Sudanese Strains Research Articles

Pyrethroids and organochlorines resistance in cotton aphidAphis gossypii(Glov.) (Homoptera: Aphididae) in the Sudan Gezira

Abstract The resistance to insecticides of six Sudanese strains of Aphis gossypii (Glov.) collected from cotton fields in Sudan Gezira over four consecutive crop seasons (1988, 1989, 1990, 1991) and that of two French strains, was studied in the laboratory. When compared with a known English susceptible strain, Sudanese aphids were found to be resistant to the four insecticides tested (fenvalerate, deltamethrin, endosulfan and γ‐HCH) while the French strains were relatively susceptible. Evolution of insecticide resistance in Sudanese strains over the four crop seasons was observed. The high synergist ratios and the decrease in resistance factor for the resistant strain, Sudan V, in experiments with piperonyl‐butoxide (PB), an inhibitor of mixed function oxidase, and pyrethroids (deltamethrin and fenvalerate) and also PB with organochlorines (endosulfan and γ‐HCH), suggested that enhancement of the activity of this class of enzyme was a cause of resistance in the Sudanese strain of A. gossypii.

Insecticide resistance in cotton aphid Aphis gossypii (Glov.) in the Sudan Gezira

AbstractThe resistance to insecticides of three Sudanese strains of A. gossypii (Glov.) collected from cotton fields in the Sudan Gezira Scheme over three seasons (1988, 1989, 1990) and that of two French strains was studied in the laboratory. When compared with a known susceptible strain, the aphids were found to be resistant‐to the eight insecticides tested. Evolution of resistance in Sudanese strains during the three crop seasons was observed. Assay of aphid homogcnate for carboxytesterase activity towards the substrates α‐naphthyl acetate and β‐naphthyl acetate showed that there was no enhancement of this class of enzyme and thus it was not a cause of resistance in this species. A study of interaction between the acetylcholinesterase (AchE) and pirimicarb established the kinetics of the inhibition process. I50 values were found to be much higher for the Sudanese strains than for the susceptible strain. First‐order inhibition kinetics revealed that resistance towards pirimicarb in Sudanese‐strains was caused by a modified AchE which had a reduced affinity (higher Ka value) and poor carbamylation ability (lower K2 value) for pirimicarb. The resistance mechanisms for the other insecticides remain to be studied.

Characterization of epidemic and nonepidemic Neisseria meningitidis serogroup A strains from Sudan and Sweden

A random selection of 25 strains isolated during an epidemic caused by serogroup A Neisseria meningitidis in Sudan (1988), 3 preepidemic meningococcal strains (1985), and 26 serogroup A strains isolated from sporadic cases of meningitis in Sweden (1973 to 1987) were assessed for multilocus enzyme genotypes (ETs), DNA restriction enzyme patterns, outer membrane proteins, lipopolysaccharides, pilus formation, and antibiograms. All of the 25 Sudanese epidemic isolates and 22 of the Swedish strains were of the same or closely related ETs (ETs 3, 4, and 5), corresponding to clone III-1, which has been responsible for two pandemic waves in the last three decades. The earlier pandemic involved Scandinavia, and the last one caused an outbreak during the pilgrimage to Mecca, Saudi Arabia (August 1987), spreading to Sudan, Chad, and Ethiopia. The three Sudanese preepidemic isolates (1985) were clone IV-1 (sulfonamide susceptible), which has been resident in the African meningitis belt for the last 25 years. The uniformity of clone III-1 strains (all sulfonamide resistant) from Sudan and Sweden was confirmed by DNA restriction enzyme patterns. ETs 3, 4, and 5 from Sudan and Sweden had 86 to 100% similarity to a Swedish clone III-1 reference strain, whereas ETs 1, 2, 6, and 7 showed 50 to 80% similarity. Class 1 protein for clone III-1 showed serosubtype antigens P1.9 and P1.x, whereas ET6 strains (clone IV-1) had serosubtype P1.7. Lipopolysaccharides were variable in the Sudanese and Swedish strains. Pili were expressed in all clone III-1 isolates from Sudan and Sweden but in none of the clone IV-1 isolates (Sudan, 1985).

Childhood Acute Bacterial Meningitis in the Suda: An Epidemiological, Clinical and Laboratory Study

The aims of the present study were to document the epidemiology, clinical features and complications of childhood acute bacterial meningitis (ABM) in The Sudan during both an inter-epidemic (endemic) period (1985-1986), and the 1988 serogroup A epidemic; and to examine the phenotypic and genetic similarities and differences of Neisseria meningitidis strains isolated in The Sudan and Sweden. A new enzyme immunoassay test (Pharmacia Meningitis EIA-Test) was evaluated as a potential rapid diagnostic method for the detection of Haemophilus influenzae (HI) type b, Neisseria meningitidis (MC) and Streptococcus pneumoniae (PNC). The test was found to have good sensitivity (0.86) and specificity (0.95) in the inter-epidemic period; and to be adaptable to the field work in The Sudan during the 1988 MC epidemic. During inter-epidemic (endemic) situations in The Sudan, greater than 90% of childhood ABM was caused by one of the three organisms, HI type b, MC and PNC. HI accounted for 57% of the cases. The peak incidence (76%) of HI cases was in infants (less than 12 months) similar to the situation in other African countries. The overall case fatality ratio was 18.6%. Prospective follow-up of survivors for 3-4 years revealed that an additional 43% either died or had permanent neurological complications, the most prevalent and persistent of which was sensorineural hearing loss recorded in 22% of long term survivors. Post-meningitic children were found to have significantly lower intelligence quotients (92.3 +/- 13.9) than their sibling controls (100.7 +/- 10.2, P = 0.029). Features of the large serogroup A sulphonamide resistant MC epidemic (February-August 1988) in Khartoum are described. An estimated annual incidence of 1,679/100,000 was recorded at the peak of the epidemic. The highest attack rate was in young children less than 5 years, as in many other African countries; nevertheless, a high morbidity was observed in adults (31% of the cases greater than or equal to 20 years). The clinical features, mortality (6.3%) and short term sequelae in Sudanese children were generally within the framework described for MC disease elsewhere. Detailed analysis of MC isolates from Sudan and Sweden by characterizing their electrophoretic enzyme types, DNA restriction endonuclease pattern and outer membrane proteins, revealed that serogroup A MC clone III-1 was responsible of The Sudan epidemic in 1988 and has been the dominant serogroup A organism in Sweden since 1973. The Sudanese strains isolated prior to the epidemic (1985) were clone IV-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative Studies on Aphid Transmission of the Sudanese Strain of Peanut Stunt Virus

AbstractThe Sudanese strain of peanut stunt virus was transmitted by Aphis craccivora, Aphis solanella, Myzus persicae and Liaphis erysimi. Of these, A. solanella and L. erysimi were reported for the first time as vectors of peanut stunt virus. A. gossypii, A. solani and Rhopalosiphum maidis failed to transmit the virus. Viruliferous aphids retained the virus for 30 minutes but post‐acquisition starvation beyond 30 minutes resulted in almost complete loss of the virus. A. craccivora transmitted the virus to four consecutive test plants and A. solanella, L. erysimi and M. persicae transmitted the virus to three consecutive test plants. It has been suggested that future research programmes should, include resistance to the virus in the major legume crops and that a crop like lucerne (Medicago sativa) which harbours both the virus and its vectors, should not be introduced in the major peanut‐growing areas of the Sudan.

Genetic studies of malathion resistance in Anopheles arabiensis Patton (Diptera: Culicidae)

AbstractCrosses of Sudanese strains of Anopheles arabiensis Patt. resistant and susceptible to malathion indicated that the resistance was incompletely dominant. The results of tests of male progeny of successive backcrosses agreed well with the hypothesis of control of the resistance by a single gene. However, the results from females suggested the additional involvement of a sex-limited modifier. Tests of mixtures initiated with a 1:1 ratio of resistant and susceptible first-instar larvae gave little evidence for selective mortality during the larval stage. However, the mortalities in tests on malathion recorded among adults emerging on successive days from these mixtures, and also from F2 and backcross progenies, indicated that the development of the resistant larvae was significantly faster than that of the susceptible ones. The fact that this occurred in the F2 and backcross progenies indicates that it may be due to a pleiotropic effect of the resistance gene, but it is pointed out that results from much more prolonged backcrossing would be necessary to rule out the possible effects of linked genes.

Haemorrhagic fever in Gabon. I. Incidence of Lassa, Ebola and Marburg viruses in Haut-Ogooué

A serological enquiry aimed at determining the incidence of infection with Lassa, Ebola and Marburg viruses was conducted on the human population of the region of Haut-Ogooué (Gabon) and on primates. The results, obtained by the indirect immunofluorescence technique, showed that more than 6% of the human population had had contact with Ebola virus but no antibodies against Marburg or Lassa viruses were found. Most sera reacted to an Ebola antigen from a Zairian strain, but showed little or no reaction to an antigen from a Sudanese strain.

Ebola and Marburg viruses: II. Thier development within Vero cells and the extra-cellular formation of branched and torus forms.

The development of Marburg virus and the Sudanese and Zaire strains of Ebola virus in Vero cells as visualized by electron microscopy is described. Despite differences in timing, all three strains appear to pass through identical stages of development. Initially there is a large increase in nucleolus material, and viral precursor material arranges itself in spirals and then into tubes. The cells fill with core material, which passes to the plasmalemma, which often proliferates. Each virion passes through the plasmalemma, acquiring a coat of host material. The formation of torus forms is discussed; the branched appearance that is often seen is believed to be an aberrant form. The reasons for this view are put forward.

Thein vivodevelopment ofSchistosoma bovisin the Nile rat

The in vivo development of the Sudanese strain of Schistosoma bovis in the Nile rat, Arvicanthus niloticus is described. Six stages in development are distinguished: the 'lung form' (stage 1), attaining maximum numbers on day 5 post-infection; the 'closed-gut form' (stage 2) on day 14, characterized by the union of the gut caeca behind the ventral sucker; 'organogeny' (stage 3) on day 17, the male possessing one testis and a gynaecophoric canal and the female a narrow uterus; 'gametogeny' (stage 4) on day 26, with pairing, the male having four fully developed testes and the female an ovary; 'egg-shell formation' (stage 5) on day 35; 'oviposition' (stage 6) on day 37, with the female showing uterine eggs. The time to complete in vivo development in the Sudanese strain of S. bovis is more rapid than in the Israeli strain, 37 and 42 days respectively.

Leishmaniasis in the Sudan Republic. 29. Comparison and Epidemiological Implications of Experimental Canine Infections with Sudanese, Mediterranean, and Kenyan Strains of Leishmania donovani

Three strains of Leishmania donovani from different geographic areas [Sudan, Mediterranean (Sicily), and Kenya] were studied comparatively in puppies and adult dogs under controlled laboratory conditions. Hematological, serological, and endocrinological investigations were included. However, only the course of infection is discussed here. The growth curve of the parasites in the liver was studied, as well as the pattern of infection in different organs at different periods. The pattern of both liver and spleen infections caused by the Mediterranean strain proved to be different from and more variable than that caused by the Sudan and Kenya strains, which developed similarly except for an earlier decline of parasite numbers followed by spontaneous cure in the Kenya strain. Assuming the results from these strains to be fully representative of their respective areas, it is suggested that the dog may be excluded as a probable natural reservoir of L. donovani in Kenya and that its role as a vertebrate reservoir in the Sudan is doubtful. The results confirm that the dog is an efficient reservoir of the pathogen in the Mediterranean area. In areas where kala azar is endemic, dogs are frequently abundant and closely associated with man. They play an important role as reservoir hosts of Leishmania donovani in China, several foci in the USSR, Brazil, and many localities in the Mediterranean basin. Canine leishmaniasis has been reported but is inadequately documented in several areas of Africa. No canine infections have been reported from Kenya (Henderson, 1937; Heisch, 1954, 1963) or the Sudan (Archibald and Mansour, 1937; Kirk, 1956; Hoogstraal et al., 1963; Hoogstraal and Heyneman, 1969). The paradoxical discrepancies between recorded distributions of human and canine infections require experimental investigation to evaluate the interrelationships between different geoReceived for publication 8 January 1970. * Parasitology Department, U. S. Naval Medical Research Unit Number Three, Cairo, Egypt, UAR. This work was undertaken at the Bureau of Biological Research, Rutgers-The State University, under the auspices of Office of Naval Research Postgraduate Research Grants NONR00038-65 and NONR-0137-66. From Research Project MF12.524.009-3001B, Bureau of Medicine and Surgery, Department of the Navy, Washington, D. C. The opinions and assertions contained herein are the private ones of the authors and are not to be construed as official or as reflecting the views of the Department of the Navy or of the naval service at large. t Bureau of Biological Research, Rutgers-The State University, New Brunswick, New Jersey 08903. graphical strains of the organism and the dog, and to assess the role of the dog in kala azar epidemiology in different areas. This report, abstracted from a more extensive study to be published elsewhere, is intended chiefly to elucidate factors influencing the epidemiological role of the dog in Central Sudan and to contribute to the results of an extensive field and laboratory study of kala azar in that country (Hoogstraal and Heyneman, 1969). Although several studies have been devoted to L. donovani infection in the dog, none has used standardized procedures for inoculation, sampling, and evaluation. Stauber (1955) established a quantitative procedure that makes it possible to follow the course of infection with reasonable accuracy. Stauber et al. (1966) emphasized the importance of standardized quantitative procedures and Stauber (1966) applied these criteria to a comparison of interstrain variation in L. donovani. These studies established that intravascular inoculation of relatively large numbers of organisms is required to produce infections of relatively low variability for accurate estimates in vivo of L. donovani strain differences. These techniques have been employed in the present study. MATERIALS AND METHODS Three groups of 4 adult dogs (average age 5 years) and 5 groups of puppies, at least 4 in each group from the same litter (average age 4 weeks), were infected with the following strains of Leishmania donovani.

Leishmaniasis in the Sudan Republic

Leishmaniasis in the Sudan Republic

The thiacetazone sensitivity of Mycobacterium tuberculosis.

Summary A statistical analysis of the results of a comparison of 4 measures of the thiacetazone sensitivity of 90 wild strains of the tubercle bacillus leads to the conclusion that the best measure is the drug concentration that inhibits growth of 20 colonies from a standard inoculum (MIC 20) after 28 days' incubation. There was no evidence of natural thiacetazone resistance among 30 British and 30 Sudanese strains; a few of the East African strains were apparently resistant to thiacetazone.

Insecticide susceptibilities of Phlebotomus papatasi (Scopoli) from Egypt and the Sudan.

Abstract : Susceptibility levels for Egyptian and Sudanese strains of Phlebotomus papatasi were determined through the use of the W.H.O. Standard Test Kit for Adult Sandflies. Mean LC30 values for DDT ranged from 0.80-1.93% and for dieldrin from 0.63-1.0%. Laboratory-colony sandflies were found to be slightly more tolerant to both insecticides than were wild-caught specimens, possibly a manifestation of vigor tolerance.

The use of pyruvate-containing EGG medium in the isolation of sudanese strains of tubercle bacilli

The benefit of simultaneous inoculation of glycerol- and pyruvic acid-containing solid egg media in the primary isolation of tubercle bacilli from Sudanese patients has been shown to be as great as in the case of European strains reported by Stonebrink (1958; 1961), Marks (1963) and Hughes (1966).

The relationship between human and animal strains of Leishmania from the Sudan

Sudanese strains of Leishmania isolated from 2 human cases of kala-azar, 3 human cases of cutaneous leishmaniasis, 2 naturally infected sandflies ( P. orientalis), naturally infected specimens of Rattus rattus, Arvicanthis niloticus luctuosus, Acomys albigena, Genetta genetta senegalensis and Felis serval philipsi, were examined serologically by growth on medium containing immune serum. With this method all these strains were indistinguishable from each other and are considered to belong to the same species. 3 cases of cutaneous leishmaniasis from which strains were studied are considered to have either abortive kala-azar or primary leishmaniomas. These findings add to the existing epidemiological evidence that kala-azar in the Sudan is a zoonosis, and that L. donovani is propagated in an animal reservoir by cyclical transmission through a sandfly, P. orientalis.

Immunity in kala-azar

1. 1) The leishmanin test is described and its interpretation discussed in the light of recent work. This test becomes positive 6–8 weeks after treatment has been completed in kala-azar, and a similar period after the intradermal inoculation of rodent strains of L. donovani. This positive reaction may revert to negative in either case with the passage of time. 2. 2) Where over 5 per cent. of the population of an area show a positive leishmanin reaction, then kala-azar is endemic in that area. 3. 3) A positive leishmanin reaction denotes resistance to superinfection with any strain of L. donovani, but not of L. tropica. This immunity, which is complete in the early stages, fades with time but can be at least partially restored by subsequent inoculations of leptomonad cultures. 4. 4) The ground-squirrel strain of L. donovani isolated by Heisch (1957) is perfectly safe for use as a live vaccine to protect against kala-azar, since it does not produce visceral lesions in man when inoculated by the dermal route. Subjects immunized with this strain are immune to challenge from East African, Sudanese, Mediterranean and Indian strains of L. donovani, but show no immunity to any strains of L. tropica. 5. 5) There is complete cross immunity between all strains of L. donovani, but none between L. donovani and L. tropica.

Prophylactic inactivity of pentamidine in experimental leishmaniasis

1. (1) Pentamidine at a single intramuscular dose of 50 mg/kg. failed as a prophylactic in the Syrian hamster against three different strains of L. donovani, one of Sudanese origin and two from the Kitui area of Kenya. The infections were induced by spleen-mash injection at an interval after treatment of 1 week with the Kenya strains (S1, S2), and of 1, 2, and 4 weeks with the Sudanese strain. 2. (2) Under these conditions, the same dose of 2-hydroxystilbamidine was prophylactically inactive against a Kenya strain (S2) at an interval of 1 week after treatment. 3. (3) The same dose of pentamidine failed to protect hamsters against infections with the Kenya strain (S2) induced by flagellate injections given twice (at 7 and 20 days after treatment). 4. (4) A single intramuscular dose of 50 mg./kg. of either pentamidine or 2-hydroxystilbamidine was therapeutically inactive in hamsters against an established spleen-mash-induced infection of the Sudanese strain.