Medical Journal of Zambia, Vol. 42, No. 4: 159-163 (2015) ORIGINAL ARTICLE Surveys for Mansonella perstans Filariasis in Kalabo, Kazungula, Choma and Kafue Districts of Zambia ST Shawa1, J Siwila2, ET Mwase1, PE Simonsen3 1Department of Paraclinical Studies, School of Veterinary Medicine, University of Zambia, Lusaka, Zambia 2Department of Clinical Studies, School of Veterinary Medicine, University of Zambia, Lusaka, Zambia 3Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark ABSTRACT malaria examination method in the other districts from conventional preparation of Giemsa stained Background: Past case reports have documented thick blood smears to use of rapid diagnostic tests. Mansonella perstans infections in Zambia. For the prospective surveys, out of the 1439 However, knowledge on the epidemiology and individuals recruited and examined, no M. perstans geographical distribution of this infection in the mf were seen in any of the blood smears. country is lacking. This paper reports on surveys for M. perstans in communities in four districts(Kalabo, Conclusions: The failure to find M. perstans mf was Kazungula, Choma and Kafue) in the Southern and surprising considering previous case reports, even Western parts of Zambia. from some of surveyed areas. There is a need for more surveys to be carried in other parts of the Design: The study was cross sectional. In the country to ascertain the distribution of M. perstans. Kalabo District surveys, individuals aged one year Health practitioners should moreover be informed and above had thick blood smears prepared and about this infection, and trained to be able to examined for M. perstans microfilariae (mf). In the accurately distinguish M. perstans infections from other three districts the study design was those of W. bancrofti, which are also endemic in retrospective and prospective, i.e. previously Zambia. examined archived malaria slides from health centres were re-examined for M. perstans mf and at the same time individuals aged 15years and above INTRODUCTION had thick blood spears prepared and examined for Mansonella perstans is a vector borne filarial M. perstans mf. nematode parasite of humans, transmitted by tiny Results: The retrospective study could only be flies of the genus Culicoides (biting midges). The undertaken in Choma District due to change in adult females produce small larvae called microfilariae (mf) which find their way to the blood Corresponding author: circulation. The mf are picked up by the vectors Sheila Tamara Shawa when they take a blood meal, and after a period of Department of Paraclinical Studies development in the thoracic muscles of the vector, School of Veterinary Medicine University of Zambia the parasites may be transmitted onward to new Lusaka, Zambia human hosts when the vector bites again [1,2].The Telephone: +260 966 757120 development in the vector takes approximately one Email: [email protected] or [email protected] 159 Medical Journal of Zambia, Vol. 42, No. 4: 159-163 (2015) to two weeks depending on the environmental surveys that were being carried out. Species of conditions but the period required for further Culicoides,which are the vectors responsible for development to mature adult stages in the human transmission of M. perstans infection, have been host is unknown. Adult worms appear to live mainly reported near Chilanga District in Lusaka Province in the serous body cavities, but have rarely been [8]. recovered[1]. Considering that Zambia is endemic for lymphatic Mansonellaperstans infections are widely filariasis caused by infection with the filarial distributed in Africa and also occur in parts of parasite Wuchereria bancrofti[9,10],and that control Central and South America and the Caribbean. activities to eliminate this disease as a public health Despite this, only a few studies have been carried out problem are currently underway, it is important that on the epidemiology and morbidity of this infection medical personnel and scientists are aware of both in endemic populations. This could probably be due parasites and are able to distinguish the mf of M. to the lack of association with a distinct and specific perstans from those of W. bancrofti for precise clinical picture or lack of effective treatment for diagnosis and treatment. As a first step, the present patients suffering from this infection [2,3]. survey was undertaken to determine the occurrence Diagnosis of M. perstans infection is mostly by of M. perstans in some districts including those that detection and identification of mf in peripheral had recent case reports of the parasites. blood. The microfilariae of M. perstans show a weak pattern of diurnal periodicity but are present in the METHODS peripheral blood both during the day and night[4]. Study sites Case reports from Zambia Spot check surveys were carried out in four districts. The first cases of M. perstans infection in Zambia The first wasin August 2012 in Kalabo District, were reported by Buckley in 1946 from hospital Western Province. Three villages at an altitude of patients in Lusaka, Ndola and Kasama[5]. Later on, 1000 – 1100 m above sea level, namely Sishekanu more cases of M. perstans were reported by Barclay (14.84071S, 22.80762E), Lutwi (15.17347S, from the Luangwa basin when he carried out a 22.38348E) and Liumena (14.98859S, 22.32845E) survey for another filarial parasite, Wuchereria were selected on the basis of previous surveys that bancrofti [6]. More cases of individuals with M. had recorded high prevalence of W. bancrofti perstans infection were recently seen in Chama infection [10]. The other surveys were carried out in District in the Luangwa valley, Eastern Province March/April 2014 in three districts in Southern parts [7].A few cases were moreover reported by medical of Zambia. In Kazungula District, study participants personnel from district health centers in the recent were recruited from two villages at an altitude of past. Thus, two cases were reported from Mambova 900-1000 m above sea level and located Health Centerin Kazungula District in 2012 by a approximately 60 km apart, namely, Mukuni medical officer, and in 2010 a woman from (17.90759S, 25.94151E) and Mambova Shimabala area in Kafue District being investigated (17.73088S, 25.19528E) under Chief Mukuni. for trypanosomiasis was found with mf of M. Mambova had previously reported two cases of M. perstansat the University Teaching Hospital in perstans infections. In Choma District, the study site Lusaka (UTH records, unpublished findings). was located approximately 20 km east of Choma However, despite these reports of M. perstans since town at an altitude of about 1200 m above sea level 1946, there has been no survey in any parts of the and in close proximity to Shamphande Health country to determine the occurrence and prevalence Centre (16.92256S, 26.99680E) which was among of M. perstans. Most of the reports of M. perstans the few communities still reporting cases of malaria infection were incidental findings as a result of other 160 Medical Journal of Zambia, Vol. 42, No. 4: 159-163 (2015) infection in the district. In Kafue District, study recruit at least 300 individuals from each of the other participants were recruited from three communities three study districts (Kazungula, Choma and Kafue) surrounding namely Nangongwe, Railways and to the prospective study, two or more communities Kafue Estates(15.78150S, 28.18368E) at an altitude were surveyed in each district. Community of approximately 900 m above sea level. members aged 15 years above and from the Study design surrounding community reporting to health centres and suspected to have malaria were recruited into A cross sectional survey was carried out in Kalabo the study and examined for M. perstans mf by District, where freshly prepared Giemsa stained thick blood smears were examined for M. perstans preparing blood slides as described above for mf from individuals aged one year and above from Kalabo. The slides were allowed to dry overnight Sishekanu, Lutwi and Liumena villages. In the other and thereafter deheamoglobinized in clean tap three districts, the surveys were initially designed to water. The slides were then fixed with methanol, be both retrospective and prospective in nature, allowed to dry in the air and stored in slides boxes. whereby previously examined archived malaria Upon arrival at the parasitology laboratory at the slides from health centres would be re-examined for University Teaching Hospital in Lusaka, the slides M. perstans mf and at the same time, freshly were stained using Giemsa and examined under a prepared Giemsa stained thick blood smears from microscope for M. perstans mf [11]. For the malaria suspected patients were also examined for retrospective study carried out in Choma district mf. For the latter part, individuals aged 15 years and only, all archived malaria slides at Shamphande above from the surrounding communities reporting health centre were examined for M. perstans mf to the health centres during the survey and suspected regardless of age, because only a few slides were to have malaria were recruited. available for examination Ethical considerations Permission to undertake the surveys was obtained RESULTS from the Biomedical Ethics Committee (ref no. 007- Although the study was designed to be both 06-11), the Ministry of Health, and the Provincial retrospective and prospective, it was only possible and District Health Offices. Permission was also to carry out the retrospective part in one of the sought from the local area chiefs and village districts because the health centres in the other headmen. Oral consent was obtained from the districts did not have archived malaria slides due to individuals before recruitment into the survey. Once change in the malaria examination procedure from they consented to participate, they were requested to conventional preparation of Giemsa stained blood provide a finger prick blood smear. Permission to re- smears to using rapid diagnostic tests (RDTs).