RP-Department of Zoological Sciences

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Biological diversity of the Yala Swamp lakes, with special emphasis on fish species composition, in relation to changes in the Lake Victoria Basin (Kenya): threats and conservation measures
(Springer Verlag, 2002-05-15) Aloo, P. A.
During the second half of the last century, the Lake Victoria ecosystem has undergone drastic ecological changes. Most notable has been the decline in the populations of many endemic cichlid fishes. The lake has lost nearly 200 haplochromines and one tilapiine, Oreochromis esculentus. The above changes have been attributed to effects of species stocking and, in particular, from predation pressure by the introduced Nile perch, Lates niloticus. Other factors that have led to the decline of the endemic species include intensive non-selective fishing, extreme changes in the drainage basin, increased eutrophication, and the invasion of the lake by the water hyacinth, Eichhornia crassipes. However, the remnants of some species that had disappeared from Lake Victoria occur abundantly in the Yala Swamp lakes (Kanyaboli, Sare and Namboyo). This paper discusses the biodiversity of the swamp and the three lakes and gives suggestions for their conservation.
Ecological Studies of Helminth Parasites of the Largemouth Bass, Micropterus Salmoides, from Lake Naivasha and the Oloidien Bay, Kenya.
(PubMed, 1999-06) Aloo, P. A.
The parasites of 541 largemouth bass, Micropterus salmoides, were studied over a period of 12 months. The results showed that the bass from Lake Naivasha are paratenic hosts of Contracaecum sp. larva and final hosts for the acanthocephalan Polyacanthorhynchus kenyensis. The nematode occurred in large numbers in fish caught in the more saline Oloidien Bay but only in small numbers in those in the main lake. Bass in the main lake, however, were more heavily infected with acanthocephalans than those in Oloidien Bay. One of the major pathological effects of the acanthocephalan was perforation of the liver by the spiny proboscis. Seasonal variation was not apparent for either of the parasites. The intensity of infection by Contracaecum sp. larva increased with the size of the host and female fish were more heavily infected than males.
Health Problems Associated with Consumption of Fish and the Role of Aquatic Environments in the Transmission of Human Diseases.
(African Journal of Health Sciences, 2000) Aloo, P. A.
The majority of the numerous fish parasites are harmless to man and many domestic animals because when eaten with their fish hosts, they are digested. However, some of the fish parasites with larval stages in freshwater or marine teleosts have zoonotic potential if eaten raw or partially cooked. These are usually parasites, which have a piscivorous mammalian carnivore as their normal final host and are able to infect man because of the low host specificity of the adult stage. The major groups of fish parasite that are known as potentially dangerous pathogens of man belong to the helminth groups cestoda, trematoda, nematoda and rarely acanthocephala. However, bacterial and viral disease of man transmitted through fish are not uncommon. Toxic substances, metals and insecticides used to control human diseases in aquatic environments may accumulate in fish in po1lluted waters at such levels as to constitute a health risk to the consumer. Other health problems associated with fish arise from its perishable nature for example, in adequate handling, processing and storage, which may lead to the accumulation of microbes enhancing the risk of food poisoning. The aquatic environment in Africa constitutes a breeding habitat to several vectors of human diseases such as mosquitoes, snails and black flies. This paper reviews the role played by fish in transmitting diseases to humans as well as the importance of the aquatic environments in the transmission of human diseases such as Malaria, Schistosomiasis and onchocerciasis.
Metazoan Parasites of Some Commercially Important Fish along the Kenyan Coast
(WIOMSA, 2004) Aloo, P. A.; Anam, R. O.; Mwangi, J. N.
The parasitic fauna of some commercial fish species along the Kenyan coast was investigated at four localities between August 2001 and March 2002. The study was carried out to establish the extent of parasitisation of different fish species and quantify the relationship between the parasites and their fish hosts. Fish samples were collected once a month from four landing beaches. Sixteen fish species were examined out of which only eight were infested with ecto-and endo parasites. The infested fish species included: the rabbitfish (Siganus sutor), the mackerels (Selar crumenophthalmus, Scomberomorus commerson and Rastrelliger kanarguta), parrot fish (Leptoscarus vagiensis), sardine (Sardinella gibbosa), tuna (Thunnus sp.) and needle fish (Hemiramphus far). Of the eight species, Si. sutor was most infested with parasites while Sardinella and Leptoscarus were primarily infested with ectoparasites (isopods). Intensity of infestation increased with age (size), especially in Si. sutor, where very young fish had a low infestation rate, while adults were heavily infested (P < 0.01). No significant differences were observed in the intensity of infestation between sexes in Si. sutor (P > 0.05).
Occurrence of Cystacanths of Polyacanthorhynchus Kenyensis Larvae (Acanthocephala) in Four Teleostean Fishes from a Tropical Lake, Lake Naivasha, Kenya.
(Folia Parasitologica, 1997) Aloo, P. A.; Dezfuli, B. S.
From January 1992 to December 1993, a total of 2158 fish, namely Oreochromis leucostictus (Trewavas, 1983), Micropterus salmoides (Lacépède, 1802), Tilapia zillii (Gervais, 1848) and Barbus amphigrama (Boulenger, 1902) were sampled from thirteen stations on Lake Naivasha, Kenya, using a fleet of gill nets and examined for helminth parasites. The prevalence of infection due to cystacanths of an acanthocephalan, Polyacanthorhynchus kenyensis Schmidt et Canaris, 1967 among parasitized O. leucostictus ranged from 30.4 to 86.9%; among T. zillii from 4.1 to 77.7%; in M. salmoides from 20 to 50%; and in B. amphigrama from 5.8 to 100%. In 735 hosts belonging to the above four species, a total of 4198 immature specimens of P. kenyensis were recovered. All cystacanths were found in extraintestinal sites, either free within the fish body cavity or encysted within the host visceral organs. There was no significant variation in the prevalence of the parasite within months (P > 0.001). Host sex ratio was significant (P < 0.001) in favour of male T. zillii, and also highly significant (P < 0.001) in favour of male O. leucostictus. Moreover, in this fish, prevalence of infection was observed to increase with the increase in the size of the fish. Among infected M. salmoides, there was no significant departure from a 1:1 sex ratio.
Occurrence of larval contracaecum (nematoda: heterocheilidae) in three teleostean fish species from lake Naivasha, Kenya
(Faculty of Science Kenyatta University, 2001) Aloo, P. A.
Occurrence of the larval nematode (Contracaecum sp.) in three teleostean species, viz: Oreochromis leucostictus (Trewavas), Micropterus salmoides (Lecepede) and Tilapia zillii (Gervais) in Lake Naivasha was investigated over a period of 12 months (September 1996 - August 1997). The/ work was carried out to establish the seasonal prevalence, variation in intensity of infection with size, sex and sampling stations and the effect of the parasite on the health status of the three hosts. Results indicate that there was no significant monthly variation in the intensity of infection in the three fish species (P>0.05) and both males and females showed no significant difference in the rate of infection by the larval nematode. Oreochromis leucostictus was observed to be the most heavily infected (Mean parasite load = 15) while Tilapia zillii was the least infected (mean parasite load = 2) Infection rate and parasitic load between length classes were very significant in 0. leucostictus (X2 3 = 212.7; P0.05). There was however, a great variation in infection rate within sampling sites in all the three species; 0. leucostictus (X2 4 = 20.66; P0.05).
Prevalence of intestinal parasitic infections in certified food-handlers working in food establishments in the City of Nairobi, Kenya
(Elsevier, 2012) Kamau, Paul; Aloo, P. A.; Kabiru, Ephantus W.; Ombacho, Kepha; Langat, Bernard; Mucherue, Obadiah; Ireri, Laban
Most intestinal parasites are cosmopolitan with the highest prevalence in the tropics and subtopics. Rural-to-urban migration rapidly increases the number of food eating places in towns and their environs. Some of these eating estabishments have poor sanitation and are overcrowded, facilitating disease transmission, especially through food-handling. Our investigations in Nairobi, therefore, were set to determine the presence of intestinal parasites in food-handlers with valid medical certificates. Direct and concentrated stool processing techniques were used. Chisquare test and ANOVA were used for data analysis. The parasites Ascaris lumbricoides, Entamoeba histolytica and Giardia lamblia were observed in certified food-handlers. Significant difference was found in parasite frequency by eating classes and gender (χ2 = 9.49, P = 0.73), (F = 1.495, P = 0.297), but not in parasite occurrence between age brackets (χ2 = 6.99, P = 0.039). The six-month medical certificate validity period may contribute significantly to the presence of intestinal parasites in certified food-handlers.

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