What is Malaria? Causes, Diagnosis & Malaria No more
Malaria is a systemic disease-causing change in most, organs. The main causes of pathology in malaria are tissue anoxia, which is due to impaired oxygen-carrying. the capacity of the blood, damage to the endothelial cells lining blood vessels;” and general and local changes in blood flow. The clinical features of malaria vary from mild to severe and complicated according to the species of malaria parasite present, the patients’ state of immunity, such as malnutrition or other diseases.
The spectacular success of the national malaria eradication program in the 1960s was short-lived and mitigated by a great resurgence in the mid-1970s globally; the concept of malaria eradication became a controversial issue and came in for a lot of criticism. The enthusiasm of the late fifties and early sixties dwindled into apathy by the late sixties and even into disillusionment by the late seventies. In view of the rapid deterioration of the malaria situation in many countries, it was realized that the diversity of the epidemiological situation must be met by a diversity of control methods, and the application of the pre-cast standardized measures of vector and parasite control was progressively less fruitful.
Over the years there had been a major shift in the Malaria Paradigm which induced a revision of clinical case definitions in many parts of the world. Social and economic considerations in malaria pave rise to new dimensions of the disease as a major public health problem. The Ministerial Conference in 1992, in Amsterdam, strongly reiterated the global political support for effective malaria control initiatives which culminated in the ”World Declaration of the Control of Malaria”.
Malaria is an age-old scourge. It was estimated that in India after 1947. 75 million suffered From malaria every Year and twice this number during epidemics with an annual mortality of about 0.8 million as a direct result of malaria. in Indonesia and Sri Lanka. the situation was had. if no; worse. with nearly 40% of the population subjected to malaria annually and malaria deaths exceeding 6% of deaths from all causes. In Bangladesh. Myanmar, Nepal. and Thailand though malaria morbidity was less pronounced, malaria mortality in these countries and especially. in Thailand was at a higher level. It was estimated that in 1950, 110 million suffered from malaria, and the annual deaths from malaria exceeded one million in the South-East Asia Region. The economic loss due to malaria has been considerable.
Comparative data for 1960. 1965 and 1975 show that. an increasing number of people had benefited from the global antimalaria campaign. The number of deaths due to malaria decreased from 2.5 million per annum to less than one-half of the figure. But the most distressing fact was the. the resurgence of endemic malaria in several countries of Central and South America and the South and South-East Asia. The overall number of malaria eases increased by 2.3 times in 1976 as compared with that in 1972. In South-east Asia Region (SEAR) it increases was more than fivefold (from 1.4 million in 1970 to 7.3 million in 1976). However, due to intensification of anti-malaria measures the disease incidence had shown a downward trend from 5.6 million cases in 1977 to 2.5 million cases in 1983 in the SEA Region; but since then the situation has remained somewhat static.
In recent years. excluding equatorial Africa, south of Sahara, the countries of South-East Asia Region have been accounting for almost” half (2.49 million in 1985) of the total reported cases of malaria ((3.3 million in 1985) in the world Fig. 13.3).
In 1993. out of an estimated world population of 5700 million, some 3400 million lived in areas where malaria never existed or had disappeared spontaneously or as a result of anti-malaria measures. In areas inhabited by 1600 million people, malaria prevalence and/or incidence have been much reduced as compared to pre-control levels. Sonic 70 million people live in areas where no malaria control effort has been made (mainly in tropical Africa) or where malaria control is practically impossible due to war, civil unrest. uncontrolled migration (200 million).
Reports and estimates of morbidity and mortality from malaria show substantial differences and variations, but it can be said that the total number of chronically infected persons exceeds 400 million worldwide. the majority living in tropical Africa. The annual incidence of manifest clinical malaria has been estimated at 120 million cases; more than 1 million persons die from malaria every year.
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Epidemiology of Malaria
Indigenous malaria has been recorded as far north as 64° North latitude (Archangel in the former USSR) and as far south as 32° South latitude (Cordoba in Argentina). It has occurred at Londiani (Kenya) at 2600 meters above sea level. However, endemic –malaria no longer occurs in many temperate-zone countries. but is a major cause of illness in many parts of tropics arid subtropics. Falciparum and vivax malaria arc found in many endemic areas; ovale malaria is seen mainly in West Africa where P. vivax is practically absent. In areas where P. fateqx.i.rurn predominates, its incidence starts increasing after P. vivax but its peak is higher and occurs towards the end of the transmission season.
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Malaria is essentially a focal disease since the transmission of malaria depends greatly on the local environment and other conditions. In Bangladesh-India-Pakistan subcontinent vivax malaria was and is still prevalent in all endemic areas and more or less evenly distributed: the quartan malaria is mostly limited to tribal areas whereas falciparum malaria predominates in foothills and forested areas; most intensive foci of falciparum malaria were observed in the north.– eastern Indian states and Orissa, contributing, more than 60% of the total falciparum cases in India.
As regards malaria problem, Bangladesh can be broadly divided into 3 distinct .epidemiological zones/areas: (a) High-risk area: this includes forested hilly areas, forest fringe areas and, foothill areas and covers C.H. Districts (Rangamatl! Khagrachhari, Bandarban, Chittagong), Cox’s Bazar District, greater. Sylhet (parts), and frontier areas, of greater Mymensingh district: the ar.ea.„.411. is characterized mostly by the presence of stable malaria and high immune status amongst the indigenous population. (b) Epidemic prone area: The area mostly covers parts of forested hill areas and is characterized by unstable malaria, endemicity varying from low to meso-endemicity. considerable population movement (both internal and across the international border) and presence of efficient vector or vectors. The area includes 20 Upazilas and 43 unions under 9 districts alongside. the north and north-eastern border namely Sylhet, Sun among, Habigonj, Moulvibazar, Netrokona, Mymensingh, Sherpur, Jamalpur, and Kurigram where a number of epidemic outbreaks were reported during 1993-95. In addition, focal outbreaks of malaria are also reported from plain areas and from valleys in Chittagong Hill Districts amongst the non-immune or semi-immune settlers from plain areas or in highly receptive plain areas due to introduction of parasite reservoir from the high-risk areas. (c) Low-risk areas: This comprises vast plain cultivable areas where, with the exception of a very few outbreaks, malaria (mostly vivax malaria) incidence is low and the disease does not constitute a major health problem and hence can be managed within the existing PHC system.
Malaria is said to be endemic in an area or among certain groups where it is constantly present in varying degrees over a succession of years. The various degrees of endemic malaria are (1) hypoendemic (child spleen rate 1-10%). here little transmission occurs: (ii) mesoendernicity (CSR 11-50%), here varying degrees of local transmission occurs; (iii) hyperendemicity (CSR constantly over 50%, adult spleen rate is also high— over 25%), here intense but seasonal transmission occurs; (iv) holoendernteity (CSR is constantly over 75%, but adult spleen rate is low), here transmission is intense and perennial.
Malaria epidemic, which is characterized by rapid increase of the incidence of malaria in the population, is caused due to (i) increased susceptibility of human population, often due to introduction of non-immunes into an endemic area; (ii) increase of the infective reservoir in the community due to introduction of large number of gametocyte carriers; (iii) increased man-mosquito contact; (iv) introduction of a new and more efficient vector mosquito in an area.
In malaria epidemic, three periods are generally recognized; (i) Pre-epidemic phase (building-up of epidemic potential); (ii) Epidemic wave (parasite rate rises sharply at the beginning than spleen rate, reaching highest point at the same time, but falling more rapidly than spleen rate); (iii) Post-epidemic period (return to usual state of endemicity). Malaria epidemic in a country occurs mainly in hypo- or mesenteric areas and may be seasonal, localized or regional; epidemics have also been seen occurring in cycles of 5-8 years. Epidemic potential in areas with hyper-to holoendemic of malaria is close to,’zero’.
Agent. Human malaria is caused by one of the four species of Plasmodium—P. vivax. P. ovate, P. falciparum and P. malaria; the causative agents of, vivax (benign tertian) malaria, ovale (ovale tertian) malaria, falciparum (malignant tertian) malaria and malaria (quartan) malaria respectively.
P falciparum and P. vivax account for than 95% of the cases of malaria in the %vorki. In the South-East Asia Region. during 1987 more than 38% of all the confirmed cases were One to P. falciparum infection. All species of plasmodium have a life cycle both in man and in various specious of anopheline. Mosquitoes.