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.

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

A recent outbreak in Australia serves as a classic exercise in Epidemiology. Although Queensland and New South Wales account for most cases of Ross River disease, rates per 100,000 are consistently highest in Northern Territory.

Update: Referenced in ProMED

A recent outbreak in Guanajato reminds us that brucellosis remains a very common disease in Mexico. In fact, current rates are comparable to those of Greece, and similar to rates that existed in the United States during the 1930’s and 1940’s. See graph:

The following background data on brucellosis in Mexico are abstracted from Gideon

Time and Place:
- Highest rates are found in Queretaro, Coahuila, Guanajuanto, Nuevo Leon, Chicuahua, Jalisco, Tamaulipas and Michoacan.
- 163 fatal cases were reported during 1978 to 1982
- Mortality rates were 0.04 per 100,000 in 1992; 0.01 per 100,000 in 1996 .

Seroprevalence surveys:
3.42% nationwide, ranging from 0.24% in Morelos, to 13.5% in Mexico State (1992 publication)
0.71% of blood donors in northeastern Mexico (2009 publication)
0.238% of equines in Tamaulipas (Brucella abortus, 2006 publication)
9.8% of goats on farms (Brucella melitensis). (Michoacan, 2007 publication)

Infecting species:
- Brucella melitensis, B. abortus and B. canis are found in Mexico.
- The predominant species is Brucella melitensis. (1968 to 1991)

Reservoirs:
- The caprine seropositivity rate was 20.7% in 1947.
- Highest rates of caprine disease are reported in Coahuila, Chihuahua, Jalisco and Zacatecas.
- Highest rates of bovine disease are reported in Chihuahua, Hidalgo and Guanajuato.
- 11.8% of stray dogs in Mexico City are infected by Brucella canis.

Vehicles:
- Most infections are acquired from unpasteurized milk, fresh cheese and other dairy products – primarily from goats (There are over 9 million goats in Mexico).
- More than 35% of cow milk is consumed unpasteurized – more than 85% of goat milk.

Update: Posted in ProMed

A recent episode in Brescia is the latest of several outbreaks of viral gastroenteritis in Italy. The following background information is abstracted from GIDEON:

Primary references are available on request.

Prevalence surveys:
Adenoviruses account for 7% of pediatric hospitalizations in Rome for diarrhea, Rotavirus 18.2%, Astrovirus 1% (1987 to 1989)
Adenoviruses account for 17.6% of pediatric hospitalizations in Rome for diarrhea, Rotavirus 26.7%, non-polio Enteroviruses 8.5%, Coronaviruses 1.8%, Parvoviruses 0.9% (1985 publication)
Adenoviruses account for 6% of pediatric hospitalizations in Sicily for diarrhea, Rotavirus 25.1%, Astrovirus 7%, Norovirus 18.6% (2003)
Adenoviruses are found in 6.2% of pediatric patients with acute diarrhea (2005)
Noroviruses account for 10.4% of hospitalized pediatric gastroenteritis cases in northern Italy (2002)
Noroviruses were the most frequently involved viruses (23.7%) in sporadic acute diarrhea among hospitalized children and were more common in children >5 years (37%) than in children <5 years (10%). The frequency of Rotavirus, enteric Adenovirus and Astrovirus was 12.2%, 1.6% and 2.4%, respectively. (Brescia, 2007 publication)
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Historical:
Tick-borne relapsing fever was first described in the United States in 1915 (Colorado).
- The first case of louse-borne infection in the United States during the twentieth century was reported in 1976 – imported from Ethiopia.

Time and Place:
Peak incidence is reported during the summer, with 47% of cases from July to August.
- The disease is most common in Arizona, California, Colorado and Oregon.
- Sporadic cases are reported from Idaho, Kansas, Montana, Nebraska, New Mexico, Oklahoma, Texas, Utah, Washington and Wyoming.
- Most cases occur in the Cascade, Rocky Mountain, San Bernadino and Sierra Nevada ranges.
- 40% of cases occur in tourists to endemic areas (1977 to 2000).
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A recent outbreak in Dulovo belies the fact that measles rates in Bulgaria and surrounding countries have decreased considerably in recent decades. See graph:

We may assume that decreasing rates are the result of excellent vaccine coverage, which currently exceeds 90% for all countries in the region. See graph:
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ProMED quoted GIDEON in this post:

there were at least 10 human cases in the Volga delta between
1963 & 1968, and that human seropositivity rates of up to 8 percent
were found in European Russia & Western Siberia (see ProMED post West
Nile virus - former Soviet Union: background 20060908.2548)

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:
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