Fishing communities worldwide are up to 10 times more vulnerable to HIV/Aids than other centres, a study says.
The high mobility of fishing communities increases the risk
University of East Anglia researchers said fishing villages were the hidden victims of the disease.
The communities were particularly vulnerable because the populations were highly mobile, lacked women's rights and had high levels of prostitution.
The report called on governments to improve access to treatment and sexual health services in fishing villages.
Many of the initiatives directed at such areas were done on a local, small-scale basis, the researchers said.
The global picture
Thailand - Up to 20% of fishing boat crews tested HIV-positive in the late 1990s, while general rate was 1.5%
Honduras - Some 8% of adults in fishing communities have HIV - four times the national average
Uganda - A quarter of fisherfolk on Lake Albert were HIV-positive in 1992, compared to 4% in nearby agricultural villages
They suggested mobile or floating clinics be established to make sure fishing communities had access to testing, advice and care.
Lead researcher Dr Edward Allison said: "The plight of fishing communities has been neglected for far too long and the consequences have been devastating.
"I hope this research will raise awareness not only of the impact of the HIV and Aids epidemic on fishermen, but also highlight the vulnerability of women in the fisheries sector."
The report said there were sub-cultures of hypermasculinity and risk taking in fishing villages with high levels of drug and alcohol abuse which contributed to higher rates of HIV.
This was exacerbated by the highly mobile populations, which moved between landing sites, markets and processing factories on a daily basis.
In Thailand one in five workers on fishing crews were HIV-positive, compared to 1.5% in the general population.
In the Cambodian port of Sihanoukville fishermen had the second highest rate of HIV. Brothel-based sex workers had the highest.
ActionAid's HIV/Aids campaigner manager Simon Wright said the nature of fishing communities meant people were at greater risk of HIV.
"We have known for a long-time that mobile populations with access to cash are among the earliest affected by HIV and Aids.
"In particular, fishing communities can see sex become an institutionalised means of bargaining for access to the catch and the right to sell in the markets.
"Targeting these groups must be an urgent action to stop HIV from spreading further."