[Current malaria situation in the Republic of Kazakhstan].Med Parazitol (Mosk). 2001 Jan-MarMP
The Republic of Kazakhstan is situated in the northern hemisphere on the boundary of two continents--Europe and Asia--at a longitude of 45 degrees E--87 degrees E and a latitude of 40 degrees N--55 degrees N. The total area of the republic is 2,724,900 square kilometers. Kazakhstan shares a border with the Russian Federation to the north-west, north and east: the border between the two countries is almost 6500 km long. To the south, Kazakhstan shares a border with the Central Asian states of Turkmenistan (380 km), Uzbekistan (2300 km) and Kyrgystan (980 km). To the south-east, it shares a border with China (1460 km): to the west is the Caspian Sea (600 km). Thus, the total length of Kazakhstan's external borders is 12,000 km. Because of the geographical, natural and climatic features prevailing throughout most of the Republic, there is a potential danger that local transmission of malaria may begin again if the disease is imported from abroad. The areas most at risk are the Panfilov and Uigur raions of Almaty oblast, which share a border with malaria-endemic regions of China, and the Saryagash and Makhtaral' raions of South Kazakhstan oblast along the border with Uzbekistan. The Government of the Republic of Kazakhstan places particular emphasis on malaria prevention and control, taking into account the historical data about the prevalence of malaria from the late 1920s to the early 1940s, amounting to hundreds of thousands of cases every year. Government Decree No. 840 entitled "Urgent Measures to Protect the Population from Blood-Sucking Insects and Ticks Dangerous to Humans", which lays down measures for the control of malarial mosquitoes in the areas most susceptible to malaria resurgence, was adopted in 1996. The Ministry of Health of the Republic of Kazakhstan issued instructions in 1998 and 1999 which were designed to motivate all health facilities in the field of malaria prevention and control. At present, as part of the directives developed by the Republican Health Epidemiology Posts, work is being done on the planning of malaria control measures in Kazakhstan for the period 2001-2003. In 1994 a programme of epidemiological malaria surveillance was introduced, which has enabled us to improve our monitoring of the epidemiological situation of malaria. The number of cases of imported malaria has declined: in 1997, there were 102 cases, in 1998-87 and in 1999-52. There have been occasional local cases in some years, and in 1998 there were four local cases in the south and north-west of the country: two cases in Almaty oblast, one case in Zhambyl oblast and one in West Kazakhstan oblast (see Fig. 1). Most malaria infections are imported from Tajikistan and Azerbaijan, with occasional cases from Pakistan, India, Turkey and Afghanistan. Analysis of the occupational status of patients shows that around 45% are military personnel who have served on the Tajik-Afghan border. The others are refugees, merchants, unemployed people or students. The overall aetiological structure of malaria cases is dominated by P. vivax malaria. For example, in 1999, there were 48 cases of P. vivax malaria (90.5% of the total), one case of tropical malaria (1.9%), two cases of quartan malaria (3.8%) and two cases of P. vivax + P. malariae (3.8%). In order to prevent indigenous malaria occurring within the country, a system of malaria screening has been set up; screening is carried out every year on groups who have visited neighbouring or more distant malaria-endemic countries and for patients with a persistent fever who are suspected of suffering from malaria. The area of water throughout the country within communities or within a 3-5 km radius of them which is susceptible to colonization by the Anopheles mosquito amounts to over 5000 hectares, according to the certification system in force. In addition, approximately 70,000 hectares in three oblasts used for rice cultivation also provide a habitat for Anopheles. The main malaria vector, An. messeae, is found throughout the country: in a few areas An. hyrcanus and An. claviger are found and, in the south, An. pulcherrimus. Data from recent years show the presence of An. superpictus, An. plumbeus and An. algeriensis. In 1999, from data collected during systematic observations of the phenology and seasonal variations in the number of Anopheles at 114 observation posts, the average seasonal numerical indicators for the mosquito imago reached a maximum of between 21 and 46.5 adult mosquitoes per cattle shed, up to 2.7-3.3 adult mosquitoes per residential building and 30-67.3 larvae per square metre of surface water. According to the results of large scale trapping programmes (486 communities were screened in 1999), the maximum value of the numerical indicator was 16.8-74.1 adult mosquitoes per cattle shed and 4.1-3.8 adult mosquitoes per residential building. In 1999, compared with 1998, the number of malarial mosquitoes detected throughout the country declined encouragingly, or stayed at the same level, which is one of the factors responsible for the country's favourable epidemiological situation with regard to malaria. According to data going back many years, there has been a significant increase in the number of mosquitoes at some observation posts in Almaty, East Kazakhstan and Kyzlorda oblasts. There is a tendency everywhere for the numbers of imagos detected in residential buildings to increase, which presents a definite epidemiological risk that indigenous malaria will re-emerge if the disease is imported into Kazakhstan from countries which suffer from it. If we consider the species of mosquito present in the country and the temperature factor (the number of days in the year when the average daily temperature is over 16 degrees C), the country can be divided, on the basis of incomplete 1999 data, into zones at very high risk of re-emergence of malaria (Almaty, Zhambyl and South Kazakhstan oblasts), high risk (Karaganda oblasts and Almaty city), medium risk (Aktyubinsk and Akmolinsk oblasts), and low risk (Kostanay oblast). The malaria risk of the other oblasts has been calculated using data from earlier years (map attached) [Translator's Note: map missing]. Preventive malaria control measures in Kazakhstan are divided into three categories to suit three different groups of communities. One hundred and seventy-nine communities have been allocated to the first group, at high risk of malaria resurgence; 1377 communities to the second group, at medium risk; and the remainder to the third group, at little or no risk of malaria resurgence. The following factors were used to categorize communities according to the risk that malaria might become reestablished if the disease should be imported from elsewhere: species of malarial mosquito present; changes in mosquito numbers and in the area of water susceptible to population by Anopheles; temperature conditions and, consequently, the length of the malaria transmission season and the season of effective susceptibility of the mosquito to infection; population migration; quality of laboratory testing for the diagnosis of malaria. Measures aimed at the destruction of mosquitoes are intended to reduce the numbers of Anopheles in the communities most at risk of malaria resurgence, i.e. those in group 1 above and the actual foci of malaria infection. Because of the economic crisis and financial difficulties, fewer areas have been treated in recent years. In 1999, 1387 hectares of water and 450,000 square metres of buildings were treated (see Fig. 2). Measures to control biting flies in health establishments, recreation areas, etc. Certainly also help to protect people from malarial mosquitoes. In 1999, 12,501 hectares of water and land were treated from the ground or the air (see Fig. 3). In the present situation, the main reasons for the difficulties affecting the malaria control and prevention campaign are as follows. Staff numbers in the Republic's parasitology service have been unjustifiably reduced. For example, the number of entomologists and entomology assistants employed is 58% and 48%, respectively, of the number laid down in Ministry of Health directives. At the health epidemiology posts, the number of disinfectors has been reduced to a minimum, and practically all engineer/water engineer posts have been abolished. The country does not possess the necessary education base for initial training or continuing education of staff for the parasitology service. The lack of basic scientific information about the problems of malaria control and prevention and parasitology in general. There is no research to test or introduce the most effective, safe and low-cost malaria control products and insecticides. The methodological literature required to use certain modern insecticides is not available. Entomologists are not provided with specialist insect control equipment. Entomological surveys are left incomplete because of shortages of transport and fuel at the health epidemiology posts. Because of the economic crisis and the high cost of the radical water engineering measures necessary to combat malaria, these measures cannot be implemented on the scale required. The equipment and materials stocks of the parasitology laboratories are highly inadequate: there is a lack of modern laboratory equipment, as well as a lack of opportunities for high-level professional training for staff. The exchange of information between the CIS countries is unsatisfactory, and there is no common information space: nor is there any systematic data available from other foreign countries. In the period 2000-2003, Kazakhstan plans to carry out malaria control activities (mosquito destruction) over an area of 2000 hectares of water and 1.5 million square metres of buildings.