Morphology and cytology study of Foleyella agamae complex (Nematoda: Filarinae) infecting the agamid lizard Agama agama in Nigeria.

Three cytotypes of Foleyella agamae were isolated from naturally infected wild-caught Agama agama in Nigeria. Cytotype A (2n = 8) has a body length/oesophageal length ratio (L/O) of 87.6 +/- 14.2 in female worms and a large somatic size (length, 63.8 +/- 12.7 mm in female worms and 25.5 +/- 3.4 mm in males). Cytotype B (2n = 6) has an L/O of 43.4 +/- 6.6 in females and a small to average somatic size (length, 36.7 +/- 11.9 mm in females and 19.5 +/- 2.3 mm in males). Cytotype C (2n = 4) has an L/O of 23.8 +/- 8.2 in female worms and a small somatic size (length, 18.8 +/- 3.8 mm in females and 14.1 +/- 3.0 mm in males). No cytotype with odd numbers of chromosomes was observed. Comparisons with similar types of speciation in medically important filarial parasites were drawn. Introgressive hydridisation in the speciation of filarial parasites is postulated.

Distribution and incidence of ectoparasites on small mammals in a rainforest belt of southern Nigeria.

A total of 174 small mammalian hosts were trapped in Ekpoma, Bendel State, Nigeria from October, 1986 to September, 1987 and examined for ectoparasites. 108 infested hosts had 10 species of ectoparasites comprising three species of mites (Laelaps (Echinolaelaps) muricola, Laelaps (E.) gigantea and Laelaps (E.) echidninus); two species of ticks (Amblyomma variegatum and Ixodes sp.); two species of fleas (Xenopsylla cheopis and X. braziliensis); and on especies each of sucking lice (Polyplax spinulosa) and subcutaneous larvae of Cordylobia anthropophaga. Rise in seasonal rainfall positively influenced the incidence of C. anthropophaga and adult fleas, but decrease reduced the incidence of ticks, mites and lice. The incidence of parasitic infestation was influenced by age of host, but not by the sex. Ectoparasite distribution was uneven on their hosts.

Human gastro-intestinal parasites in Bendel State, Nigeria.

Faecal samples from 862 male and female donors of nine age groups (1-90 years) in three geographical zones were screened by the examination of concentrates from formal other concentration technique. The overall percentage incidence of six parasites which were encountered were as follows: Entamoeba coli (19.7%), E. histolytica (3.9%), Giradia lamblia (1.4%), hookworm (29.4%), Ascaris lumbricoides (38.2%) and Trichuris trichiura (7.3%). However, the percentage incidence of parasites in the delta mangrove zone subject to heavy flooding and excess run-offs during the rainy season, were as follows: E. coli (44.7%), E. histolytica (0%), G. lamblia (37.5%), hookworm (44.9%), A. lumbricoides (51.0%) and T. trichiura (77.6%). Except for E. histolytica and G. lamblia, the percentage incidence in the delta zone were comparatively higher than values observed in the better drained middle rainforest and savanna zones. The age groups in the first two decades of life had 61.7% infection and this stabilised to a low level of 2.8% in the eighth and ninth decades. Males and higher protozoan and helminthic infections than females.

Lipid biosynthesis in Paramphistomum microbothrium (Trematoda).

In vitro studies with Paramphistomum microbothrium indicated that the trematode is capable of synthesizing its complex lipids using exogenous substrates. U-14C glucose and 2-14C acetate were predominantly incorporated into phospholipids while 1-14C oleic acid and U-14C palmitic acid appeared more in the neutral lipids. A large proportion of the labelled acetic acid incorporated into neutral lipids appeared in the triglycerides. P. microbothrium is capable of synthesizing its cholesterol de novo.

The relationship between microfilarial density and uptake of Foleyella candezi microfilariae by Aedes aegypti.

There was a linear regression in the square root of the numbers of microfilariae abstracted (square root of y) by Aedes aegypti refm strain on the square root of the density of microfilariae in the infecting blood (square root of x). The linear regression is represented by the equation, square root of y = 0.080,59 square root of x + 4.556 (r = 0.627; P less than 0.01). - Ae. aegypti abstracted microfilariae about 1.60 times that expected from the infecting blood meal. This value however decreased, when the microfilariae in the infecting blood meal increased possibly due to error in counting large numbers of microfilariae. - The volumes of blood ingested by three strains of Aedes aegypti (+fm/+fm, refm/refm, reF/reF) appeared to be unaffected by genes controlling susceptibility or refractoriness to filariae (Foleyella candezi). - The Duncan's multiple range test showed similarity (p greater than 0.01) in percentage uptake efficiency, 157.28 and 164.28 for black-eyed homozygous susceptible and red-eyed homozygous susceptible strains respectively. There was significant difference between either of the homozygous susceptible strains and the homozygous refractory triple marker strain (calculated F-value = 28.61; critical tabular F-value = 10.92; p less than 0.01). Therefore, the % uptake efficiency of Ae. aegypti for F. candezi microfilariae is influenced by the gene (fm) which also allows the development of the filariae. - The percentage efficiency (observed/expected X 100) in abstracting microfilariae from infecting blood source by homozygous susceptible strains was about twice that (80.98%) observed for a homozygous refractory triple marker strain.

The influence of the gene sb in Culex pipiens on the development of sub-periodic Brugia malayi and Wuchereria bancrofti.

The gene sb (filarial susceptibility, Brugia pahangi) in Culex pipiens controls the development also of sub-periodic B. malayi, but has no influence on the development of periodic Wuchereria bancrofti (Ceylon strain). C.p. fatigans (Kuala Lumpur), C.p. molestus (London) and Aedes aegypti (re fm strain) were all susceptible to the Ceylon strain of W. bancrofti, with susceptibility rate of 90.3%, 92.9% and 52.6% respectively. However, a low proportion of the larvae in A. aegypti developed to maturity, and this mosquito is less well adapted to W. bancrofti than is C. pipiens.

Susceptibility to Brugia pahangi of geographical strains of Culex pipiens fatigans.

Five strains of Culex pipiens fatigans from Kuala Lumpur, Tanga, Bobo Dioulasso, Ibadan and Maracay were tested for susceptibility to Brugia pahangi. The mosquitoes were membrane-fed on infected blood in which the parasite density ranged from 1-3 to 20-4 mff/mm(3). The susceptibility rates were low, and were not directly related to the parasitaemia. If the susceptible individuals represent homozygotes for the gene sb (the gene controlling susceptibility to B pahangi in C. pipiens), the gene frequencies in the five strains were 0-33, 0-23, 0-28, 0-12 and 0-31 respectively.

The fate of ingested Brugia pahangi microfilariae in susceptible and refractory strains of Culex pipiens and Aedes aegypti.

The uptake and migration of microfilariae of Brugia pahangi in susceptible and refractory Culex pipiens and Aedes aegypti were compared after membrane-feeding the mosquitoes on infected blood and anti-coagulant. There was no difference between the strains within each species in the pattern of migration, but in C pipiens only 24% of the microfilariae reached the thorax whereas in A. aegypti 73-6% were successful. In both susceptible strains the filariae in the thorax developed normally to maturity, but in both refractory strains almost all filariae died within a few days.

The pattern of parasitic infection in human gut at the Specialist Hospital, Benin City, Nigeria.

In a survey of 6213 persons conducted between January 1973 to December 1974, at the Specialist Hospital, Benin City, the most common helminths were Necator americanus (16.8%), Ascaris lumbricoides (19l5%) and Trichuris trichiur (5-9%). Dicrocoelium hospes (0-06%) was also recorded and this may become an important liver parasite of man in Nigeria. Its snail vectors are believed to be species of Limicolaria and Achatina which are widely dispersed in Nigeria. Entamoeba coli and E. histolytica showed peaks during the "fly seasons", indicating that the housefly, as well as water, may be an important source of contamination. Trichomonas hominis showed peaks in the rainy seasons, and this suggests that in Benin City transmission is chiefly via contaminated domestic water-supply. The incidence of A. lumbricoides and N. americanus was high throughout the rainy and dry seasons, indicating poor disposal of human excreta and a continuous pattern of infection. The type of food and method of cooking prevented or reduced the incidence of Taenia solium, T. saginata, Diphyllobothrium latum and Fasciola gigantica.