Leptospirosis is a fatal animal-borne disease that can result in high fever, internal bleeding and organ failure, said the Health Ministry.

Four of 15 people reported to have been infected with the bacterial disease have died since the onset of the outbreak in late January, a case fatality rate of 27%.

Indonesia's Director-General of Disease Control and Environmental Health at the Health Ministry, Tjandra Yoga Aditama, said infected rats may have caused the epidemic.

"We have traced the root of the problem. I have asked several farmers in Bantul and they said currently there are a lot of rats in that area. I think that is one of the causes because the rat population is increasing. We are not sure why, and we do not know if the population increase is related to the weather."

Rodents and other mammals carry the disease, and can infect people who come into contact with animal urine-infected water, food or soil. Leptospirosis is spread in urban slums through rats, but also hits rural areas, killing unknown numbers of barefoot rice paddy workers, water buffaloes and sugar cane workers. It is thus known as rice field, mud or dairy-farm fever, as well as cane cutter's and swineherd's disease.

Because of their work conditions, the World Health Organization (WHO) estimated nearly one billion agricultural workers in Southeast Asia were at risk of infection as of 2007.

Outbreaks have been reported following flooding and hurricanes elsewhere in the region.

Changing weather trends, including extreme weather, have increased the threat of severe epidemics worldwide, according to the Leptospirosis Burden Epidemiology Reference Group (LERG), founded by WHO.

 

Under-reporting

In 2010 there were 110 infections and one fatality from leptospirosis reported in Indonesia, but this is grossly underreported, said Rudy Hartskeerl, a molecular microbiologist who was involved as consultant following a 2002 outbreak and heads the WHO, Food and Agriculture Organization and World Organisation for Animal Health (OIE) leptospirosis reference centre of the Royal Tropical Institute in the Netherlands.

"Do not be misled by low [reported] numbers. There is no research or surveillance. Indonesia is a high-endemic country and all its islands are vulnerable. Leptospirosis is a major public health problem there and gathering data is essential."

It is a "poverty disease" that is often overlooked or confused with other diseases, most often as the viral disease dengue because of similar fever, muscle pain and headache symptoms at the onset, he added.

The number of dengue infections governments reported to WHO multiplied four times from nearly 64,000 cases in 2000 to 258,000 in 2009, even when the region's population grew by only 1.2 % during that period, according to the UN Population Fund.

Because surveillance and proper laboratory-based diagnosis [are] lacking, health care providers and officials tend to overlook leptospirosis [as a cause of death] because you would have to go looking for it.

"Whereas dengue is a mosquito-borne disease - and mosquitoes bite everybody, everywhere - leptospirosis affects mostly poor people such as farmers and those living in slums who [cannot] easily seek medical care in hospitals. Because surveillance and proper laboratory-based diagnosis [are] lacking, health care providers and officials tend to overlook leptospirosis [as a cause of death] because you would have to go looking for it."

In the 1990s, researchers isolated about 80 of 250 total types of bacteria in Indonesia and Malaysia that can result in leptospirosis, indicating a potentially high disease prevalence, said Hartskeerl.

 

Outbreak response

Indonesia's Health Ministry is coordinating with the animal husbandry office in the central Indonesian province of Yogyakarta to target the rat population, said Aditama.

Experts from Gadjah Mada University in Yogyakarta and WHO are expected to investigate further.

"We have also asked the health agency to inform the public about the importance of personal hygiene. Farmers have been asked to wash their feet properly after coming back from their fields and they are also asked to visit the nearest clinic if they have been bitten by rodents."

Beyond emergency control, education and treatment, Hartskeerl said an in-country reference centre capable of research and surveillance of haemorrhagic fevers, including leptospirosis, is "desperately" needed to ward off future epidemics.

 

This post was originally published in IRIN in February 2011.