development is deficient. Four species of plasmodium are capable of infecting human: P. falciparum, P. malariae, P. vivax and P. ovale.
1 The latest species was not reported in Islamic Republic of Iran.2 The parasites are transmitted to human by the bite of an infective female anopheline. Malaria transmission occurs in more than 100 countries throughout Africa, Asia, and Latin America and on certain Caribean and Pacific islands. More than two billion inhabitants of these areas are at risk of malaria infection. The estimated annual global incidence of disease is 300-500 million clinical cases although health care providers do not see many others.3 Malaria is responsible for 1.5-2.7 million global deaths annually in the world.4 The Islamic Republic of Iran belongs to the EMRO region of WHO and in the past malaria was highly endemic in most parts of this country. In 1924, it was estimated that out of a population of 13 million, 4-5 million people had contracted disease.5 There has been a decreasing trend in the malaria incidence in recent years.6 The prevalence rate of malaria was reported about 1 in 10000 population at first midyear of 2002 and most of the cases were reported in summer.7Generally, three epidemiological zones were defined including north of the Zagros range with a population of approximately 43 million, south of the Zagros range with a population of approximately 15 million and the south eastern corner which consists of Sistine and Buluchestan province, Hormozgan province and the tropical part of Kerman province with a combined population of approximately 3 million.
8 To our knowledge prevalence rate and some related factors of disease were not defined in boundaries of north east of Iran. The aim of this study was to determine prevalence rate, age, sex, geographgic distribution of disease and anopheline vectors in these areas.patients and Methods
This is a cross-sectional study.
9 In this survey, the target population was 10367 living on border areas of Sarakhs District in Khorasan Province in north east of Iran. The population studied were 3848 persons of which 2139 were living in flat area, 1286 in slope area and 423 in mountain area respectively. This survey lasted for one year.Data collection was based on clinical signs and symptoms, laboratory blood film (thick and thin smears) findings in field study. Thick and thin blood smears were made, fixed in the field and sent to the laboratory. Diagnoses were confirmed on laboratory investigations. According to WHO,s manual total catch were made for determine anopheles vectors.
10 Iranian anophelines Key Identification was used for differential diagnosis of anopheles.11 Data was analyzed using SPSS Version 10, software12 with use of descriptive and analytical statistics.13Results
In this study a total 164 cases of malaria were seen. No cases of malaria were seen in flat area where we didn’t catch any vectors. Overall prevalence rate of Malaria was 96 in 1000 persons in other regions. The mean age of patients was 22.5 years with standard deviation of 18 years. Minimum and maximum age of patients were between 1-90 years respectively. Majority of these patients were in 10-14 years age group and lowest between 25-29 years age group respectively. (Table-I) Infection with PV was 61 percent, PF was 20.7 percent and mixed (PV+PF) was 18.3 percent respectively.
Most of the cases (81.7%) was seen in Summer during July and August. (Table-II) Proportion of malaria in male and female were 53% and 47% respectively. Sex differences of disease were not statistically significant. (P> 0.05)
In this survey, vector infectious rate was not studied. However, anophelines were trapped by total catch method and were identified. A. marteri had highest proportion (70.6%) and A. algeriensis had lowest proportion(7.4%) of anopheles in total catch findings. (Table-III)
Discussion
Generally transmission of malaria occurs in 64 degree of North and 32 degree of South of the earth where there are favourable conditions for life cycle of malaria parasite.
14 The regions that were studied are located in this limited area. In this study no malaria cases were seen in flat area and we didn’t detect any vectors of disease as well. This region has hot weather and no pounds of stagnant water which are considered the causative factors for malaria. Since there was not a single case in this area, prevalence rate of malaria was calculated in other regions. (164/1709= 96 in 1000 persons)There are two rivers and lot of impounded water near the later regions. Malaria and vectors, therefore, were seen in these areas. About 416 species of anopheline have been detected around the world so far. From these, only 64 species are as vectors.
15 There are 19 species of anophelines in Iran, of which seven species are proven vectors including A. superpictus, A. maculipenis, A. sacharovi, A. culicifacies, A. stephensi, A. fluviatilis and A. dethali.8 Therefore, A. superpictus was known as vectors in these regions.This survey like other studies showed that, sex differences was not statistically significant, but because they are often related to frequency of exposure via social behavior particularly coverage, and thus development of immunity, it can be important host factor. Thus both of them were at the same risk of the disease and must use the same guidelines for prevention.
Prevalence rate of disease was 11 percent in under 10 years age group. If the likely prevalence rate in this age group is equal to spleen measure, it shows that these regions are at least Mesoendemic of malaria. Immunity develops by frequent exposure to disease.
16 In this study disease was seen in all age groups particularly it had high prevalence (55%) in adults. Therefore people who live in this area have not developed immunity that is why we have seen the recent emergence of malaria.3,17 Improving sanitation such as filling and draining areas of impounded water will result in permanent elimination or reduction of anopheline breeding habits. Larvaicides and biological control with larvivorous fish may be useful. Application of residual insecticide is useful on the inside walls of dwellings and other surfaces upon which endophelic vector anophelines habitually rest. Three to eight thoushand cases of malaria come from neighboring countries to Islamic Republic of Iran each year.18 Thus, it is recommended that border, traffic must be controlled intensively. Furthermore initiating screening programme and use of bed nets in these regions are very important. Insect repellents applied to uncovered skin of persons exposed to bites of vectors are useful when applied repeatedly. Prompt and effective treatment of acute and chronic cases is an important adjunct to malaria control. Non-immune travelers who will be exposed to mosquitoes in these areas should regularly use malaria prophylaxis.References
1. Harison DL, Fauci AS, Braunwald E, Issel bacher KJ, Wilson JD, Martin JB, et al. Principles of internal medicine. 14th edition. McGraw-Hill compaines, USA 1998; 1180.
2. Manouchehri AV, Zaim M, Emadi AM. A review of malaria in Iran, (1975-1990). J Amer Mosquito Control Assoc 1992; 8: 381-5.
3. Strickland GT. Hunter’s tropical medicine and emerging infectious diseases. 8th edition. W.B. Saunders company 2000; 614-43.
4. World Health Organization. World malaria situation. Weekly epidemiological record, WHO, Geneva 1997; 36: 269-74.
5. Sadrizadeh B. Malaria in the world, in the eastern mediteranian region and in Iran. Arch Iranian Medicine 1999; 2(4).
6. Edrissian CH. Malaria history and status in Iran. J School Pub Health 2002; 1(1): 50-61.
7. Ministry of health of Islamic Republic of Iran. Center for Disease Control 2002.
8. Motabar M. Malaria. In: Azizi F, Janghorbani M, Hatami H. Epidemiology and control of common disorders in Iran. Second edition. Khosravi publication. Tehran 2003; 502-22.
9. Hully SB, Cummings SB, Browner WS, Grady D, Hearst N, Newman Th B. Designing clinical research. Second Edition. Lippincott William and Wilkins. Philadelphia, USA 2001; 107-23.
10. World Health Organization. Manual on practical entomology in malaria part I&II. Methods & techniques. WHO, Geneva 1975; No.13.
11. Edalat H. Key identification of female Anopheline of Iran. Medical University of Tehran. Faculty of health. Department of entomology and vector control.1990.
12. SPSS for Windows, version 10.0(2000), Chicago. Illinois: SPSS, Inc.
13. Lioyd Ch J. Statistical analysis of categorical data. John Wiley & Sons, New York 1999; 124-5.
14. Bruce, Chwatt L. J Essential malariology, Second edition, William Heineman Medical Books 1985; 493.
15. Estrada, F. Charactrization of Anophels pseudo- punctipennis sensulato from three countries of neotropical America from variation in allozymes & ribosomal DNA. Am J Trop Med Hyg 1993; 49: 45-73.
16. Collins: Malaria, current and future prospects for control. Ann Rev Entomolo 1995; 40: 195-219.
17. Robinson D. Epidemiology and the community control of disease in warm climate countries. Second edition, Churchill Livingstone, Edinburgh. 1985; p: 419.
18. Edrissian Ch. H. Status of the response of P.falciparum to chloroquine and mefloquine in Iran. Trop Geog Med 1989; 41: 297-303.
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