Duty travel to Sierra Leone and Mali

' Ye' u' '[t.+A^z l"A^f* "+ffitr c,r,t ) a . Y. DadzielEPI "tdHS 4,. ."t , )€A-, '//rZnr^ r. l-, i'r / f.iwrr rc , -t'll ...----4,? 1 i',ii - From: Dr Thro' Ch Ref:59/91/EPI To: Dr. Programne Director Subject: DUTY TRAVEL TO SIERRA LEONE AND MALI Samba Date: 7 /03/91 Originator: Ophthalnological surveys were c&rried out in Sierra Leone from 23 January to 5 February 1991. The ain of the activity was to attempt to clarify further the distribution of blinding onchocerciasis in the country. The surveys were carried out in two villages in the Rockel river basin and three in the basins of the tributaries of the Sewa river. These villages have undergone parasitological surveys previously. The attendence rate was fair in all the villages except in the village of Gbukuma where it was very poor because nost of the inhabitants of the village were attending funeral rites in a neibouring village. Table 1 shows the prevalence of indices of ocular onchocerciasis including blindness and the CMFL and the census population of the villages surveyed. The prevalence of eye lesions was fairly moderate and blindness was fairly low in aII the villages except in the village of Wanjama where the prevalence of eye Iesions was relatively low. The CMFL's of the villages were also not high, around 30 in aII the villages. Except in Wanjama where the community pattern of ocular onchocerciasis doubtless resembles the forest or the less blinding type, it is not possible to classify the onchocerciasis in the other villages into either the blinding or less blinding type. Nevertheless, the data from the four other villages could very weII fit into the lower levels of blinding onchocerciasis which has been described in the area where the villages are found. Other activities carried out in Sierra Leone were investigations into the migration history of persons in three villages who have undergone nodulectomy in connection with studies on DNA probe being carried out in collaboration with Dr. Unnasch of Alabama University in Birmingham, USA. These investigations will help to clarify some of the discrepancies in the results so far furnished by Dr. Unnasch. Six villages in the Bakoye river basin in Mali were examined from 11-26 February 1991. These villages were aII hypoendemic and were examined ophthalmologically in the context of a planned study to assess the level of public health problem in communities with low intensities of infection. The presentation was good to very good in aII the villages. Table 2 summarises the preliminary results from the survey. As can be seen the from the table, the CMFL or the prevalence of onchocerciasis in the villages are aII very low and range from 3,22 to 8.20 and 30.% to 8.2% respectively. The prevalence of ocular microfilariae is also very 1ow and ranges generally from 6.2% to 7,5% except in the village of Masala where it was exceptionally low, L,9%, The prevalence of eye Iesions ranged from 3.4% to 8.5% but in the village of Badougou it hras a little higher,12,3% and in this village also, the prevalence of total blindness was rather excessive, 3. 8%. t*- / Following the objective of the survey, it was rather important to know whether the high prevalence of blindness in sone of the villages was due to onchocerciasis or not. It is clear from the table that the prevalence of onchocercal blindness is generally low in aII the villages. A comment should also be made with respect to the preval-ence of onchocercal eye lesions which though was low on the face of it, appears, in fact, rather high in relation to the prevalence of ocular microfilariae. It is worthy of note that this region in Mali forms part of the Sahel area in West Africa where severe drought in the last 7 Lo 2 decades has presuurably reduced the severity of onchocerciasisgenerally. Since it is the intensity of infection which first decreases under srrch circumstance, whilst the prevalence of eye lesions lingers on, it is possible that this factor have contributed to the dissociation of the two indices in question. However detailed analysis is necessary to clarify the observation. FinalIy, it should be mentioned that trachoma is very prevalent in the villages. Trachoma was found to cause blindness at the same frequency as onchocerciasis in aII the villages except in Fataba where no trachoma trlindness was found. In the big village of Mansala whose size apparently exerts a diluting effect on the severity of onchocerciasis, blindness wa.s caused uniquely by trachoma. Table 1 DISTRIBUTION OF PREVALENCE OF INDICES OF OCULAR ONCHOCERCIASIS, BLINDNESS CMFL AND CENSUS IN 5 VILLAGES OF SIEBRA LEONE village census CMFL ophthal. ocular exan. mfs ocular les ion total bI ind Kabare Kasok i ra Maima 1 Wanjama Gbukuna t22 737 99 113 t28 30. 23 77 33. 85 90 27 .48 65 27.53 72 30.91 46 19.52 27.5% 32.8% 9.7% 23.9% 10. 4Z 8.8% 4.7% 2.8% 8,7% 0.82 0.7% 0% 0. 9z L.6% Table 2 village DISTRIBUTION OF PARASITOLOGICAL AND OPHTHALMOLOGICAL INDICES AND CENSUS IN 6 VILLAGES IN THE BAKOYE RIVER BASIN IN MALI census prev. CMFL ophthal ocular exan. mfs ocular Iesion total bl ind oncho bI ind Mansala Kourounouma Fataba Baniankafata Lenguema Badougou 460 25L 146 190 156 130 32.8% 45.7% 30. 8Z 39.7% 45.3% 48,2% 3.26 4.34 qoo 4. 36 8. 20 4.20 mfls nfls rnf /s nf /s mfls mfls 323 186 148 123 118 81 1. 9% 7.5% 6.2% 6. 5% 3.4% 6,2% 4.3% 3.8% 8. 3Z 8. 1% 8. 5U 12.3% 0.4% 1.2% L.3% 2.7% 2.6% 3. 8% 0% 0.4% 1. 3Z 0. 5z 0. 6z 2,3% a