I find your comment very unfair towards God.
You speak about highly complex malaria parasites, but what about humans?
Were they designed to murder, to torture, to lust, to abuse, to oppress, to hate, to steal, etc…?
The answer is no: it is the result of sin, rebellion against God’s law.
God created a perfect world, which sin has corrupted, and which is now groaning in pain because of sin — until the appointed time in which God shall restore the world to its original state of perfection.
In many cases, man is the cause of suffering, because, as you have also alluded, viruses can be and have been engineered by man in laboratories, rivers and ocean are polluted by man, air is made toxic by man, diseases can be and have been caused by man (mad cow disease for instance which appeared because man gave animal proteins to vegetarian animals just to maximise profits) , oppression, abuse, suffering, crimes, wars and socio-economic injustices are perpetrated and perpetuated by man, nuclear bombs and weapons of mass destructions were invented by man, deadly chemicals such as gliphosate (roundup) or agent orange contaminating soil and crops for decades were created by man, and the list goes on and on.
But Satan is also actively engaged in a work of destruction (like he did against Job), either directly or indirectly through human agents.
“God could have destroyed Satan and his sympathizers as easily as one can cast a pebble to the earth; but He did not do this. Rebellion was not to be overcome by force. Compelling power is found only under Satan’s government. The Lord’s principles are not of this order. His authority rests upon goodness, mercy, and love; and the presentation of these principles is the means to be used. God’s government is moral, and truth and love are to be the prevailing power.
It was God’s purpose to place things on an eternal basis of security, and in the councils of heaven it was decided that time must be given for Satan to develop the principles which were the foundation of his system of government. He had claimed that these were superior to God’s principles. Time was given for the working of Satan’s principles, that they might be seen by the heavenly universe.
Satan led men into sin, and the plan of redemption was put in operation. For four thousand years, Christ was working for man’s uplifting, and Satan for his ruin and degradation. And the heavenly universe beheld it all.” (DA 759.1-3)
The following description of the new earth to come gives us an idea of what creation looked like before sin:
“The wolf also shall dwell with the lamb, the leopard shall lie down with the young goat, the calf and the young lion and the fatling together; and a little child shall lead them.
The cow and the bear shall graze; their young ones shall lie down together; and the lion shall eat straw like the ox.
The nursing child shall play by the cobra’s hole, and the weaned child shall put his hand in the viper’s den.
They shall not hurt nor destroy in all My holy mountain, for the earth shall be full of the knowledge of the Lord, as the waters cover the sea.” (Isaiah 11:6-9)
"The earth shall be full of the knowledge of the Lord, as the waters cover the sea.”
In its current state the world corrupted by sin is not full of the knowledge of the Lord, so there is violence, suffering, disease, and death.
Mosquitoes who were designed to suck only fruit nectar (the male mosquito still does) now suck blood and spread diseases.
However, natural remedies (Artemisia in the case of malaria) and healthy diet and lifestyle, are effective ways to combat many diseases.
Things could have been much worse, and many authors have given a glimpse of what the world could look like if Satan had free reins (SAW, The purge, I am a legend, Handmaid’s tale and many more that I would not recommended to read or watch), if God did not hold the winds (Revelation 7:1).
We are approaching the end of 6000 years of mercy before the judgement and the 1000 years of rest, and the sign of Jesus’ second coming are multiplying, "and God shall wipe away all tears from their eyes; and there shall be no more death, neither sorrow, nor crying, neither shall there be any more pain: for the former things are passed away.’” (Revelation 21:4)