Health Stream Literature Summary - Issue 32 December 2003

Risk assessment of waterborne coxsackievirus.
Mena K D, Gerba C P, Haas C N, Rose J B. J AWWA 2003;95 (7):122-131.

This paper considers the risk associated with exposure to water contaminated with coxsackieviruses. Coxsackieviruses are the most common cause of nonpolio enterovirus infections and have the potential to cause a wide range of symptoms including fever, vomiting, abdominal pain, headache, rash, jaundice and diarrhoea as well as other serious outcomes including aseptic meningitis. Coxsackie-viruses are transmitted by the faecal-oral route, and have been found in sewage, recreational water and drinking water.

Published literature in the Medline database on coxsackieviruses and the diseases they cause was reviewed. There are two groups of coxsackieviruses (types A and B). Most infections attributed to coxsackieviruses are symptomatic. The World Health Organization reported the most common diseases associated with coxsackieviruses for the period 1975-83 were: cardiovascular disease, respiratory illness, gastroenteritis and central nervous system disorder. Coxsackieviruses type B has been shown to be the most frequent viral etiological agent associated with heart disease, causing more the 50% of all cases of viral myocarditis. Over the past 20 years several studies have been conducted to investigate the association between coxsackievirus infection and the development of insulin-dependent diabetes mellitus (IDDM). Around 50% of children with IDDM have antibodies to coxsackievirus and it has been documented that 33.3% of all IDDM cases are preceded by coxsackievirus type B infections. Around 70% of all meningitis cases are attributed to enteroviruses, in particular coxsackievirus types A7, A9 and B2-5. There have been only two recreational waterborne outbreaks and one tentative drinking water outbreak associated with coxsackievirus.

An exponential risk assessment model was developed using human dose-response studies to determine the probability of infection with coxsackievirus type B and calculate estimates of daily and yearly risks of infection, morbidity and mortality. An exposure assessment was carried out by examining the occurrence of coxsackievirus in water, its resistance to inactivation by disinfectants and its survival. Chlorine disinfection of coxsackieviruses has been examined. A study on Potomac River water found that after poliovirus type 2, coxsackievirus types A5 and B5 were the most resistant to chlorine exposure. Also compared with other enteroviruses, coxsackievirus B5 appeared to be the most resistant to ultraviolet light inactivation. Temperature has the greatest effect on the survival of coxsackievirus of the environmental influences assessed. Coxsackievirus B5 has been found to be more stable at any temperature when compared with echovirus 6 and poliovirus 1.

To characterise the risks associated with coxsackieviruses, the amount of water consumed and the concentration of coxsackievirus in the water was considered and the dose-response model was used to develop point estimates associated with the probability of infection. The general population and the elderly were considered separately because it has been shown that the elderly consume twice as much water as the general population. An exposure of 2 L/day per person was used for the general population and 4 L/day for the elderly. The risks of infection and illness associated with drinking water from surface water supplies varied from 10-5 daily to 10-2 annually. The risks of infection and illness associated with drinking contaminated nondisinfected groundwater ranged from a 10-3 daily risk to 3.9-5.2 x 10-1 annual risk. Risks for ingestion of 100ml of freshwater contaminated with coxsackievirus while swimming were 10-2 for a 10 day exposure.

Coxsackieviruses are a significant problem for the water industry and are a potential public health threat as they are widespread, survive well in the environment, show resistance to common disinfectants and are capable of causing a wide variety of serious illnesses.