CHARACTERISATION OF ANOPHELES MOSQUITOES, BREEDING SITES AND RETROSPECTIVE STUDY OF MALARIA IN KATSINA STATE, NIGERIA
CHARACTERISATION OF ANOPHELES MOSQUITOES, BREEDING SITES AND RETROSPECTIVE STUDY OF MALARIA IN KATSINA STATE, NIGERIA
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Date
2014-05
Authors
UMAR, Aliyu Mohammed
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Abstract
An entomological survey was conducted between 2009 and 2011 in some parts of Katsina State, Nigeria to establish the species of Anopheles present, the characteristics of their breeding sites and the prevalence of malaria infection from hospital records in selected hospitals. The state was zoned into three: A, B and C to represent the Guinea, Sudan and Sahel savannah respectively. Anopheline mosquitoes were collected indoors and from larval surveys. The collection was first identified morphologically using mosquito morphological keys, then subjected to PCR analysis, and Gel electrophoresis for M and S rDNA assay. Incrimination of malaria vectors was by detection of circumsporozoite protein using Vectest kits (MAS TM; Camarillo, CA, USA). A retrospective study of malaria prevalence during both dry and wet seasons was done by collecting hospital records of malaria in Dutsinma, Katsina and Funtua government hospitals. Geo-referencing and characterization of mosquito breeding sites were also carried out. Pictures of all man-made mosquito breeding sites sampled were taken using an ES 15 Samsung digital camera. A total of 3027 anopheline mosquitoes were collected and morphologically identified as Anopheles mosquitoes. Of the 1649 adults reared from larvae 1027 (62.28%) were An. gambiae s.l. followed by An. funestus 580 (35.17%). Of the 1378 adults collected indoors, 926 (67.2%) were An. gambiae while the least was An. quadrimaculatus with 9 (0.65%). In addition, An. maculipennis and An. quadrimaculatus, which are recognized as secondary malaria vectors, were also encountered. Larvae were most abundant in Zone A 555 (33.7%) at Dandume followed by Funtua with 298 (18.1%) while Zone C had the least with 148 (9.0%) from Katsina. Similarly, a preponderance of adults was observed in Zone A with 301 (21.8%) at Dandume followed by Funtua with 299 (21.7%) and the least was Zone C at Daura, with 98 (7.1%). An. gambiae adults were most abundant in homes. They were more preponderant in Zone B at Kankara with 200 (14.51%) and the lowest collection was made in Zone C at Katsina with 70 (5.08%). There was no significant difference between indoor collections between Zone A at Dandume, Zone B at Dutsinma and Zone C at Daura (p >0.05, F=10.13). In addition, An. funestus had its highest collection in Zone A at Funtua with 88 (6.39%) and the lowest in
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Zone C with 28 (2.03%) in Daura. An. quadrimaculatus was the least abundant in all the zones combined, having only 2 specimens in Zone A (at Funtua). An. gambiae was most abundant in July, 2009 with 47 at Dandume in Zone A while An. funestus was the most abundant in February, 2009 also in Zone A (at Dandume). There was no statistically significant difference between An. gambiae and An. funestus population in Zone A, Zone B and Zone C (p >0.05, F=5.05). Anopheles mosquitoes were collected from five different types of breeding sites. An. gambiae were the most preponderant in pools with 332 (20.13%)] and least abundance were 120 (7.28%) in overhead tanks. An. funestus was most proponderant in concrete reservoirs. An. maculipalpis and An. quadrimaculatus were collected from rice farms only. There was no significant difference (p >0.05, F=9.28) between pool and pond nor between concrete reservoir and overhead tank in terms of collected larvae. The S form predominated over the M form in all the sampled towns. For indoor collections, the S form was the most preponderant in Zone B with 187 (19.75%) at Kankara and the lowest of 56 (5.91%) was in Zone C (at Daura). Of the 1069 adults reared from larvae, the S forms were the most preponderant with 354 (33.12%) in Zone A (at Dandume) and its lowest abundance was 45 (4.21%) in Zone C (at Katsina). The M forms were the most proponderant in Zone A (with 5 and 3 specimens reared from larvae at Funtua and Dandume respectively). There was no significant difference between the zones in terms of larval collections of M and S forms; however there was a significant difference in terms of indoor collections between Zones A, B and C and also between the two forms (p >0.05, F=9.28). The cocktail PCR-assay on the An. funestus group showed 518 (51.24%), to be An. funestus s.s and 67 (6.624%) to be An. brucei and 35 (3.46%) as An. rivolurum. The three species were identified from all the sampled towns. An. funestus adults and larvae identified by PCR showed no significant difference between the zones (p <0.05, F=6.39). The Vectest evaluation indicated that the most prevalent infection of P. falcifarum was 88 (6.61%) in Zone B (Kankara) and the lowest was 36 (2.70%) in Zone C (Daura). P. malariae recorded its highest prevalence of 206 (15.47%) also in Zone A (Funtua) and its least was 55 (4.13%) in Zone C (Daura). There was a very high significant difference between P. falciparum and P. malariae isolated from An. gambiae and An. arabiensis within the zones. No P. Vivax was collected during the study. The highest number of identified Plasmodium species both in 2009 and 2010 was in the month of July. This study has shown that An. gambiae was the most abundant species in wet months, followed by An. funestus at the end of the rainy season, and An. arabiensis in drier months. An. funestus has been confirmed to be responsible for transmission of malaria during the dry season. In addition, Anopheles mosquitoes survived and proliferated during the dry season by breeding in temporary ponds, concrete and overhead water reservoirs. Plasmodium vivax was not encountered in Katsina State
Description
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF A DEGREE OF DOCTOR OF PHILOSOPHY (Ph.D) IN ZOOLOGY. DEPARTMENT OF BIOLOGICAL SCIENCES, FACULTY OF SCIENCE, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA. May, 2014
Keywords
CHARACTERISATION,, ANOPHELES,, MOSQUITOES,, BREEDING SITES, RETROSPECTIVE, STUDY,, MALARIA,, KATSINA STATE,, NIGERIA.