However, 8% of children and 20% of adults with melioidosis have no risk factors. HIV infection does not appear to predispose to melioidosis, although several other co-infections have been reported. Infant cases have been reported possibly due to mother-to-child transmission, community-acquired infection, or healthcare-associated infection. Those who are well may also be infected with B. pseudomallei. For example, 25% of children started producing antibodies against B. pseudomallei between 6 months to 4 years of staying in endemic areas although they did not experience any melioidosis symptoms; suggesting they were exposed to it over this time. This means that many people without symptoms will test positive in serology tests in endemic areas. In Thailand, the seropositivity rate exceeds 50%, while in Australia the seropositivity rate is only 5%. The disease is clearly associated with increased rainfall, with the number of cases rising following increased precipitation. Severe rainfall increases the concentration of the bacteria in the topsoil, thus increasing thus of transmitting the bacteria through the air. A recent CDC Advisory indicated that the recent detection of the organism in the environment in Mississippi following the occurrence of two indigenous cases of melioidosis, confirms that parts of the southern USA should now be regarded as melioidosis-endemic. History
Pathologist Alfred Whitmore and his assistant Krishnaswami first reported melioidosis among beggars and morphine addicts at autopsy in Rangoon, present-day Myanmar, in a report published in 1912. Whitmore was able to grow the organism in culture and its showed similarity with B. mallei, another bacteria that was known causing glanders in animals.
Congenital cases may have developmental abnormality due to abnormal muscle structure, usually muscle atrophy / hypertrophy or rarely, absence of the muscle and incorrect placement. Specific & common causes include:

Superior oblique Palsy / Congenital fourth nerve palsy
Inferior oblique overaction
Browns syndrome
Duanes retraction syndrome
Double elevator palsy
Fibrosis of rectus muscle in Graves Disease (most commonly inferior rectus is involved)
Surgical trauma to the vertical muscles (e.g. during scleral buckling surgery or cataract surgery causing iatrogenic trauma to the vertical muscles).Sudden onset hypertropia in a middle aged or elderly adult may be due to compression of the trochlear nerve and mass effect from a tumor, requiring urgent brain imaging using MRI to localise any space occupying lesion. It could also be due to infarction of blood vessels supplying the nerve, due to diabetes and atherosclerosis. In other instances it may be due to an abnormality of neuromuscular transmission, i.e., Myasthenia Gravis. Treatment
In general, strabismus can be approached and treated with a variety of procedures. Depending on the individual case, treatment options include:

Correction of refractive errors by glasses
Prism therapy (if tolerated, to manage diplopia)
Vision Therapy
Patching (mainly to manage amblyopia in children and diplopia in adults)
Botulinum toxin injection
Surgical correctionSurgical correction of the hypertropia is desired to achieve binocularity, manage diplopia and/or correct the cosmetic defect. Steps to achieve the same depend on mechanism of the hypertropia and identification of the offending muscles causing the misalignment.