The Geology of Burma - Zomi Online Library

Bibliography of Burman Earth Science
dominant external parasites of small mammals in all the areas
investigated. The life cycle of the vector has been studied by Mr.
Cockings by breeding it through several generations in the laboratory,
in which conditions the cycle is being completed in 5 ½ to 8 weeks.
The cycle of T. deliensis in nature appeared to be completed in 8 to 12
weeks during the monsoon in the Imphal area. The vector is
distributed on the smallest scale as restricted colonies or “miteislands”
which form an irregular pattern on the ground. The basic
infestation pattern is decided largely by the behaviour and numbers of
the primary hosts of the parasitic larvae. Though not always the
principal hosts in individual foci, the most important and universal
hosts of the larvae of the vector are field forms of Rattus rattus—in
Imphal, R. r. bullocki; in Malaya, R. r. argentiventer—but others may
take their place, e.g., the bandicoot, Bandicota bengalensis, in villages
and towns in Burma, and forms of R. exulans (e.g., concolor, browni)
in Pacific Islands. Some small birds such as quail contribute to the
basic pattern. An important group of other hosts with longer ranges
are responsible for distributing mites but not appreciably for the basic
pattern of infestation. The common giant rats (R. sabanus, R. mülleri)
in the Malayan forest are the proper hosts of members of the vectorspecies
group of mites, and R. mülleri is the most prominent host of T.
deliensis itself in the forest. Heavy infestations by the vector are,
however, found outside the forest on forms of R. rattus. The number
of questing larvae of the vector (and, therefore, the risk of infection) is
related to soil moisture and surface humidity, and hence to rainfall
(seasonal incidence) and to the lowered humidity which obtains during
sunny days and after clearing undergrowth. Even in very dry seasons
larvae persist in foci which are kept moist by ground water. Rainfall
affects the distribution of the vector in both space and time, and also
influences the activity of the rodent hosts to a marked extent. Studies
on infection in and infectivity of the vector mite, and of the congenital
transmission of infection, are progressing in collaboration with Dr. S.
R. Savoor. Some evidence has been gained that the congenital
transmission of infection may be inefficient.
Auldridge, Larry, Bartlett, Dan C., Houbert, S., Guyonnet, P., Collins,
Bart and Hatley, Allen G. 1978. “Southeast Asia Report.” Oil Gas J.
September 2008 42