Leptospirosis was first identified in Argentina in 1915.
- Most cases are reported from Greater Buenos Aires.
- 276 cases were diagnosed in the Greater Buenos Aires area during 1990 to 1999 – 43 of these characterized by pneumonia.
- 32 cases (6 fatal) were reported in Santa Fe during the first two months of 2010.

The following graphs depict incidence and case rates of Leptospirosis in Argentina, and contrast these data with those of surrounding countries:

Notes:
Individual years:
1998 – Included 53 cases in Santa Fe and 16 in Buenos Aires.
2001 – Included 63 cases in Santa Fe and 89 in Buenos Aires.
2005 – Three fatal.

Twelve serovars were identified in human infection during the 1970′s, with most cases due to serovars bratislava, icterohaemorrhagiae and butembo.
- 41% of infections during 1984 to 1994 were due to Leptospira interrogans canicola.

Seroprevalence surveys:
15.7% of the population, nationwide (1976 publication)
8.7% of healthy persons in Corrientes and 0.5% in Neuquen are seropositive (1979 publication)

Reservoirs:
The principal hosts in this country are rats, pigs and dogs.
- 25% to 40% of rats and 10% to 60% of dogs in Buenos Aires are seropositive – most often toward L. interrogans canicola and L. i. pyrogenes.
- Antibody toward serovars pomona, hebdomadis group, pyrogenes, tarassovi, and canicola has been demonstrated in healthy horses.

Notable outbreaks:
1976 – An outbreak (10 cases) in Buenos Aires followed swimming in a drainage canal contaminated by pigs.
1977 (publication year) – An outbreak was reported among children in Longchamps, Buenos Aires Province.
1998 – An outbreak (12 confirmed and 2 suspicious cases) in Santa Fe was related to water.
2004 – An outbreak (12 suspect cases, 1 fatal) was reported in Entre Rios.
2007 – An outbreak (400 cases or more) was reported in Santa Fe.

A recent ProMED warning to backpackers is well taken – leptospirosis is a common disease in the Pacific region. In the following graphs I’ve compared disease rates for Australia and New Zealand with those of the United States.

Leptospirosis rates in nearby New Caledonia are even more striking, and exceed those of salmonellosis, hepatitis A, hepatitis B, gonorrhea, and tuberculosis.

A recent death in Ireland highlights the fact that the incidence of leptospirosis in this country has been increasing in recent years. In fact, during the past decade, leptospirosis rates have expanded well beyond those of those of the United Kingdom, including those for adjoining Northern Ireland. See graph:

Update: Published in ProMED

In view of a massive ongoing outbreak in Manila, the following chronology of published large outbreaks (>50 cases) of leptospirosis was abstracted from GIDEON. Outbreaks known to be associated with heavy rains or flooding are denoted by * A number of additional outbreaks have been associated with floods, but without specific mention of case numbers. Thus, a major outbreak in Krasnodar (Russia) in 1997 followed local flooding; as did epidemics in China during 1962 to 1963, 1966, 1973 to 1974 and 1984.

The Epidemiology module in GIDEON currently contains details of 8,910 Infectious Diseases outbreaks (Primary references are available on request)

Update: Reported in ProMED

A recent outbreak in Manila belies the fact that reported rates of leptospirosis in the Philippines had actually decreased in recent years. See graph:

The following additional background data are abstracted from GIDEON www.GideonOnline.com (primary references available on request):

Leptospirosis was first reported n the Philippines in 1932.
– 65 cases were documented in literature published during 1932 to 1970; 390 during 1971 to 1973; approxomately 840 during 1998 to 2001.
– Leptospirosis is common in flood-prone areas of urban setting such as Metro Manila.
– The average age of patients is 32 years, 87% of cases were males and 70% are outdoor workers.
– The case fatality rate is 12 to 14 percent.
– Rates in Cabatuan, Iloilo are estimated at 147 cases per 100,000 population (2007 publication).

Prevalence surveys:
5% of aseptic meningitis cases in Manila (1989 publication)

Seroprevalence surveys:
43.6% of rice farmers in Central Luzon (1988 publication)
0% of dogs (RMAT, 1970 to 1973)

The following serovars of Leptospira interrogans have been demonstrated among patients in the Manila area: poi, tarassovi, manilai, pyrogenes, australis, grippotyphosa, javanica and automnalis.

Notable outbreaks:
1976 to 1983 – An outbreak of leptospirosis was reported on a penal farm in Sablayan, Mindoro.
1999 – An outbreak (17 cases) of leptospirosis involved participants in an ‘iron-man contest’ – from Germany, Hong Kong and the Philippines.

Update: Posted in ProMED

Time and Place:
Most outbreaks of leptospirosis are reported in coastal regions: Gujarat, Mumbai, Kerala, Chennai and the Andaman Islands.
- High rates have been reported from Valsad district (Gujurat) for several years.
- Outbreaks of ‘Andaman hemorrhagic fever’ were first reported in 1988, and identified as leptospirosis in 1993.
- Highest rates occur during October to November.

Prevalence surveys:
22.57% of FUO in Guwahti, Assam (2008 publication)
3.2% of febrile patients and 7.0% of febrile patients with jaundice in Delhi (1966). 32 cases were confirmed in the region during 2000 to 2001.
23.81% of patients hospitalized for febrile jaundice in Kolkata.

Seroprevalence surveys:
(more…)

Recently, a British woman died of leptospirosis acquired from the scratch of a rodent. Few people realize that leptospirosis is not uncommon in the United Kingdom. In fact, 18 fatal cases were reported in England and Wales during 1988 to 2006. In the following graph, I’ve contrasted disease rates for the region with those of the United States.

Update: Also quoted in ProMED

A recent outbreak highlights the fact that New Caledonia has one of the highest rates of leptospirosis in the Pacific region (see graph). In fact, in these islands, Leptospirosis is more common than Salmonellosis, Hepatitis A, Hepatitis B, Gonorrhea and Tuberculosis (see graph).

The following background information regarding Leptospirosis in New Caledonia is abstracted from GIDEON:

Leptospirosis is most common in west coast cattle-farming areas and rural Melanesian settings

• Disease rates are highest in the Bourail area.
• Disease rates peak during March to May.

Notes:

1. An average of 4 fatal cases are reported yearly.
2. 57 cases were diagnosed during 1983 to 1985.
3. 239 cases were reported during 2001 to 2005. The principal serogroups were Icterohaemorrhagiae (69%), Australis (8%), Pyrogenes (6%)

58% of cattle are seropositive.

The principal reservoirs in this country are rodents, pigs, horses and cattle.

The principal species are Leptospira serovars. Icterohaemorrhagiae, tarassovi, pyrogenes, canicola, australis and pomona.

• Serovar tarassovi accounts for 22% of cases, icterohaemorrhagiae 18% and pyrogenes 17%.

Notable outbreaks:
1989 – An outbreak (144 cases, 6 fatal) was reported, with 41% of the cases caused by serovar icterohaemorrhagiae.

Update: Also mentioned in ProMED