Food & Travel [Solved] Diseases in the southeast Asia community

TICK-BORNE DISEASE
Q fever is an acute, febrile rickettsial disease contracted mainly by inhaling airborne dust which includes the pathogen, Coxiella burnettii, or by direct contact with secretions of infected domestic animals. Certain tick species have been reported to be natural reservoirs of the pathogen. Transmission by ticks to humans is possible but apparently rarely occurs. Serological surveys indicate that Q fever is widespread throughout Southeast Asia and infects a wide variety of wild and domestic animals, especially sheep and goats. Even though most human cases aremild and self-limited, military personnel operating in this region should avoid exposure to sheep, goats, cattle and other domestic animals and should not sleep or rest in animal shelters.
Rare sporadic cases of tick-borne relapsing fever, caused by Borrelia recurrentis, have been reported from this region. The disease is enzootic in rocky, rural areas where livestock are tended and effective vector soft ticks, Carios spp., are present. The incidence of B. recurrentis is low and effective vector ticks are rare. Therefore, the military threat due to this disease is minimal.

MITE-BORNE DISEASE
Scrub typhus, caused by the rickettsia Orientia tsutsugamushi, is focally distributed
throughout the region from coastal lowlands to over 1,500 m in the Himalayan foothills near the northern end of the Myanmar and Thailand border. The disease is transmitted by chigger mites of the genus Leptotrombidium, subgenus Leptotrombidium, that are mainly associated with rodents of the genus Rattus. Scrub typhus is prevalent in disturbed habitat characterized by secondary scrub vegetation and grasses. During World War II, it was a leading cause of morbidity in military personnel in the Asia-Pacific area. Although the overall incidence of human scrub typhus infection in Southeast Asia is hard to determine, it is enzootic in all countries of the region and is a significant threat to military forces in the field, especially in parts of Indonesia,
Malaysia, and Thailand.

LOUSE-BORNE DISEASE
Epidemic typhus may still be endemic among poor people and tribes living in more remote rural areas and higher elevations of northern Myanmar, Thailand, Laos and Vietnam. Declining sanitary and living conditions caused by natural disasters, civil unrest, and illegal drug operations have increased the likelihood in such places that this, and other vector-borne diseases, may reemerge and be maintained there. Body lice are not uncommon in colder mountainous sites and in slums of large cities in Southeast Asia. Sporadic cases of louse-borne relapsing fever have also been reported from the region, which, like epidemic typhus, it is mainly a winter disease.

FLEA-BORNE DISEASE
Murine typhus is a rickettsial disease similar to louse-borne typhus but milder. It is enzootic at low levels at some places in this region in domestic rats and mice and possibly other small mammals. Infected rat fleas, mainly Xenopsylla cheopis, defecate infective rickettsiae while sucking blood, and airborne infections may occur. Fairly rare human cases have been reported throughout Southeast Asia. Enzootic plague is widespread and endemic in rural areas of Laos, Myanmar, and Vietnam. Most recent outbreaks in humans have resulted from hunting or handling infected small mammals or rodents and contacting their associated fleas. An important reservoir of the disease, X. cheopis is fairly common in Southeast Asia, especially associated with ports and urban areas. At least 2 other flea species common in the region are known to be competent plague vectors. A large number of other flea species and small mammals are involved
in the complex cycle of wild rodent plague. lebotomus argentipes. Recent cases have been reported from northwestern Myanmar, near its border with Bangladesh; 2 recent locally acquired (autochthonous) cases have occurred in Thailand. The suspected wild reservoir hosts include canids and related mammals. Transmission of leishmaniasis usually occurs in warmer months of the year, when the vectors are most active. The distribution of sand flies and the diseases they carry is often very focal because of the specialized habitats required by their larvae and the limited flight range of adults.

VERTEBRATE-BORNE DISEASE
Leptospirosis should be considered enzootic in most countries of Southeast Asia. The
spirochete is transmitted when abraded skin or mucous membranes are contacted by water contaminated with urine of infected domestic and wild animals, especially rats. Military personnel would be at high risk of infection from this disease. Troops should never handle rodents and should not sleep or rest near rodent burrows or swim or bathe in stagnant pools or sluggish streams, or go into rice paddies unnecessarily.

Hantaviral diseases are an emerging public and military health threat in parts of Asia, but in this region, they are not very well documented, not routinely surveyed for, and apparently of lower incidence and importance than many other diseases (e.g., malaria, dengue). Field rodents are reservoirs for several closely related viruses that can be transmitted to humans exposed to airborne pathogens from dried rodent urine or feces, through direct contact with those materials or on virus-contaminated eating utensils. Serological evidence of hantaviral infection has been detected in humans or wild animals in several countries in this region, including Indonesia, Malaysia, Thailand, and Vietnam. At least one mild form, referred to as hemorrhagic fever with renal syndrome (HFRS), caused by Hantaan virus and closely related viruses, is associated with wild rodents in open fields, rice paddies, or unforested habitats. At least one serotype reported from this region infects Rattus norvegicus and can cause clinical disease in humans.

A few cases of Nipah virus have been reported recently from Malaysia, Indonesia and Singapore, but it is rather uncommon. This virus has been found at low incidence levels in a wide range of wild and domestic animals, from water buffalo to dogs, and is most commonly associated with either bats or swine. Transmission is reported to be mainly by direct contact of a susceptible animal (or human) with an infected animal. The epidemiology of Nipah virus would make it unlikely to have a significant impact on military operations in this region.

Avian Flu virus (influenza A, H5N1) occurs naturally and is widespread in many and very
diverse taxa of birds around the world. Some highly pathogenic strains of this virus emerged in Asia in 2003, and have since caused several epizootic outbreaks in wild and domestic birds, and have infected humans, too. Based on case reports since 2003, once humans develop a suite of serious symptoms due to H5N1, more than half of them die. Transmission is primarily via direct contact with an infected bird, or its excretions or secretions. So far, direct secondary transmission from human to human has not been carefully documented, but a few reports have strongly implied that may have happened. This virus, like many influenza A viruses, seems to change its genetic and behavioral characteristics and rapidly adapts to different hosts. If its transmissibility to and between humans increases, it could lead to a pandemic. Earliest symptoms of human cases usually include respiratory symptoms, fever, headache, myalgia, and coughing. A number of recent H5N1 outbreaks have occurred in Southeast Asia, with human cases and deaths in several countries including: Indonesia in 2006, and 2008; Thailand in 2004; and Vietnam in 2004, 2005, 2006, and 2009. For current information on avian flu and outbreak updates, go to: www.cdc.gov
or www.who.org , and then search by appropriate topic or links.

SNAIL-BORNE DISEASE
Schistsomiasis. Worldwide, there are over 100 million people at risk of infection within
schistosomiasis-endemic areas. There are two species of these parasitic bloodworms
(schistosomes) which frequently causes serious human illness in Southeast Asia. They are the Schistosoma japonicum complex, which still poses a major public health threat in large areas of Indonesia (especially Sulawesi) and the Philippines; and Schistosoma mekongi, which is indigenous to the main Mekong River system. It causes many human cases annually but is life-threatening mainly to heavily infested young children, 5 years old or younger. Cases of S.
japonicum has been reported sporadically from other nearby countries, but quite a few of those may have been imported cases in expatriate travelers. Schistosoma mekongi is highly endemic in Laos, Cambodia, and parts of Thailand and Vietnam. Good habitat for the suitable host (vector) snail species is essential to maintaining the natural cycle of a given schistosome species. The main snails supporting S. japonicum are members of the genus Oncomelania, and those mainly
supporting S. mekongi are certain members of the genera Neotricula and Tricula. Control or reduction of schistosomiasis must include treatment of human hosts and physical elimination, modification, or treatment of their main host snails’ habitat.

CONJUNCTIVITIS
Bacterial and viral conjunctivitis is common in Southeast Asia and has epidemic potential.Enteroviruses have been implicated in some outbreaks. Trachoma is endemic in many coastal plain areas of Southeast Asia and is often spread mechanically by certain species of small flies or eye gnats (e.g., Hippelates spp.). Transmission is normally through contact with secretions of infected persons or contaminated articles. Several species of eye-frequenting moths, primarily in the family Noctuidae, are known from Southeast Asia which feed on the lacrimal secretions of wild or domestic animals as well as humans. Some species may actually actively take up blood from open wounds (maybe even physically helping to re-open recently formed soft scabs). These
may also play a role in the transmission of ocular pathogens besides causing serious irritation.