In recent years leptospirosis has been shown to be an important cause of human febrile illness in Malaya. Studies were therefore undertaken to determine its animal reservoirs and the factors influencing spread of infection from them to man and domestic animals. This paper presents the board picture obtained. A wide range of animal species were trapped in forest localities, ricefield areas, areas of scrub and cultivation and in several towns and villages. The maintenance hosts of leptospirosis in Malaya appear to be mainly or entirely rats, although evidence of infection has been found throughout the animal kingdom. Some rat species have characteristics which suggest that they are better maintenance hosts than others. Evidence was found of practically every serogroup of leptospires infecting animals in Malaya. Altogether 104 strains were isolated and identified, and 155 animals were found to have serological evidence of infection. Of 1763 rodents examined, 194 had evidence of infection, and 41 of 1083 other animals. A serum survey of domestic animals showed the highest incidence of antibodies to be in goats and the lowest in oxen.
Leptospirosis is a re-emerging zoonotic infection. In developing countries large outbreaks have occurred in urban slums and following floods. Individuals from developed nations are also now more frequently exposed to the infection as a result of international travel and greater participation in certain outdoor recreational activities. Leptospirosis remains a diagnostic challenge since it often presents as a non-specific febrile event and laboratory diagnosis is still currently inadequate. Rapid tests may not be sufficiently sensitive in early disease and culture facilities are not widely available. A severe pulmonary haemorrhagic form of the infection is increasingly being encountered in many countries including Malaysia. The control of leptospirosis is largely dependent on general hygienic measures and rodent control. An effective human vaccine is still not available. There remains much that is unknown about this disease and there is scope and opportunity for good quality research.
In a previous paper the authors reported on the methods and zoogeographical background of a survey of animal leptospirosis in Malaya, giving a broad analysis of results. In the present paper the localities studied in towns and villages, in ricefields, in secondary forest and scrub and in primary forest are compared in detail. In towns and villages infection rates in rats were low, except in a seaport town where the invading R. norvegicus was heavily infected. In ricefields infection is maintained in R. argentiventer, alone or in association with R. exulans. In secondary forest and scrub there is overlap with forest species and the main hosts of leptospires appear to be R. exulans and R. jalorensis. In primary forest giant rats and, to a lesser degree, spiny rats are the main hosts.Ground-living rats appear to be better maintenance hosts than those scrambling on vegetation or arboreal rats. With some exceptions the incidence of infection of a rat species in an area was found to be in direct relation to the proportion that species formed of the total rat population. The critical number of rats for maintenance of leptospirosis in an area is estimated to be about two rats of the maintenance species per hectare.
We report a case of leptospirosis infected in Sabah, Borneo island, Malaysia. The case is 25-year-old male who had participated in the EcoChallenge Sabah 2000 Expedition Race, a multisport event held during August 20 to September 3, 2000 at various sites in Sabah in Malaysian Borneo. He developed a high fever and headache on September 7, and he was admitted to our hospital on September 9. On admission he also had conjunctivitis and myalgias. Laboratory findings on admission revealed leukocytosis with left shift, slightly elevated transaminase levels, high CRP levels and proteinuria. Plasmodium spp. were negative on blood smears, and no bacteria were isolated from blood and feces cultures. We performed the laboratory tests for leptospirosis, based on the information about the probable leptospirosis outbreak among athletes who participated in the EcoChallenge Race, however both Leptospira antigens and antibodies were negative at that time. We diagnosed leptospirosis clinically because he manifested persistent symptoms, and minocycline 100 mg b.i.d. was administered intravenously resulting in excellent efficacy. Serum antibody tests by microscopic agglutination test (MAT) at convalescent stage revealed significant increased antibodies against Leptospira interrogans serovar hebdomadis, and the diagnosis of leptospirosis was confirmed. Infectious diseases have been global and it is important to have information concerning worldwide infectious disease situations as much as possible for accurate diagnosis.
A study of 1,437 unselected febrile patients in rural Malaysia yielded a diagnosis of leptospirosis in 86 (6.0%). The clinical syndrome was mild to moderate in all cases, jaundice was observed in only 2 (2.3%) and no deaths were documented. The diagnosis was not clinically obvious in most cases, and it is apparent that many infections must be going unnoticed at present.