Expert: Jana Connell RVT, CVT - 11/8/2011

Question
dear madam. i hope you can help me with an answer to my question. we live in a village, near to the woods and sometimes our dog runs away on his own... last weeks he keeps hunting mice.. i discussed this with our VET, he says he can catch leptospirosis. he is vaccinated, but only for several kinds of most common leptospira, and i am affraid he can catch some other kinds and then infect us (we have two year old son). can you help me with this problem in any way? how to booster his immunity, any info about infection via people, if all leptospiras are dangerous for us etc.. thank you very much.

Answer
One thing you can do Zdenka is keep him from running off. If he isn't neutered then get him neutered and he will be less likely to run off all the time.

Mice are a problem but larger animals usually spread leptospira, like deer etc.
Here is a break down on the spirochete that causes leptospirosis:

Leptospirosis is caused by a spirochaete bacterium called Leptospira spp. There are at least five serovars of importance in the United States and Canada, all of which cause disease in dogs (Icterohaemorrhagiae, Canicola, Pomona, Grippotyphosa, and Bratislava).[5][6][7]

There are other (less common) infectious strains. Genetically different leptospira organisms may be identical serologically and vice versa. Hence, an argument exists on the basis of strain identification. The traditional serologic system is seemingly more useful from a diagnostic and epidemiologic standpoint at the moment (which may change with further development and spread of technologies like polymerase chain reaction (PCR)).

Leptospirosis is transmitted by the urine of an infected animal and is contagious as long as it is still moist. Although rats, mice and moles are important primary hosts, a wide range of other mammals including dogs, deer, rabbits, hedgehogs, cows, sheep, raccoons, possums, skunks, and certain marine mammals are able to carry and transmit the disease as secondary hosts. Dogs may lick the urine of an infected animal off the grass or soil, or drink from an infected puddle. There have been reports of "house dogs" contracting leptospirosis apparently from licking the urine of infected mice that entered the house. The type of habitats most likely to carry infective bacteria are muddy riverbanks, ditches, gullies, and muddy livestock rearing areas where there is regular passage of either wild or farm mammals. There is a direct correlation between the amount of rainfall and the incidence of leptospirosis, making it seasonal in temperate climates and year-round in tropical climates.

Leptospirosis is also transmitted by the semen of infected animals.[8] Slaughterhouse workers may contract the disease through contact with infected blood or body fluids.

Humans become infected through contact with water, food, or soil containing urine from these infected animals. This may happen by swallowing contaminated food or water, or through skin contact. The disease is not known to be spread from person to person and cases of bacterial dissemination in convalescence are extremely rare in humans. Leptospirosis is common among water-sport enthusiasts in specific areas as prolonged immersion in water is known to promote the entry of the bacteria. Surfers and whitewater paddlers[9] are at especially high risk in areas that have been shown to contain the bacteria, and can contract the disease by swallowing contaminated water, splashing contaminated water into their eyes or nose, or exposing open wounds to infected water.[10] Occupations at risk include veterinarians, slaughterhouse workers, farmers, sewer workers, and people working on derelict buildings. Rowers are also sometimes known to contract the disease.[5]

A good clinical history is often the key to accurate diagnosis in leptospirosis. Important features include a plausible exposure history and a clinical picture consistent with the disease.

Leptospirosis occurs worldwide wherever risk of contact with the urine, kidneys, or conception products of infected animals exists. Typically, rodents, dogs, cattle, and pigs are considered reservoirs for this organism; however, increasing diversity of travel and exotic-pet trade are expanding the list. The leptospires may live for years in the renal tubules of animals and are excreted in the urine into standing water or soil. This explains sources of both direct infection (eg, body fluids or organs of infected animals) and indirect infection (eg, inoculated soil or water). In 2004, cases were linked to flood water in urban endemic regions of Hawaii. In tropical settings, leptospirosis is becoming more prevalent among travelers and residents. For example, recreational activities in rivers (eg, white-water rafting) may be a significant risk factor for infection with leptospires.

Leptospires can live outside the body for several weeks. They enter the body through disrupted skin or mucosal barriers, such as abrasions or waterlogged skin. Other means of infection have been documented, including inhalation of aerosolized leptospires and direct infection across intact mucus membranes or conjunctivae. After an incubation period of 2-30 days (typically 5-14 d), clinical symptoms ensue. A plausible history of possible exposure must precede clinical symptoms in order to consider the diagnosis of leptospirosis.

Expert consensus is that leptospirosis occurs as two recognizable clinical syndromes. A third syndrome of asymptomatic infection is more controversial. Anicteric leptospirosis is a self-limited disease similar to a mild flulike illness. Icteric leptospirosis, also known as Weil disease, is a severe illness characterized by multiorgan involvement or even failure. Two distinct phases of illness are observed in the mild form—the septicemic (acute) phase and the immune (delayed) phase. In icteric leptospirosis, the 2 phases of illness are often continuous and indistinguishable. At disease onset, clinically predicting the severity of disease is not possible. Subsequent sequelae depend on the serovar involved and the health, nutritional status, and age of the patient, as well as the rapidity of definitive and supportive treatment.

An acute illness follows any infection with any serovar of leptospirosis. Most of the following symptoms develop in varying degrees: high temperature (38-40°C), rigors, sudden headache, nausea and vomiting, anorexia, diarrhea, cough, pharyngitis, nonpruritic skin rash, and muscle pain. Muscle pains are typically localized to the calf and lumbar areas. This phase of illness lasts 5-7 days and either regresses to a relatively asymptomatic period or progresses to a more severe illness. In anicteric leptospirosis, the acute illness is followed by 1-3 days without fever and then progresses to 4-30 days of the immune (delayed) phase of the illness. (http://en.wikipedia.org/wiki/Leptospirosis)

Now I am sure that information will make your head spin but the bottom line is this:
To prevent any kind of infection from your dog to your family you MUST keep him confined if leptospirosis is a problem where you live.

Common hygiene practices and restraint of errant pets are the best protection coupled with vaccination protocol, which you are doing now.

Keep rodents out of your house and deer out of your yard and your dog confined and you should all be fine as well.

I hope that this helps somewhat.:-)