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lowing work by Brecher and Wigglesworth (1944) on the blood_sucking hemipteron Rhodinus olixus, was to test the ability of symbiotes in the tick to produce gro§th.promoting vitamins in th absence of these substances in host blood. Thiamin, it appears, cannt be manufactured by symbiotes under these conditions but riboflavin can be produced in sufficient quantities for normal development and reproduction. Incidentally, it was noticed that the severity of host skin reaction to bites of 0. moubata is greater in animals that are deficient in thiamin than'it is in normal rats. In the former, an extensive hemorrhage develops at the site of each bite GDe Meillon and Goldberg l947A,B,_De Meillon 1949).
Laboratory Rearing Methods
This subject has been discussed in more or less detail by all students of the life cycle, mentioned above. Methods for rearing 0. moubata, care of hosts, caging, precautions, host diet and handling, etc., have been presented by Harvey (1947).
A capillary tube method for the artificial feeding of Q. moubata and other ticks for studies of disease transmission and physio ogy has been developed by Chabaud (l95OA).
Travellers in infested areas should be cautious especially in choosing sleeping and sitting sites. Indigenous habitations whenever possible should be avoided for sleeping, a.nd care should
*Although it is not the policy of this study to deal with control and prevention subjects because these are more logically included in a separate report now being prepared, an exception is made in the case of O. moubata. The control and preventive measures re. quired for this species are unique among African ticks, and its biological and host predilections are different from all others. Idoreover, it is possibly the only medically important African tick that has little or no veterinary importance.
be taken to protect one's self from tampan bites in rest houses, barracks, meeting places, and sometimes in European houses. In Tanganyika, Morstatt (1914) noted, those huts that were exposed to the rain were free of ticks while others in places more pro. tected from the elements harbored tampans. Norstatt suggested camping in grassy spots some distance from huts.
Any program of labor introduction from an infested area should include an initial inspection of newcomers‘ personal effects, bed. ding rolls, and extra clothes.
Strict sanitary measures are of proven success in labor camps.
If floor and walls are hard, dry, and free from all cracks and if dust ad unnecessary objects that might provide concealment are removed, the tampan's hiding places may be kept to a minimum. Frequent inspection of personal effects, which should be kept in tightly closed boxes or cabinets, or hung away from walls, are
of proven success. Persons living in barracks should be warned to report the presence of ticks. Beds must be provided and nos. quito nets may be necessary. In infested buildings, placing of bedlegs in cans of kerosene has been recommended to deter hungry tampans.
Special tickproof construction of military huts in heavily infested East African areas has been recommended (Hyn 1945). The base is a six.inch deep bitumen floor (or cheaper hard.beaten tar and earth) with a metal strip inserted at the outer edge midway through its thickness and projecting three inches outwards to prevent ticks from reaching the floor level from outside. A second strip, about one foot above the floor level and extending both inside and outside, helps to confine the searching area for ticks brought in on clothes and gear. Hynd found that the tanpan climbs upwards only when it is not able to burrow into the ground. It searches for hiding places in wall cracks or roofing but can. not circumvent horizontal metal strips extending outward from walls.
Jack (l928,l938,1942) suggested that pigsties be constructed of smooth concrete that is easily cleaned and does not provide a hiding place for tampans.
A valuable account of building methods to eliminate tampan infestation has recently been published by Annecke and Quin (1952) and Annecke (1952). Reinforced concrete buildings, which replaced wattle and daub huts at a cost of L 13 per person, are said to have reduced deaths from relapsing fever on a large South African citrus plantation from forty to a single case annually. Addi_ tional benefits resulted from employees‘ social and economic betterment. These buildings were constructed by casting walls in a steel framed mold and raising precast concrete roof sections over them. Floors were made from a vermiculite and cement mixture. Acceptability to indigenous labor, ease of cleaning, and crackproof construction were important considerations. As the economic level of African labor rises, such prevention methods will become normal and expected, but today they are revolutionary.
The effect of domestic animals on Q. moubata populations in houses appears to be moot. Under usual conditions it seems that domestic animals allowed to live in human habitations tend to allow an increase of ticks in these buildings. An exception is cited by Walton (l95QA), who believes that in areas of high humfi_ dity additional moisture provided by domestic animals in huts is enough to discourage the tampan. Rooms in which goats are kept in humid Kenya hills are free of ticks (Teasdale l952).
Inasmuch as chickens often are said to be a favorite nymphal host, they probably should be excluded fr5m‘buildings except pos_ sibly for periodic forays to feed on ticks near the surface of the ground. Knowles and Terry (1950) reported that chickens in Tanganyika are heavily infested with nymphal 0. moubata, but Phipps (1950) found no significant relation between the presence of ticks and fowls in the same area.
Gammexane (Hexachlorocyclohexane, BH or benzene hexachloride) is generally considered to be the most promising chemical for controlling Q. nnubata.
Ticks coming in contact with 0.5 per cent dust lose coordination after five or six hours. During the first day they lose muchof their body weight by excessive coxal fluid loss, defecation of milky fluid, and possibly by increased integumental
permeability. Their color darkens; they become more or less immobile and usually die in a little over a week. Those that live fail to produce viable eggs. Application of 0.5 per cent gammaxane dust to floors and lower parts of walls spinkled from perforated cigarette tins at the rate of three or four pounds of
dust per hundred square feet is recomended, but frequent checks should be made where reinfestation is liable to occur (Jepson
Application of Jepson's findings on a township scale in Tanganyika was described in detail by Knowles and Terry (1950) using "'0 dust“ (1)220 compound one part, and diatomite four parts). These authors found that although total eradication is probably impossible, a townshipwide control program can almost eliminate relapsing fever in a fairly static population and is much cheaper than hospital treatment of the disease. Sampling methods and application methods were also stressed.
Factors to be considered in a control program and need for further research were discussed by Phipps (1950), who indicated the necessity of using tested diluents and making accuate surveys before and after treatment.’ The incidence of ticks and disease should also be checked before large scale programs are instituted for, in Phipps‘ opinion, not all places in which ticks abound are disease foci.
In Annecke and Quin's (1952) extensive chemical control
program on a heavily infested South African citrus plantation,
it was found that BHC applied as a spray to inner walls of huts in concentrations of 300 mg. gamma isomer (or upwards) per square foot (emulsion of 12% BHC with 4% gamma isomer) gave effective control. With lesser concentrations, tick populations increased rapidly after seven weeks. Surviving ticks from sprayed huts deposited considerably fewer eggs than normal females.
Nevertheless, the same authors report, reintroductions were so frequent that the authorities finally resolved to construct tickproof habitations. In spite of comparatively high initial cost in comparison with daub and wattle huts, this was found to be the only realistic approach to reducing deaths and man hours lost to relapsing fever.
Subsequently, Annecke (1952) reported that all huts treated with 600 mg. gamma isomer per square foot BH3 remained free of 0.
moubata for at least 27 months. When 300 mg. per square foot
were used, huts remained free of ticks for twelve months.
The small amounts of BID used in malaria control programs, 25 to thirty mg. gamma isomer per square foot BI-I3 wettable powder, applied twice three months apart, has little effect on 0. moubata, but Annecke (loc. cit.) believes the cumulative effect may rauce or destroy th'e—tick.—
The above remark immediately suggests the potentiality of tampan resistence to chemicals. So far as known, none has yet been demonstrated.
A control program in Fort Jameson townshi of Northern Rhoda. sia has recently been reported by Holmes (19538. Heavy spraying with a five percent BI!) solution resulted in general diminution of the tick population but did not result in its elimination.
It was found that the most economical form for achieving a hundred percent kill was five percent BID powder mixed with 95% (by weight) sawdust diluent, or with chaff left from poundi corn. To obtain a sackful of this mixture, a container holding pounds of forty percent BK} cattle dip wettable powder was mixed with fifty pounds of sawdust. This mixture was then laid as a four inch wide bar. rier, thick enough to insure that ticks must come in contact with it when passing, at the base of all inside walls of the house.
The barrier was maintained for three weeks and frequently inspected, especially where it passed door openings, to insure that it was
not scattered. This time period should reach all nymphs hatching from eggs laid before the chemical is applied (more or less ex.ceptionally a somewhat longer hatching period may be involved,
but for practical purposes this time is probably usually effective I-IE). Elimination of tampans was obtained by this method, but re. infestation occurred within a year to a year and a half. Fleas, Congo floor maggots, a.nd bedbugs were also killed. In the fol... lowing year, the number of cases of relapsing fever from treated houses was considerably reduced. The cost of this program was so low that other authorities commenced similar control program.