Suggested dosage rates of melarsoprol in the treatment of mice experimentally infected with Trypanosoma brucei gambiense

One group of BALB/c mice infected with a highly virulent strain of Trypanosoma brucei gambiense were treated intraperitoneally with three series of three injections (each injection of 10 mg/kg) of Mel-B separated by seven days of rest, while a second group was treated once by a single injection. All the Mel-B treated mice in both experiments were negative for parasites when examined using either the wet blood film or buffy coat methods, but were intermittently PCR positive during the sampling period. We encourage the use of a repeat negative PCR test over a one month period in combination with corroborative clinical and parasitological investigation to be suggestive of cure in experimental animals previously infected with trypanosomosis. In view of the exorbitant costs of Mel-B and its extreme toxicity, it is recommended that Mel-B be given as one course of two injections (each equivalent to 10 mg/kg) separated by 2 d of rest in experimentally infected rodent models.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.Japan International Cooporation Agency (JICA) through the Ministry of Research. Technical Training of the Government of Kenya.mn201

Leishmania major infections in Phlebotomus duboscqi fed on murine models immunized with L. major subcellular antigens and sandfly gut antigens

The ability of antibodies in bloodmeals of mice and hamsters immunized with Leishmania major subcellular fractions and sandfly (Phlebotomus duboscqi) gut antigens to inhibit development of L. major in its vector P. duboscqi was examined. Antibodies from animals immunized with either L. major subcellular fractions alone or sandfly gut antigen alone were not very effective in inhibiting development of L. major in the sandfly. When P. duboscqi were fed on blood from animals immunized with both parasite flagella and sandfly gut antigen, development of L. major was significantly inhibited ( P<0.05). Control sandflies fed on naive animals displayed a normal pattern of parasite development to the metacyclic stage. Electron microscopy studies showed that one of the mechanisms through which antisandfly gut antibody can cause inhibition of parasite development is by lysing sandfly gut epithelium. This study has demonstrated that it is possible to reduce transmission of leishmaniosis through immunization against both the parasite and its sandfly vector.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.UNDP/WORLD BANK/WHO, Special Programme for Research and Training in Tropical Diseases. Kenya Medical Research Institute (KEMRI).mn201

A survey of tick control methods used by resource-poor farmers in the Qwa-Qwa area of the eastern Free State Province, South Africa

A survey conducted in five villages in a resource-poor farming community in Qwa-Qwa, using the rapid rural appraisal technique and a questionnaire survey, showed that a significant proportion of the farmers (84 %) use traditional or alternative methods to control ectoparasites, while 16 % use commercial acaricides (c2 = 7.1; P < 0.05). Alternative control methods included the use of used engine oil, household disinfectant and paraffin. Killing of ticks was the main reason for control (40 %), with disease control being second (20 %). Other reasons given for controlling ticks were to prevent damage to teats, to provide animals with a clean appearance and to protect hides. Some 40 % of farmers were aware of the effects of ticks on their animals. There is a need for farmer education that will provide information on integrated tick management and its advantages over absolute reliance on commercial acaricides

Seasonal abundance of adult ixodid ticks infesting cattle belonging to resource-limited farmers in the north-eastern Free State Province of South Africa

A study was undertaken to determine the seasonal abundance of the ticks infesting cattle owned by resource-limited farmers in the northeastern Free State Province of South Africa. Infestations of Boophilus decoloratus, Rhipicephalus evertsi evertsi, R. follis, R. gertrudae and Rhipicephalus warburtoni were monitored on cattle of mixed breeds at monthly intervals from May 1998 to April 1999. High tick intensity on the cattle was observed between March and June, with a peak in May to June 1998 for B. decoloratus and R. evertsi evertsi. Few ticks from the other three species were recovered from the cattle. Small peaks in November to December 1998 for R. warburtoni and in December 1998 for R. follis and R. gertrudae were observed. Following the winter (June to August), numbers of B. decoloratus declined markedly, while those of R. evertsi evertsi and other rhipicephalids increased. These results represent the first published information on ticks of veterinary importance infesting cattle in the northeastern part of the Free State Province.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.National Research Foundation. University of the North, Qwa-Qwa Campus.mn201

Diseases of free-ranging chickens in the Qwa-Qwa district of the northeastern Free State province of South Africa

A total of 177 free-ranging chickens from 19 Qwa-Qwa villages were bled from wing veins over a period of 6 months (June-November 2000). Serological tests indicated that 5 % of chickens tested had been exposed to Newcastle disease, 43 % to infectious bronchitis and 63 % to Mycoplasma gallisepticum infection. McMaster and Visser sieve techniques were used to determine helminth and coccidia from pooled fresh faecal samples. Helminths isolated in 37 % of the villages investigated were Heterakis, Ascaridia and Capillaria species. Eimeria species were also isolated in 32 % of the villages investigated. The red fowl mite (Dermanyssus gallinae) was isolated from some of the birds and their nests. Data from a questionnaire survey indicated that all farmers interviewed had never received any technical support and that their chickens had never been vaccinated against any avian diseases. Only 10.5 % of the owners interviewed had scientific knowledge on poultry diseases. There is an urgent need for the government to support free-ranging poultry farmers by providing subsidised vaccinations and technical support in order to develop and stimulate economic development in impoverished rural areas of South Africa

Cross-reactivity between antigens from Amblyomma cajennense and A. hebraeum (Acari : Ixodidae)

Laboratory animals exposed to feeding ticks develop resistance which is reflected by a decline in tick engorgement weight, egg-laying by adults and reduced egg viability. Serum antibodies from these hosts and their reaction with tick antigens have been detected by different methods, including precipitation techniques, immunofluorescent techniques, ELISA and Western blots. However, little is known about the effects of antibodies on ticks that engorge on resistant hosts, or which tissues of the tick body are possibly immunogenic. Some researchers, using immunohistochemistry, have detected host antibodies in the gut, salivary glands and haemolymph of ticks engorged on resistant animals. The same technique has helped considerably in determining antigenic sites or antibody targets in other arthropods. Consequently, immunohistochemistry techniques were used in this study to detect cross-reactivity between sera raised against Amblyomma cajennense (Fabricius, 1787) with Amblyomma hebraeum (Koch, 1844), and vice versa. The results show the existence of shared antigens between the 2 tick species. In general, our results point more to a 1-way cross-reactivity of A. hebraeum with A. cajennense than a reciprocal crossreactivity, suggesting that A. hebraeum is more immunogenic than A. cajennense

<i>Leishmania donovani<i/>-derived lipophosphoglycan plus BCG induces a Th1 type immune response but does not protect Syrian golden hamsters (<i>Mesocricetus auratus<i/>) and BALB/c mice against <i>Leishmania donovani<i/>

The efficacy of Leishmania donovani-derived lipophosphoglycan (LPG) plus Mycobacterium bovis Bacille Calmette-Guérin (BCG) as a vaccine candidate against visceral leishmaniosis in susceptible BALB/c mouse and Syrian golden hamster (Mesocricetus auratus) models was investigated. Following a triple vaccination with a total dose of 150 µl BCG plus 60 µg or 30 µg of LPG for hamsters and BALB/c mice respectively, there were no noticeable side effects both locally and systemically; implying that the molecule was safe at this dosage level. Vaccinated animals demonstrated an activation of both the humoral as well as cell-mediated responses to LPG, which correlated with resistance against the disease. Protection by LPG plus BCG, was however, poor as the remaining immunized animals showed disease progression leading to severity of the disease as illustrated by emaciation, mass loss and heavy splenic parasitaemia in hamsters. These data nevertheless suggest that it may be rewarding to further evaluate the potential of LPG as a vaccine candidate in leishmaniosis using other adjuvants, which may enhance its immunogenicity

Leishmania donovani-derived lipophosphoglycan plus BCG induces a Th1 type immune response but does not protect Syrian golden hamsters (Mesocricetus auratus) and BALB/c mice against Leishmania donovani

The efficacy of Leishmania donovani-derived lipophosphoglycan (LPG) plus Mycobacterium bovis Bacille Calmette-Guerin (BCG) as a vaccine candidate against visceral leishmaniosis in susceptible BALB/c mouse and Syrian golden hamster (Mesocricetus auratus) models was investigated. Following a triple vaccination with a total dose of 150 µI BCG plus 60 µg or 30 µg of LPG for hamsters and BALB/c mice respectively, there were no noticeable side effects both locally and systemically; implying that the molecule was safe at this dosage level. Vaccinated animals demonstrated an activation of both the humoral as well as cell-mediated responses to LPG, which correlated with resistance against the disease. Protection by LPG plus BCG, was however, poor as the remaining immunized animals showed disease progression leading to severity of the disease as illustrated by emaciation, mass loss and heavy splenic parasitaemia in hamsters. These data nevertheless suggest that it may be rewarding to further evaluate the potential of LPG as a vaccine candidate in leishmaniosis using other adjuvants, which may enhance its immunogenicity.The articles have been scanned with a HP Scanjet 8300; 600dpi, saved in TIFF format. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.Intemational Society for Infectious diseases (lSID). Intemational Atomic Agency (IAEA). Kenya Medical Research Institute.mn201

TRANSMISSION BLOCKING VACCINE STUDIES IN LEISHMANIASIS: 11. EFFECT OF IMMUNISATION USING LEISHMANIA MAJOR DERIVED 63 KILODALTON GLYCOPROTEIN, LIPOPHOSPHOGLYCAN AND WHOLE PARASITE ANTIGENS ON THE COURSE OF L. MAJOR INFECTION IN BALBIC MICE

Background: Safe, effective and inexpensive vaccines may be the most practical tool for controlof any form of leishmaniasis. Leishmaniasis produces a state of pre-immunition which is theunderlying mechanism for prolonged immunity to re-infection. Low doses of parasites has beenshown to beable to induce protection in mice. It is not known, however, how immunesel-a froma susceptible host imrnunised with Leishmania-derived antigens when taken in by the sandflyaffects the development and the subsequent transmission of the parasite to naive hosts.Objective: To monitor the course of disease in BALBlc mice following challenge using L.rnajor infected P. duboscqi which had previously fed on immunised mice.Methods: BALBIc mice were immunised adequately withLeishrnania major-derived antigensnamely, crude whole parasite (WPA), recombinant 63 kilodalton glycoprotein (rgp63),lipophosphoglycan (LPG;) ancl a cocktail composed of rgp63 plus LPG antigens. Laboratoryreared Phlebotornus duboscqi sandflies, the natural vector for L. major were later allwwed tofeed on immunised animals, interrupted and allowed to continue feeding on infected animalsfor an equal amount of time until they became fully engorged. The sandflies were maintainedon apples as a carbohydrate source in an insectary maintained at a temperature of 2S°C and80% relative humidity. On the seventh day these sandflies were used to infect naivc B:ALB/c mice and the course of infection followed for a period of at least three months.Results: Mice infected usingsandflies which had previously fed on WPA or rgp63-immunizedmice showed disease exacerbation as the infection progressed, whereas those infected usingsandflies which had previously fed on LPG-immunised mice had the least lesion sizescompared to control mice infected using sandflies which had fed on saline immunised mice(p&lt;0.05).Conclusions: Results from this study indicate that the course of L. major infection in BALBIc mice was dependent on the infective dose of parasites transmitted by the sandflies. R~:sultsfrom this study suggests that sub-infective doses of the parasite from sandflies previously fedon animals immunised with Leishmania-derived antigens needs to be evaluated for theirpotential in vaccine development against Leishmania infections

TRANSMISSION BLOCKING VACCINE STUDIES IN LElISHMANIASIS: I . LIPOPHOSPHOGLYCAN IS A PROMISING TRANSMISSION BLOCKING VACCINE MOLECULE AGAINST CUTANEOUS LEISHMANIASIS

Background: New strategies for control of leishmaniasis is needed as chemotherapy usingantimonial drugs is prolonged, expensive, associated with side effects and relapses. Vectorcontrol has limitations and a vaccine which may be the best approach is not available.Objectives: To assess the level of inhibition of promastigote development and gut morphologyin infected Phlebotomus dubotcqi sandflies fed on different groups of BALBlc mice immunisedwith rgp63, lipophosglycan (LPG) or their cocktail and whole parasite antigens preparedfrom L. major culture-derived promastigotes.Methods: BALBlc mice were immunised adequately with Leishmania major-derived antigensnamely, crude whole para5ite ( WPA), recombinant 63 kilodalton glycoprotein (rgp63), LPG anda cocktail composed of rgp63 plus LPG antigens . Laboratory reared Phlebotomus duboscqisandflies, the natural vector for I, major were later allowed to feed on immunised animals,interrupted and allowed to continue feeding on infected animals for an equal amount of tirne untilthey became fully engorged. The sandflies were maintained on apples as a carbohydrate sourcein an insectary maintained at a temperature of 2S°C and 80% relative humidity. Some of thesandflies were dissected on days 2,4 and 6 after feeding and observed using the light :and thetransmission electron microscopy for any changes in their gut morphology. The remainingsandflies werealldissectdon thesixthday post-feeding and examinedfor procyclics,necton~onads,haptomonads and metacyclic promastigote forms of Leishmania.Results: Sandflies which had previously fed on WPA, LPG plus rgp63 cocktail ant1 LPGimmunisedmice showed the lowest infection rates compared to control sandflies fed on salineimmunised mice (p&lt;0.05). A significant number of procyclic promastigotes, th~e firstdevelopmental form of the parasite in culture as well as in the sandfly was observed insandflies which fed on LPG-immunised mice (pe0.05). The dominant parasite form insandflies which fed on rgp63 or LPG-immunised mice was the nectomonad form but very fewof the infective metacyclic forms (pe0.05). Control sandflies fed on saline immunised orinfected mice alone displayed a normal pattern of parasite development up to the metacyclicstage. Studies showed that two possible mechanisms through which immune sera fromimmunised mice may came inhibition of parasite development is by exflagellation ofnectomonad forms and degeneration of the sandfly midgut epithelium as revealed by lightand electron microscopy studies respectively.Conclusions: This studj has shown that immune-mediated transmission blocking rnay beapplied to Leishmania infections. Based on observation of the procyclic promastigoles, thedominance of the nectomonad forms, low infectivity rates in sandflies fed on LPG-immunisedmice, we concluded that LPG stands out to be a promising transmission blocking vaccinecandidate in leishmaniasis