الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Sudan is one of the countries that are highly contributed of malaria burden in Africa and insect resistance was identified for insecticides used for malaria vector control activity in Sudan. Resistance of malaria vector to insecticide need updating mapping and abundance of vector, updating resistance situation, conducting vector control measures and introducing monitoring and management plans.
The aim of present work is to study the abundance of malaria vectors and to monitor their insecticides resistance in Sudan.
This study was conducted in Sennar State, about 300 kms south to Khartoum capital of Sudan, the seven selected localities lay in Blue Nile valley and two of them are out of zone (Eldender and Emazmom).
Type, positivity and characterization of breeding sites were take on and larval density was calculated. Collected larvae from each probable breeding site for all localities were differentiated morphologicaly also adults An. mosquitoes were morpholoicaly diffrentiated and also identified by PCR method in Elgadal laboratory.
Susceptibility test were carried out to detect the presence of resistance of An.mosquito larvae (3rd instar) against three tested larvicides, (Temephos, Fenthion and Chlorpyrifos). Also adult females mosquito were tested against four adulticides; Pirimiphos-methyl, Bendiocarb, Deltamethrin and DDT by using WHO protocol, 2013.
Knock down resistance gene (Kdr gene) of adult An. arabiensis population was detected by PCR method following exposure to Deltamethrin and DDT.
Indoor residual spray (IRS) was evaluated by measuring bio-efficacy of Bendiocarb using WHO cons method also indoor resting density was calculated by spray sheet method also incidence of malaria in population was calculated for each locality by dividing the number of cases reported by ministry of health monthly over total population multiplied by 1000.
Knowledge, attitude and practice of people were assessed using questionnaire for 350 person whose work relevant to the use of insecticide (sample of 50 person from each locality).
Data from the present study revealed that:
- There was a difference in number of positivity of breeding sites between dry and rainy seasons; 25 and 34 sites in dry and rainy respectively.
- Broken water pips (BWP) were the dominant breeding sites in all localities (51%), irrigated farm 22%, rain bonds 19%, constructed bonds 4% and river banks 4%. The positivity of breading sites fluctuated between all recorded breeding sites but BWP, showed the highest number of positivity of breeding sites (56%) especially in Eldender locality (26%).
- Breeding sites with vegetation were high (127 sites) than that without vegetation (53 sites), and breeding sites without shade (152 sites) was higher than those with shade (28 sites), also An. mosquito breeding sites in deep water (21- 45cm) were more (130 sites) than those of shallow one 10-20 cm (50 sites).
- As regards abundance of An. mosquitoes larvae there was a insignificant difference in larval density (larvae /dip) between dry and rainy seasons, where it was 21 and 28. larvae /dip respectively.
- Morphological identification of An. mosquitoes larvae collected from different tested localities revealed that. An. gambiae larvae were dominant (99.8%) in all sample collected in both dry and rainy season with few occurrence of An. pharonsese in dry and in rainy season (0.12 - 0.14%), and An. rufibs was about (0.05 - 0.07%) in dry and rainy season.
- As regards adult mosquitoes , An. gambiae counted in dry season was almost the same as in rainy season (98 %),while An. phareonsis were not recorded in both seasons, also a lower percente (about 2%) of An. rufibus was recorded in dry and rainy season.
- Molecular assay to identify An. gambiae revealed that all An.gambiae (100%) tested were An.arabiensis.
- Susceptibility of 3rd instar An. arabiensis larvae revealed highly mortality (91-100%) was detected after exposure to the tested larvicides. (Temephos, Fenthion and chloropyrifos). Temephos showed the highest effective larvicide where LC50 was 37×10-4 mg/l followed by chloropyfose (66×10-4 mg/l) while Fenthion had the lowest efficacy value (LC50 was 858×10-4 mg/l).
- Susceptibility tests of female adult An. arabiensis against the WHO recommended concentrations of the four tested adulticids, revealed that An. arabienses population from Sennar State were highly susceptible to primphos-mthyl (0.25%) and Bendiocarb (0.1%) where 100% mortality was detected in dry and rainy seasons. On the other hand An. arabienses population were resistance to DDT(4%) and Deltamethrin (0.05%). A low mortality percent (about 71% and 82%) was detected in both dry and rainy season following exposure to DDT (4%) and Deltamethrin (0.05%), respectively.
- A highly knock down time was observed after exposure of An. arabiensis to DDT (4%) and Deltamethrin (0.05%). KDT50 value for DDT (4%) ranged between 31.2 min in Elssuki locality and 53.4 min in East Sennar locality in dry season. In rainy season KDT50, ranged between 29.1 min in Abo hogar locality and 53.8 min in Elssuki locality.
- In case of Deltamethrin (0.05%) KDT50 value in dry season ranged between 36.9 min in East Sennar and 49.4 min in Sennar locality. Also, in rainy season KDT50 value ranged between 24.7min in Abu hogar and 50.7min in Sennar locality.
- Following exposure of female adult An. arabiensis to DDT (4%),1014f allele (kdr) detected in 34% of dead specimen and 53% of survivor specimen, and the distribution of (kdr) 1014f in An. arabiensis exposed to deltamethrin in dead specimen was 42% and in survivor specimen 48%.Also 77% of dead specimen were heterozygous following adult female An. arabiensis exposure to DDT while 5% were homozygous and18% were susceptible,while in survivor specimen 89% were heterozygous,8% were homozygous and 3% were susceptible. On the other hand, the study reported that 80% of dead specimen after exposure to Deltamethrin were heterozygous while 2% were homozygous and 18% were susceptible. In survivor specimen 78% were heterozygous, 9% were homozygous and 13% were susceptible.
- There was a reduction in total count of An. arabiensis female mosquito (collected by pyrethrum spray sheet) pre and post Bendiocarb IRS application, where they collected 143 insect pre application and 46 insecte post application. In unfed mosquitoes the decrease of number of mosquito was from 22 insects pre to zero post application while fresh feed insects 60 insect pre and 18 post application. Half gravid female mosquito were 29 insects pre to18 insects post application. Gravid female were 32 insects pre and 16 insects post application. On the other hand density /room was 4.1 insect pre application decreased to1.3 insects/room post. Also man biting rate was 2.5 bite pre to 0.7 bite post IRS application.
- Also, efficacy of Bendiocarb IRS application was tested 4 months by cons bioassay tests (recommended by WHO, the recorded mortality of An. mosquito was 99%, 95%, 48% and 23% for August, September, October and November respectively for susceptible strain of An. mosquito also mortality percent for the field strain was 100%, 88.5%, 43.8% and 0.7% in August, September, October and November respectively.
- On the other hand the recorded malaria prevelance in Sennar State four months after application of IRS were (5.18, 5.0, 4.31 and 5.15 cases /1000 pop for September, October, November and December, respectively).
- The study found that 47.1% of persons (workers, sallers, farmers) reveled that the dominant insecticides used were Pyrethroids followed by Organophosphates (39.4%) , and Carbamates (13.4%).
- The study concluded that An. arabiensis was the dominant species in Sudan and the occurrence of resistance in An. arabiensis population of Sennar State following exposure to DDT and deltamethrin and these population still susceptible to the other tested insecticides bendiocarb and Primfos-mythyl.
- The present study recommended that a comprehensive plan of insecticide monitoring and management against mosquito vector of malaria must be conducted. Also different activities that should be directed to manage resistance problem and forecasting for future existence of resistance of malaria vectors to insecticides
The study concluded that:-
1. Anopheles gambiae was the main malaria vector species in all localities of Sennar State with low occurance of An. phareoensis and An. rufipse.
2. There was a slight increase in number of An. larvae in rainy seasons compared to dry season.
3. Broken Water Pipe was the principal breeding sites in Sennar State.
4. There was association between presences of Anopheles mosquito larvae and breeding sites characters such as shadow, vegetations and depth.
5. Anopheles gambiae larvae found to be susceptible to the tested larvicides Temephos, Fenthion and chloropyrifos. Also Temephos record the highest efficacy against An. mosquito.
6. Adults An. arabiensis population reported resistance to DDT (4%) and Deltamethrin (0.05%) in dry and rainy season in Sennar State. However, An. arabienses population found to be susceptible to primiphos-methyl (0.25%) and Bendiocarb (0.1%) during both rainy and dry seasons.
7. Bendiocarb (Ficam® 80% WP) as indoor residual spraying persisted efficient only one month after spraying.
8. There was an existence of 1014F allele in An. arabiensis population collected from Sennar State using PCR technique.
9. According to the persons whose work was related to the field of pesticide, (47.1%) of them reveald that Pyrethroid was the wildly used insecticide in Sennar State.
10. There was a reduction in malaria cases in parralle to a reduction in An. gambiae density after IRS application in Sennar State.
Recommendations:
Overcome the decrease of the efficacy of Bendiocarb compound used in IRS application.
1. Study different factors disturbing its residue on the wall surfaces.
2. Training of spray men for indoor residual spraying is important before starting application to ensure best quality of spraying operations.
Monitoring mosquito resistance to insecticides in Sudan that should contain
1. Plan and implement insecticide resistance strategies for all the country.
i. Delegated characterized sectors for insecticide resistance concern in Sudan.
ii. Reviewer for assistance and consultation in insecticide experts.
iii. Enable all needed together to carry out insecticide resistance management (advocacy, human and financial resources).
2. Ensure proper, suitable entomological and resistance monitoring and effective data management.
i. Monthly survey for larvae and adults of Anopheles mosquito also morphological and molecular identification in all Sudanese localities.
ii. Monthly susceptibility test must be piloted in different species of An. mosquitoes found in the State.
iii. Recognition of different types of insecticide resistance occur in different States in Sudan (kdr, metabolic, behavioural).
3. Develop new, innovative vector control tools.
i. Alternative insecticide must be used to impregnate LLNS other than Pyrathyroid with the same safety properties and residue.
ii. Encourage use of alternative method of control of agriculture pests.
iii. Training farmers and labors for insecticides application.
iv. Encourage use of alternative method of larval mosquitoes control
(environmental management, manipulation and modification also biological control).
v. Replacement of pyrethroids insecticide that used in malaria vector control activity in Sudan by other effective compounds such as Organophosphates, Carbamats and biopesticides in rotation used by time.