Survival and reproductive performance of female Glossina morsitans morsitans when maintained on the blood of different species of wild mammals.

A study was carried out to determine the effect on the reproductive performance of female Glossina morsitans morsitans Westwood when allowed to feed, in vitro, for 63 days on fresh defibrinated blood of buffalo, bushbuck, cattle, eland, oryx, warthog, waterbuck or wildebeest. There were marginal differences in the survival and reproductive performance between eight different groups of tsetse, 200 per group, when fed on the blood of these mammalian species. When allowed to feed for 14 consecutive days on the blood of buffalo, wildebeest or warthog, the mean number of feeds were 6.2 +/- 0.3, 6.5 +/- 0.3 and 6.3 +/- 0.3, respectively. The mean weight of the bloodmeal taken also did not differ significantly between these three groups. Whereas the protein patterns of the blood plasma of the above eight host animals were different, the protein patterns of the haemolymph from tsetse fed on the blood of these hosts were identical. It is thus concluded that the preference shown by tsetse for some mammalian species investigated here may not be based on any aspect of the nutritional value of their blood.

Immune effector mechanisms involved in the control of parasitaemia in Trypanosoma brucei-infected wildebeest (Connochaetes taurinus).

The course of Trypanosoma brucei infection in the wildebeest (Connochaetes taurinus) was studied. A low but persistent parasitaemia developed in all five wildebeest following intravenous inoculation with 1 X 10(8) organisms of clone ILTat 2.1. Unlike cattle controls, however, the wildebeest did not develop anaemia. In both cattle and wildebeest, radioimmunoassay studies revealed a classical sequence of production of IgM, IgG1 and IgG2 antibodies which had the capacity to bind to the corresponding purified variable surface glycoprotein and to neutralize the infectivity of ILTat 2.1. Investigations into the interaction between post-infection sera, trypanosomes and freshly isolated peripheral blood leucocytes (PBL) of wildebeest and cattle showed that sera from the wildebeest had a higher capacity to induce adherence of trypanosomes to homologous PBL. The adherence and phagocytosis-inducing activity resided in the IgM fraction. Cross-testing of the antibodies and PBL revealed that wildebeest IgM antibodies induced high adherence indices when tested on cattle PBL. High adherence indices were also observed when cattle IgM antibodies were tested on PBL of wildebeest. It was concluded that the phagocytic system of the wildebeest was superior to that of cattle, that freshly prepared wildebeest PBL bear receptors for wildebeest as well as cattle IgM, and that cattle PBL bear a receptor for wildebeest IgM that would appear to be different from that for cattle IgM.

Antibodies to Brucella spp. among blue wildebeest and African buffalo in Kenya.

A serologic survey of blue wildebeest (Connochaetes taurinus Burchell) and African buffalo (Syncerus caffer Sparrman) in the Masai Mara area was conducted. Antibodies to Brucella spp. were found in 18% of the blue wildebeest and 30% of the African buffalo examined. There were titers in all age groups and in both sexes. Hygromata were seen in both species. The increase in numbers of blue wildebeest and African buffalo which share grazing and watering areas with cattle of the Masai people, makes the presence of infections by Brucella spp. in wildlife an important consideration in any program for control of brucellosis.

Hydatid disease in the Turkana District of Kenya, IV. The prevalence of Echinococcus granulosus infections in dogs, and observations on the role of the dog in the lifestyle of the Turkana.

The prevalence of Echinococcus granulosus in dogs in the Turkana District of Kenya was 39.4% of 695 examined. Of these, 98 (35.8%) had heavy Echinococcus worm burdens (10(3)-5 X 10(4) ), while 54 (19.7%) and 122 (44.5%) had medium (201-1000) and light (1-200) burdens. The possible sources of these infections are discussed. The prevalence rate differed in various parts of the district, ranging from 63.5% in the northwest, where the highest incidence of human hydatidosis also occurs, to nil along the shores of Lake Turkana. Infection rates of 32.0% and 16.7% were recorded at Lokitaung (north-east) and Lodwar (central), while in the south 48.9% of dogs harboured Echinococcus. This latter figure is surprising as the area has a low incidence of human hydatidosis. The Turkana keep a large number of dogs, and the reasons for this and the social role of the dog in the district is discussed. No difference in susceptibility was found between Turkana-type dogs and those of mixed breeds from Nairobi when they were experimentally infected with hydatid protoscolices from man, camels, cattle, sheep and goats. However, it proved difficult to infect the Turkana-type of dogs with viable protoscolices of cattle origin. The reasons for this and its epidemiological implications remain unclear. It is suggested that droughts, which affect Turkana every six to ten years, may play an important role in the perpetuation of hydatid disease in the area.

Re-emergence of rinderpest as a threat in East Africa since 1979.

Following the success of the JP15 scheme and subsequent annual vaccination campaigns, East Africa was virtually free of rinderpest after the mid 1960s and the disease was considered beaten. However, economic difficulties have recently reduced the expensively maintained vaccine cover and the disease has reappeared throughout much of the region. In 1979 rinderpest was diagnosed in cattle in north eastern Uganda and caused considerable losses until finally brought under control in 1981. No field outbreaks of the disease in cattle have been seen in Kenya but there is serological evidence that the virus has recently infected unvaccinated sheep and goats and wild ungulates in that country. In 1982 rinderpest was confirmed in the laboratory as the cause of death of large numbers of buffaloes in northern Tanzania and implicated as the cause of a rinderpest-like disease of cattle which is reported to be still active in that area. Substantial aid is essential for further control and research if the virus is not again to become endemic in the region.

Role of wildebeest fetal membranes and fluids in the transmission of malignant catarrhal fever virus.

Malignant catarrhal fever virus was not isolated from samples of fetal membranes or fluid collected from 93 calving wildebeest (Connochaetes taurinus) in Kenya Maasailand. Cell-free strains of malignant catarrhal fever virus were very rapidly inactivated when exposed to the sun under field conditions, at least 3.0 log10 units/25 microliter being lost per hour at midday. It is suggested that wildebeest fetal membranes and fluids act as visual markers for areas of pasture which are particularly heavily contaminated with malignant catarrhal fever virus in oculonasal secretions of wildebeest calves. It is possible that starting to graze cattle one to two hours later each morning may be a useful measure for helping to protect cattle from malignant catarrhal fever in areas where they are forced to share pastures with calving wildebeest.

Hydatid disease in the Turkana District of Kenya. III. The significance of wild animals in the transmission of Echinococcus granulosus, with particular reference to Turkana and Masailand in Kenya.

The results are given of a study on the role of wildlife in the transmission of Echinococcus granulosus in the Turkana and Narok Districts of Kenya. A total of 76 wild carnivores belonging to three separate species was examined from Turkana District. Echinococcus adults were found in 11 of 38 silver-backed jackals (Canis mesomelas) and in six of 22 golden jackals (Canis aureus). This is the first record of golden jackals being infected with this parasite in Kenya. None of 16 spotted hyaenas (Crocuta crocuta) harboured the parasite. Morphological features of the parasites obtained from the jackals were compared with material obtained from dogs in the same area. No morphological differences were recorded when this material was compared with data reported by others, hence the Turkana material belonged to the single species E. granulosus. Three silver-backed jackals and three puppies (Canis familiaris) were successfully infected with protoscolices obtained from a hydatid cyst surgically removed from a Turkana patient. Three spotted hyaenas fed the same material failed to become infected. None of 152 wild herbivores of five species examined in Turkana harboured hydatid cysts. The natural jackal infections in this District are thought to be incidental and dependent on the continuance of the domestic cycle. The role of the Turkana themselves in the perpetuation of the cycle is discussed. Twenty-six wild herbivores of six species were examined for hydatid cysts, in Narok District; hydatids were found in three wildebeest (Connochaetes taurinus) and a single topi (Damaliscus korrigum). The discovery of fertile cysts in wildebeest and the reported infections in lions (Panthera leo), Cape hunting dogs (Lycaon pictus) and silver-backed jackals, support previous evidence of the existence of a wildlife cycle in the Masailand and Serengeti regions of East Africa. The relationship of this cycle to the domestic cycle operating in the same area is unclear and requires further investigation.

Antibodies in carrier wildebeest to the lymphoproliferative herpesvirus of malignant catarrhal fever.

Six types of antibody to malignant catarrhal fever virus (MCFV) were measured in 132 sera collected from Wildebeest in Kenya Masailand. The titre of all types of antibody declined slowly with increasing age of the wildebeest. A significantly greater proportion of wildebeest calves had higher titres of antibodies to MCFV early antigens, IgM antibodies to MCFV late antigens and complement-fixing antibodies, than did older animals. One seronegative calf, reared in isolation without colostrum, became seropositive 4 1/2 weeks after birth but did not show any clinical signs indicative of MCFV infection. Similarities between MCFV infection of wildebeest calves and other inapparent infections with lymphoproliferative herpesviruses are discussed.

Neutralising antibodies to rinderpest virus in wild animal sera collected in Kenya between 1970 and 1981.

Four hundred and twenty five sera were collected from 18 species of wild mammals in Kenya between 1970 and 1981. Neutralising activity to rinderpest virus (RV) was detected in 35 samples from 13 species. This activity appeared to be specific antibody to RV since it did not neutralise the virus of peste des petits ruminants. It was associated with the serum globulin fraction and it blocked the staining of a rabbit immunofluorescent antibody conjugate to RV. Positive sera were not restricted to any particular area of Kenya. It is possible that strains of RV with low pathogenicity and low transmissibility are still present in wildlife in East Africa, a fact which must be considered when studying the epidemiology and control of rinderpest.

Malignant catarrhal fever virus specific secretory IgA in nasal secretions of wildebeest calves.

Wildebeest IgA was isolated from nasal secretions and precolostrum. It was identified by cross-reaction with anti-human and anti-bovine IgA sera. Nasal secretions collected from wildebeest calves over 3 months old had malignant catarrhal fever virus neutralizing antibody activity. They also contained specific IgA to the virus as detected by indirect immunofluorescence. It is suggested that production of malignant catarrhal fever virus specific IgA in the nasal cavity, contributes to the elimination and cessation of the virus shed in the nasal secretions of wildebeest calves over 3 months. old.

The demonstration of cell-free malignant catarrhal fever herpesvirus in wildebeest nasal secretions.

Malignant catarrhal fever (MCF) herpesvirus was isolated from the nasal secretions of 4/11 young wildebeest calves. In two cases virus was demonstrated in filtered secretions. The presence of cell-free MCF virus would suggest that the virus can be transferred from wildebeest to wildebeest and into cattle in nasal secretions.