Reference no: EM134005195

Question

Dr. Dhewantara, an epidemiologist from the communicable disease section of the Indonesian Ministry of Health, was notified by his colleague Dr. Gasem, a professor at the University Hospital in the municipality of Semarang, Indonesia, of an outbreak of leptospirosis in the city. Between November 1st and December 30th, which corresponded to the monsoon season, physicians at the hospital identified 346 cases of suspected leptospirosis, which was higher than the number (41) of suspected cases identified in the preceding period from April 1st to October 31st and the number of cases (82-201) reported during monsoon seasons (November 1st to March 31st) in preceding the five preceding years.

Semarang is a city of 1.7 million people and roughly 5% of the city's population is living in poverty as defined by the World Bank. It is served by 14 hospitals and the University Hospital serves as a reference center for infectious diseases in the public sector health system. The majority of hospitalized patients on the infectious diseases service comprise of adults with complications of HIV and tuberculosis and children who with bacterial meningitis, pneumonia and severe dengue.

Physicians identified suspected cases referred to the infectious disease hospital based on having an abrupt onset of fever, chills, conjunctival suffusion, headache, myalgia, jaundice, cardiac or renal failure, and/or pulmonary hemorrhage. Dr. Gasem said that clinical and laboratory evaluation excluded the diagnosis of gram-negative bacterial sepsis, endocarditis, dengue, scrub typhus and hantavirus among suspected cases of leptospirosis. Among the 346 cases, 86 required ICU monitoring and 43 (12%) had died.

Dr. Dhewantara, who is based in Jakarta, mobilized a team from the Ministry of Health to travel to Semarang and conduct the investigation. As they were departing, Dr. Dhewantara asked Dr. Gasem to collect samples from suspected cases and send them to the leptospirosis reference laboratory at the Ministry of Health, to confirm the diagnosis of leptospirosis.

1. Dr. Gasem was able to send stored blood, sera and urine samples from a total of 73 of the 346 cases. Among the blood and urine samples from 24 suspected cases which were collected at the time of admission, the leptospirosis reference laboratory found that 14 had lipl32 PCR positive reactions. Dr. Gasem also sent acute-phase serum samples from the 73 patients, of which 47 had evidence of a positive microscopic agglutination titer (≥1:100) against a Leptospira serovar. Among the paired acute and convalescent-phase serum samples obtained from 38 suspected cases who survived leptospirosis, 34 demonstrated seroconversion (negative agglutination in acute phase sera and titer of ≥1:400 in convalescent-phase sera) or a four-fold titer rise to a Leptospira serovar in the microscopic agglutination test.

Do these laboratory findings confirm leptospirosis as the cause of the outbreak?